Research and Development Expenses
R&D expenses for the six months ended June 30, 2020 and June 30, 2019 were $43.8 million and $31.0 million, respectively, reflecting an increase of $12.8 million or 41%.
The acquisition of Avedro resulted in an increase in R&D expenses of $2.1 million that were not in our results for the six months ended June 30, 2019, primarily comprised of stock-based compensation resulting from post-combination services associated with the Replacement Awards.
We incurred $10.7 million in normal and recurring Avedro R&D expenses during the six months ended June 30, 2020 that were not in our 2019 results primarily comprised of $4.4 million in compensation and related employee expenses with the remaining $6.3 million primarily spent on the continued development of a pharmaceutical therapeutic system for the treatment of keratoconus without the removal of the epithelium (often referred to as “epi-on”), as well as projects for presbyopia and earlier stage technology and therapeutic investments.
The remaining change in R&D expenses was primarily due approximately $0.5 million in increased compensation and related employee expenses as well as an overall decrease of approximately $1.6 million in other core R&D and clinical expenses, primarily related to a reduction of $1.0 million for inventory and supplies for iDose and future iStent product candidates.
In-process research and development expenses
IPR&D expenses for the six months ended June 30, 2019 were $2.2 million related to the purchase of certain DOSE assets. There were no IPR&D expenses for the six months ended June 30, 2020.
Non-Operating (Expense) Income, Net
We had non-operating expense, net of $2.0 million and non-operating income, net of $0.7 million for the six months ended June 30, 2020 and June 30, 2019, respectively. The change from net non-operating income to net non-operating expense primarily relates to interest expense associated with the financing lease for our Aliso Viejo, California facility and our Convertible Notes and recognition of unrealized foreign currency losses due to higher intercompany loan balances denominated in, and impacted by, changes in foreign currency exchange rates.
Income Tax Provision
Our effective tax rate for the six months ended June 30, 2020 was 7.7%. For the six months ended June 30, 2020 and June 30, 2019, we recorded a (benefit)/provision for income taxes of $(7.8) million and $0.2 million, respectively. The tax benefit for the six months ended June 30, 2020 was primarily the result of the deferred tax liability recorded in conjunction with the Convertible Notes as a source of taxable income to benefit current year losses, partially offset by current U.S. state and foreign income taxes. The tax provision recorded for the six months ended June 30, 2019 primarily related to current U.S. state and foreign income taxes.
Liquidity and Capital Resources
For the six months ended June 30, 2020, we incurred a net loss of $94.0 million and used cash from operations of $24.0 million. As of June 30, 2020, we had an accumulated deficit of approximately $283.7 million. We fund our operations from cash generated from commercial operations and proceeds from exercises of stock options, in addition to utilizing funds from the June 2020 issuance of the Convertible Notes. We have made and expect to continue to make significant investments in our global sales force, marketing programs, research and development activities, clinical studies and general and administrative infrastructure. FDA-approved IDE and IND studies and new product development programs in our industry are expensive. However, due to the COVID-19 economic slowdown, as previously mentioned, we have also sought to preserve our cash position by instituting a number of cost saving initiatives, including substantial reductions in discretionary spending and capital expenditures, as well as a temporary salary reduction for our executive team, senior leadership, and many others throughout the Company, although we currently anticipate restoring full salaries for our impacted employees beginning in the third quarter of 2020.
We have incurred a significant increase in administrative costs since we began operating as a public company. Our operating expenses have increased significantly following our acquisition of Avedro, and we also expect to incur additional construction costs related to our new facility in Aliso Viejo, California. Accordingly, although we have been