Glaukos (GKOS) 10-Q 6 Nov 19 2019 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Nov. 05, 2019
Document and Entity Information
Entity Registrant Name	GLAUKOS Corp
Entity Central Index Key	0001192448
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Sep. 30, 2019
Entity File Number	001-37463
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	33-0945406
Entity Address, Address Line One	229 Avenida Fabricante
Entity Address, City or Town	San Clemente
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92672
City Area Code	949
Local Phone Number	367-9600
Title of 12(b) Security	Common Stock
Trading Symbol	GKOS
Security Exchange Name	NYSE
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		36,927,816
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 39,534	$ 29,821
Short-term investments	113,385	110,667
Accounts receivable, net	24,345	18,673
Inventory, net	12,801	13,282
Prepaid expenses and other current assets	19,223	4,124
Total current assets	209,288	176,567
Restricted cash	8,881	8,775
Property and equipment, net	20,038	19,153
Operating lease right-of-use asset	12,146
Finance lease right-of-use asset	53,343
Income tax receivable	213	213
Deposits and other assets	3,527	2,262
Total assets	307,436	206,970
Current liabilities:
Accounts payable	3,501	6,286
Accrued liabilities	29,602	23,964
Deferred rent		115
Total current liabilities	33,103	30,365
Operating lease liability	11,406
Finance lease liability	68,851
Other liabilities	3,960	2,745
Total liabilities	117,320	33,110
Commitments and contingencies (Note 10)
Stockholders' equity:
Preferred stock, $0.001 par value; 5,000 shares authorized; no shares issued and outstanding
Common stock, $0.001 par value; 150,000 shares authorized; 36,945 and 36,135 shares issued and 36,917 and 36,107 shares outstanding as of September 30, 2019 and December 31, 2018, respectively	37	36
Additional paid-in capital	414,665	378,352
Accumulated other comprehensive income	1,837	738
Accumulated deficit	(226,291)	(205,134)
Less treasury stock (28 shares as of September 30, 2019 and December 31, 2018)	(132)	(132)
Total stockholders' equity	190,116	173,860
Total liabilities and stockholders' equity	$ 307,436	$ 206,970

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (PARENTHETICAL) - $ / shares	Sep. 30, 2019	Dec. 31, 2018
CONDENSED CONSOLIDATED BALANCE SHEETS
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	36,945,000	36,135,000
Common stock, shares outstanding	36,917,000	36,107,000
Treasury stock, shares	28,000	28,000

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS
Net sales	$ 58,509,000	$ 43,908,000	$ 171,135,000	$ 127,202,000
Cost of sales	7,703,000	6,011,000	22,684,000	17,957,000
Gross profit	50,806,000	37,897,000	148,451,000	109,245,000
Operating expenses:
Selling, general and administrative	44,443,000	31,632,000	117,024,000	87,425,000
Research and development	17,278,000	13,202,000	48,277,000	36,719,000
In-process research and development (Note 1)	1,500,000		3,745,000
Total operating expenses	63,221,000	44,834,000	169,046,000	124,144,000
Loss from operations	(12,415,000)	(6,937,000)	(20,595,000)	(14,899,000)
Non-operating income (expense):
Interest income	780,000	583,000	2,368,000	1,568,000
Interest expense	(1,028,000)		(2,041,000)
Other expense, net	(656,000)	(230,000)	(508,000)	(1,346,000)
Total non-operating (expense) income	(904,000)	353,000	(181,000)	222,000
Loss before taxes	(13,319,000)	(6,584,000)	(20,776,000)	(14,677,000)
Provision for income taxes	187,000	37,000	381,000	53,000
Net loss	$ (13,506,000)	$ (6,621,000)	$ (21,157,000)	$ (14,730,000)
Basic and diluted net loss per share (in dollar per share)	$ (0.37)	$ (0.19)	$ (0.58)	$ (0.42)
Weighted-average shares used to compute basic and diluted net loss per share	36,831	35,541	36,507	35,075

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS
Net loss	$ (13,506)	$ (6,621)	$ (21,157)	$ (14,730)
Other comprehensive income:
Foreign currency translation gain	530	322	364	1,369
Unrealized gain (loss) on short-term investments, net of tax	74	74	735	(71)
Other comprehensive income	604	396	1,099	1,298
Total comprehensive loss	$ (12,902)	$ (6,225)	$ (20,058)	$ (13,432)

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Common Stock	Additional Paid-in-Capital	Accumulated Other Comprehensive Income	Accumulated Deficit	Treasury Stock	Total
Balance at Dec. 31, 2017	$ 35	$ 331,073	$ (591)	$ (192,183)	$ (132)	$ 138,202
Balance (in shares) at Dec. 31, 2017	34,647				(28)
Stockholders' Deficit
Common stock issued under stock plans		2,839				2,839
Common stock issued under stock plans (in shares)	208
Stock-based compensation		5,402				5,402
Other comprehensive income			(704)			(704)
Net loss				(2,711)		(2,711)
Balance at Mar. 31, 2018	$ 35	339,314	(1,295)	(194,894)	$ (132)	143,028
Balance (in shares) at Mar. 31, 2018	34,855				(28)
Balance at Dec. 31, 2017	$ 35	331,073	(591)	(192,183)	$ (132)	138,202
Balance (in shares) at Dec. 31, 2017	34,647				(28)
Stockholders' Deficit
Other comprehensive income						1,298
Net loss						(14,730)
Balance at Sep. 30, 2018	$ 36	369,709	707	(206,913)	$ (132)	163,407
Balance (in shares) at Sep. 30, 2018	35,995				(28)
Balance at Mar. 31, 2018	$ 35	339,314	(1,295)	(194,894)	$ (132)	143,028
Balance (in shares) at Mar. 31, 2018	34,855				(28)
Stockholders' Deficit
Common stock issued under stock plans		2,836				2,836
Common stock issued under stock plans (in shares)	311
Stock-based compensation		6,461				6,461
Other comprehensive income			1,606			1,606
Net loss				(5,398)		(5,398)
Balance at Jun. 30, 2018	$ 35	348,611	311	(200,292)	$ (132)	148,533
Balance (in shares) at Jun. 30, 2018	35,166				(28)
Stockholders' Deficit
Common stock issued under stock plans	$ 1	13,925				13,926
Common stock issued under stock plans (in shares)	829
Stock-based compensation		7,173				7,173
Other comprehensive income			396			396
Net loss				(6,621)		(6,621)
Balance at Sep. 30, 2018	$ 36	369,709	707	(206,913)	$ (132)	163,407
Balance (in shares) at Sep. 30, 2018	35,995				(28)
Balance at Dec. 31, 2018	$ 36	378,352	738	(205,134)	$ (132)	$ 173,860
Balance (in shares) at Dec. 31, 2018	36,135				(28)	36,107
Stockholders' Deficit
Common stock issued under stock plans		5,406				$ 5,406
Common stock issued under stock plans (in shares)	226
Stock-based compensation		7,129				7,129
Other comprehensive income			436			436
Net loss				(1,342)		(1,342)
Balance at Mar. 31, 2019	$ 36	390,887	1,174	(206,476)	$ (132)	185,489
Balance (in shares) at Mar. 31, 2019	36,361				(28)
Balance at Dec. 31, 2018	$ 36	378,352	738	(205,134)	$ (132)	$ 173,860
Balance (in shares) at Dec. 31, 2018	36,135				(28)	36,107
Stockholders' Deficit
Other comprehensive income						$ 1,099
Net loss						(21,157)
Balance at Sep. 30, 2019	$ 37	414,665	1,837	(226,291)	$ (132)	$ 190,116
Balance (in shares) at Sep. 30, 2019	36,945				(28)	36,917
Balance at Mar. 31, 2019	$ 36	390,887	1,174	(206,476)	$ (132)	$ 185,489
Balance (in shares) at Mar. 31, 2019	36,361				(28)
Stockholders' Deficit
Common stock issued under stock plans	$ 1	318				319
Common stock issued under stock plans (in shares)	305
Stock-based compensation		8,247				8,247
Other comprehensive income			59			59
Net loss				(6,309)		(6,309)
Balance at Jun. 30, 2019	$ 37	399,452	1,233	(212,785)	$ (132)	187,805
Balance (in shares) at Jun. 30, 2019	36,666				(28)
Stockholders' Deficit
Common stock issued under stock plans		6,666				6,666
Common stock issued under stock plans (in shares)	279
Stock-based compensation		8,547				8,547
Other comprehensive income			604			604
Net loss				(13,506)		(13,506)
Balance at Sep. 30, 2019	$ 37	$ 414,665	$ 1,837	$ (226,291)	$ (132)	$ 190,116
Balance (in shares) at Sep. 30, 2019	36,945				(28)	36,917

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating Activities
Net loss	$ (21,157)	$ (14,730)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	2,674	5,063
Amortization of lease right-of-use assets	2,405
Loss on disposal of fixed assets	26	83
Stock-based compensation	23,923	19,036
Unrealized foreign currency losses	469	1,541
Amortization of discount on short-term investments	(298)	(205)
Deferred rent and other liabilities	3,666	1,491
Changes in operating assets and liabilities:
Accounts receivable, net	(5,828)	(3,209)
Inventory, net	414	(2,511)
Prepaid expenses and other current assets	(2,326)	(1,695)
Accounts payable and accrued liabilities	(60)	(2,000)
Other assets	(86)	(1,128)
Net cash provided by operating activities	3,822	1,736
Investing activities
Purchases of short-term investments	(64,726)	(70,100)
Proceeds from sales and maturities of short-term investments	61,870	64,185
Purchases of property and equipment	(3,530)	(2,733)
Net cash used in investing activities	(6,386)	(8,648)
Financing activities
Proceeds from exercise of stock options	14,005	16,418
Proceeds from share purchases under Employee Stock Purchase Plan	3,388	3,509
Payments of employee taxs related to vested restricted stock units	(5,002)	(325)
Net cash provided by financing activities	12,391	19,602
Effect of exchange rate changes on cash and cash equivalents	(8)	80
Net increase in cash, cash equivalents and restricted cash	9,819	12,770
Cash, cash equivalents and restricted cash at beginning of period	38,596	24,508
Cash, cash equivalents and restricted cash at end of period	48,415	37,278
Supplemental disclosures of cash flow information
Taxes paid	$ 96	$ 13

Organization and Basis of Prese

Organization and Basis of Presentation	9 Months Ended
	Sep. 30, 2019
Organization and Basis of Presentation
Organization and Basis of Presentation	Note 1. Organization and Basis of Presentation Organization and business Glaukos Corporation (Glaukos or the Company), incorporated in Delaware on July 14, 1998, is an ophthalmic medical technology and pharmaceutical company focused on the development and commercialization of novel therapies designed to treat glaucoma, corneal disorders and retinal diseases. The Company initially developed Micro-Invasive Glaucoma Surgery (MIGS) to address the shortcomings of traditional glaucoma treatment options. MIGS procedures involve the insertion of a micro-scale device or drug delivery system from within the eye’s anterior chamber through a small corneal incision. The Company’s MIGS devices are designed to reduce intraocular pressure (IOP) by restoring the natural outflow pathways for aqueous humor. The Company’s MIGS drug delivery systems are designed to reduce IOP by continuously eluting a glaucoma drug from within the eye, potentially providing sustained pharmaceutical therapy for extended periods of time. Glaukos intends to leverage its capabilities to build a portfolio of micro-scale surgical and pharmaceutical therapies in corneal health and retinal disease as well. The accompanying condensed consolidated financial statements include the accounts of Glaukos and its wholly-owned subsidiaries. All significant intercompany balances and transactions among the consolidated entities have been eliminated in consolidation. Basis of presentation The accompanying condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP) for interim financial information and pursuant to the instructions to Form 10-Q and Article 10 of Regulation S-X. The unaudited interim financial statements have been prepared on a basis consistent with the audited financial statements. As permitted under those rules, certain footnotes and other financial information that are normally required by GAAP have been condensed or omitted. In the opinion of management, the unaudited interim financial statements reflect all adjustments, which include normal recurring adjustments, necessary for the fair presentation of the Company’s financial information contained herein. The condensed consolidated balance sheet as of December 31, 2018 has been derived from audited financial statements at that date, but excludes disclosures required by GAAP for complete financial statements. These interim financial statements do not include all disclosures required by GAAP and should be read in conjunction with the Company’s financial statements and accompanying notes for the fiscal year ended December 31, 2018, which are contained in the Company’s Annual Report on Form 10-K filed with the United States Securities and Exchange Commission (SEC) on February 28, 2019. The results for the period ended September 30, 2019 are not necessarily indicative of the results to be expected for the year ending December 31, 2019 or for any other interim period. Proposed Acquisition of Avedro, Inc. On August 7, 2019, the Company entered into an Agreement and Plan of Merger by and among Glaukos, Atlantic Merger Sub, Inc. (Merger Sub) and Avedro, Inc. (Avedro), pursuant to which Merger Sub will merge with and into Avedro, with Avedro continuing as the surviving corporation and a wholly owned subsidiary of the Company (the Merger). The Merger is subject to certain closing conditions, including but not limited to, the adoption of the Agreement and Plan of Merger by holders of a majority of the outstanding common stock of Avedro entitled to vote which is expected to occur on November 19, 2019. The closing of the Merger was also subject to the expiration or termination of any applicable waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended (the HSR Act); however, early termination under the HSR Act was granted on August 28, 2019. If all remaining conditions are satisfied, upon the closing of the Merger, all issued and outstanding shares of Avedro common stock will be automatically cancelled and converted into the right to receive a number of shares of Glaukos common stock equal to the product of the number of shares of Avedro common stock multiplied by existing Glaukos stockholders are expected to own approximately 85% of the combined company, with the former Avedro stockholders expected to own the remaining 15%, on a fully diluted basis. Avedro provides several corneal strengthening solutions, including Photrexa, a bio-activated pharmaceutical therapy for the corneal cross-linking treatment of keratoconus. Through 2018, over The Merger is intended to expand the Company’s portfolio of pipeline products beyond the treatment of glaucoma to include pharmaceutical therapies for the treatment of corneal disorders as part of the Company’s strategic objective to build a portfolio of micro-scale surgical and pharmaceutical therapies in corneal health and retinal disease. Licensing Arrangement with Intratus, Inc. On July 22, 2019, the Company entered into a global licensing agreement with Intratus, Inc. (Intratus) for $1.5 million in cash, plus future performance-based consideration upon achievement of certain development, regulatory approvals and commercial milestones and royalties on commercial sales, pursuant to which the Company obtained an exclusive, royalty-bearing license to research, develop, manufacture and commercialize Intratus’ patented, non-invasive drug delivery platform designed for use in the treatment of dry eye disease, glaucoma and other corneal disorders such as blepharitis, conjunctivitis and related conditions. ​ Acquisition of DOSE Medical On June 19, 2019, the Company entered into a definitive agreement and plan of merger to acquire DOSE Medical Corporation (DOSE) for $2.5 million in cash, plus potential future performance-based consideration upon achievement of certain regulatory approvals and commercial milestones and royalties on commercial sales (the DOSE Merger). If certain DOSE products receive United States Food and Drug Administration (FDA) approval within ten years following the closing of the DOSE Merger, the Company will pay the DOSE shareholders amounts between $5.0 million and $22.5 million, depending on the type of DOSE product approved. The Company will pay additional performance-based payments to DOSE shareholders if within ten years of closing of the DOSE Merger, such DOSE products receive approval from the EU European Medicines Agency, in which case the Company will pay the DOSE shareholders either $1.25 million and/or $2.5 million, depending on the type of DOSE product approved. Following FDA approval of such DOSE products, the Company will pay the DOSE shareholders quarterly royalty payments equal to 5% of net sales of such DOSE products for a period of ten years . The Company will also pay the DOSE shareholders additional performance-based payments of $7.5 million and $20.0 million upon the achievement of certain net sales milestones with respect to such DOSE products. Finally, under the terms of the DOSE Merger, the Company may elect to buyout the additional milestone and royalty payments described above by paying former DOSE shareholders between $10.0 and $55.0 million, depending on the type of DOSE product involved. On June 27, 2019, the Company completed its acquisition of DOSE and DOSE became a wholly-owned subsidiary of the Company. The transaction was accounted for as an asset acquisition. Of the $2.5 million initial cash payment, $2.2 million was immediately charged to IPR&D expense as management determined there was no alternative future use related to the single group of identifiable assets purchased. The remaining $0.3 million of upfront consideration was capitalized as property & equipment, net and is being depreciated over the corresponding asset’s useful life. Management will account for the payment of the future performance-based consideration if and when earned. DOSE was previously a wholly-owned subsidiary of the Company. In 2010, it was spun-out as a standalone entity and was accounted for as a consolidated variable interest entity. In 2015, the Company acquired the iDose product line and related assets from DOSE and upon the acquisition, the Company derecognized DOSE as a consolidated variable interest entity in the financial statements, and in 2017 the Company acquired DOSE’s IOP sensor system. Thomas W. Burns, the Company’s President, Chief Executive and a member of its board of directors, and William J. Link, Ph.D., Chairman of the Company’s board of directors, served on the board of directors of DOSE and certain members of the Company’s management and board of directors held an equity interest in DOSE prior to being acquired by the Company.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2019
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	Note 2. Summary of Significant Accounting Policies There have been no significant changes in the Company’s significant accounting policies during the nine months ended September 30, 2019, as compared with those disclosed in its Annual Report on Form 10-K for the year ended December 31, 2018 filed with the SEC on February 28, 2019, with the exception of the Company’s adoption of Accounting Standards Update (ASU) No. 2016-02, Leases (Topic 842) Leases Use of estimates The preparation of the condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts in the condensed consolidated financial statements and accompanying notes. Actual results could differ materially from those estimates and assumptions. Management considers many factors in selecting appropriate financial accounting policies and controls and in developing the estimates and assumptions that are used in the preparation of these condensed consolidated financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of reasonable estimates of the ultimate future outcomes, and management must select an amount that falls within that range of reasonable estimates. The most significant estimates in the accompanying condensed consolidated financial statements relate to revenue recognition, the incremental borrowing rate related to the Company’s leased assets and stock-based compensation expense. Although these estimates are based on the Company’s knowledge of current events and actions it may undertake in the future, this process may result in actual results differing materially from those estimated amounts used in the preparation of the condensed consolidated financial statements. Foreign currency translation The accompanying condensed consolidated financial statements are presented in United States (U.S.) dollars. The Company considers the local currency to be the functional currency for its international subsidiaries. Accordingly, their assets and liabilities are translated into U.S. dollars using the exchange rate in effect on the balance sheet date. Revenues and expenses are translated at average exchange rates prevailing throughout the periods presented. As a result, currency translation adjustments arising from period to period are charged or credited to accumulated other comprehensive income in stockholders’ equity. For the three and nine months ended September 30, 2019, the Company reported foreign currency translation gains of approximately $0.5 million and $0.4 million, respectively. For the three and nine months ended September 30, 2018, the Company reported foreign currency translation gains of approximately $0.3 million and $1.4 million, respectively. Unrealized gains and losses that arise from exchange rate fluctuations on transactions denominated in a currency other than the functional currency, primarily gains and losses on intercompany loans, are included in the condensed consolidated statements of operations as a component of other expense, net. For the three and nine months ended September 30, 2019 the Company reported net unrealized foreign currency transaction losses of $0.6 million and $0.5 million, respectively. For the three and nine months ended September 30, 2018, the Company reported net unrealized foreign currency transaction losses of $0.4 million and $1.5 million, respectively. Cash, cash equivalents and short-term investments The Company invests its excess cash in marketable securities, including money market funds, money market securities, bank certificates of deposits, corporate bonds, corporate commercial paper, U.S. government bonds and U.S. government agency bonds. For financial reporting purposes, liquid investment instruments purchased with an original maturity of three months or less are considered to be cash equivalents. Cash and cash equivalents are recorded at face value or cost, which approximates fair market value. The Company maintains cash balances in excess of amounts insured by the Federal Deposit Insurance Commission. Investments are stated at fair value as determined by quoted market prices. Investments are considered available-for-sale and, accordingly, unrealized gains and losses are included in accumulated other comprehensive income within stockholders’ equity. The Company’s entire investment portfolio, except for restricted cash, is considered to be available for use in current operations and, accordingly, all such investments are stated at fair value using quoted market prices and classified as current assets, although the stated maturity of individual investments may be one year or more beyond the balance sheet date. The Company did not have any trading securities or restricted investments at September 30, 2019 or December 31, 2018. Realized gains and losses and declines in value, if any, judged to be other-than-temporary on available-for-sale securities are reported in other expense, net. When securities are sold, any associated unrealized gain or loss previously reported as a separate component of stockholders’ equity is reclassified out of stockholders’ equity and recorded in the statements of operations in the period sold using the specific identification method. Accrued interest and dividends from investments are included in other expense, net. The Company periodically reviews its available-for-sale securities for other-than-temporary declines in fair value below the cost basis, and whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Restricted cash The Company had a bank issue a letter of credit in the amount of $8.8 million related to its Aliso Viejo, California office building lease, which commenced on April 1, 2019. The letter of credit is secured with an amount of cash held in a restricted account of $8.9 million and $8.8 million as of September 30, 2019 and December 31, 2018, respectively. Beginning on the first day of the thirty-seventh month of the lease term, and on each twelve month anniversary thereafter, the letter of credit will be reduced by 20% until the letter of credit amount has been reduced to $2.0 million. See Note 10, Commitments and Contingencies The following table provides a reconciliation of cash and cash equivalents and restricted cash reported within the condensed consolidated balance sheets that equate to the amount reported in the condensed consolidated statement of cash flows as of the beginning and end of the nine month period ended September 30, 2019 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ ​ 2019 ​ 2018 Cash and cash equivalents ​ $ 39,534 ​ $ 29,821 ​ Restricted cash ​ ​ 8,881 ​ ​ 8,775 ​ Cash, cash equivalents and restricted cash in the condensed consolidated statements of cash flows ​ $ 48,415 ​ $ 38,596 ​ ​ Fair value of financial instruments The carrying amounts of cash equivalents, accounts receivable, accounts payable, and accrued liabilities are considered to be representative of their respective fair values because of the short-term nature of those instruments. The valuation of assets and liabilities is subject to fair value measurements using a three-tiered approach and fair value measurements are classified and disclosed by the Company in one of the following three categories: Level 1: Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities; Level 2: Quoted prices for similar assets and liabilities in active markets, quoted prices in markets that are not active, or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liability; and Level 3: Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (i.e., supported by little or no market activity). Leases In February 2016, the Financial Accounting Standards Board (FASB) issued ASU No. 2016-02, Leases (Topic 842) Consistent with historical guidance, a lessee’s recognition, measurement, and presentation of expenses and cash flows arising from a lease will continue to depend primarily on its classification. ASC 842 was effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. The Company adopted the requirements of ASC 842 effective January 1, 2019 and elected the modified retrospective method for all lease arrangements at the beginning of the period of adoption. Results for reporting periods beginning on or after January 1, 2019 are presented under ASC 842, while prior period amounts were not adjusted and continue to be reported in accordance with the Company’s historic accounting under ASC 840, Leases. ​ For leases that commenced before the effective date of ASC 842, the Company elected the transition package of three practical expedients permitted within ASC 842, which eliminates the requirements to reassess prior conclusions about lease identification, lease classification, and initial direct costs. ​ The Company did not elect the hindsight practical expedient, which permits the use of hindsight when determining lease term and impairment of right-of-use assets. Further, the Company elected a short-term lease exception policy, permitting the Company to not apply the recognition requirements of this standard to short-term leases (i.e., leases with terms of 12 months or less) and an accounting policy to account for lease and non-lease components as a single component for certain classes of assets. As a result of adopting ASC 842 as of January 1, 2019, the Company recorded an operating lease right-of-use asset of $12.8 million and related operating lease liability of $13.4 million, respectively, primarily related to facilities and certain equipment, based on the present value of the future lease payments on the date of adoption . Leases ​ The Company determines if an arrangement is a lease at inception. As a lessee, right-of-use assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent an obligation to make lease payments arising from the lease. Right-of-use assets and lease liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. As the Company does not have any outstanding debt or committed credit facilities, the Company estimates the incremental borrowing rate based on prevailing financial market conditions, peer company credit analyses, and management judgment. Operating lease right-of-use assets also include any lease payments made at or before lease commencement and exclude any lease incentives received. The lease terms used to calculate the right-of-use asset and related lease liability include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense for operating leases is recognized on a straight-line basis over the lease term as an operating expense while the expense for finance leases is recognized as depreciation expense and interest expense using the accelerated interest method of recognition. ​ As of April 1, 2019, the Company recorded a finance lease right-of-use asset of $54.5 million and related finance lease liability of $67.2 million with respect to the commencement of its lease in Aliso Viejo, California based on the present value of the future lease payments on the date of commencement. As of September 30, 2019, the finance lease right-of-use asset excludes lease incentives totaling $12.7 million included in prepaid expenses and other current assets on the condensed consolidated balance sheets. ​ Revenue recognition The Company accounts for revenue in accordance with ASC 606, Revenue Recognition – Revenue from Contracts with Customers and its related amendments ​ The Company derives its revenue from sales of its products in the United States and internationally. Customers are primarily comprised of ambulatory surgery centers and hospitals, with distributors being used in certain international locations where the Company does not have a direct commercial presence. ​ The Company concluded that one performance obligation exists for the majority of its contracts with customers which is to deliver products in accordance with the Company’s normal delivery times. Revenue is recognized when this performance obligation is satisfied, which is the point in time when the Company considers control of a product to have transferred to the customer. Revenue recognized reflects the consideration to which the Company expects to be entitled in exchange for those products or services. The Company has determined the transaction price to be the invoice price, net of adjustments, which includes estimates of variable consideration for product returns. ​ The Company offers volume-based rebate agreements to certain customers and, in these instances, the Company provides a rebate (in the form of a credit memo) at the contract’s conclusion, if earned by the customer. In such cases, the transaction price is allocated between the Company’s delivery of product and the issuance of a rebate at the contract’s conclusion for the customer to utilize on prospective purchases. The performance obligation to issue a customer’s rebate, if earned, is transferred over time and the Company’s method of measuring progress is the output method, whereby the progress is measured by the estimated rebate earned to date over the total rebate estimated to be earned over the contract period. The provision for volume-based rebates is estimated based on customers' contracted rebate programs and the customers’ projected sales levels. The Company periodically monitors its customer rebate programs to ensure the rebate allowance is fairly stated. The Company’s rebate allowance is included in accrued liabilities in the condensed consolidated balance sheets and estimated rebates accrued were not material during the periods presented. ​ Customers are not granted specific rights of return; however, the Company may permit returns of product from customers if such product is returned in a timely manner and in good condition. The Company provides a warranty on its products for one year from the date of shipment, and any product found to be defective or out of specification will be replaced at no charge during the warranty period. Estimated allowances for sales returns and warranty replacements are recorded at the time of sale of the product and are estimated based upon the historical patterns of product returns matched against sales, and an evaluation of specific factors that may increase the risk of product returns. Product returns and warranty replacements to date have been consistent with amounts reserved or accrued and have not been significant. ​ Research and development expenses Major components of research and development expense include personnel costs, preclinical studies, clinical trials and related clinical product manufacturing, materials and supplies, and fees paid to consultants. Research and development costs are expensed as goods are received or services are rendered. Costs to acquire technologies to be used in research and development that have not reached technological feasibility and have no alternative future use are also expensed as incurred as IPR&D. At each financial reporting date, the Company accrues the estimated unpaid costs of clinical study activities performed during a period by third party clinical sites with whom the Company has agreements that provide for fees based upon the quantities of subjects enrolled and clinical evaluation visits that occur over the life of the study. The cost estimates are determined based upon a review of the agreements and data collected by internal and external clinical personnel as to the status of enrollment and subject visits, and are based upon the facts and circumstances known to the Company at each financial reporting date. If the actual performance of activities varies from the assumptions used in the cost estimates, the accruals are adjusted accordingly. There have been no material adjustments to the Company’s prior period accrued estimates for clinical trial activities during the three and nine months ended September 30, 2019. Stock-based compensation The Company recognizes compensation expense for all stock-based awards granted to employees and nonemployees, including members of its board of directors. The fair value of stock option awards is estimated at the grant date using the Black-Scholes option pricing model, and the portion that is ultimately expected to vest is recognized as compensation cost over the requisite service period using the straight-line method. The determination of the fair value-based measurement of stock options on the date of grant using an option pricing model is affected by the determination of the fair value of the underlying stock as well as assumptions regarding a number of highly complex and subjective variables. These variables include, but are not limited to, the Company’s stock price volatility over the expected term of the grants, and actual and projected stock option exercise behaviors. In the future, as additional empirical evidence regarding these estimates becomes available, the Company may change or refine its approach of deriving them, and these changes could impact the fair value-based measurement of stock options granted in the future. Changes in the fair value-based measurement of stock awards could materially impact the Company’s operating results. The fair value of restricted stock unit (RSU) awards is equal to the closing market price of the Company’s common stock on the grant date. Software costs The Company currently expenses software service costs along with any associated implementation costs as services are provided and implementation costs are incurred. Comprehensive loss All components of comprehensive loss, including net loss, are reported in the condensed consolidated financial statements in the period in which they are recognized. Comprehensive loss is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources, including unrealized gains and losses on marketable securities and foreign currency translation adjustments. Net loss per share Basic net loss per share is calculated by dividing the net loss by the weighted average number of common shares that were outstanding for the period, without consideration for common stock equivalents. For periods when the Company realizes a net loss, no common stock equivalents are included in the calculation of weighted average number of dilutive common stock equivalents as the effect of applying the treasury stock method is considered anti-dilutive. For periods when the Company realizes net income, diluted net income per share is calculated by dividing the net income by the weighted average number of common shares plus the sum of the weighted average number of dilutive common stock equivalents outstanding for the period determined using the treasury stock method. Common stock equivalents are comprised of stock options outstanding and unvested RSUs under the Company’s incentive compensation plans, and shares issuable under the Company’s Employee Stock Purchase Plan (ESPP). Potentially dilutive securities not included in the calculation of diluted net loss per share because to do so would be anti-dilutive were as follows (in common stock equivalent shares, in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ ​ September 30, ​ September 30, ​ 2019 2018 2019 2018 ​ Stock options outstanding ​ 3,602 ​ 4,781 ​ 3,636 ​ 5,707 ​ Unvested restricted stock units ​ 232 ​ 196 ​ 364 ​ 355 ​ Employee stock purchase plan ​ 1 ​ 15 ​ 5 ​ 42 ​ ​ ​ 3,835 ​ 4,992 ​ 4,005 ​ 6,104 ​ ​ Recently adopted accounting pronouncements In February 2018, the FASB issued ASU No. 2018-02, Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income In June 2018, the FASB issued ASU No. 2018-07, Improvements to Nonemployee Share-Based Payment Accounting 2018, including interim periods within those fiscal years. The Company adopted the guidance effective January 1, 2019 and the guidance did not have a material impact to the Company’s condensed consolidated financial statements. In August 2018, the SEC adopted the final rule under SEC Release No. 33-10532, Disclosure Update and Simplification See above under “ Leases Recently issued accounting pronouncements not yet adopted In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments Codification Improvements to Topic 326, Financial Instruments—Credit Losses ​ In January 2017, the FASB issued ASU No. 2017-04, Intangibles – Goodwill and Other (Topic 250): Simplifying the Test for Goodwill Impairment ​ In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820) ​ In August 2018, the FASB issued ASU No. 2018-14, Disclosure Framework—Changes to the Disclosure Requirements for Defined Benefit Plans ​ In August 2018, the FASB issued ASU No. 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract In November 2018, the FASB issued ASU No. 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction Between Topic 808 and Topic 606

Balance Sheet Details

Balance Sheet Details	9 Months Ended
	Sep. 30, 2019
Balance Sheet Details
Balance Sheet Details	Note 3. Balance Sheet Details Short-term investments Short-term investments consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ At September 30, 2019 ​ ​ Maturity ​ Amortized cost ​ Unrealized ​ Unrealized ​ Estimated ​ (in years) or cost gains losses fair value U.S. government agency bonds ​ less than 1 ​ ​ 500 ​ ​ — ​ ​ — ​ ​ 500 ​ Bank certificates of deposit ​ less than 1 ​ ​ 10,500 ​ ​ 12 ​ ​ — ​ ​ 10,512 ​ Commercial paper ​ less than 1 ​ 9,442 ​ 12 ​ — ​ 9,454 ​ Corporate notes ​ less than 3 ​ 66,697 ​ 331 ​ (2) ​ 67,026 ​ Asset-backed securities ​ less than 3 ​ 25,777 ​ 124 ​ (8) ​ 25,893 ​ Total ​ ​ ​ $ 112,916 ​ $ 479 ​ $ (10) ​ $ 113,385 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ At December 31, 2018 ​ ​ Maturity ​ Amortized cost ​ Unrealized ​ Unrealized ​ Estimated ​ (in years) or cost gains losses fair value U.S. government bonds ​ less than 1 ​ $ 1,300 ​ $ - ​ $ (3) ​ $ 1,297 ​ U.S. government agency bonds ​ less than 1 ​ ​ 1,994 ​ ​ - ​ ​ (12) ​ ​ 1,982 ​ Bank certificates of deposit ​ less than 2 ​ ​ 15,201 ​ ​ 2 ​ ​ (3) ​ ​ 15,200 ​ Commercial paper ​ less than 1 ​ 9,597 ​ 1 ​ (5) ​ 9,593 ​ Corporate notes ​ less than 3 ​ 60,923 ​ 24 ​ (194) ​ 60,753 ​ Asset-backed securities ​ less than 3 ​ 21,918 ​ 18 ​ (94) ​ 21,842 ​ Total ​ ​ ​ $ 110,933 ​ $ 45 ​ $ (311) ​ $ 110,667 ​ ​ Accounts receivable, net Accounts receivable consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2019 2018 Accounts receivable ​ $ 25,085 ​ $ 19,333 ​ Allowance for doubtful accounts ​ ​ (740) ​ ​ (660) ​ ​ ​ $ 24,345 ​ $ 18,673 ​ ​ Inventory, net Inventory consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2019 2018 Finished goods ​ $ 4,260 ​ $ 4,256 ​ Work in process ​ ​ 4,404 ​ ​ 3,197 ​ Raw material ​ ​ 4,137 ​ ​ 5,829 ​ ​ ​ $ 12,801 ​ $ 13,282 ​ ​ Accrued liabilities Accrued liabilities consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2019 2018 Accrued bonuses ​ $ 6,714 ​ $ 8,604 Accrued vacation benefits ​ ​ 2,696 ​ ​ 2,446 Accrued legal expenses ​ ​ 4,604 ​ ​ 2,466 Other accrued liabilities ​ ​ 15,588 ​ ​ 10,448 ​ ​ $ 29,602 ​ $ 23,964 ​

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2019
Fair Value Measurements
Fair Value Measurements	Note 4. Fair Value Measurements Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. The following tables present information about the Company's financial assets measured at fair value on a recurring basis as of September 30, 2019 and December 31, 2018 and indicate the fair value hierarchy of the valuation techniques utilized by the Company to determine such fair value (in thousands). The Company did not have any financial liabilities measured at fair value on a recurring basis as of September 30, 2019 and December 31, 2018. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ At September 30, 2019 ​ ​ ​ ​ ​ Quoted prices ​ Significant ​ ​ ​ ​ ​ ​ ​ in active ​ other ​ Significant ​ ​ ​ ​ ​ markets for ​ observable ​ unobservable ​ ​ September 30, ​ identical assets ​ inputs ​ inputs ​ 2019 (Level 1) (Level 2) (Level 3) Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds (i) ​ $ 114 ​ $ 114 ​ $ - ​ $ - U.S. government agency bonds (ii) ​ ​ 500 ​ ​ - ​ ​ 500 ​ ​ - Bank certificates of deposit (ii) (iii) ​ ​ 11,713 ​ ​ - ​ ​ 11,713 ​ ​ - Commercial paper (ii) ​ ​ 9,454 ​ ​ - ​ ​ 9,454 ​ ​ - Corporate notes (ii) ​ ​ 67,026 ​ ​ - ​ ​ 67,026 ​ ​ - Asset-backed securities (ii) ​ ​ 25,893 ​ ​ - ​ ​ 25,893 ​ ​ - ​ ​ $ 114,700 ​ $ 114 ​ $ 114,586 ​ $ - ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ At December 31, 2018 ​ ​ ​ ​ ​ Quoted prices ​ Significant ​ ​ ​ ​ ​ ​ ​ in active ​ other ​ Significant ​ ​ ​ ​ ​ markets for ​ observable ​ unobservable ​ ​ December 31, ​ identical assets ​ inputs ​ inputs ​ 2018 (Level 1) (Level 2) (Level 3) Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds (i) ​ $ 1,156 ​ $ 1,156 ​ $ - ​ $ - U.S. government agency bonds (ii) ​ ​ 1,982 ​ ​ - ​ ​ 1,982 ​ ​ - U.S. government bonds (ii) ​ ​ 1,297 ​ ​ - ​ ​ 1,297 ​ ​ - Bank certificates of deposit (ii) ​ ​ 15,201 ​ ​ - ​ ​ 15,201 ​ ​ - Commercial paper (ii) ​ ​ 9,593 ​ ​ - ​ ​ 9,593 ​ ​ - Corporate notes (ii) (iv) ​ ​ 61,752 ​ ​ - ​ ​ 61,752 ​ ​ - Asset-backed securities (ii) ​ ​ 21,842 ​ ​ - ​ ​ 21,842 ​ ​ - ​ ​ $ 112,823 ​ $ 1,156 ​ $ 111,667 ​ $ - (i) Included in cash and cash equivalents with a maturity of three months or less from date of purchase on the condensed consolidated balance sheets. (ii) Included in short-term investments on the condensed consolidated balance sheets. (iii) As of September 30, 2019, a bank certificate of deposit investment totaling $1,201 (in thousands) is included in cash and cash equivalents on the condensed consolidated balance sheets, as the investment has a maturity of three months or less from the date of purchase on the condensed consolidated balance sheets. (iv) As of December 31, 2018, a corporate note investment totaling $1,000 (in thousands) is included in cash and cash equivalents on the condensed consolidated balance sheets, as the investment has a maturity of three months or less from the date of purchase on the condensed consolidated balance sheets. Money market funds and currency are highly liquid investments and are actively traded. The pricing information on these investment instruments is readily available and can be independently validated as of the measurement date. This approach results in the classification of these securities as Level 1 of the fair value hierarchy. U.S. government agency bonds, U.S. government bonds, bank certificates of deposit, commercial paper, corporate notes and asset-backed securities are measured at fair value using Level 2 inputs. The Company reviews trading activity and pricing for these investments as of each measurement date. When sufficient quoted pricing for identical securities is not available, the Company uses market pricing and other observable market inputs for similar securities obtained from third party data providers. These inputs represent quoted prices for similar assets in active markets or these inputs have been derived from observable market data. This approach results in the classification of these securities as Level 2 of the fair value hierarchy. There were no transfers between levels within the fair value hierarchy during the periods presented.

Leases

Leases	9 Months Ended
	Sep. 30, 2019
Leases
Leases	Note 5. Leases The Company has operating and finance leases for facilities and certain equipment. Leases with an initial term of 12 months or less are not recorded on the condensed consolidated balance sheet. Lease expense for leases is recognized on a straight-line basis over the lease term. For lease agreements entered into or reassessed after the adoption of ASC 842, the Company combines lease and non-lease components. See Note 2, Summary of Significant Accounting Policies The Company's leases have remaining non-cancelable lease terms of approximately one year to thirteen years, some of which include options to extend the leases for up to ten years, and some of which include options to terminate the lease within one year. The exercise of lease renewal options is at the Company's sole discretion. In certain of the Company’s lease agreements, the rental payments are adjusted periodically to reflect actual charges incurred for common area maintenance, landlord incentives and/or inflation. The Company leases two adjacent facilities located in San Clemente, California. During December 2018, the Company extended the term of these facilities by three years, both of which now expire on December 31, 2024. Each agreement contains an option to extend the lease for one additional three year period at market rates. The total leased square footage of these facilities equals approximately 98,000. In conjunction with these extensions, the lease landlord agreed to provide the Company with a tenant improvement allowance in the amount of the cost of any leasehold improvements, not to exceed approximately $0.3 million upon the Company providing the necessary documentation evidencing the costs of the allowable leasehold improvements. On November 14, 2018, the Company entered into an office building lease pursuant to which the Company will lease one property containing three existing office buildings, comprising approximately 160,000 rentable square feet of space, located in Aliso Viejo, California (Aliso Facility) which was accounted for as a finance lease. The term of the Aliso Facility commenced on April 1, 2019 and continues for thirteen years. The agreement contains an option to extend the lease for two additional five year periods at market rates. The Company intends to relocate its corporate administrative headquarters, along with certain laboratory, research and development and warehouse space, to the Aliso Facility. The Company currently intends to maintain its manufacturing facilities at its San Clemente location for the foreseeable future. The Company’s remaining U.S.-based and foreign subsidiaries’ leased office space totals less than 14,000 square feet. The following table presents the lease balances within the condensed consolidated balance sheets: ​ ​ ​ ​ ​ ​ ​ Leases ​ September 30, (in thousands) ​ Classification ​ 2019 Assets ​ ​ ​ Operating ​ Operating lease right-of-use asset ​ $ 12,146 Finance ​ Finance lease right-of-use asset ​ ​ 53,343 Total lease assets ​ ​ ​ $ 65,489 Liabilities ​ ​ ​ Current ​ ​ ​ ​ ​ Operating ​ Accrued liabilities ​ $ 1,561 Finance ​ Accrued liabilities ​ ​ 387 Noncurrent ​ ​ ​ ​ ​ Operating ​ Operating lease liability ​ ​ 11,406 Finance ​ Finance lease liability ​ ​ 68,851 Total lease liabilities ​ ​ $ 82,205 ​ Note: As the implicit rates in the Company’s leases are not readily available, the incremental borrowing rate was determined based on the information available at commencement date in determining the present value of lease payments. ​ For the three and nine month periods ended September 30, 2019, the components of operating and finance lease expenses were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ Lease Cost ​ ​ ​ September 30, ​ September 30, ​ (in thousands) ​ Classification ​ 2019 ​ 2019 ​ Fixed operating lease cost ​ Selling, general and administrative expenses ​ $ 596 (a) $ 1,770 (a) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Finance lease cost ​ Amortization of right-of-use asset included in Selling, General and Administrative Expenses ​ $ 593 ​ $ 1,185 ​ Finance lease cost ​ Interest on lease liability ​ $ 1,028 ​ $ 2,041 ​ (a) Includes short-term leases, which are immaterial. ​ The following table presents the maturity of the Company’s operating and finance lease liabilities as of September 30, 2019: ​ ​ ​ ​ ​ ​ ​ ​ Maturity of Lease Liabilities ​ Operating ​ Finance (in thousands) Leases (a) ​ Leases (b) Remainder of 2019 ​ $ 548 ​ $ — 2020 ​ ​ 1,973 ​ ​ 1,547 2021 ​ ​ 1,758 ​ ​ 4,744 2022 ​ ​ 1,666 ​ ​ 4,887 2023 ​ ​ 1,986 ​ ​ 5,033 Thereafter ​ ​ 8,313 ​ ​ 123,546 Total lease payments ​ $ 16,244 ​ $ 139,757 Less: imputed interest ​ ​ 3,277 ​ ​ 70,519 Total lease liabilities ​ $ 12,967 ​ $ 69,238 (a) Operating lease payments include $12.0 million related to options to extend lease terms that are reasonably certain of being exercised. (b) Finance lease payments include $75.8 million related to options to extend lease terms that are reasonably certain of being exercised. ​ The weighted-average remaining lease term and weighted-average discount rate related to the Company’s operating and finance leases as of September 30, 2019 were: ​ ​ ​ ​ ​ Lease Term and Discount Rate 2019 Weighted-average remaining lease term (years) ​ ​ Operating leases ​ 7.8 ​ Finance leases ​ 22.5 ​ Weighted-average discount rate ​ ​ Operating leases ​ 5.5 % Finance leases ​ 6.0 % ​ Supplemental cash flow information related to the Company’s operating and finance leases was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended Nine Months Ended Other Information ​ September 30, September 30, (in thousands) ​ 2019 2019 Cash paid for amounts included in the measurement of lease liabilities: ​ ​ ​ ​ ​ ​ Operating cash flows from operating leases ​ $ 540 ​ $ 1,480 Right-of-use asset obtained in exchange for lease obligations: ​ ​ ​ ​ ​ ​ Operating lease ​ $ 194 ​ $ 13,366 Finance lease ​ ​ — ​ ​ 54,528 ​

Intangible Assets

Intangible Assets	9 Months Ended
	Sep. 30, 2019
Intangible Assets
Intangible Assets	Note 6. Intangible Assets GMP Vision Solutions intangible asset In January 2007, the Company entered into an agreement (the Original GMP Agreement) with GMP Vision Solutions, Inc. (GMP) to acquire certain IPR&D in exchange for periodic royalty payments equal to a single-digit percentage of revenues received for royalty-bearing products and periodic royalty payments at a higher royalty rate applied to all amounts received in connection with the grant of licenses or sub-licenses of the related intellectual property. ​ In November 2013, the Company entered into an amended agreement with GMP in which remaining royalties payable to GMP (the Buyout Agreement) were canceled in exchange for the issuance of $17.5 million in promissory notes payable to GMP and a party related to GMP. The Company concluded that the $17.5 million transaction represented the purchase of an intangible asset. The Company estimated a useful life of five years over which the intangible asset was amortized to cost of sales in the accompanying statements of operations, which amortization period was determined after consideration of the projected outgoing royalty payment stream had the Buyout Agreement not occurred, and the remaining life of the patents obtained in the Original GMP Agreement. After determining that the pattern of future cash flows associated with this intangible asset could not be reliably estimated with a high level of precision, the Company concluded that the intangible asset would be amortized on a straight-line basis over the estimated useful life. ​ The Company recorded amortization expense of $0.9 million and $2.6 million related to this intangible asset in cost of sales for the three and nine months ended September 30, 2018 ,

Revenue from Contracts with Cus

Revenue from Contracts with Customers	9 Months Ended
	Sep. 30, 2019
Revenue from Contracts with Customers
Revenue from Contracts with Customers	Note 7. Revenue from Contracts with Customers The Company’s net sales are generated primarily from sales of iStent ​ Disaggregation of revenue ​ The Company’s disaggregation of revenue is consistent with its operating segments disclosed in Note 11 , Business Segment Information ​ Contract balances ​ Amounts are recorded as accounts receivable when the Company’s right to consideration becomes unconditional. As payment terms on invoiced amounts are typically 30 days, the Company does not consider any significant financing components in customer contracts given the expected time between transfer of the promised products and the payment of the associated consideration is less than one year. As of September 30, 2019 and December 31, 2018, all amounts included in accounts receivable, net on the condensed consolidated balance sheets are related to contracts with customers. ​ The Company does not have any contract assets given that the Company does not have any unbilled receivables and sales commissions are expensed within selling, general and administrative expenses within the condensed consolidated statement of operations when incurred as any incremental cost of obtaining contracts with customers would have an amortization period of less than one year . ​ Contract liabilities reflect consideration received from customers’ purchases allocated to the Company’s performance obligation to issue a rebate to customers who may be eligible for a rebate at the conclusion of their contract term. This performance obligation is transferred over time and the Company’s method of measuring progress is the output method, whereby the progress is measured by the estimated rebate earned to date over the total rebate estimated to be earned over the contract period. The Company’s rebate allowance is included in accrued liabilities in the condensed consolidated balance sheets and estimated rebates accrued were not material during the periods presented. ​ During the three and nine months ended September 30, 2019 and September 30, 2018, the Company did not recognize any revenue related to changes in transaction prices regarding its contracts with customers and did not recognize any material changes in revenue related to amounts included in contract liabilities at the beginning of the period.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2019
Stock-Based Compensation.
Stock-Based Compensation	Note 8. Stock-Based Compensation The Company has four stock-based compensation plans (collectively, the Stock Plans)—the 2001 Stock Option Plan (the 2001 Stock Plan), the 2011 Stock Plan (the 2011 Stock Plan), the 2015 Omnibus Incentive Compensation Plan (the 2015 Stock Plan) and the ESPP. The 2015 Stock Plan permits grants of RSU awards. The purpose of these plans is to provide incentives to employees, directors and nonemployee consultants. The Company no longer grants any awards under the 2001 Stock Plan or the 2011 Stock Plan. The maximum term of any stock options granted under the Stock Plans is 10 years. For employees and nonemployees, stock options generally vest 25% on the first anniversary of the original vesting date, with the balance vesting monthly or annually over the remaining three years. Stock options are granted at exercise prices at least equal to the fair value of the underlying stock at the date of the grant. For employees and nonemployees, generally, RSU awards vest 25% on each of the first, second, third and fourth anniversaries of the grant date and in certain cases, vest one year after grant date. In 2019, the Compensation Committee approved the grant of performance-based equity awards (PBEAs) to the Company’s named executive officers and certain other employees pursuant to the 2015 Stock Plan. These PBEAs will only vest upon the Compensation Committee’s confirmation of the satisfaction of a pre-determined Company operational goal. The goal must be reached within three years of the grant date or the PBEA grants will lapse and be forfeited for no consideration. The ESPP permits eligible employees to purchase shares of the Company’s common stock, using contributions via payroll deductions of up to 15% of their earnings, at a price per share equal to 85% of the lower of the stock’s fair market value on the offering date or purchase date. The ESPP is intended to qualify as an “employee stock purchase plan” under Section 423 of the Internal Revenue Code. Stock Options The following table summarizes stock option activity under the 2001 Stock Plan, 2011 Stock Plan and 2015 Stock Plan during the nine months ended September 30, 2019 (in thousands except option exercise price): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- ​ ​ ​ ​ ​ ​ Number of ​ ​ ​ Average ​ ​ ​ ​ ​ ​ Shares ​ ​ Weighted- ​ Remaining ​ ​ ​ ​ ​ ​ Underlying ​ Average ​ Contractual ​ ​ Aggregate ​ ​ Options Exercise Price Life (in years) ​ Intrinsic Value ​ Outstanding at December 31, 2018 ​ 6,307 ​ $ 23.69 ​ 6.7 ​ $ 204,896 ​ Granted ​ 186 ​ ​ 68.10 ​ ​ ​ ​ ​ ​ Exercised ​ (583) ​ ​ 24.08 ​ ​ ​ $ 27,515 ​ Canceled/forfeited/expired ​ (13) ​ ​ 38.57 ​ ​ ​ ​ ​ ​ Outstanding at September 30, 2019 ​ 5,897 ​ $ 25.04 ​ 6.2 ​ $ 222,005 ​ Vested and expected to vest at September 30, 2019 ​ 5,834 ​ $ 24.85 ​ 6.1 ​ $ 220,714 ​ Exercisable at September 30, 2019 ​ 4,352 ​ $ 19.79 ​ 5.5 ​ $ 185,936 ​ ​ Intrinsic value is calculated as the difference between the exercise price of the underlying options and the fair value of the common stock for the options that had exercise prices that were lower than the fair value per share of the common stock on the date of exercise. The weighted average estimated grant date fair value per share of stock options granted during the three months ended September 30, 2019 was $30.71. There were not any stock options granted during the three months ended September 30, 2018. The weighted average estimated grant date fair value per share of stock options granted during the nine months ended September 30, 2019 and September 30, 2018 was $33.02 and $15.19, respectively. The total fair value of stock options that vested during the three months ended September 30, 2019 and September 30, 2018 was $4.3 million and $4.7 million, respectively. The total fair value of stock options that vested during the nine months ended September 30, 2019 and September 30, 2018 was $15.3 million and $20.4 million, respectively. The fair value of each option award is estimated on the date of grant using a Black-Scholes option pricing model applying the assumptions noted in the following table. The weighted average assumptions used to estimate the fair value of options granted to employees and non-employees were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ ​ September 30, ​ September 30, ​ ​ 2019 2018 2019 2018 ​ Risk-free interest rate ​ 1.61 % ** % 2.17 % 2.67 % Expected dividend yield ​ 0.00 % ** % 0.00 % 0.0 % Expected volatility ​ 47.0 % ** % 46.8 % 44.9 % Expected term (in years) ​ 6.01 ​ ** ​ 6.01 ​ 6.10 ​ ​ **There were no stock options granted in the period. Restricted Stock Units The following table summarizes the activity of unvested RSUs (including PBEAs) under the Stock Plans during the nine months ended September 30, 2019: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- ​ ​ ​ ​ Number of ​ ​ average ​ ​ ​ ​ shares ​ ​ grant date ​ ​ ​ (in thousands) ​ fair value ​ Unvested at December 31, 2018 ​ ​ 532 ​ $ 35.17 ​ Granted ​ ​ 301 ​ ​ 70.42 ​ Vested ​ ​ (210) ​ ​ 34.93 ​ Canceled/forfeited ​ ​ (17) ​ ​ 42.14 ​ Unvested at September 30, 2019 ​ ​ 606 ​ $ 52.39 ​ ​ The total fair value of RSUs made to employees and nonemployees is equal to the closing market price of the Company’s common stock on the grant date. The total fair value of RSUs that vested during the three and nine months ended September 30, 2019 was $1.4 million and $7.3 million, respectively. The total fair value of RSUs that vested during the three and nine months ended September 30, 2018 was $0.1 million and $1.2 million, respectively. All share-based compensation arrangements The following table summarizes the allocation of stock-based compensation related to stock options and RSUs in the accompanying condensed consolidated statements of operations (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ ​ September 30, ​ September 30, ​ ​ 2019 2018 2019 2018 Cost of sales ​ $ 259 ​ $ 175 ​ $ 752 ​ $ 526 ​ Selling, general and administrative ​ ​ 6,727 ​ ​ 5,538 ​ ​ 18,555 ​ ​ 14,418 ​ Research and development ​ ​ 1,561 ​ ​ 1,460 ​ ​ 4,616 ​ ​ 4,092 ​ Total ​ $ 8,547 ​ $ 7,173 ​ $ 23,923 ​ $ 19,036 ​ ​ ​ At September 30, 2019, the total unamortized stock-based compensation expense was approximately $54.4 million. Of the approximately $54.4 million in unamortized stock-based compensation expense, $28.9 million was attributable to stock options and is to be recognized over the stock options’ remaining vesting terms of approximately 4.0 years (2.1 years on a weighted average basis). The remaining $25.5 million was attributable to RSUs and is to be recognized over the restricted stock units’ vesting terms of approximately 4.0 years (1.6 years on a weighted-average basis). The total stock-based compensation cost capitalized in inventory was not material for the three and nine month periods ended September 30, 2019 and September 30, 2018.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2019
Income Taxes
Income Taxes	Note 9. Income Taxes The provision for income taxes is determined using an estimated annual effective tax rate. For the three and nine months ended September 30, 2019, the Company’s effective tax rate of (1.4)% and (1.8)%, respectively, was lower than the U.S. federal statutory rate primarily due to the generation of U.S. net operating loss carryforwards for which no benefit has been recognized due to the Company’s full valuation allowance, as well as state and foreign income taxes. The effective tax rate may be subject to fluctuations during the year as new information is obtained which may affect the assumptions used to estimate the annual effective tax rate, including factors such as expected utilization of net operating loss carryforwards, changes in or the interpretation of tax laws in jurisdictions where the Company conducts business, the Company’s expansion into new states or foreign countries, and the amount of valuation allowances against deferred tax assets. For the three and nine months ended September 30, 2019, the Company recorded a provision for income taxes of $0.2 million and $0.4 million, respectively, which was primarily comprised of state and foreign income taxes. For the three and nine months ended September 30, 2018, the Company recorded a provision for income taxes of $37,000 and $53,000, respectively, which was primarily comprised of state income taxes. ​ The Company recognizes deferred tax assets and liabilities for temporary differences between the financial reporting basis and the tax basis of its assets and liabilities, along with net operating loss and tax credit carryforwards. The Company records a valuation allowance against its deferred tax assets to reduce the net carrying value to an amount it believes is more likely than not to be realized. When the Company establishes or reduces the valuation allowance against its deferred tax assets, the provision for income taxes will increase or decrease, respectively, in the period such determination is made. For the three and nine months ended September 30, 2019, the Company has established a valuation allowance for all deferred tax assets. ​ Additionally, the Company follows an accounting standard addressing the accounting for uncertainty in income taxes that prescribes rules for recognition, measurement and classification in the financial statements of tax positions taken or expected to be taken in a tax return. As of September 30, 2019 and December 31, 2018, the Company has gross unrecognized tax benefits of $13.8 million and $13.5 million, respectively. ​

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2019
Commitments and Contingencies
Commitments and Contingencies	Note 10. Commitments and Contingencies Legal Proceedings Patent Litigation On April 14, 2018, the Company filed a patent infringement lawsuit against Ivantis, Inc. (Ivantis) in the U.S. District Court for the Central District of California, Southern Division (the Court), alleging that Ivantis’ Hydrus ® iStent inject ​ Securities Litigation On October 1, 2019, an alleged Avedro stockholder filed a lawsuit challenging the Merger. Such lawsuit, a putative class action complaint, is captioned Kent v. Avedro, Inc., et. al, 1:19-cv-01845-MN (the Kent complaint), and was filed by Michael Kent in the United States District Court for the District of Delaware. The Kent complaint names as defendants Avedro and each member of the Avedro board of directors, including former directors Dr. Gilbert H. Kliman and Thomas W. Burns, as well as Glaukos and Merger Sub. The Kent complaint alleges violations of Section 14(a) and 20(a) of the Exchange Act, and Rule 14a-9. The plaintiff in this action generally alleges that the Registration Statement omits material information with respect to the Merger, which renders such Registration Statement false and misleading. The complaint seeks preliminary and permanent injunction of the Merger and, if the Merger is consummated, rescission or rescissory damages. The complaint also seeks the dissemination of a registration statement that discloses certain information requested by the plaintiff. In addition, the complaint seeks attorneys' and experts' fees. ​ Three additional lawsuits challenging the Merger have also been filed by alleged Avedro stockholders. Those additional lawsuits allege similar causes of action, based on similar allegations, and seek similar relief to the Kent Payne v. Avedro, Inc. et. al Bushansky v. Avedro, Inc. et. al, Thompson v. Avedro, Inc., et. al, Kent complaint. The Company believes that all four of these complaints are without merit. With respect to each of the matters described above in this Legal Proceedings ​ Secured letter of credit The Company had a bank issue a letter of credit in the amount of $8.8 million that is related to its Aliso Facility. The letter of credit is secured with an amount of cash held in a restricted account of approximately $8.9 million as of September 30, 2019. Beginning as of the first day of the thirty-seventh month of the lease term, and on each twelve month anniversary thereafter, the letter of credit will be reduced by 20% until the letter of credit amount has been reduced to $2.0 million. ​ Regents of the University of California On December 30, 2014, the Company executed an agreement (the UC Agreement) with the Regents of the University of California (the University) to correct inventorship in connection with a group of the Company’s U.S. patents (the Patent Rights) and to obtain from the University a covenant that it did not and would not claim any right or title to the Patent Rights and will not challenge or assist any others in challenging the Patent Rights. In connection with the UC Agreement, Glaukos agreed to pay to the University a low single-digit percentage of worldwide net sales of certain current and future products, including the Company’s iStent Executive Deferred Compensation Plan Pursuant to the Company’s deferred compensation plan (the Deferred Compensation Plan), eligible senior level employees are permitted to make elective deferrals of compensation to which he or she will become entitled in the future. The Company has also established a rabbi trust that serves as an investment to shadow the Deferred Compensation Plan liability. The investments of the rabbi trust consist of company-owned life insurance policies (COLIs). The fair value of the Deferred Compensation Plan liability, included in other liabilities on the condensed consolidated balance sheets, was approximately Global enterprise systems implementation Beginning in the first quarter of 2019, the Company is implementing new enterprise systems and other technology optimizations and facilities infrastructure globally. As of September 30, 2019, the Company has firm purchase commitments related to software costs and these systems implementations of approximately $7.2 million.

Business Segment Information

Business Segment Information	9 Months Ended
	Sep. 30, 2019
Business Segment Information
Business Segment Information	Note 11. Business Segment Information Operating segments are identified as components of an enterprise about which segment discrete financial information is available for evaluation by the chief operating decision maker in making decisions regarding resource allocation and assessing performance. The Company operates its business on the basis of one reportable segment—ophthalmic medical devices. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Nine months ended ​ ​ ​ September 30, ​ September 30, ​ Geographic Net Sales Information (in thousands) 2019 2018 2019 2018 United States ​ $ 47,588 ​ $ 36,413 ​ $ 139,893 ​ $ 106,337 ​ International ​ ​ 10,921 ​ ​ 7,495 ​ ​ 31,242 ​ ​ 20,865 ​ Total net sales ​ $ 58,509 ​ $ 43,908 ​ $ 171,135 ​ $ 127,202 ​ ​

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2019
Summary of Significant Accounting Policies
Use of estimates	Use of estimates The preparation of the condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts in the condensed consolidated financial statements and accompanying notes. Actual results could differ materially from those estimates and assumptions. Management considers many factors in selecting appropriate financial accounting policies and controls and in developing the estimates and assumptions that are used in the preparation of these condensed consolidated financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of reasonable estimates of the ultimate future outcomes, and management must select an amount that falls within that range of reasonable estimates. The most significant estimates in the accompanying condensed consolidated financial statements relate to revenue recognition, the incremental borrowing rate related to the Company’s leased assets and stock-based compensation expense. Although these estimates are based on the Company’s knowledge of current events and actions it may undertake in the future, this process may result in actual results differing materially from those estimated amounts used in the preparation of the condensed consolidated financial statements.
Foreign currency translation	Foreign currency translation The accompanying condensed consolidated financial statements are presented in United States (U.S.) dollars. The Company considers the local currency to be the functional currency for its international subsidiaries. Accordingly, their assets and liabilities are translated into U.S. dollars using the exchange rate in effect on the balance sheet date. Revenues and expenses are translated at average exchange rates prevailing throughout the periods presented. As a result, currency translation adjustments arising from period to period are charged or credited to accumulated other comprehensive income in stockholders’ equity. For the three and nine months ended September 30, 2019, the Company reported foreign currency translation gains of approximately $0.5 million and $0.4 million, respectively. For the three and nine months ended September 30, 2018, the Company reported foreign currency translation gains of approximately $0.3 million and $1.4 million, respectively. Unrealized gains and losses that arise from exchange rate fluctuations on transactions denominated in a currency other than the functional currency, primarily gains and losses on intercompany loans, are included in the condensed consolidated statements of operations as a component of other expense, net. For the three and nine months ended September 30, 2019 the Company reported net unrealized foreign currency transaction losses of $0.6 million and $0.5 million, respectively. For the three and nine months ended September 30, 2018, the Company reported net unrealized foreign currency transaction losses of $0.4 million and $1.5 million, respectively.
Cash, cash equivalents and short-term investments	Cash, cash equivalents and short-term investments The Company invests its excess cash in marketable securities, including money market funds, money market securities, bank certificates of deposits, corporate bonds, corporate commercial paper, U.S. government bonds and U.S. government agency bonds. For financial reporting purposes, liquid investment instruments purchased with an original maturity of three months or less are considered to be cash equivalents. Cash and cash equivalents are recorded at face value or cost, which approximates fair market value. The Company maintains cash balances in excess of amounts insured by the Federal Deposit Insurance Commission. Investments are stated at fair value as determined by quoted market prices. Investments are considered available-for-sale and, accordingly, unrealized gains and losses are included in accumulated other comprehensive income within stockholders’ equity. The Company’s entire investment portfolio, except for restricted cash, is considered to be available for use in current operations and, accordingly, all such investments are stated at fair value using quoted market prices and classified as current assets, although the stated maturity of individual investments may be one year or more beyond the balance sheet date. The Company did not have any trading securities or restricted investments at September 30, 2019 or December 31, 2018. Realized gains and losses and declines in value, if any, judged to be other-than-temporary on available-for-sale securities are reported in other expense, net. When securities are sold, any associated unrealized gain or loss previously reported as a separate component of stockholders’ equity is reclassified out of stockholders’ equity and recorded in the statements of operations in the period sold using the specific identification method. Accrued interest and dividends from investments are included in other expense, net. The Company periodically reviews its available-for-sale securities for other-than-temporary declines in fair value below the cost basis, and whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable.
Restricted cash	Restricted cash The Company had a bank issue a letter of credit in the amount of $8.8 million related to its Aliso Viejo, California office building lease, which commenced on April 1, 2019. The letter of credit is secured with an amount of cash held in a restricted account of $8.9 million and $8.8 million as of September 30, 2019 and December 31, 2018, respectively. Beginning on the first day of the thirty-seventh month of the lease term, and on each twelve month anniversary thereafter, the letter of credit will be reduced by 20% until the letter of credit amount has been reduced to $2.0 million. See Note 10, Commitments and Contingencies The following table provides a reconciliation of cash and cash equivalents and restricted cash reported within the condensed consolidated balance sheets that equate to the amount reported in the condensed consolidated statement of cash flows as of the beginning and end of the nine month period ended September 30, 2019 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ ​ 2019 ​ 2018 Cash and cash equivalents ​ $ 39,534 ​ $ 29,821 ​ Restricted cash ​ ​ 8,881 ​ ​ 8,775 ​ Cash, cash equivalents and restricted cash in the condensed consolidated statements of cash flows ​ $ 48,415 ​ $ 38,596 ​ ​
Fair value of financial instruments	Fair value of financial instruments The carrying amounts of cash equivalents, accounts receivable, accounts payable, and accrued liabilities are considered to be representative of their respective fair values because of the short-term nature of those instruments. The valuation of assets and liabilities is subject to fair value measurements using a three-tiered approach and fair value measurements are classified and disclosed by the Company in one of the following three categories: Level 1: Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities; Level 2: Quoted prices for similar assets and liabilities in active markets, quoted prices in markets that are not active, or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liability; and Level 3: Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (i.e., supported by little or no market activity).
Leases	Leases In February 2016, the Financial Accounting Standards Board (FASB) issued ASU No. 2016-02, Leases (Topic 842) Consistent with historical guidance, a lessee’s recognition, measurement, and presentation of expenses and cash flows arising from a lease will continue to depend primarily on its classification. ASC 842 was effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. The Company adopted the requirements of ASC 842 effective January 1, 2019 and elected the modified retrospective method for all lease arrangements at the beginning of the period of adoption. Results for reporting periods beginning on or after January 1, 2019 are presented under ASC 842, while prior period amounts were not adjusted and continue to be reported in accordance with the Company’s historic accounting under ASC 840, Leases. ​ For leases that commenced before the effective date of ASC 842, the Company elected the transition package of three practical expedients permitted within ASC 842, which eliminates the requirements to reassess prior conclusions about lease identification, lease classification, and initial direct costs. ​ The Company did not elect the hindsight practical expedient, which permits the use of hindsight when determining lease term and impairment of right-of-use assets. Further, the Company elected a short-term lease exception policy, permitting the Company to not apply the recognition requirements of this standard to short-term leases (i.e., leases with terms of 12 months or less) and an accounting policy to account for lease and non-lease components as a single component for certain classes of assets. As a result of adopting ASC 842 as of January 1, 2019, the Company recorded an operating lease right-of-use asset of $12.8 million and related operating lease liability of $13.4 million, respectively, primarily related to facilities and certain equipment, based on the present value of the future lease payments on the date of adoption . Leases ​ The Company determines if an arrangement is a lease at inception. As a lessee, right-of-use assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent an obligation to make lease payments arising from the lease. Right-of-use assets and lease liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. As the Company does not have any outstanding debt or committed credit facilities, the Company estimates the incremental borrowing rate based on prevailing financial market conditions, peer company credit analyses, and management judgment. Operating lease right-of-use assets also include any lease payments made at or before lease commencement and exclude any lease incentives received. The lease terms used to calculate the right-of-use asset and related lease liability include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense for operating leases is recognized on a straight-line basis over the lease term as an operating expense while the expense for finance leases is recognized as depreciation expense and interest expense using the accelerated interest method of recognition. ​ As of April 1, 2019, the Company recorded a finance lease right-of-use asset of $54.5 million and related finance lease liability of $67.2 million with respect to the commencement of its lease in Aliso Viejo, California based on the present value of the future lease payments on the date of commencement. As of September 30, 2019, the finance lease right-of-use asset excludes lease incentives totaling $12.7 million included in prepaid expenses and other current assets on the condensed consolidated balance sheets.
Revenue recognition	Revenue recognition The Company accounts for revenue in accordance with ASC 606, Revenue Recognition – Revenue from Contracts with Customers and its related amendments ​ The Company derives its revenue from sales of its products in the United States and internationally. Customers are primarily comprised of ambulatory surgery centers and hospitals, with distributors being used in certain international locations where the Company does not have a direct commercial presence. ​ The Company concluded that one performance obligation exists for the majority of its contracts with customers which is to deliver products in accordance with the Company’s normal delivery times. Revenue is recognized when this performance obligation is satisfied, which is the point in time when the Company considers control of a product to have transferred to the customer. Revenue recognized reflects the consideration to which the Company expects to be entitled in exchange for those products or services. The Company has determined the transaction price to be the invoice price, net of adjustments, which includes estimates of variable consideration for product returns. ​ The Company offers volume-based rebate agreements to certain customers and, in these instances, the Company provides a rebate (in the form of a credit memo) at the contract’s conclusion, if earned by the customer. In such cases, the transaction price is allocated between the Company’s delivery of product and the issuance of a rebate at the contract’s conclusion for the customer to utilize on prospective purchases. The performance obligation to issue a customer’s rebate, if earned, is transferred over time and the Company’s method of measuring progress is the output method, whereby the progress is measured by the estimated rebate earned to date over the total rebate estimated to be earned over the contract period. The provision for volume-based rebates is estimated based on customers' contracted rebate programs and the customers’ projected sales levels. The Company periodically monitors its customer rebate programs to ensure the rebate allowance is fairly stated. The Company’s rebate allowance is included in accrued liabilities in the condensed consolidated balance sheets and estimated rebates accrued were not material during the periods presented. ​ Customers are not granted specific rights of return; however, the Company may permit returns of product from customers if such product is returned in a timely manner and in good condition. The Company provides a warranty on its products for one year from the date of shipment, and any product found to be defective or out of specification will be replaced at no charge during the warranty period. Estimated allowances for sales returns and warranty replacements are recorded at the time of sale of the product and are estimated based upon the historical patterns of product returns matched against sales, and an evaluation of specific factors that may increase the risk of product returns. Product returns and warranty replacements to date have been consistent with amounts reserved or accrued and have not been significant.
Research and development expenses	Research and development expenses Major components of research and development expense include personnel costs, preclinical studies, clinical trials and related clinical product manufacturing, materials and supplies, and fees paid to consultants. Research and development costs are expensed as goods are received or services are rendered. Costs to acquire technologies to be used in research and development that have not reached technological feasibility and have no alternative future use are also expensed as incurred as IPR&D. At each financial reporting date, the Company accrues the estimated unpaid costs of clinical study activities performed during a period by third party clinical sites with whom the Company has agreements that provide for fees based upon the quantities of subjects enrolled and clinical evaluation visits that occur over the life of the study. The cost estimates are determined based upon a review of the agreements and data collected by internal and external clinical personnel as to the status of enrollment and subject visits, and are based upon the facts and circumstances known to the Company at each financial reporting date. If the actual performance of activities varies from the assumptions used in the cost estimates, the accruals are adjusted accordingly. There have been no material adjustments to the Company’s prior period accrued estimates for clinical trial activities during the three and nine months ended September 30, 2019.
Stock-based compensation	Stock-based compensation The Company recognizes compensation expense for all stock-based awards granted to employees and nonemployees, including members of its board of directors. The fair value of stock option awards is estimated at the grant date using the Black-Scholes option pricing model, and the portion that is ultimately expected to vest is recognized as compensation cost over the requisite service period using the straight-line method. The determination of the fair value-based measurement of stock options on the date of grant using an option pricing model is affected by the determination of the fair value of the underlying stock as well as assumptions regarding a number of highly complex and subjective variables. These variables include, but are not limited to, the Company’s stock price volatility over the expected term of the grants, and actual and projected stock option exercise behaviors. In the future, as additional empirical evidence regarding these estimates becomes available, the Company may change or refine its approach of deriving them, and these changes could impact the fair value-based measurement of stock options granted in the future. Changes in the fair value-based measurement of stock awards could materially impact the Company’s operating results. The fair value of restricted stock unit (RSU) awards is equal to the closing market price of the Company’s common stock on the grant date.
Software Costs	Software costs The Company currently expenses software service costs along with any associated implementation costs as services are provided and implementation costs are incurred.
Comprehensive loss	Comprehensive loss All components of comprehensive loss, including net loss, are reported in the condensed consolidated financial statements in the period in which they are recognized. Comprehensive loss is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources, including unrealized gains and losses on marketable securities and foreign currency translation adjustments.
Net loss per share	Net loss per share Basic net loss per share is calculated by dividing the net loss by the weighted average number of common shares that were outstanding for the period, without consideration for common stock equivalents. For periods when the Company realizes a net loss, no common stock equivalents are included in the calculation of weighted average number of dilutive common stock equivalents as the effect of applying the treasury stock method is considered anti-dilutive. For periods when the Company realizes net income, diluted net income per share is calculated by dividing the net income by the weighted average number of common shares plus the sum of the weighted average number of dilutive common stock equivalents outstanding for the period determined using the treasury stock method. Common stock equivalents are comprised of stock options outstanding and unvested RSUs under the Company’s incentive compensation plans, and shares issuable under the Company’s Employee Stock Purchase Plan (ESPP). Potentially dilutive securities not included in the calculation of diluted net loss per share because to do so would be anti-dilutive were as follows (in common stock equivalent shares, in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ ​ September 30, ​ September 30, ​ 2019 2018 2019 2018 ​ Stock options outstanding ​ 3,602 ​ 4,781 ​ 3,636 ​ 5,707 ​ Unvested restricted stock units ​ 232 ​ 196 ​ 364 ​ 355 ​ Employee stock purchase plan ​ 1 ​ 15 ​ 5 ​ 42 ​ ​ ​ 3,835 ​ 4,992 ​ 4,005 ​ 6,104 ​ ​
Recently adopted and issued accounting pronouncements	Recently adopted accounting pronouncements In February 2018, the FASB issued ASU No. 2018-02, Income Statement – Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income In June 2018, the FASB issued ASU No. 2018-07, Improvements to Nonemployee Share-Based Payment Accounting 2018, including interim periods within those fiscal years. The Company adopted the guidance effective January 1, 2019 and the guidance did not have a material impact to the Company’s condensed consolidated financial statements. In August 2018, the SEC adopted the final rule under SEC Release No. 33-10532, Disclosure Update and Simplification See above under “ Leases Recently issued accounting pronouncements not yet adopted In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments Codification Improvements to Topic 326, Financial Instruments—Credit Losses ​ In January 2017, the FASB issued ASU No. 2017-04, Intangibles – Goodwill and Other (Topic 250): Simplifying the Test for Goodwill Impairment ​ In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820) ​ In August 2018, the FASB issued ASU No. 2018-14, Disclosure Framework—Changes to the Disclosure Requirements for Defined Benefit Plans ​ In August 2018, the FASB issued ASU No. 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract In November 2018, the FASB issued ASU No. 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction Between Topic 808 and Topic 606

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2019
Summary of Significant Accounting Policies
Schedule of cash and cash equivalents and restricted cash	The following table provides a reconciliation of cash and cash equivalents and restricted cash reported within the condensed consolidated balance sheets that equate to the amount reported in the condensed consolidated statement of cash flows as of the beginning and end of the nine month period ended September 30, 2019 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ ​ 2019 ​ 2018 Cash and cash equivalents ​ $ 39,534 ​ $ 29,821 ​ Restricted cash ​ ​ 8,881 ​ ​ 8,775 ​ Cash, cash equivalents and restricted cash in the condensed consolidated statements of cash flows ​ $ 48,415 ​ $ 38,596 ​
Schedule of potentially dilutive securities not included in the calculation of diluted net loss per share attributable to common stockholders	Potentially dilutive securities not included in the calculation of diluted net loss per share because to do so would be anti-dilutive were as follows (in common stock equivalent shares, in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ ​ September 30, ​ September 30, ​ 2019 2018 2019 2018 ​ Stock options outstanding ​ 3,602 ​ 4,781 ​ 3,636 ​ 5,707 ​ Unvested restricted stock units ​ 232 ​ 196 ​ 364 ​ 355 ​ Employee stock purchase plan ​ 1 ​ 15 ​ 5 ​ 42 ​ ​ ​ 3,835 ​ 4,992 ​ 4,005 ​ 6,104 ​

Balance Sheet Details (Tables)

Balance Sheet Details (Tables)	9 Months Ended
	Sep. 30, 2019
Balance Sheet Details
Schedule of short-term investments	Short-term investments consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ At September 30, 2019 ​ ​ Maturity ​ Amortized cost ​ Unrealized ​ Unrealized ​ Estimated ​ (in years) or cost gains losses fair value U.S. government agency bonds ​ less than 1 ​ ​ 500 ​ ​ — ​ ​ — ​ ​ 500 ​ Bank certificates of deposit ​ less than 1 ​ ​ 10,500 ​ ​ 12 ​ ​ — ​ ​ 10,512 ​ Commercial paper ​ less than 1 ​ 9,442 ​ 12 ​ — ​ 9,454 ​ Corporate notes ​ less than 3 ​ 66,697 ​ 331 ​ (2) ​ 67,026 ​ Asset-backed securities ​ less than 3 ​ 25,777 ​ 124 ​ (8) ​ 25,893 ​ Total ​ ​ ​ $ 112,916 ​ $ 479 ​ $ (10) ​ $ 113,385 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ At December 31, 2018 ​ ​ Maturity ​ Amortized cost ​ Unrealized ​ Unrealized ​ Estimated ​ (in years) or cost gains losses fair value U.S. government bonds ​ less than 1 ​ $ 1,300 ​ $ - ​ $ (3) ​ $ 1,297 ​ U.S. government agency bonds ​ less than 1 ​ ​ 1,994 ​ ​ - ​ ​ (12) ​ ​ 1,982 ​ Bank certificates of deposit ​ less than 2 ​ ​ 15,201 ​ ​ 2 ​ ​ (3) ​ ​ 15,200 ​ Commercial paper ​ less than 1 ​ 9,597 ​ 1 ​ (5) ​ 9,593 ​ Corporate notes ​ less than 3 ​ 60,923 ​ 24 ​ (194) ​ 60,753 ​ Asset-backed securities ​ less than 3 ​ 21,918 ​ 18 ​ (94) ​ 21,842 ​ Total ​ ​ ​ $ 110,933 ​ $ 45 ​ $ (311) ​ $ 110,667 ​
Schedule of accounts receivable, net	Accounts receivable consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2019 2018 Accounts receivable ​ $ 25,085 ​ $ 19,333 ​ Allowance for doubtful accounts ​ ​ (740) ​ ​ (660) ​ ​ ​ $ 24,345 ​ $ 18,673 ​
Schedule of inventory	Inventory consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2019 2018 Finished goods ​ $ 4,260 ​ $ 4,256 ​ Work in process ​ ​ 4,404 ​ ​ 3,197 ​ Raw material ​ ​ 4,137 ​ ​ 5,829 ​ ​ ​ $ 12,801 ​ $ 13,282 ​
Schedule of accrued liabilities	Accrued liabilities consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2019 2018 Accrued bonuses ​ $ 6,714 ​ $ 8,604 Accrued vacation benefits ​ ​ 2,696 ​ ​ 2,446 Accrued legal expenses ​ ​ 4,604 ​ ​ 2,466 Other accrued liabilities ​ ​ 15,588 ​ ​ 10,448 ​ ​ $ 29,602 ​ $ 23,964

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2019
Fair Value Measurements
Schedule of the Company's financial assets and financial liabilities measured at fair value on a recurring basis	The following tables present information about the Company's financial assets measured at fair value on a recurring basis as of September 30, 2019 and December 31, 2018 and indicate the fair value hierarchy of the valuation techniques utilized by the Company to determine such fair value (in thousands). The Company did not have any financial liabilities measured at fair value on a recurring basis as of September 30, 2019 and December 31, 2018. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ At September 30, 2019 ​ ​ ​ ​ ​ Quoted prices ​ Significant ​ ​ ​ ​ ​ ​ ​ in active ​ other ​ Significant ​ ​ ​ ​ ​ markets for ​ observable ​ unobservable ​ ​ September 30, ​ identical assets ​ inputs ​ inputs ​ 2019 (Level 1) (Level 2) (Level 3) Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds (i) ​ $ 114 ​ $ 114 ​ $ - ​ $ - U.S. government agency bonds (ii) ​ ​ 500 ​ ​ - ​ ​ 500 ​ ​ - Bank certificates of deposit (ii) (iii) ​ ​ 11,713 ​ ​ - ​ ​ 11,713 ​ ​ - Commercial paper (ii) ​ ​ 9,454 ​ ​ - ​ ​ 9,454 ​ ​ - Corporate notes (ii) ​ ​ 67,026 ​ ​ - ​ ​ 67,026 ​ ​ - Asset-backed securities (ii) ​ ​ 25,893 ​ ​ - ​ ​ 25,893 ​ ​ - ​ ​ $ 114,700 ​ $ 114 ​ $ 114,586 ​ $ - ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ At December 31, 2018 ​ ​ ​ ​ ​ Quoted prices ​ Significant ​ ​ ​ ​ ​ ​ ​ in active ​ other ​ Significant ​ ​ ​ ​ ​ markets for ​ observable ​ unobservable ​ ​ December 31, ​ identical assets ​ inputs ​ inputs ​ 2018 (Level 1) (Level 2) (Level 3) Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds (i) ​ $ 1,156 ​ $ 1,156 ​ $ - ​ $ - U.S. government agency bonds (ii) ​ ​ 1,982 ​ ​ - ​ ​ 1,982 ​ ​ - U.S. government bonds (ii) ​ ​ 1,297 ​ ​ - ​ ​ 1,297 ​ ​ - Bank certificates of deposit (ii) ​ ​ 15,201 ​ ​ - ​ ​ 15,201 ​ ​ - Commercial paper (ii) ​ ​ 9,593 ​ ​ - ​ ​ 9,593 ​ ​ - Corporate notes (ii) (iv) ​ ​ 61,752 ​ ​ - ​ ​ 61,752 ​ ​ - Asset-backed securities (ii) ​ ​ 21,842 ​ ​ - ​ ​ 21,842 ​ ​ - ​ ​ $ 112,823 ​ $ 1,156 ​ $ 111,667 ​ $ - (i) Included in cash and cash equivalents with a maturity of three months or less from date of purchase on the condensed consolidated balance sheets. (ii) Included in short-term investments on the condensed consolidated balance sheets. (iii) As of September 30, 2019, a bank certificate of deposit investment totaling $1,201 (in thousands) is included in cash and cash equivalents on the condensed consolidated balance sheets, as the investment has a maturity of three months or less from the date of purchase on the condensed consolidated balance sheets. (iv) As of December 31, 2018, a corporate note investment totaling $1,000 (in thousands) is included in cash and cash equivalents on the condensed consolidated balance sheets, as the investment has a maturity of three months or less from the date of purchase on the condensed consolidated balance sheets.

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2019
Leases
Schedule of operating lease balance sheet information	​ ​ ​ ​ ​ ​ ​ Leases ​ September 30, (in thousands) ​ Classification ​ 2019 Assets ​ ​ ​ Operating ​ Operating lease right-of-use asset ​ $ 12,146 Finance ​ Finance lease right-of-use asset ​ ​ 53,343 Total lease assets ​ ​ ​ $ 65,489 Liabilities ​ ​ ​ Current ​ ​ ​ ​ ​ Operating ​ Accrued liabilities ​ $ 1,561 Finance ​ Accrued liabilities ​ ​ 387 Noncurrent ​ ​ ​ ​ ​ Operating ​ Operating lease liability ​ ​ 11,406 Finance ​ Finance lease liability ​ ​ 68,851 Total lease liabilities ​ ​ $ 82,205
Schedule of component of operating lease expense	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ Lease Cost ​ ​ ​ September 30, ​ September 30, ​ (in thousands) ​ Classification ​ 2019 ​ 2019 ​ Fixed operating lease cost ​ Selling, general and administrative expenses ​ $ 596 (a) $ 1,770 (a) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Finance lease cost ​ Amortization of right-of-use asset included in Selling, General and Administrative Expenses ​ $ 593 ​ $ 1,185 ​ Finance lease cost ​ Interest on lease liability ​ $ 1,028 ​ $ 2,041 ​ (a) Includes short-term leases, which are immaterial.
Schedule of maturity of lease liability	​ ​ ​ ​ ​ ​ ​ ​ Maturity of Lease Liabilities ​ Operating ​ Finance (in thousands) Leases (a) ​ Leases (b) Remainder of 2019 ​ $ 548 ​ $ — 2020 ​ ​ 1,973 ​ ​ 1,547 2021 ​ ​ 1,758 ​ ​ 4,744 2022 ​ ​ 1,666 ​ ​ 4,887 2023 ​ ​ 1,986 ​ ​ 5,033 Thereafter ​ ​ 8,313 ​ ​ 123,546 Total lease payments ​ $ 16,244 ​ $ 139,757 Less: imputed interest ​ ​ 3,277 ​ ​ 70,519 Total lease liabilities ​ $ 12,967 ​ $ 69,238 (a) Operating lease payments include $12.0 million related to options to extend lease terms that are reasonably certain of being exercised. (b) Finance lease payments include $75.8 million related to options to extend lease terms that are reasonably certain of being exercised.
Schedule of operating lease weighted average lease term and discount rate	​ ​ ​ ​ ​ Lease Term and Discount Rate 2019 Weighted-average remaining lease term (years) ​ ​ Operating leases ​ 7.8 ​ Finance leases ​ 22.5 ​ Weighted-average discount rate ​ ​ Operating leases ​ 5.5 % Finance leases ​ 6.0 %
Schedule of operating lease supplemental cash flow information	​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended Nine Months Ended Other Information ​ September 30, September 30, (in thousands) ​ 2019 2019 Cash paid for amounts included in the measurement of lease liabilities: ​ ​ ​ ​ ​ ​ Operating cash flows from operating leases ​ $ 540 ​ $ 1,480 Right-of-use asset obtained in exchange for lease obligations: ​ ​ ​ ​ ​ ​ Operating lease ​ $ 194 ​ $ 13,366 Finance lease ​ ​ — ​ ​ 54,528

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2019
Stock-Based Compensation.
Schedule summarizing stock option activity under the 2001 Stock Plan, 2011 Stock Plan and 2015 Stock Plan	The following table summarizes stock option activity under the 2001 Stock Plan, 2011 Stock Plan and 2015 Stock Plan during the nine months ended September 30, 2019 (in thousands except option exercise price): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- ​ ​ ​ ​ ​ ​ Number of ​ ​ ​ Average ​ ​ ​ ​ ​ ​ Shares ​ ​ Weighted- ​ Remaining ​ ​ ​ ​ ​ ​ Underlying ​ Average ​ Contractual ​ ​ Aggregate ​ ​ Options Exercise Price Life (in years) ​ Intrinsic Value ​ Outstanding at December 31, 2018 ​ 6,307 ​ $ 23.69 ​ 6.7 ​ $ 204,896 ​ Granted ​ 186 ​ ​ 68.10 ​ ​ ​ ​ ​ ​ Exercised ​ (583) ​ ​ 24.08 ​ ​ ​ $ 27,515 ​ Canceled/forfeited/expired ​ (13) ​ ​ 38.57 ​ ​ ​ ​ ​ ​ Outstanding at September 30, 2019 ​ 5,897 ​ $ 25.04 ​ 6.2 ​ $ 222,005 ​ Vested and expected to vest at September 30, 2019 ​ 5,834 ​ $ 24.85 ​ 6.1 ​ $ 220,714 ​ Exercisable at September 30, 2019 ​ 4,352 ​ $ 19.79 ​ 5.5 ​ $ 185,936 ​
Schedule of the weighted-average assumptions used to estimate the fair value of options granted to employees	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ ​ September 30, ​ September 30, ​ ​ 2019 2018 2019 2018 ​ Risk-free interest rate ​ 1.61 % ** % 2.17 % 2.67 % Expected dividend yield ​ 0.00 % ** % 0.00 % 0.0 % Expected volatility ​ 47.0 % ** % 46.8 % 44.9 % Expected term (in years) ​ 6.01 ​ ** ​ 6.01 ​ 6.10 ​
Schedule summarizing restricted stock unit activity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted- ​ ​ ​ ​ Number of ​ ​ average ​ ​ ​ ​ shares ​ ​ grant date ​ ​ ​ (in thousands) ​ fair value ​ Unvested at December 31, 2018 ​ ​ 532 ​ $ 35.17 ​ Granted ​ ​ 301 ​ ​ 70.42 ​ Vested ​ ​ (210) ​ ​ 34.93 ​ Canceled/forfeited ​ ​ (17) ​ ​ 42.14 ​ Unvested at September 30, 2019 ​ ​ 606 ​ $ 52.39 ​
Schedule summarizing the allocation of stock-based compensation	The following table summarizes the allocation of stock-based compensation related to stock options and RSUs in the accompanying condensed consolidated statements of operations (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ ​ September 30, ​ September 30, ​ ​ 2019 2018 2019 2018 Cost of sales ​ $ 259 ​ $ 175 ​ $ 752 ​ $ 526 ​ Selling, general and administrative ​ ​ 6,727 ​ ​ 5,538 ​ ​ 18,555 ​ ​ 14,418 ​ Research and development ​ ​ 1,561 ​ ​ 1,460 ​ ​ 4,616 ​ ​ 4,092 ​ Total ​ $ 8,547 ​ $ 7,173 ​ $ 23,923 ​ $ 19,036 ​

Business Segment Information (T

Business Segment Information (Tables)	9 Months Ended
	Sep. 30, 2019
Business Segment Information
Schedule of Geographic Net Sales Information	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three months ended ​ Nine months ended ​ ​ ​ September 30, ​ September 30, ​ Geographic Net Sales Information (in thousands) 2019 2018 2019 2018 United States ​ $ 47,588 ​ $ 36,413 ​ $ 139,893 ​ $ 106,337 ​ International ​ ​ 10,921 ​ ​ 7,495 ​ ​ 31,242 ​ ​ 20,865 ​ Total net sales ​ $ 58,509 ​ $ 43,908 ​ $ 171,135 ​ $ 127,202 ​

Organization and Basis of Pre_2

Organization and Basis of Presentation - (Details) $ in Thousands	Jul. 22, 2019USD ($)	Jun. 27, 2019USD ($)	Jun. 19, 2019USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2019USD ($)	Aug. 07, 2019shares	Dec. 31, 2018item
Organization and basis of presentation information
In-process research and development expensed				$ 1,500	$ 3,745
Proposed acquisition of Avedro, Inc.
Organization and basis of presentation information
Number of shares received in connection with Merger for each share of company owned stock | shares						0.365
Ownership percentage of combined company						85.00%
Licensing Arrangement with Intratus, Inc.
Organization and basis of presentation information
In-process research and development expensed	$ 1,500
Cash payments for the acquisition of certain assets	$ 1,500
DOSE Medical Corporation
Organization and basis of presentation information
In-process research and development expensed		$ 2,200
Period for U.S. Food and Drug Administration (FDA) approval for additional consideration			10 years
Period for EU European Medicines Agency approval for additional consideration			10 years
Quarterly royalty rate (as a percent)			5.00%
Period for the quarterly royalty rate payments			10 years
Cash payments for the acquisition of certain assets of related party			$ 2,500
Capitalized property and equipment		$ 300
DOSE Medical Corporation | Minimum
Organization and basis of presentation information
Additional future consideration for U.S. Food and Drug Administration (FDA) approval			5,000
Additional future consideration for European Medicines Agency approval			1,250
Additional future consideration for certain net sales milestones			7,500
Buyout of additional consideration amount			10,000
DOSE Medical Corporation | Maximum
Organization and basis of presentation information
Additional future consideration for U.S. Food and Drug Administration (FDA) approval			22,500
Additional future consideration for European Medicines Agency approval			2,500
Additional future consideration for certain net sales milestones			20,000
Buyout of additional consideration amount			$ 55,000
Avedro, Inc.
Organization and basis of presentation information
Number of procedures performed | item							400,000
Number of procedures performed in the United States | item							18,000
Avedro, Inc. | Proposed acquisition of Avedro, Inc.
Organization and basis of presentation information
Ownership percentage of combined company						15.00%

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Summary (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2019USD ($)item	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)item	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Foreign Currency Translation
Foreign currency translation gain	$ 530,000	$ 322,000	$ 364,000	$ 1,369,000
Foreign currency transaction unrealized gains (losses)	(600,000)	(400,000)	(469,000)	(1,541,000)
Trading Securities
Trading securities	0		0		$ 0
Restricted cash
Letter of Credit outstanding	8,800,000		8,800,000		8,800,000
Cash and cash equivalents	39,534,000		39,534,000		29,821,000
Restricted cash	8,881,000		8,881,000		8,775,000
cash, cash equivalents and restricted cash in the condensed consolidated statements of cash flows	$ 48,415,000	37,278,000	$ 48,415,000	37,278,000	$ 38,596,000	$ 24,508,000
Number of Months from start of lease for adjustments to Letter of Credit | item	37		37
Frequency of adjustment to Letter of Credit			12 months
Adjustment rate of Letter of Credit (as a percent)			20.00%
Amount of Letter of Credit outstanding after adjustments	$ 2,000,000		$ 2,000,000
Revenue Recognition
Number of performance obligations that exist for majority of the contracts with customers | item			1
Warranty period from date of shipment			1 year
Numerator:
Net loss - basic and diluted	$ (13,506,000)	$ (6,621,000)	$ (21,157,000)	$ (14,730,000)

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Antidilutive Securities (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Anti-dilutive securities
Anti-dilutive securities excluded from computation of earnings per share	3,835	4,992	4,005	6,104
Stock options
Anti-dilutive securities
Anti-dilutive securities excluded from computation of earnings per share	3,602	4,781	3,636	5,707
RSU
Anti-dilutive securities
Anti-dilutive securities excluded from computation of earnings per share	232	196	364	355
ESPP
Anti-dilutive securities
Anti-dilutive securities excluded from computation of earnings per share	1	15	5	42

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Leases (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Apr. 01, 2019	Jan. 01, 2019
Recent Accounting Pronouncements
Operating lease right-of-use asset	$ 12,146
Operating lease liability	$ 12,967
Practical Expedients, Package	true
Practical Expedient, Use of Hindsight	false
Finance lease right-of-use asset	$ 53,343
Total Finance lease liabilities	69,238
Aliso Facility
Recent Accounting Pronouncements
Finance lease right-of-use asset		$ 54,500
Total Finance lease liabilities		$ 67,200
Finance lease incentive assets, current	$ 12,700
ASU No 2016-02 Leases | Adjustment
Recent Accounting Pronouncements
Operating lease right-of-use asset			$ 12,800
Operating lease liability			$ 13,400

Balance Sheet Details - Short-T

Balance Sheet Details - Short-Term Investments (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Short-term investments
Amortized cost	$ 112,916	$ 110,933
Unrealized gains	479	45
Unrealized losses	(10)	(311)
Estimated fair value	113,385	110,667
U.S. Government bonds
Short-term investments
Amortized cost		1,300
Unrealized losses		(3)
Estimated fair value		$ 1,297
U.S. Government bonds | Maximum
Short-term investments
Maturity		1 year
U.S. Government agency bonds
Short-term investments
Amortized cost	500	$ 1,994
Unrealized losses		(12)
Estimated fair value	$ 500	$ 1,982
U.S. Government agency bonds | Maximum
Short-term investments
Maturity	1 year	1 year
Bank certificates of deposit
Short-term investments
Amortized cost	$ 10,500	$ 15,201
Unrealized gains	12	2
Unrealized losses		(3)
Estimated fair value	$ 10,512	$ 15,200
Bank certificates of deposit | Maximum
Short-term investments
Maturity	1 year	2 years
Commercial paper
Short-term investments
Amortized cost	$ 9,442	$ 9,597
Unrealized gains	12	1
Unrealized losses		(5)
Estimated fair value	$ 9,454	$ 9,593
Commercial paper | Maximum
Short-term investments
Maturity	1 year	1 year
Corporate notes
Short-term investments
Amortized cost	$ 66,697	$ 60,923
Unrealized gains	331	24
Unrealized losses	(2)	(194)
Estimated fair value	$ 67,026	$ 60,753
Corporate notes | Maximum
Short-term investments
Maturity	3 years	3 years
Asset-backed securities
Short-term investments
Amortized cost	$ 25,777	$ 21,918
Unrealized gains	124	18
Unrealized losses	(8)	(94)
Estimated fair value	$ 25,893	$ 21,842
Asset-backed securities | Maximum
Short-term investments
Maturity	3 years	3 years

Balance Sheet Details - Other (

Balance Sheet Details - Other (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Accounts Receivable, Net
Accounts receivable	$ 25,085	$ 19,333
Allowance for doubtful accounts	(740)	(660)
Accounts receivable, net	24,345	18,673
Inventory
Finished goods	4,260	4,256
Work in process	4,404	3,197
Raw materials	4,137	5,829
Total inventory	12,801	13,282
Accrued Liabilities
Accrued bonuses	6,714	8,604
Accrued vacation benefits	2,696	2,446
Accrued legal expenses	4,604	2,466
Other accrued liabilities	15,588	10,448
Total accrued liabilities	$ 29,602	$ 23,964

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value Hierarchy (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Assets
Total assets	$ 114,700	$ 112,823
Fair Value, Inputs, Level 1
Assets
Total assets	114	1,156
Fair Value, Inputs, Level 2
Assets
Total assets	114,586	111,667
Fair Value, Measurements, Recurring
Liabilities
Total liabilities	0	0
Money market funds
Assets
Total assets	114	1,156
Money market funds | Fair Value, Inputs, Level 1
Assets
Total assets	114	1,156
U.S. Government agency bonds
Assets
Total assets	500	1,982
U.S. Government agency bonds | Fair Value, Inputs, Level 2
Assets
Total assets	500	1,982
U.S. Government bonds
Assets
Total assets		1,297
U.S. Government bonds | Fair Value, Inputs, Level 2
Assets
Total assets		1,297
Bank certificates of deposit
Assets
Cash equivalents	1,201
Total assets	11,713	15,201
Bank certificates of deposit | Fair Value, Inputs, Level 2
Assets
Total assets	11,713	15,201
Commercial paper.
Assets
Total assets	9,454	9,593
Commercial paper. | Fair Value, Inputs, Level 2
Assets
Total assets	9,454	9,593
Corporate notes
Assets
Cash equivalents		1,000
Total assets	67,026	61,752
Corporate notes | Fair Value, Inputs, Level 2
Assets
Total assets	67,026	61,752
Asset-backed securities
Assets
Total assets	25,893	21,842
Asset-backed securities | Fair Value, Inputs, Level 2
Assets
Total assets	$ 25,893	$ 21,842

Fair Value Measurements - Trans

Fair Value Measurements - Transfers (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Fair Value Measurements
Amount of transfers of assets and liabilities measured on a recurring basis between Levels 1, 2 and 3 of the fair value hierarchy	$ 0	$ 0

Leases - Terms (Details)

Leases - Terms (Details)	9 Months Ended
	Sep. 30, 2019
Leases
Operating Lease Existence of Option to Extend	true
Optional lease extension term	10 years
Operating Lease Existence of Option to Terminate	true
Operating lease period for lease termination	1 year
Minimum
Leases
Operating lease remaining lease term	1 year
Maximum
Leases
Operating lease remaining lease term	13 years

Leases - Leases Details (Detail

Leases - Leases Details (Details) $ in Millions	Nov. 14, 2018ft²item	Dec. 31, 2018USD ($)item	Sep. 30, 2019ft²item
Operating Leases
Optional lease extension term			10 years
Domestic Office Leases
Operating Leases
The number of adjacent facilities rented			2
Extended lease term		3 years
Number of lease renewal periods		1
Optional lease extension term		3 years
Area of leased space | ft²			98,000
Domestic Office Leases | Maximum
Operating Leases
Tenant improvement allowance | $		$ 0.3
Foreign Subsidiaries Office Leases
Operating Leases
Area of leased space | ft²			14,000
Aliso Facility
Operating Leases
Number of properties leased	1
Number of buildings leased	3
Number of lease renewal periods	2
Optional lease extension term	5 years
Area of leased space | ft²	160,000
Term of lease	13 years

Leases - Balance Sheet and Expe

Leases - Balance Sheet and Expense (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2019USD ($)
Leases
Assets Operating	$ 12,146	$ 12,146
Assets Finance	53,343	53,343
Total lease assets	65,489	65,489
Liabilities Current Operating	1,561	1,561
Liabilities Current Finance	387	387
Liabilities Noncurrent Operating	11,406	11,406
Liabilities Noncurrent Finance	68,851	68,851
Total lease liabilities	82,205	82,205
Fixed operating lease cost	596	1,770
Finance lease cost - amortization of right-of-use asset	593	1,185
Finance lease cost - interest on lease liability	$ 1,028	$ 2,041

Leases - Maturity (Details)

Leases - Maturity (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)
Leases
Existence of option to extend	true
Operating Leases
Remainder of 2019	$ 548
2020	1,973
2021	1,758
2022	1,666
2023	1,986
Thereafter	8,313
Total Operating lease payments	16,244
Less: imputed interest	3,277
Total Operating lease liabilities	12,967
Amount of operating leases with option to extend commitment	12,000
Finance Leases
2020	1,547
2021	4,744
2022	4,887
2023	5,033
Thereafter	123,546
Total Finance lease payments	139,757
Less: imputed interest	70,519
Total Finance lease liabilities	69,238
Amount of financing leases with option to extend commitment	$ 75,800

Leases - Lease Term And Discoun

Leases - Lease Term And Discount Rate And Cash Flow Information (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2019USD ($)
Leases
Weighted average remaining lease term - operating leases	7 years 9 months 18 days	7 years 9 months 18 days
Weighted average remaining lease term - finance leases	22 years 6 months	22 years 6 months
Weighted average discount rate - operating leases (as a percent)	5.50%	5.50%
Weighted average discount rate - finance leases (as a percent)	6.00%	6.00%
Cash paid for amounts included in the measurement of lease liabilities - Operating cash flows from operating leases	$ 540	$ 1,480
Cash paid for amounts included in the measurement of lease liabilities - Operating cash flows from finance leases	1,028	2,041
Right-of-use asset obtained in exchange for lease obligations: Operating leases	$ 194	13,366
Right-of-use asset obtained in exchange for lease obligations: Finance leases		$ 54,528

Intangible Assets - Summary and

Intangible Assets - Summary and Other (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	9 Months Ended
	Nov. 30, 2013	Sep. 30, 2018	Sep. 30, 2018
Composition of intangible assets
Amortization expense		$ 0.9	$ 2.6
GMP royalty buyout
Composition of intangible assets
Intangible asset purchase amount	$ 17.5
Buy-out Agreement with GMP | GMP royalty buyout
Composition of intangible assets
Useful life/amortization period	5 years
Notes Payable | Buy-out Agreement with GMP | GMP Note Parties
Composition of intangible assets
Face amount at time of issuance	$ 17.5

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Details)	9 Months Ended
	Sep. 30, 2019
Revenue from Contracts with Customers
Typical payment terms on invoiced amounts	30 days
Practical expedient financing component	true
Practical expedient cost of obtaining contract	true

Stock-Based Compensation - Plan

Stock-Based Compensation - Plan Information (Details)	9 Months Ended
	Sep. 30, 2019item
Stock-based compensation
Number of stock plans	4
Expiration period	10 years
Vesting percentage on first anniversary of grant date	25.00%
Remaining vesting period	3 years
Employee Stock Purchase Plan 2015
Stock-based compensation
Maximum employee contributions as a percentage of earnings under the ESPP	15.00%
Purchase price per share expressed as a percentage of the lower of the stock's fair market value on the offering date or purchase date under the ESPP	85.00%
First anniversary | RSU
Stock-based compensation
Vesting (as a percent)	25.00%
Second anniversary | RSU
Stock-based compensation
Vesting (as a percent)	25.00%
Third anniversary | RSU
Stock-based compensation
Vesting (as a percent)	25.00%
Fourth anniversary | RSU
Stock-based compensation
Vesting (as a percent)	25.00%

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock Option Activity (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Number of Shares Underlying Options
Outstanding at beginning of period (in shares)			6,307,000
Granted (in shares)		0	186,000
Exercised (in shares)			(583,000)
Canceled/forfeited/expired (in shares)			(13,000)
Outstanding at end of period (in shares)	5,897,000		5,897,000		6,307,000
Vested and expected to vest at end of period (in shares)	5,834,000		5,834,000
Exercisable at end of period (in shares)	4,352,000		4,352,000
Weighted Average Exercise Price
Outstanding at beginning of period (in dollars per share)			$ 23.69
Granted (in dollars per share)			68.10
Exercised (in dollars per share)			24.08
Canceled/forfeited/expired (in dollars per share)			38.57
Outstanding at end of period (in dollars per share)	$ 25.04		25.04		$ 23.69
Vested and expected to vest at end of period (in dollars per share)	24.85		24.85
Exercisable at end of period (in dollars per share)	$ 19.79		$ 19.79
Additional disclosures
Weighted Average Remaining Contractual Life			6 years 2 months 12 days		6 years 8 months 12 days
Weighted Average Remaining Contractual Life, Vested and expected to vest at end of period			6 years 1 month 6 days
Weighted Average Remaining Contractual Life, Exercisable at end of period			5 years 6 months
Aggregate Intrinsic Value for outstanding options	$ 222,005		$ 222,005		$ 204,896
Exercised, Aggregate Intrinsic Value			27,515
Vested and expected to vest, Aggregate Intrinsic Value	220,714		220,714
Exercisable, Aggregate Intrinsic Value	$ 185,936		$ 185,936
Weighted average estimated grant date fair value of options granted (in dollars per share)	$ 30.71		$ 33.02	$ 15.19
Fair value of stock options vested	$ 4,300,000	$ 4,700,000	$ 15,300,000	$ 20,400,000

Stock-Based Compensation - Fair

Stock-Based Compensation - Fair Value Assumptions (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2018
Stock-based compensation
Unamortized stock-based compensation expense not yet recognized	$ 54.4	$ 54.4
RSU
Stock-based compensation
Unamortized stock-based compensation expense not yet recognized	25.5	$ 25.5
Options remaining vesting period		4 years
Weighted average period of recognition		1 year 7 months 6 days
Stock options
Stock-based compensation
Unamortized stock-based compensation expense not yet recognized	$ 28.9	$ 28.9
Options remaining vesting period		4 years
Weighted average period of recognition		2 years 1 month 6 days
Stock-based awards - weighted average assumptions used to estimate fair value of options granted
Risk-free interest rate (as a percent)	1.61%	2.17%	2.67%
Expected dividend yield (as a percent)	0.00%	0.00%	0.00%
Expected volatility rate (as a percent)	47.00%	46.80%	44.90%
Expected term	6 years 3 days	6 years 3 days	6 years 1 month 6 days

Stock-Based Compensation - Rest

Stock-Based Compensation - Restricted Stock Units (Details) - RSU - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Stock-based compensation
Total fair value of units vested	$ 1.4	$ 0.1	$ 7.3	$ 1.2
Number of shares
Unvested at beginning of period (in shares)			532
Granted (in shares)			301
Vested (in shares)			(210)
Canceled/forfeited (in shares)			(17)
Unvested at end of period (in shares)	606		606
Weighted average grant date fair value
Unvested at beginning of period (in dollar per share)			$ 35.17
Granted (in dollar per share)			70.42
Vested (in dollar per share)			34.93
Canceled/forfeited (in dollar per share)			42.14
Unvested at end of period (in dollar per share)	$ 52.39		$ 52.39

Stock-Based Compensation - Allo

Stock-Based Compensation - Allocation of Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Allocation of stock-based compensation
Stock-based compensation expense	$ 8,547	$ 7,173	$ 23,923	$ 19,036
Cost of sales
Allocation of stock-based compensation
Stock-based compensation expense	259	175	752	526
Selling, general and administrative
Allocation of stock-based compensation
Stock-based compensation expense	6,727	5,538	18,555	14,418
Research and development
Allocation of stock-based compensation
Stock-based compensation expense	$ 1,561	$ 1,460	$ 4,616	$ 4,092

Income Taxes (Details)

Income Taxes (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Income Taxes
Effective tax rate (as a percent)	(1.40%)		(1.80%)
Provision for income taxes	$ 187,000	$ 37,000	$ 381,000	$ 53,000
Unrecognized tax benefits	$ 13,800,000		$ 13,800,000		$ 13,500,000

Commitments and Contingencies (

Commitments and Contingencies (Details)	Oct. 01, 2019item	Dec. 31, 2018USD ($)item	Aug. 31, 2018item	Sep. 30, 2019USD ($)item	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)item	Sep. 30, 2018USD ($)
Other commitments
Letter of Credit outstanding		$ 8,800,000		$ 8,800,000		$ 8,800,000
Restricted cash		8,775,000		$ 8,881,000		$ 8,881,000
Number of Months from start of lease for adjustments to Letter of Credit | item				37		37
Frequency of adjustment to Letter of Credit						12 months
Adjustment rate of Letter of Credit (as a percent)						20.00%
Amount of Letter of Credit outstanding after adjustments				$ 2,000,000		$ 2,000,000
Deferred compensation plan liability		2,000,000		3,200,000		3,200,000
Deferred compensation plan assets		$ 1,900,000		3,100,000		3,100,000
Purchase commitment obligation				7,200,000		7,200,000
Agreement with the Regents
Other commitments
Minimum required annual payment of the commitment obligation, based on net sales of current and future products				500,000		500,000
Cost of sales | Agreement with the Regents
Other commitments
Commitment obligation payments				1,500,000	$ 1,100,000	4,200,000	$ 3,200,000
Patent Litigation | Pending Litigation
Other commitments
Number of patent infringements | item			3
Number of new new petitions filed | item		2
Securities Litigation | Pending Litigation
Other commitments
Accrual for loss contingency				$ 0		$ 0
Number of additional lawsuits filed | item	3
Number of lawsuits that name Avedro and Avedro board of directors as defendants | item	2
Number of total lawsuits filed | item	4

Business Segment Information (D

Business Segment Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)segment	Sep. 30, 2018USD ($)
Business Segment Information
Number of Reportable Segments | segment			1
Total net sales	$ 58,509	$ 43,908	$ 171,135	$ 127,202
United States
Business Segment Information
Total net sales	47,588	36,413	139,893	106,337
International
Business Segment Information
Total net sales	$ 10,921	$ 7,495	$ 31,242	$ 20,865