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Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2019	Mar. 11, 2020	Jun. 28, 2019
Cover [Abstract]
Entity Registrant Name	Clearside Biomedical, Inc.
Amendment Flag	false
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Trading Symbol	CLSD
Document Type	10-K
Entity Central Index Key	0001539029
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		44,868,558
Entity Public Float			$ 33,200,000
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock, par value $0.001 per share
Security Exchange Name	NASDAQ
Entity File Number	001-37783
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	45-2437375
Entity Address, Address Line One	900 North Point Parkway
Entity Address, Address Line Two	Suite 200
Entity Address, City or Town	Alpharetta
Entity Address, State or Province	GA
Entity Address, Postal Zip Code	30005
City Area Code	678
Local Phone Number	270-3631
Document Annual Report	true
Document Transition Report	false
Documents Incorporated by Reference	Portions of the Company’s definitive proxy statement, to be filed pursuant to Regulation 14A under the Securities Exchange Act of 1934, for its 2020 Annual Meeting of Stockholders are incorporated by reference in Part III of the Form 10-K.

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 22,595	$ 8,043
Short-term investments		32,835
Prepaid expenses	1,139	2,049
Other current assets	1,485	17
Total current assets	25,219	42,944
Property and equipment, net	541	790
Operating lease right-of-use asset	656
Restricted cash	360	360
Other assets		26
Total assets	26,776	44,120
Current liabilities:
Accounts payable	1,280	6,869
Accrued liabilities	2,930	2,923
Current portion of long-term debt	1,333	556
Current portion of operating lease liabilities	360
Current portion of deferred rent		128
Deferred revenue	5,000
Total current liabilities	10,903	10,476
Long-term debt	3,819	9,419
Operating lease liabilities	897
Deferred rent		605
Total liabilities	15,619	20,500
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.001 par value; 10,000,000 shares authorized and no shares issued at December 31, 2019 and 2018
Common stock, $0.001 par value; 100,000,000 shares authorized at December 31, 2019 and 2018; 44,413,372 and 32,119,227 shares issued and outstanding at December 31, 2019 and 2018, respectively	44	32
Additional paid-in capital	248,770	230,475
Accumulated deficit	(237,657)	(206,887)
Total stockholders’ equity	11,157	23,620
Total liabilities and stockholders’ equity	$ 26,776	$ 44,120

Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares, issued	44,413,372	32,119,227
Common stock, shares outstanding	44,413,372	32,119,227

Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
License and other revenue	$ 2,173	$ 30	$ 345
Type of Revenue [Extensible List]	clsd:LicenseAndOtherRevenueMember	clsd:LicenseAndOtherRevenueMember	clsd:LicenseAndOtherRevenueMember
Operating expenses:
Research and development	$ 15,658	$ 68,291	$ 49,053
General and administrative	16,819	14,684	9,700
Total operating expenses	32,477	82,975	58,753
Loss from operations	(30,304)	(82,945)	(58,408)
Other (expense) income	(466)	127	(567)
Net loss	$ (30,770)	$ (82,818)	$ (58,975)
Net loss per share of common stock — basic and diluted	$ (0.81)	$ (2.69)	$ (2.33)
Weighted average shares outstanding — basic and diluted	38,170,830	30,733,600	25,311,614
Net loss	$ (30,770)	$ (82,818)	$ (58,975)
Unrealized gain on available-for-sale investments			5
Comprehensive loss	$ (30,770)	$ (82,818)	$ (58,970)

Statement of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Private Placement	Common Stock	Common Stock Private Placement	Additional Paid-In-Capital	Additional Paid-In-Capital Private Placement	Accumulated Deficit	Accumulated Other Comprehensive Loss
Beginning balance at Dec. 31, 2016	$ 71,659		$ 25		$ 136,892		$ (65,245)	$ (13)
Beginning balance, shares at Dec. 31, 2016			24,573,033
Issuance of common stock in follow-on offering	5,057				5,057
Issuance of common stock in follow-on offering, shares			600,000
Issuance of common shares under employee stock purchase plan	66				66
Issuance of common shares under employee stock purchase plan, shares			9,692
Exercise of stock options	239				239
Exercise of stock options, shares			171,926
Share-based compensation expense	3,364				3,364
Net loss	(58,975)						(58,975)
Other comprehensive gain	5							5
Ending balance at Dec. 31, 2017	21,415		$ 25		145,618		(124,220)	(8)
Ending balance, shares at Dec. 31, 2017			25,354,651
Cumulative effect of accounting change	159						151	$ 8
Issuance of common stock in follow-on offering	79,564		$ 7		79,557
Issuance of common stock in follow-on offering, shares			6,548,712
Issuance of common shares under employee stock purchase plan	50				50
Issuance of common shares under employee stock purchase plan, shares			12,595
Exercise of stock options	465				465
Exercise of stock options, shares			203,269
Share-based compensation expense	4,785				4,785
Net loss	(82,818)						(82,818)
Ending balance at Dec. 31, 2018	23,620		$ 32		230,475		(206,887)
Ending balance, shares at Dec. 31, 2018			32,119,227
Issuance of common shares from at-the-market sales agreement	10,319		$ 9		10,310
Issuance of common shares from at-the-market sales agreement, shares			8,976,940
Issuance of common shares in private placement		$ 3,324		$ 3		$ 3,321
Issuance of common shares from private placement, shares				3,178,367
Issuance of common shares under employee stock purchase plan	45				45
Issuance of common shares under employee stock purchase plan, shares			52,476
Exercise of stock options	7				7
Exercise of stock options, shares			16,362
Vesting and settlement of restricted stock units, shares			70,000
Share-based compensation expense	4,612				4,612
Net loss	(30,770)						(30,770)
Ending balance at Dec. 31, 2019	$ 11,157		$ 44		$ 248,770		$ (237,657)
Ending balance, shares at Dec. 31, 2019			44,413,372

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
Statements of Cash Flows - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating activities
Net loss	$ (30,770)	$ (82,818)	$ (58,975)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	211	189	182
Share-based compensation expense	4,612	4,785	3,364
Non-cash interest expense	163	154	211
Accretion of debt discount	67	112	212
Loss on disposal of fixed assets	63
Amortization and accretion on available-for-sale investments, net	(115)	(748)	(31)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(558)	(505)	(833)
Other assets and liabilities	(159)	(55)	92
Accounts payable and accrued liabilities	(5,582)	(314)	4,715
Deferred revenue	5,000		(20)
Net cash used in operating activities	(27,068)	(79,200)	(51,083)
Investing activities
Maturities of available-for-sale-investments	32,950	76,470	68,543
Purchase of available-for-sale investments		(80,142)	(48,116)
Acquisition of property and equipment	(25)	(88)	(306)
Net cash provided by (used in) investing activities	32,925	(3,760)	20,121
Financing activities
Proceeds from at-the-market sales agreement, net of issuance costs	10,319
Proceeds from private placement, net of issuance costs	3,324
Proceeds from follow-on offering, net of issuance costs		79,564	5,057
Proceeds from exercise of stock options	7	465	239
Proceeds from shares issued under employee stock purchase plan	45	50	66
Proceeds from issuance of long-term debt		10,000
Principal payments made on long-term debt	(5,000)	(8,300)
Net cash provided by financing activities	8,695	81,779	5,362
Net decrease in cash, cash equivalents and restricted cash	14,552	(1,181)	(25,600)
Cash, cash equivalents and restricted cash, beginning of period	8,403	9,584	35,184
Cash, cash equivalents and restricted cash, end of period	22,955	8,403	9,584
Supplemental disclosure
Interest paid	843	751	653
Tenant improvements paid by landlord			637
Reconciliation of cash, cash equivalents and restricted cash;
Cash and cash equivalents	22,595	8,043	9,224
Restricted cash	360	360	360
Cash, cash equivalents and restricted cash, end of period	$ 22,955	$ 8,403	$ 9,584

The Company

12 Months Ended

Dec. 31, 2019

Organization Consolidation And Presentation Of Financial Statements [Abstract]

The Company

1. The Company

Clearside Biomedical, Inc. (the “Company”) is a biopharmaceutical company dedicated to developing and delivering treatments that restore and preserve vision for people with serious back of the eye diseases. The Company’s proprietary SCS Microinjector targeting the suprachoroidal space offers unique access to the macula, retina and choroid where sight-threatening disease often occurs. This suprachoroidal space injection platform is an inherently flexible, in-office, non-surgical procedure, intended to provide targeted delivery to the site of disease and to work with both established and new formulations of medications, as well as future therapeutic innovations such as gene therapy. Incorporated in the State of Delaware on May 26, 2011, the Company has its corporate headquarters in Alpharetta, Georgia.

The Company’s activities since inception have primarily consisted of developing product and technology rights, raising capital and performing research and development activities. The Company has no current source of revenue to sustain present activities, and does not expect to generate meaningful revenue until and unless the Company receives regulatory approval of and successfully commercializes its product candidates, either on its own or with a third party. The Company has funded its operations primarily through the sale of convertible preferred stock and common stock and the issuance of long-term debt. The Company is subject to a number of risks and uncertainties similar to those of other life science companies at a similar stage of development, including, among others, the need to obtain adequate additional financing, successful development efforts including regulatory approval of products, compliance with government regulations, successful commercialization of potential products, protection of proprietary technology and dependence on key individuals.

Liquidity

The Company had cash and cash equivalents of $22.6 million as of December 31, 2019. The Company has funded its operations primarily through the sale of convertible preferred stock and common stock and the issuance of long-term debt. The Company will continue to need to obtain additional financing to fund future operations, including completing the development, partnering and potential commercialization of its primary product candidates. The Company will need to obtain additional financing to conduct additional trials for the regulatory approval of its product candidates if requested by regulatory bodies, and completing the development of any additional product candidates that might be acquired. If such products were to receive regulatory approval, the Company would need to obtain additional financing to prepare for the potential commercialization of its product candidates, if the Company decides to commercialize the products on its own.

The Company has suffered recurring losses and negative cash flows from operations since inception and anticipates incurring additional losses until such time, if ever, that it can obtain FDA approval to sell, and then generate significant revenue from commercializing its lead product candidate, XIPERE, either on its own or together with a third party. In the absence of product or other revenues, the amount, timing, nature or source of which cannot be predicted, the Company’s losses will continue as it conducts its research and development activities.

These conditions raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date the financial statements are issued. Until the Company can generate sufficient revenue, the Company will need to finance future cash needs through public or private equity offerings, license agreements, debt financings or restructurings, collaborations, strategic alliances and marketing or distribution arrangements.

The Company’s financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the normal course of business. The financial statements do not include any adjustments to reflect the possible future effects on the recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might result should the Company be unable to continue as a going concern.

Significant Accounting Policies

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Significant Accounting Policies

2. Significant Accounting Policies

Basis of Presentation

The Company’s financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”).

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and reported amounts of income and expenses during the reporting periods. Significant items subject to such estimates and assumptions include the accounting for useful lives to calculate depreciation and amortization, clinical trial accruals, share-based compensation expense and income tax valuation allowance. Actual results could differ from these estimates.

Revenue Recognition

The Company recognizes revenue from its contracts with customers under Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Topic 606, Revenue from Contracts with Customers (“ASC Topic 606”). The Company’s primary revenue arrangements are license agreements which typically include upfront payments, regulatory and commercial milestone payments and royalties based on future product sales. The arrangements may also include payments for the Company’s SCS Microinjector devices as well as payments for assistance and oversight of the customer’s use of the Company’s technology. In determining the amount of revenue to be recognized under these agreements, the Company performs the following steps: (i) identifies the promised goods and services to be transferred in the contract, (ii) identifies the performance obligations, (iii) determines the transaction price, (iv) allocates the transaction price to the performance obligations and (v) recognizes revenue as the performance obligations are satisfied.

The Company receives payments from its customers based on billing schedules established in each contract. Up-front and other payments may require deferral of revenue recognition to a future period until the Company performs its obligations under the arrangement. Amounts are recorded as accounts receivable when the Company’s right to consideration is unconditional. The Company does not assess whether a contract has a significant financing component if the expectation at contract inception is such that the period between payment by the customer and the transfer of the promised goods or services to the customer will be one year or less.

Segment Information

Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one operating segment.

Property and Equipment, Net

Property and equipment is recorded at historical cost. Depreciation is calculated using the straight-line method over the estimated useful lives of the related assets, or for leasehold improvement the lesser of the useful life or remaining lease term. Repairs and maintenance are expensed when incurred. Upon retirement or sale, the cost of the assets disposed of and the related accumulated depreciation are removed from the accounts, and any resulting gain or loss is included in the determination of net income.

Debt Discount

All debt discounts are recorded against the related debt obligation and are amortized using the effective interest rate method over the term of the underlying debt obligation and reflected in interest expense.

Fair Value Measurements

The Company records certain financial assets and liabilities at fair value in accordance with the provisions of ASC Topic 820, Fair Value Measurements and Disclosures. As defined in the guidance, fair value, defined as an exit price, represents the amount that would be received to sell an asset or pay to transfer a liability in an orderly transaction between market participants. As a result, fair value is a market-based approach that should be determined based on assumptions that market participants would use in pricing an asset or a liability. As a basis for considering these assumptions, the guidance defines a three-tier value hierarchy that prioritizes the inputs used in the valuation methodologies in measuring fair value.

•

Level 1—Unadjusted quoted prices in active, accessible markets for identical assets or liabilities.

•

Level 2—Other inputs that are directly or indirectly observable in the marketplace.

•

Level 3—Unobservable inputs that are supported by little or no market activity.

The fair value hierarchy also requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value.

Income Taxes

Deferred tax assets or liabilities are recorded for temporary differences between financial statement and tax basis of assets and liabilities, using enacted rates in effect for the year in which the differences are expected to reverse. A valuation allowance is recorded if it is more likely than not that a deferred tax asset will not be realized. The Company has provided a full valuation allowance on its deferred tax assets, which primarily consist of cumulative net operating losses for the period from May 26, 2011 (inception) to December 31, 2019. Due to its history of operating losses since inception and losses expected to be incurred in the foreseeable future, a full valuation allowance was considered necessary.

Research and Development Costs

Research and development costs are charged to expense as incurred and include:

•

employee-related expenses, including salaries, benefits, travel and share-based compensation expense for research and development personnel;

•

expenses incurred under agreements with contract research organizations, contract manufacturing organizations and consultants that conduct clinical and preclinical studies;

•

costs associated with preclinical and development activities;

•

costs associated with submitting regulatory approval applications for the Company’s product candidates;

•

costs associated with training physicians on the suprachoroidal injection procedure and educating and providing them with appropriate product candidate information;

•

costs associated with technology and intellectual property licenses;

•

costs for the Company’s research and development facility; and

•

depreciation expense for assets used in research and development activities.

Costs for certain development activities, such as clinical studies, are recognized based on an evaluation of the progress to completion of specific tasks using data such as patient enrollment, clinical site activations, or information provided to the Company by its vendors on their actual costs incurred. Payments for these activities are based on the terms of the individual arrangements, which may differ from the patterns of costs incurred, and are reflected in the financial statements as prepaid or accrued liabilities.

Share-Based Compensation

Compensation cost related to share-based awards granted to employees is measured based on the estimated fair value of the award at the grant date. The Company estimates the fair value of stock options using a Black-Scholes option pricing model. Compensation expense for options granted to non-employees is determined as the fair value of consideration received or the fair value of the equity instruments issued, whichever is more reliably measured. The fair value of restricted stock units granted is measured based on the market value of the Company’s common stock on the date of grant. Share-based compensation costs are expensed on a straight-line basis over the relevant vesting period.

Compensation cost related to shares purchased through the Company’s employee stock purchase plan, which is considered compensatory, is based on the estimated fair value of the shares on the offering date, including consideration of the discount and the look back period. The Company estimates the fair value of the shares using a Black-Scholes option pricing model. Compensation expense is recognized over the six-month withholding period prior to the purchase date.

All share-based compensation costs are recorded in general and administrative or research and development costs in the statements of operations and comprehensive loss based upon the underlying employees’ roles within the Company.

Cash Equivalents

Cash equivalents consist of short-term, highly liquid investments with an original term of three months or less at the date of purchase.

Short-Term Investments

Short-term investments are investments with original maturities of between 90 and 365 days when purchased and are comprised of certificates of deposit, commercial paper, corporate and government bonds and treasury bills. The Company classifies its short-term investments as available-for-sale securities. Short-term investments are recorded at fair value and unrealized gains and losses are recorded within interest income. In addition, the Company evaluates the short-investments with unrealized losses to determine whether such losses are other-than-temporary.

Restricted Cash

The Company is required to maintain a stand-by letter of credit as a security deposit for its facility lease in Alpharetta, Georgia. The Company’s bank requires the Company to maintain a restricted cash balance to serve as collateral for the letter of credit issued to the landlord by the bank. As of December 31, 2019, the restricted cash balance was invested in a commercial money market account.

Concentration of Credit Risk Arising From Cash Deposits in Excess of Insured Limits

The Company maintains its cash in bank deposits that at times may exceed federally insured limits. The Company has not experienced any loss in such accounts. The Company believes it is not exposed to any significant risks with respect to its cash balances.

Recent Accounting Pronouncements

Accounting Pronouncements Recently Adopted

In February 2016, the FASB issued Accounting Standards Update (“ASU”) 2016-02, Leases (ASC 842), and subsequently issued updates as part of ASU 2018-11, Leases, Targeted Improvements. The new guidance requires organizations that lease assets with lease terms of more than 12 months to recognize assets and liabilities for the rights and obligations created by those leases on their balance sheets. The Company adopted ASC 842 effective January 1, 2019 using the optional transition method, did not restate any prior periods and adopted the package of practical expedients. Under the package of practical expedients permitted by the new standard, the Company does not have to reassess whether any expired contracts are or contain leases, the classification of leases or whether initial direct costs should be capitalized. The adoption of the new standard resulted in the recognition of right-of use assets of $1.0 million and lease obligations of $1.7 million on the Company’s balance sheet as of January 1, 2019. The adoption did not have a material impact on the Company’s statements of operations or cash flows.

In June 2018, the FASB issued ASU 2018-07, Compensation-Stock Compensation: Improvements to Nonemployee Shared-Based Payment Accounting. The ASU update expands the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from nonemployees. The Company adopted ASU 2018-07 effective January 1, 2019, and the adoption did not have a material impact on its financial statements and related disclosures.

Recent Accounting Pronouncements Not Yet Adopted

In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820-10): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”), which changes the fair value measurement disclosure requirements of ASC Topic 820, Fair Value Measurements and Disclosures. Under this ASU, certain disclosure requirements for fair value measurements are eliminated, amended or added. These changes aim to improve the overall usefulness of disclosures to financial statement users and reduce unnecessary costs to companies when preparing the disclosures. The guidance is effective for the Company beginning on January 1, 2020 and prescribes different transition methods for the various provisions. The Company does not expect the adoption of ASU 2018-13 to have a material impact on its financial statements and disclosures.

In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU 2019-12”), which simplifies the accounting for income taxes by removing certain exceptions related to the approach for intraperiod tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. The new ASU also simplifies aspects of the accounting for franchise taxes and enacted changes in tax laws or rates. These changes aim to improve the overall usefulness of disclosures to financial statement users and reduce unnecessary costs to companies when preparing the disclosures. The guidance is effective for the Company beginning on January 1, 2021 and prescribes different transition methods for the various provisions. The Company does not expect the adoption of ASU 2019-12 to have a material impact on its financial statements and related disclosures.

In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which requires the measurement and recognition of expected credit losses for financial assets held at amortized cost, including trade receivables. ASU 2016-13 replaces the existing incurred loss impairment model with an expected loss model that requires the use of forward-looking information to calculate credit loss estimates. This guidance is effective for annual reporting periods beginning after December 15, 2019, with early adoption permitted. Entities will apply the amendments using a modified retrospective approach. The Company does not expect the adoption of ASU 2016-13 to have a material impact on its financial statements and related disclosures.

Property and Equipment, Net

12 Months Ended

Dec. 31, 2019

Property Plant And Equipment [Abstract]

Property and Equipment, Net

3. Property and Equipment, Net

Property and equipment, net consisted of the following (dollar amounts in thousands):

	Estimated Useful Lives (Years)	December31,
		2019			2018
Furniture and fixtures	5	$	337		$	382
Machinery and equipment	5		121			121
Computer equipment	3		13			19
Leasehold improvements	Lesser of useful life or remaining lease term		667			677
Total property and equipment			1,138			1,199
Less: Accumulated depreciation			(597	)		(409	)
Property and equipment, net		$	541		$	790

Accrued Liabilities

12 Months Ended

Dec. 31, 2019

Payables And Accruals [Abstract]

Accrued Liabilities

4. Accrued Liabilities

Accrued liabilities consisted of the following (in thousands):

	December 31,
	2019		2018
Accrued research and development	$	359	$	1,263
Accrued employee costs		1,530		1,191
Accrued severance		751		—
Accrued professional fees		58		63
Accrued interest payable		—		76
Accrued expense		232		330
	$	2,930	$	2,923

Long-Term Debt

12 Months Ended

Dec. 31, 2019

Debt Disclosure [Abstract]

Long-Term Debt

5. Long-Term Debt

Loan and Security Agreements

In September 2016, the Company entered into an amended and restated loan and security agreement, which was subsequently amended on October 31, 2017 (as amended, the “1^st A&R loan agreement”) with the Lenders, which amended and restated in its entirety the Company’s prior loan agreement. The 1^st A&R loan agreement provided for new term loans of up to $15.0 million, with a floating interest rate equal to 7% plus the greater of (i) the 30-day U.S. LIBOR, reported in the Wall Street Journal on the last business day of the month that immediately precedes the month in which the interest will accrue, or (ii) 0.50%.

Under the terms of the 1^st A&R loan agreement, an initial tranche of $8.0 million was advanced on September 28, 2016. The draw period of the remaining $7.0 million available under the 1^st A&R loan agreement expired on March 31, 2018. The Company was required to pay accrued interest only on the outstanding $8.0 million balance through December 31, 2017, followed by 30 equal payments of principal and accrued interest. The Company had the option to prepay the outstanding balance of the term loans in full, subject to a prepayment fee of 2% of the original principal amount of the aggregate term loans for any prepayment through May 31, 2020. A final payment of $0.5 million was due at the maturity of the loan on June 1, 2020, or upon the prepayment of the facility or the acceleration of amounts due under the facility as a result of an event of default, and was being accreted in long-term debt over the life of the loan. Of the $8.0 million borrowed, $5.3 million was used to repay all amounts outstanding under the original loan agreement. Closing costs incurred in the refinancing portion of the loan were recorded as expense while the financing costs for the new portion of the loan are recorded in long-term debt and being accreted over the life of the loan. Upon repayment of the original loan agreement, all remaining closing costs associated with the original loan agreement are being accreted to long-term debt over the life of the 1^st A&R loan agreement.

On May 14, 2018, the Company entered into the 2^nd A&R loan agreement with the Lenders, which amended and restated in its entirety the 1^st A&R loan agreement. The 2^nd A&R loan agreement provides for new term loans of up to $20.0 million, with a floating interest rate equal to 6.50% plus the greater of (i) the 30-day U.S. LIBOR, as reported in the Wall Street Journal on the last business day of the month the immediately precedes the month in which the interest will accrue, or (ii) 1.89%. The 2^nd A&R Loan Agreement includes, among other things, the ability of the Lenders to accelerate the payment of the term loan in the event of a material adverse change and restrictions on the Company’s ability to sell, assign, license, transfer or otherwise dispose of its assets, including intellectual property assets, without the prior written consent of the Lenders.

The Company borrowed an initial tranche of $10.0 million on May 14, 2018, of which $7.0 million was used to repay all amounts outstanding under the 1^st A&R loan agreement, including fees associated with the final payment. The prepayment fees were waived. Of the remaining $10.0 million available under the 2^nd A&R loan agreement, the Company elected not to draw $5.0 million and the other $5.0 million is not available for draw.

On October 18, 2019, the Company entered into the 3^rd Amendment with the Lenders. Pursuant to the 3^rdAmendment, the

Company repaid $5.0 million of the outstanding principal balance of the $10.0 million term loan. The Company did not pay any final

payment or termination fees in connection with the $5.0 million prepayment. In addition, the Company and the Lenders agreed to

modify the term loan repayment schedule. As amended, the term loan repayment schedule provides for interest only payments through

April 30, 2020, or if the Company completes a specified financial milestone, through October 31, 2020, followed by consecutive equal

monthly payments of principal and interest in arrears continuing through the maturity date of October 1, 2022. The Company has the option to prepay the outstanding balance in full, subject to a prepayment fee of 2% of the original principal amount for any prepayment prior to October 1, 2022. A final payment of 5.50% of the aggregate borrowed amount is due at maturity of the loan on October 1, 2022, or upon the prepayment of the facility or the acceleration of amounts due under the facility as a result of an event of default. In addition, the Company agreed that if the Company’s cash and cash equivalents balance with SVB falls below $10.0 million, the Company will transfer to a pledged account an amount of cash and cash equivalents equal to the sum of the then-outstanding principal balance of the term loan plus a final payment fee of $340,441. As a result of the 3^rd Amendment, as of December 31, 2019, the Company has reflected in current liabilities the amount of principal it expects to pay within the next 12 months.

The term loans under the 2^nd A&R loan agreement are secured by substantially all of the Company’s assets.

Interest expense on the borrowings under the loan agreements described above was $804,000, $791,000 and $653,000 for the years ended December 31, 2019, 2018 and 2017, respectively. Accretion of the scheduled final payment was $163,000, $154,000 and $211,000 for the years ended December 31, 2019, 2018 and 2017, respectively. Accretion of the deferred closing costs was $67,000, $112,000 and $212,000 for the years ended December 31, 2019, 2018 and 2017, respectively.

As of December 31, 2019, the scheduled payments for the Loan Agreement, including the scheduled final payment in 2022, were as follows (in thousands):

Year Ending December 31,	Principal		Interest and Final Payment		Total
2020	$	1,333	$	384	$	1,717
2021		2,000		219		2,219
2022		1,667		393		2,060
	$	5,000	$	996	$	5,996

Preferred and Common Stock

12 Months Ended

Dec. 31, 2019

Equity [Abstract]

Preferred and Common Stock

6. Preferred and Common Stock

The Company’s amended and restated certificate of incorporation authorizes the Company to issue 10,000,000 shares of $0.001 par value of preferred stock. As of December 31, 2019 and 2018, there were 10,000,000 shares of preferred stock authorized, none of which were issued and outstanding.

The Company’s amended and restated certificate of incorporation authorizes the Company to issue 100,000,000 shares of $0.001 par value common stock. As of December 31, 2019 and 2018, there were 44,413,372 and 32,119,227 shares of common stock outstanding, respectively.

Common Stock Warrants

12 Months Ended

Dec. 31, 2019

Common Stock Warrants [Abstract]

Common Stock Warrants

7. Common Stock Warrants

In September 2016, in connection with the 1^st A&R loan agreement, the Company issued warrants to the Lenders to purchase up to 29,796 shares of common stock at a price per share of $10.74. The warrants expire in September 2026, or earlier upon the occurrence of specified mergers or acquisitions of the Company, and are immediately exercisable. The warrants were recorded in equity at the time of issuance and had a remaining life of 6.75 years as of December 31, 2019.

Share-Based Compensation

12 Months Ended

Dec. 31, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Share-Based Compensation

8. Share-Based Compensation

Stock Options

In January 2016, the Company’s board of directors adopted and approved the Clearside Biomedical, Inc. 2016 Equity Incentive Plan (the “2016 Plan”) which became effective on June 1, 2016. The 2016 Plan provides for the grant of share-based awards to employees, directors and consultants of the Company. The 2016 Plan provides for the grant of incentive stock options to employees, and for the grant of nonqualified stock options, restricted stock awards, restricted stock unit awards, stock appreciation rights, performance stock awards and other forms of stock compensation to the Company’s employees, directors, and non-employee third parties. The number of shares of common stock reserved for issuance under the 2016 Plan will automatically increase on January 1 each year, for a period of ten years, from January 1, 2017 through January 1, 2026, by 4% of the total number of shares of the Company’s common stock outstanding on December 31 of the preceding calendar year, or a lesser number of shares as may be determined by the Company’s board of directors. At December 31, 2019, under the 2016 Plan, options to purchase 3,391,838 shares of the Company’s common stock were outstanding at a weighted average price of $5.05 per share and 394,545 shares remained available for future grant. As of January 1, 2020, the number of shares of common stock that may be issued under the 2016 Plan was automatically increased by 1,776,534 shares, representing 4% of the total number of shares of common stock outstanding on December 31, 2019, increasing the number of shares of common stock available for issuance under the 2016 Plan as of that date to 2,171,079 shares.

As a result of the adoption of the 2016 Plan, no further grants may be made under the Company’s 2011 Stock Incentive Plan (the “2011 Plan”). The 2011 Plan provided for the grant of share-based awards to employees, directors and consultants of the Company. At December 31, 2019, options to purchase 695,376 shares of the Company’s common stock were outstanding under the 2011 Plan at a weighted average exercise price of $2.53 per share.

The Company has granted stock option awards to employees, directors and consultants. The total share-based compensation expense recognized is reflected in the statements of operations and comprehensive loss as follows (in thousands):

	Year Ended December 31,
	2019		2018		2017

Research and development	$	1,379	$	1,766	$	1,348
General and administrative		2,728		3,004		1,988
Total	$	4,107	$	4,770	$	3,336

Share-based compensation is accounted for in accordance with the provisions of ASC 718, Compensation-Stock Compensation. The estimated fair value of options granted is determined as of the date of grant using the Black-Scholes option pricing model. The resulting fair value is recognized ratably over the requisite service period, which is generally the vesting period of the awards.

The following table sets forth the weighted average assumptions utilized in the Black-Scholes option pricing model to calculate the fair value of the underlying common stock for the years ended December 31, 2019, 2018 and 2017.

	Year Ended December 31,
	2019			2018			2017

Expected term (years)		7.00			7.00			7.00
Expected stock price volatility		109.49	%		93.08	%		96.85	%
Risk-free interest rate		2.49	%		2.87	%		2.20	%
Expected dividend yield		0.00	%		0.00	%		0.00	%

Expected term (in years): The Company utilized the simplified method as prescribed by ASC 718, as the Company does not have sufficient historical exercise and post-vesting termination data to provide a reasonable basis upon which to estimate the expected term of stock options granted to employees.

Risk-free interest rate: The risk-free interest rate is based on the yields of U.S. Treasury securities with maturities similar to the expected time to a possible liquidity event.

Expected dividend yield: The Company has not paid and does not anticipate paying any dividends in the foreseeable future.

Expected stock price volatility: For the years ended December 31, 2019 and 2018, the expected volatility is based on the Company’s historical volatility. For the year ended December 31, 2017, the volatility assumption is based on the historical volatilities of the stock of several public entities that are similar to the Company, as the Company did not have sufficient historical transactions in its own shares on which to base expected volatility. The Company selected representative companies from the pharmaceutical industry with similar characteristics, including stage of product development and therapeutic focus.

Forfeitures: As of January 1, 2017, upon adopting ASU 2016-09, the Company began recording forfeitures as they occurred. In prior years, the Company had estimated its forfeiture rate to be zero for the periods presented and any expense true-ups for terminated employees have been immaterial.

The following table summarizes the activity related to stock options during the year ended December 31, 2019:

				Weighted
	Number of			Average
	Shares			Exercise Price

Options outstanding at December 31, 2018		3,463,096		$	6.62
Granted		1,920,100			1.23
Exercised		(16,362	)		0.40
Cancelled/Forfeited		(1,262,384	)		5.01
Options outstanding at December 31, 2019		4,104,450			4.63

Options exercisable at December 31, 2018		1,583,749			5.63

Options exercisable at December 31, 2019		2,452,764			5.44

The following table provides additional information about the Company’s stock options that were outstanding and exercisable at December 31, 2019 (aggregate intrinsic values in thousands):

							Weighted								Weighted
			Weighted				Average				Weighted				Average
			Average		Aggregate		Remaining				Average		Aggregate		Remaining
Exercise	Options		Exercise		Intrinsic		Contractual		Options		Exercise		Intrinsic		Contractual
Price	Outstanding		Price		Value		Life (Years)		Exercisable		Price		Value		Life (Years)

$0.00 - $2.99		1,759,903						7.40		716,893					4.87
$3.00 - $6.99		1,465,336					5.41			1,012,211					4.06
$7.00 - $8.99		677,433					5.05			568,759					4.61
$9.00 - $20.84		201,778						7.76		154,901					7.76
		4,104,450	$	4.63	$	3,191	6.32			2,452,764	$	5.44	$	1,472	4.66

As of December 31, 2019, the Company had $4.0 million of unrecognized compensation expense related to unvested stock options, which is expected to be recognized over a weighted average period of 2.2 years. The weighted average fair values of all stock options granted for the years ended December 31, 2019, 2018 and 2017 was $1.09 per share, $5.98 per share and $5.25 per share, respectively. The intrinsic value is calculated as the difference between the fair market value and the exercise price per share of the stock options. The fair market value per share of common stock as of December 31, 2019 was $2.90, which was the closing sale price of the Company’s common stock on the Nasdaq Global Market on that date.

Restricted Stock Units

The Company has granted restricted stock units (“RSUs”) to employees under the 2016 Plan. The shares underlying the RSU

awards have vesting terms of eight months to two years from the date of grant, subject to the employees’ continuous service and

subject to accelerated vesting in specified circumstances. The fair value of the RSUs granted is measured based on the market value of the Company’s common stock on the date of grant and is recognized ratably over the requisite service period, which is generally the vesting period of the awards.

The following table summarizes the activity related to RSUs during the year ended December 31, 2019:

				Weighted Average
	Number of			Grant Date
	Shares			Fair Value
Non-vested RSUs outstanding at December 31, 2018		—		$	—
Granted		1,339,300			0.88
Vested		(70,000	)		1.09
Non-vested RSUs outstanding at December 31, 2019		1,269,300			0.87

The Company recorded $0.2 million of share-based compensation expense in research and development and $0.3 million of share-based compensation expense in general and administrative for the year ended December 31, 2019 for the RSUs. As of December 31, 2019, the Company had $0.7 million of unrecognized compensation expense related to the RSUs, which amount is expected to be recognized over a weighted average period of 1.3 years.

Employee Stock Purchase Plan

In January 2016, the Company’s board of directors adopted and approved the Clearside Biomedical, Inc. 2016 Employee Stock Purchase Plan (the “2016 ESPP”) which became effective on June 1, 2016. The 2016 ESPP permits employees to purchase shares of the Company’s common stock through payroll deductions up to 15% of their earnings. The number of shares reserved for issuance under the 2016 ESPP will automatically increase for a period of ten years, from January 1, 2017 through January 1, 2026, by the lesser of (i) 1% of the total number of shares of the Company’s common stock outstanding on December 31 of the preceding calendar year, (ii) 454,545 shares of common stock or (iii) a lesser number of shares as may be determined by the Company’s board of directors. The Company’s board of directors elected not to increase the shares reserved for issuance on January 1, 2020. The number of shares of common stock available for issuance under the 2016 ESPP as of December 31, 2019 was 658,807 shares.

The first offering period for the 2016 ESPP commenced on January 1, 2017. The 2016 ESPP is considered a compensatory plan and the fair value of the discount and the look-back period are estimated using the Black-Scholes option pricing model and expense is recognized over the six-month withholding period prior to the purchase date. During the years ended December 31, 2019, 2018 and 2017, the Company issued 52,476, 12,595 and 9,692 shares, respectively, of common stock purchased under the 2016 ESPP.

The share-based compensation expense recognized for the 2016 ESPP is reflected in the statements of operations and comprehensive loss as follows (in thousands):

	Year Ended December 31,
	2019		2018		2017
Research and development	$	11	$	5	$	7
General and administrative		9		10		21
Total	$	20	$	15	$	28

Income Taxes

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Income Taxes

9. Income Taxes

No provision for U.S. federal or state income taxes has been recorded as the Company has incurred net operating losses since inception. Significant components of the Company’s net deferred income tax assets consist of the following (in thousands):

	December 31,
	2019			2018			2017
Deferred tax asset (liability)
Net operating loss carryforwards	$	46,305		$	41,152		$	27,999
Non-deductible accrued expenses		422			245			248
Right of use asset		(138	)		—			—
Lease liability		264			—			—
Deferred rent		—			148			49
Deferred revenue		—			—			38
Stock compensation expense		1,472			899			387
Depreciation differences		(94	)		(125	)		(18	)
Federal tax credits		7,249			6,481			3,437
State tax credits		623			757			524
Disallowed interest expense		99			—			—
Charitable contributions		4			6			6
Valuation allowance		(56,206	)		(49,563	)		(32,670	)
Net deferred tax asset	$	—		$	—		$	—

A reconciliation of the statutory tax rates and the effective tax rates is as follows:

	Year Ended December 31,
	2019			2018			2017
U.S. federal tax rate		21.00	%		21.00	%		34.00	%
State tax rate		—			(0.73	)		2.42
Permanent difference and other		(1.33	)		(0.33	)		(2.84	)
Tax credit		2.06			3.96			3.97
Valuation allowance		(21.73	)		(20.39	)		(12.42	)
ASC 740-10		—			(3.51	)		—
Impact of federal rate change		—			—			(25.13	)
		0.00	%		0.00	%		0.00	%

In December 2017, the 2017 Tax Cuts and Jobs Act (the “2017 Tax Act”) was signed into law. The 2017 Tax Act significantly revises the U.S. corporate income tax by, among other things, lowering the statutory corporate tax rate from 34% to 21%, eliminating certain deductions, imposing a mandatory one-time tax on accumulated earnings of foreign subsidiaries, introducing new tax regimes, and changing how foreign earnings are subject to U.S. tax. The 2017 Tax Act also enhanced and extended through 2026 the option to claim accelerated depreciation deductions on qualified property. As of December 31, 2017, the Company recorded a provisional tax expense of the impact of the 2017 Tax Act of approximately $14.9 million. This amount was primarily comprised of the re-measurement of federal deferred tax liabilities resulting from the permanent reduction in the U.S. statutory corporate tax rate to 21% from 34%. As of December 31, 2018, the Company had completed the accounting for the effects of the 2017 Tax Act and recorded an insignificant adjustment to the provisional estimate recognized as of December 31, 2017.

Certain items of income and expense are not reported in tax returns and financial statements in the same year. The tax effect of such temporary differences is reported as deferred income taxes. The measurement of deferred tax assets is reduced, if necessary, by the amount of any tax benefit that, based on available evidence, is not expected to be realized. The Company establishes a valuation allowance for deferred tax assets for which realization is not likely. As of each reporting date, management considers new evidence, both positive and negative, that could affect its view of the future realization of deferred tax assets.

At December 31, 2019, the Company had a valuation allowance of $56.2 million recorded against the benefit of certain deferred tax assets. The valuation allowance was primarily related to federal and state net operating loss ("NOL") carryforwards that, in the judgment of management, are not more likely than not to be realized. In assessing the recoverability of the Company’s deferred tax assets, management considered, among other things, its deferred tax liabilities, its historical earnings and losses, projections of future income, and tax-planning strategies available to the Company in the relevant jurisdiction. The Company will release this valuation allowance when management determines that it is more likely than not that its deferred tax asset will be realized.

At December 31, 2019, the Company had income tax NOL carryforwards for federal and state purposes of $219.8 million and $7.6 million, respectively. The Company has recorded a deferred tax asset for both federal and state carryforwards of $46.2 million and $150,000, respectively. If not utilized, the federal NOL carryforwards will begin to expire beginning in 2031, and the state NOL carryforwards will begin to expire at various dates beginning in 2027. Additionally, under the 2017 Tax Act, federal net operating losses incurred in 2018 and beyond may be carried forward indefinitely. However, the deductibility of such federal net operating losses is limited. Certain states have also adopted the indefinite carryforward period beginning with the 2018 tax year, but state conformity varies state by state.

Ownership changes, as defined by Section 382 of the Internal Revenue Code of 1986, as amended (the “Code”), may limit the amount of net operating losses that a company may utilize to offset future taxable income and taxes payable. Pursuant to Section 382 of the Code, an ownership change occurs when the stock ownership of 5% stockholders increases by more than 50% over a testing period of three years. It is possible that the Company has undergone an ownership change as defined by Section 382 of the Code or that the Company may undergo such a change in the future. Any such ownership change may limit the Company’s ability to utilize net operating losses.

The Company is subject to taxation in the United States and certain state jurisdictions. The U.S. federal statute of limitations remains open for the periods from inception and forward. The Company has not been the subject of examination by the taxing authorities.

Liabilities for uncertain tax positions are recognized based on a two-step process. The first step is to evaluate the tax position for recognition by determining if the weight of available evidence indicates that it is more likely than not that the position will be sustained on audit, including resolution of related appeals or litigation processes, if any. Once it is determined that the position meets the recognition threshold, the second step requires the Company to estimate and measure the largest amount of tax benefit that is more likely than not to be realized upon ultimate settlement. The difference between the amount of recognizable tax benefit and the total amount of tax benefit from positions filed or to be filed with the tax authorities is recorded as a liability for uncertain tax benefits.

During 2019, the Company analyzed its uncertain tax positions and recorded an ASC 740-10 reserve in the amount of $2.9 million against its prior year Georgia NOLs. There are no other ASC 740-10 reserves as of December 31, 2019.

Commitment and Contingencies

12 Months Ended

Dec. 31, 2019

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

10. Commitments and Contingencies

Lease Commitment Summary

The Company leases its facilities and some of its equipment under noncancelable operating lease arrangements that expire at various dates through 2023. In November 2016, the Company signed an office lease agreement to lease approximately 20,000 square feet of office space in Alpharetta, Georgia for its corporate headquarters. The lease agreement is for a six and one-half year term with a renewal option for one additional five-year term. Rental payments are $35,145 per month subject to an increase of 3% per year. Operating lease cost under this lease is recognized on a straight-line basis over the term of the lease. In addition, the lease agreement requires payment of the pro-rata share of the annual operating expenses associated with the premises. The Company relocated to this space in March 2017.

In August 2018, the Company signed an office lease agreement to lease approximately 3,500 square feet of office space in Berkeley, California for its commercial operations. The lease agreement was for a two-year term with a renewal option for an additional one-year term. The Company did not exercise the renewal option for the Berkeley lease and terminated the lease on December 15, 2019, with no further payments due. The termination of the lease did not have a material impact on the Company’s statements of operations. Operating lease cost under this lease was recognized on a straight-line basis over the term of the lease. The Company also paid a pro-rata share of the annual operating expenses associated with the premises.

The Company’s operating leases included on the balance sheet are as follows (in thousands):

	December 31, 2019
Operating lease right-of-use asset	$	656

Liabilities
Current portion of operating lease liabilities	$	360
Operating lease liabilities		897
Total operating lease liabilities	$	1,257

The Company recognizes a right-of-use asset for the right to use the underlying asset for the lease term, and a lease liability, which represents the present value of the Company’s obligation to make payments over the lease term. The renewal option is not included in the calculation of the right-of-use asset and the lease liabilities as the Company has not yet determined if the Alpharetta, Georgia lease will be renewed. The present value of the lease payments is calculated using an incremental borrowing rate as the Company’s leases do not provide an implicit interest rate. At December 31, 2019, the Company’s incremental borrowing rate was 11.0% and the remaining lease term was 3.75 years.

Minimum lease payments were as follows at December 31, 2019 (in thousands):

Year ending December 31,
2020	$	378
2021		392
2022		407
2023		316
Total minimum lease payments		1,493
Less imputed interest		(236	)
Total operating lease liabilities	$	1,257

Operating lease cost, variable lease cost and short-term lease cost were $393,000, $83,000 and $20,000, respectively, for the year ended December 31, 2019.

Contract Service Providers

In the course of the Company’s normal business operations, it has agreements with contract service providers to assist in the performance of its research and development, clinical research and manufacturing. Substantially all of these contracts are on an as needed basis.

In May 2018, the Company entered into a manufacturing supply agreement (the “Supply Agreement”), with Gerresheimer Regensburg GmbH, a company incorporated under the laws of Germany (“Gerresheimer”). Gerresheimer will manufacture and supply the Company’s proprietary SCS Microinjector. The Company will provide Gerresheimer with a rolling forecast schedule of its projected purchase orders for at least the next four calendar quarters. The Supply Agreement contains an initial five-year term that will automatically renew for successive periods of three years, unless terminated by either party at least 12 months prior to the end of the applicable term.

License and Other Agreements

12 Months Ended

Dec. 31, 2019

License And Other Agreement [Abstract]

License and Other Agreements

11. License and Other Agreements

Bausch + Lomb

On October 22, 2019, the Company entered into a License Agreement with Bausch + Lomb, a division of Bausch Health Companies, Inc. (“Bausch”). Pursuant to the License Agreement, the Company has granted an exclusive license to Bausch to develop, manufacture, distribute, promote, market and commercialize XIPERE using the Company’s proprietary microneedle (the “Device”), as well as specified other steroids, corticosteroids and NSAIDs in combination with the Device (“Other Products”), subject to specified exceptions, in the United States and Canada for the treatment of ophthalmology indications, including non-infectious uveitis.

Pursuant to the License Agreement, Bausch made an upfront payment of $5.0 million, which is subject to a refund if the License Agreement is terminated in specified circumstances. In addition, Bausch has agreed to make additional payments of up to $15.0 million upon the achievement of specified pre-launch development and regulatory milestones and up to an aggregate of $56.0 million in additional milestone payments upon the achievement of (i) specified regulatory approvals for specified additional indications of XIPERE and (ii) specified levels of annual net sales (as defined in the License Agreement). Further, during the applicable royalty term, the Company will also be entitled to receive tiered royalties at increasing percentages, from the high-teens to twenty percent, based on the achievement of certain annual net sales thresholds in the United States and Canada, as well as a lower royalty on annual net sales of Other Products, in each case subject to reductions in specified circumstances; provided that the Company will not receive any royalties on the first $30.0 million of cumulative net sales of all products.

The Company is responsible for all development expenses for XIPERE until the Company’s New Drug Application (“NDA”) for XIPERE is approved by the FDA, subject to specified exceptions, as well as manufacturing costs in connection with the NDA. The Company is also responsible for all clinical and development expenses conducted to satisfy the FDA’s requests in the complete response letter issued on October 18, 2019 related to the NDA and any subsequent complete response letter related to the NDA (the “CRL-related expenses”). If XIPERE is approved by the FDA, Bausch will be responsible for all expenses following such approval; provided that the Company will be responsible for the CRL-related expenses and for one-half of the costs of any post-approval clinical trials required by the FDA, up to a specified maximum amount.

Due to the refund provisions in the License Agreement, the upfront payment of $5.0 million received from Bausch is included on the balance sheet as deferred revenue as of December 31, 2019 and will remain in deferred revenue until the refund provisions lapse.

REGENXBIO, Inc.

On August 29, 2019, the Company entered into an option and license agreement with REGENXBIO, Inc. (“REGENXBIO”) pursuant to which the Company granted REGENXBIO an exclusive option to enter into a commercial license agreement (the “Option”), which grants REGENXBIO an exclusive, worldwide and sublicensable license to the Company’s SCS Microinjector for the delivery of adeno-associated virus-based gene therapies for the treatment of wet age-related macular degeneration, diabetic retinopathy and other conditions for which anti-vascular endothelial growth factor treatment is currently the standard of care. REGENXBIO exercised the Option on October 29, 2019 and paid the Company an option fee equal to $2.0 million, less a credit of $0.5 million previously received under a technology access agreement. In addition, REGENXBIO has agreed to pay the Company up to an aggregate of $34.0 million in milestone payments upon the achievement of specified development milestones and up to an aggregate of $102.0 million in sales-based milestone payments, as well as mid-single digit royalties on net sales of products using the SCS Microinjector during the royalty term.

As of December 31, 2019, it was determined the Company had completed its performance obligation under the license agreement and recognized license revenue of $2.0 million.

Other

The Company periodically enters into short-term agreements with other customers to evaluate the potential use of its proprietary SCS Microinjector with third-party product candidates for the treatment of various diseases. Funds received from these agreements are recognized as revenue over the term of the agreement. The Company recorded $105,000, $30,000 and $325,000 of revenue from these agreements during the years ended December 31, 2019, 2018 and 2017, respectively.

Fair Value Measurements

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Fair Value Measurements

12. Fair Value Measurements

The Company’s material financial instruments at December 31, 2019 and 2018 consisted primarily of cash and cash equivalents, short-term investments and long-term debt. The fair value of cash and cash equivalents, treasury bills, other current assets and accounts payable approximate their respective carrying values due to the short-term nature of these instruments and are classified as Level 1 in the fair value hierarchy. The fair value of long-term debt approximates the carrying value due to variable interest rates that correspond to market rates. The Company has determined its short-term investments, comprised of commercial paper, to be Level 2 in the fair value hierarchy. The fair value was determined using a market approach, based on prices and other relevant information generated by market transactions involving similar assets. The short-term investments consist of investments with original maturity dates from date of acquisition of 90 to 365 days and are classified as available-for-sale.

There were no significant transfers between Levels 1, 2 and 3 during the years ended December 31, 2019 and 2018.

The following tables summarize the fair value of financial assets and liabilities that are measured at fair value and the classification by level of input within the fair value hierarchy (in thousands):

	December 31, 2019
	Level 1		Level 2		Level 3		Recorded Value
Financial Assets:
Cash and money markets	$	22,595	$	—	$	—	$	22,595
Restricted cash money market		360		—		—		360
Total financial assets	$	22,955	$	—	$	—	$	22,955

	December 31, 2018
	Level 1		Level 2		Level 3		Recorded Value
Financial Assets:
Cash and money markets	$	8,042	$	—	$	—	$	8,042
Restricted cash money market		360		—		—		360
Treasury bills		7,490		—		—		7,490
Commercial paper		—		25,346		—		25,346
Total financial assets	$	15,892	$	25,346	$	—	$	41,238

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Net Loss per Share

12 Months Ended

Dec. 31, 2019

Earnings Per Share [Abstract]

Net Loss Per Share

13. Net Loss Per Share

Basic net loss per share is calculated by dividing the net loss by the weighted average number of shares of common stock outstanding for the period, without consideration of the dilutive effect of potential common stock equivalents. Diluted net loss per share gives effect to all dilutive potential shares of common stock outstanding during this period.

For all periods presented, the Company’s potential common stock equivalents, which included convertible preferred stock, stock options, unvested restricted stock and stock purchase warrants, have been excluded from the computation of diluted net loss per share as their inclusion would have the effect of reducing the net loss per share. Therefore, the denominator used to calculate both basic and diluted net loss per share is the same in all periods presented.

The Company’s potential common stock equivalents that have been excluded from the computation of diluted net loss per share for all periods presented because of their antidilutive effect consisted of the following:

	Year Ended December 31,
	2019		2018		2017
Outstanding stock options		4,104,450		3,075,349		2,243,575
Non-vested restricted stock units		1,269,300		—		—
Stock purchase warrants		29,796		29,796		29,796
		5,403,546		3,105,145		2,273,371

Related Party Transactions

12 Months Ended

Dec. 31, 2019

14. Related Party Transactions

On November 22, 2019, the Company issued shares of common stock in a private placement offering at an offering price of $1.054 per share. Two of the purchasers, Hatteras Venture Partners IV SBIC, LP and Hatteras Venture Partners IV, LP, are affiliated with certain of the Company’s directors and purchased 1,347,629 and 170,397 shares, respectively.

Quarterly Financial Information (Unaudited)

12 Months Ended

Dec. 31, 2019

Quarterly Financial Data [Abstract]

Quarterly Financial Information (Unaudited)

15. Quarterly Financial Information (unaudited)

Summarized quarterly financial information for each of the years ended December 31, 2019 and 2018 are as follows (in thousands except per share data):

	Quarter Ended
	March 31, 2019			June 30, 2019			September 30, 2019			December 31, 2019
Operating expenses ⁽¹⁾	$	(15,351	)	$	(5,662	)	$	(6,509	)	$	(4,955	)
Net loss	$	(15,404	)	$	(5,734	)	$	(6,536	)	$	(3,096	)
Net loss per share of common stock — basic and diluted	$	(0.45	)	$	(0.15	)	$	(0.17	)	$	(0.07	)

(1)

Based upon final reconciliations from the CRO for SAPPHIRE and TOPAZ, the operating expenses include credits related to previously recorded expenses of $2.6 million and $2.0 million in the three months ended June 30, 2019 and December 31, 2019, respectively.

	Quarter Ended
	March 31, 2018			June 30, 2018			September 30, 2018			December 31, 2018
Operating expenses	$	(16,453	)	$	(20,904	)	$	(23,956	)	$	(21,662	)
Net loss	$	(16,607	)	$	(20,701	)	$	(23,872	)	$	(21,638	)
Net loss per share of common stock — basic and diluted	$	(0.62	)	$	(0.65	)	$	(0.75	)	$	(0.68	)

Subsequent Event

12 Months Ended

Dec. 31, 2019

Subsequent Events [Abstract]

Subsequent Event

16. Subsequent Event

On March 10, 2020, the Company entered into a License Agreement (the “License Agreement”) with Arctic Vision (Hong Kong) Limited (“Arctic Vision”). Pursuant to the License Agreement, the Company has granted an exclusive license to Artic Vision to develop, distribute, promote, market and commercialize XIPERE, the Company’s proprietary suspension of the corticosteroid triamcinolone acetonide formulated for administration to the back of the eye using the Company’s proprietary SCS Microinjector, subject to specified exceptions, in China, Hong Kong, Macau, Taiwan and South Korea (the “Territory”). Under the terms of the License Agreement, neither party may commercialize XIPERE in the other party’s territory and Arctic Vision may pursue development and commercialization of XIPERE for indications associated with uveitis or, upon receipt of the Company’s consent, additional indications.

Pursuant to the License Agreement, Arctic Vision has agreed to pay the Company up to a total of $35.5 million. This amount includes an upfront payment of $4.0 million as well as an aggregate of up to $31.5 million in development milestone payments for specified events prior to and including receipt of approval of XIPERE in the United States and sales milestone payments for achievement of specified levels of net sales. Further, during the applicable royalty term, the Company will also be entitled to receive tiered royalties of ten to twelve percent of net sales based on achieving certain annual net sales thresholds in the Territory, subject to customary reductions in specified circumstances.

Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Basis of Presentation

The Company’s financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”).

Use of Estimates

Revenue Recognition

Segment Information

Property and Equipment, Net

Debt Discount

Fair Value Measurements

•

Level 1—Unadjusted quoted prices in active, accessible markets for identical assets or liabilities.

•

Level 2—Other inputs that are directly or indirectly observable in the marketplace.

•

Level 3—Unobservable inputs that are supported by little or no market activity.

The fair value hierarchy also requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value.

Income Taxes

Research and Development Costs

Research and development costs are charged to expense as incurred and include:

•

employee-related expenses, including salaries, benefits, travel and share-based compensation expense for research and development personnel;

•

expenses incurred under agreements with contract research organizations, contract manufacturing organizations and consultants that conduct clinical and preclinical studies;

•

costs associated with preclinical and development activities;

•

costs associated with submitting regulatory approval applications for the Company’s product candidates;

•

costs associated with training physicians on the suprachoroidal injection procedure and educating and providing them with appropriate product candidate information;

•

costs associated with technology and intellectual property licenses;

•

costs for the Company’s research and development facility; and

•

depreciation expense for assets used in research and development activities.

Share-Based Compensation

Cash Equivalents

Cash equivalents consist of short-term, highly liquid investments with an original term of three months or less at the date of purchase.

Short-Term Investments

Restricted Cash

Concentration of Credit Risk Arising From Cash Deposits in Excess of Insured Limits

Recent Accounting Pronouncements

Accounting Pronouncements Recently Adopted

Recent Accounting Pronouncements Not Yet Adopted

Property and Equipment, Net (Tables)

12 Months Ended

Dec. 31, 2019

Property Plant And Equipment [Abstract]

Schedule of Property and Equipment, Net

Property and equipment, net consisted of the following (dollar amounts in thousands):

	Estimated Useful Lives (Years)	December31,
		2019			2018
Furniture and fixtures	5	$	337		$	382
Machinery and equipment	5		121			121
Computer equipment	3		13			19
Leasehold improvements	Lesser of useful life or remaining lease term		667			677
Total property and equipment			1,138			1,199
Less: Accumulated depreciation			(597	)		(409	)
Property and equipment, net		$	541		$	790

Accrued Liabilities (Tables)

12 Months Ended

Dec. 31, 2019

Payables And Accruals [Abstract]

Schedule of Accrued Liabilities

Accrued liabilities consisted of the following (in thousands):

	December 31,
	2019		2018
Accrued research and development	$	359	$	1,263
Accrued employee costs		1,530		1,191
Accrued severance		751		—
Accrued professional fees		58		63
Accrued interest payable		—		76
Accrued expense		232		330
	$	2,930	$	2,923

Long-Term Debt (Tables)

12 Months Ended

Dec. 31, 2019

Debt Disclosure [Abstract]

Scheduled Payments for the Loan Agreement

As of December 31, 2019, the scheduled payments for the Loan Agreement, including the scheduled final payment in 2022, were as follows (in thousands):

Year Ending December 31,	Principal		Interest and Final Payment		Total
2020	$	1,333	$	384	$	1,717
2021		2,000		219		2,219
2022		1,667		393		2,060
	$	5,000	$	996	$	5,996

Share-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Summary of Share-based Compensation Expense

The total share-based compensation expense recognized is reflected in the statements of operations and comprehensive loss as follows (in thousands):

	Year Ended December 31,
	2019		2018		2017

Research and development	$	1,379	$	1,766	$	1,348
General and administrative		2,728		3,004		1,988
Total	$	4,107	$	4,770	$	3,336

Weighted Average Assumptions Used in Black-Scholes Option Pricing Model to Calculate Fair Value of Underlying Common Stock

	Year Ended December 31,
	2019			2018			2017

Expected term (years)		7.00			7.00			7.00
Expected stock price volatility		109.49	%		93.08	%		96.85	%
Risk-free interest rate		2.49	%		2.87	%		2.20	%
Expected dividend yield		0.00	%		0.00	%		0.00	%

Summary of Activity Related to Stock Options

The following table summarizes the activity related to stock options during the year ended December 31, 2019:

				Weighted
	Number of			Average
	Shares			Exercise Price

Options outstanding at December 31, 2018		3,463,096		$	6.62
Granted		1,920,100			1.23
Exercised		(16,362	)		0.40
Cancelled/Forfeited		(1,262,384	)		5.01
Options outstanding at December 31, 2019		4,104,450			4.63

Options exercisable at December 31, 2018		1,583,749			5.63

Options exercisable at December 31, 2019		2,452,764			5.44

Additional Information about the Stock Option Outstanding and Exercisable

The following table provides additional information about the Company’s stock options that were outstanding and exercisable at December 31, 2019 (aggregate intrinsic values in thousands):

							Weighted								Weighted
			Weighted				Average				Weighted				Average
			Average		Aggregate		Remaining				Average		Aggregate		Remaining
Exercise	Options		Exercise		Intrinsic		Contractual		Options		Exercise		Intrinsic		Contractual
Price	Outstanding		Price		Value		Life (Years)		Exercisable		Price		Value		Life (Years)

$0.00 - $2.99		1,759,903						7.40		716,893					4.87
$3.00 - $6.99		1,465,336					5.41			1,012,211					4.06
$7.00 - $8.99		677,433					5.05			568,759					4.61
$9.00 - $20.84		201,778						7.76		154,901					7.76
		4,104,450	$	4.63	$	3,191	6.32			2,452,764	$	5.44	$	1,472	4.66

2016 Employee Stock Purchase Plan

Summary of Share-based Compensation Expense

The share-based compensation expense recognized for the 2016 ESPP is reflected in the statements of operations and comprehensive loss as follows (in thousands):

	Year Ended December 31,
	2019		2018		2017
Research and development	$	11	$	5	$	7
General and administrative		9		10		21
Total	$	20	$	15	$	28

Restricted Stock Units (RSUs)

Summary of the Activity Related to RSUs

The following table summarizes the activity related to RSUs during the year ended December 31, 2019:

				Weighted Average
	Number of			Grant Date
	Shares			Fair Value
Non-vested RSUs outstanding at December 31, 2018		—		$	—
Granted		1,339,300			0.88
Vested		(70,000	)		1.09
Non-vested RSUs outstanding at December 31, 2019		1,269,300			0.87

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Schedule of Net Deferred Tax Assets

Significant components of the Company’s net deferred income tax assets consist of the following (in thousands):

	December 31,
	2019			2018			2017
Deferred tax asset (liability)
Net operating loss carryforwards	$	46,305		$	41,152		$	27,999
Non-deductible accrued expenses		422			245			248
Right of use asset		(138	)		—			—
Lease liability		264			—			—
Deferred rent		—			148			49
Deferred revenue		—			—			38
Stock compensation expense		1,472			899			387
Depreciation differences		(94	)		(125	)		(18	)
Federal tax credits		7,249			6,481			3,437
State tax credits		623			757			524
Disallowed interest expense		99			—			—
Charitable contributions		4			6			6
Valuation allowance		(56,206	)		(49,563	)		(32,670	)
Net deferred tax asset	$	—		$	—		$	—

Schedule of Statutory and Effective Income Tax Rate Reconciliation

A reconciliation of the statutory tax rates and the effective tax rates is as follows:

	Year Ended December 31,
	2019			2018			2017
U.S. federal tax rate		21.00	%		21.00	%		34.00	%
State tax rate		—			(0.73	)		2.42
Permanent difference and other		(1.33	)		(0.33	)		(2.84	)
Tax credit		2.06			3.96			3.97
Valuation allowance		(21.73	)		(20.39	)		(12.42	)
ASC 740-10		—			(3.51	)		—
Impact of federal rate change		—			—			(25.13	)
		0.00	%		0.00	%		0.00	%

Commitment and Contingencies (Tables)

12 Months Ended

Dec. 31, 2019

Commitments And Contingencies Disclosure [Abstract]

Operating Leases Included on the Balance Sheet

The Company’s operating leases included on the balance sheet are as follows (in thousands):

	December 31, 2019
Operating lease right-of-use asset	$	656

Liabilities
Current portion of operating lease liabilities	$	360
Operating lease liabilities		897
Total operating lease liabilities	$	1,257

Future Minimum Commitments Due Under Non-Cancelable Operating Leases

Minimum lease payments were as follows at December 31, 2019 (in thousands):

Year ending December 31,
2020	$	378
2021		392
2022		407
2023		316
Total minimum lease payments		1,493
Less imputed interest		(236	)
Total operating lease liabilities	$	1,257

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Summary of Assets and Liabilities Measured at Fair Value

	December 31, 2019
	Level 1		Level 2		Level 3		Recorded Value
Financial Assets:
Cash and money markets	$	22,595	$	—	$	—	$	22,595
Restricted cash money market		360		—		—		360
Total financial assets	$	22,955	$	—	$	—	$	22,955

	December 31, 2018
	Level 1		Level 2		Level 3		Recorded Value
Financial Assets:
Cash and money markets	$	8,042	$	—	$	—	$	8,042
Restricted cash money market		360		—		—		360
Treasury bills		7,490		—		—		7,490
Commercial paper		—		25,346		—		25,346
Total financial assets	$	15,892	$	25,346	$	—	$	41,238

- Definition

Tabular disclosure of financial instruments measured at fair value, including those classified in shareholders' equity measured on a recurring or nonrecurring basis. Disclosures include, but are not limited to, fair value measurements recorded and the reasons for the measurements, level within the fair value hierarchy in which the fair value measurements are categorized and transfers between levels 1 and 2. Nonrecurring fair value measurements are those that are required or permitted in the statement of financial position in particular circumstances.

+ References + Details

Net Loss per Share (Tables)

12 Months Ended

Dec. 31, 2019

Earnings Per Share [Abstract]

Potential Common Stock Equivalents Excluded from Computation of Diluted Net Loss per Share

	Year Ended December 31,
	2019		2018		2017
Outstanding stock options		4,104,450		3,075,349		2,243,575
Non-vested restricted stock units		1,269,300		—		—
Stock purchase warrants		29,796		29,796		29,796
		5,403,546		3,105,145		2,273,371

Quarterly Financial Information (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2019

Quarterly Financial Data [Abstract]

Summary of Quarterly Financial Information

Summarized quarterly financial information for each of the years ended December 31, 2019 and 2018 are as follows (in thousands except per share data):

	Quarter Ended
	March 31, 2019			June 30, 2019			September 30, 2019			December 31, 2019
Operating expenses ⁽¹⁾	$	(15,351	)	$	(5,662	)	$	(6,509	)	$	(4,955	)
Net loss	$	(15,404	)	$	(5,734	)	$	(6,536	)	$	(3,096	)
Net loss per share of common stock — basic and diluted	$	(0.45	)	$	(0.15	)	$	(0.17	)	$	(0.07	)

(1)

	Quarter Ended
	March 31, 2018			June 30, 2018			September 30, 2018			December 31, 2018
Operating expenses	$	(16,453	)	$	(20,904	)	$	(23,956	)	$	(21,662	)
Net loss	$	(16,607	)	$	(20,701	)	$	(23,872	)	$	(21,638	)
Net loss per share of common stock — basic and diluted	$	(0.62	)	$	(0.65	)	$	(0.75	)	$	(0.68	)

The Company - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Entity incorporation date	May 26, 2011
Cash and cash equivalents	$ 22,595	$ 8,043	$ 9,224

Significant Accounting Policies - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) Segment	Jan. 01, 2019 USD ($)
Significant Accounting Policies [Line Items]
Number of operating segments \| Segment	1
Short-term investments maturity start period	90 days
Short-term investments maturity end period	365 days
Recognition of a right-of use asset	$ 656
Recognition of a lease obligations	$ 1,257
ASU 2016-02
Significant Accounting Policies [Line Items]
Recognition of a right-of use asset		$ 1,000
Recognition of a lease obligations		$ 1,700

Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Property Plant And Equipment [Line Items]
Total property and equipment	$ 1,138	$ 1,199
Less: Accumulated depreciation	(597)	(409)
Property and equipment, net	541	790
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total property and equipment	$ 337	382
Estimated Useful Lives (Years)	5 years
Machinery and Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	$ 121	121
Estimated Useful Lives (Years)	5 years
Computer Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	$ 13	19
Estimated Useful Lives (Years)	3 years
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment	$ 667	$ 677
Estimated Useful Lives (Years)	Lesser of useful life or remaining lease term

Accrued Liabilities - Schedule of Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Payables And Accruals [Abstract]
Accrued research and development	$ 359	$ 1,263
Accrued employee costs	1,530	1,191
Accrued severance	751
Accrued professional fees	58	63
Accrued interest payable		76
Accrued expense	232	330
Accrued liabilities, current	$ 2,930	$ 2,923

Long-Term Debt - Additional Information (Details) - USD ($)				1 Months Ended	12 Months Ended
	Oct. 18, 2019	May 14, 2018	Sep. 28, 2016	Sep. 30, 2016	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Mar. 31, 2018
Debt Instrument [Line Items]
Long term debt					$ 5,000,000
Interest expense on borrowings					804,000	$ 791,000	$ 653,000
Accretion of scheduled final payment					163,000	154,000	211,000
Accretion of deferred closing costs					$ 67,000	$ 112,000	$ 212,000
Third Amended And Restated Loan And Security Agreement
Debt Instrument [Line Items]
Debt instrument, payment terms					On October 18, 2019, the Company entered into the 3rd Amendment with the Lenders. Pursuant to the 3rd Amendment, the Company repaid $5.0 million of the outstanding principal balance of the $10.0 million term loan. The Company did not pay any final payment or termination fees in connection with the $5.0 million prepayment. In addition, the Company and the Lenders agreed to modify the term loan repayment schedule. As amended, the term loan repayment schedule provides for interest only payments through April 30, 2020, or if the Company completes a specified financial milestone, October 31, 2020, followed by consecutive equal monthly payments of principal and interest in arrears continuing through the maturity date of October 1, 2022.
Silicon Valley Bank , MidCap Funding XII Trust and MidCap Financial Trust \| First Amended and Restated Loan and Security Agreement
Debt Instrument [Line Items]
Fixed interest rate				7.00%
Variable interest rate				0.50%
Debt instrument, description of variable rate basis					30-day U.S. LIBOR
Line of credit facility, maximum borrowing capacity				$ 15,000,000
Long term debt			$ 8,000,000
Line of credit facility, remaining borrowing capacity								$ 7,000,000
Line of credit facility, expiration date					Mar. 31, 2018
Debt instrument, payment terms					The Company was required to pay accrued interest only on the outstanding $8.0 million balance through December 31, 2017, followed by 30 equal payments of principal and accrued interest.
Final payment during maturity					$ 500,000
Debt instrument, maturity date					Jun. 01, 2020
Repayment of outstanding amount under the loan agreement including fees			$ 5,300,000
Silicon Valley Bank , MidCap Funding XII Trust and MidCap Financial Trust \| First Amended and Restated Loan and Security Agreement \| Final Payment
Debt Instrument [Line Items]
Repayment of outstanding amount under the loan agreement including fees		$ 7,000,000
Silicon Valley Bank , MidCap Funding XII Trust and MidCap Financial Trust \| First Amended and Restated Loan and Security Agreement \| Prepayments Through May 31, 2020
Debt Instrument [Line Items]
Prepayment fee percentage of the original principal amount of the aggregate term loans				2.00%
Silicon Valley Bank , MidCap Funding XII Trust and MidCap Financial Trust \| Third Amended And Restated Loan And Security Agreement
Debt Instrument [Line Items]
Long term debt	$ 10,000,000
Debt instrument, maturity date	Oct. 01, 2022
Repayment of outstanding amount under the loan agreement including fees	$ 5,000,000
Debt instrument final payment	340,441
Minimum balance requirement cash and cash equivalents	$ 10,000,000
Final payment during maturity, percentage					5.50%
Silicon Valley Bank , MidCap Funding XII Trust and MidCap Financial Trust \| Third Amended And Restated Loan And Security Agreement \| Prepayments Through May 31, 2020
Debt Instrument [Line Items]
Prepayment fee percentage of the original principal amount of the aggregate term loans					2.00%
Silicon Valley Bank, MidCap Funding III Trust and MidCap Financial Trust \| Second Amended and Restated Loan and Security Agreement
Debt Instrument [Line Items]
Fixed interest rate		6.50%
Variable interest rate		1.89%
Debt instrument, description of variable rate basis					30-day U.S. LIBOR
Line of credit facility, maximum borrowing capacity		$ 20,000,000
Long term debt		10,000,000
Line of credit facility remaining borrowing capacity not available for withdraw		5,000,000
Silicon Valley Bank, MidCap Funding III Trust and MidCap Financial Trust \| Second Amended and Restated Loan and Security Agreement \| Term C Loan
Debt Instrument [Line Items]
Line of credit facility, remaining borrowing capacity		5,000,000
Line of credit facility, remaining borrowing capacity description					Of the remaining $10.0 million available under the 2nd A&R loan agreement, the Company elected not to draw $5.0 million and the other $5.0 million is not available for draw.
Silicon Valley Bank, MidCap Funding III Trust and MidCap Financial Trust \| Second Amended and Restated Loan and Security Agreement, Initial Tranche
Debt Instrument [Line Items]
Long term debt		$ 10,000,000

Long-Term Debt - Scheduled Payments for the Loan Agreement (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Debt Disclosure [Abstract]
Principal, 2020	$ 1,333
Principal, 2021	2,000
Principal, 2022	1,667
Principal	5,000
Interest and Final Payment, 2020	384
Interest and Final Payment, 2021	219
Interest and Final Payment, 2022	393
Interest and Final Payment	996
Total, 2020	1,717
Total, 2021	2,219
Total, 2022	2,060
Total	$ 5,996

Preferred and Common Stock - Additional Information (Detail) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Equity [Abstract]
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, shares authorized	100,000,000	100,000,000
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares outstanding	44,413,372	32,119,227

Common Stock Warrants - Additional Information (Details) - Convertible Stock Warrant - First Amended and Restated Loan and Security Agreement - $ / shares	1 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2019
Class Of Warrant Or Right [Line Items]
Class of warrant Exercise	$ 10.74
Warrants expiration term	2026-09
Weighted average remaining life of warrants		6 years 9 months
Maximum
Class Of Warrant Or Right [Line Items]
Number of stock that can be purchased by each warrant	29,796

Share-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended
	Jan. 01, 2020	Jan. 31, 2016	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
2016 Stock Incentive Plan \| Subsequent Event
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Annual increase of common stock reserved for issuance	4.00%
Increase in common stock for future issuance, shares	1,776,534,000
Shares common stock reserved for issuance	2,171,079,000
2016 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based compensation arrangement description			The number of shares reserved for issuance under the 2016 ESPP will automatically increase for a period of ten years, from January 1, 2017 through January 1, 2026, by the lesser of (i) 1% of the total number of shares of the Company’s common stock outstanding on December 31 of the preceding calendar year, (ii) 454,545 shares of common stock or (iii) a lesser number of shares as may be determined by the Company’s board of directors
Annual increase of common stock reserved for issuance		1.00%
Shares common stock reserved for issuance			658,807
Employee payroll deductions, percent		15.00%
Number of shares reserved for issuance increase in years		10 years
Addition of common stock shares reserved for future issuance		454,545
Common stock purchased			52,476	12,595	9,692
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares grants			1,920,100
Option to purchase common stock shares outstanding			4,104,450	3,463,096
Weighted average exercise price			$ 4.63	$ 6.62
Unrecognized compensation expense related to unvested stock options			$ 4,000
Expected to be recognized over a weighted average period			2 years 2 months 12 days
Weighted-average fair values granted			$ 1.09	$ 5.98	$ 5.25
Fair market value per share of common stock			$ 2.90
Share-based compensation expense			$ 4,107	$ 4,770	$ 3,336
Stock Options \| Research And Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense			1,379	1,766	1,348
Stock Options \| General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense			$ 2,728	$ 3,004	$ 1,988
Stock Options \| 2016 Stock Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based compensation arrangement description			The number of shares of common stock reserved for issuance under the 2016 Plan will automatically increase on January 1 each year, for a period of ten years, from January 1, 2017 through January 1, 2026, by 4% of the total number of shares of the Company’s common stock outstanding on December 31 of the preceding calendar year, or a lesser number of shares as may be determined by the Company’s board of directors.
Annual increase of common stock reserved for issuance			4.00%
Option to purchase common stock shares outstanding			3,391,838
Weighted average exercise price			$ 5.05
Shares available for future grant			394,545
Stock Options \| 2011 Stock Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares grants			0
Option to purchase common stock shares outstanding			695,376
Weighted average exercise price			$ 2.53
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected to be recognized over a weighted average period			1 year 3 months 18 days
Unrecognized compensation expense related to the RSUs			$ 700
Restricted Stock Units (RSUs) \| Research And Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense			200
Restricted Stock Units (RSUs) \| General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense			$ 300

Share-Based Compensation - Summary of Share-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
2016 Employee Stock Purchase Plan
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 20	$ 15	$ 28
Research and Development \| 2016 Employee Stock Purchase Plan
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	11	5	7
General and Administrative \| 2016 Employee Stock Purchase Plan
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	9	10	21
Stock Options
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	4,107	4,770	3,336
Stock Options \| Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	1,379	1,766	1,348
Stock Options \| General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 2,728	$ 3,004	$ 1,988

Share-Based Compensation - Weighted Average Assumptions Used in Black-Scholes Option Pricing Model to Calculate Fair Value of Underlying Common Stock (Details) - Stock Options	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Expected term (years)	7 years	7 years	7 years
Expected stock price volatility	109.49%	93.08%	96.85%
Risk-free interest rate	2.49%	2.87%	2.20%
Expected dividend yield	0.00%	0.00%	0.00%

Share-Based Compensation - Summary of Activity Related to Stock Options (Details) - Stock Options - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Options outstanding, Beginning balance	3,463,096
Number of Shares, Granted	1,920,100
Number of Shares, Exercised	(16,362)
Number of Shares, Cancelled/Forfeited	(1,262,384)
Number of Shares, Options outstanding, Ending balance	4,104,450	3,463,096
Number of Shares, Options exercisable	2,452,764	1,583,749
Weighted Average Exercise Price, Options outstanding, Beginning balance	$ 6.62
Weighted Average Exercise Price, Granted	1.23
Weighted Average Exercise Price, Exercised	0.40
Weighted Average Exercise Price, Cancelled/Forfeited	5.01
Weighted Average Exercise Price, Options outstanding, Ending balance	4.63	$ 6.62
Weighted Average Exercise Price, Options exercisable	$ 5.44	$ 5.63

Share-Based Compensation - Additional Information about the Stock Option Outstanding and Exercisable (Details) - Stock Options - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	4,104,450	3,463,096
Weighted Average Exercise Price	$ 4.63	$ 6.62
Aggregate Intrinsic Value	$ 3,191
Weighted Average Remaining Contractual Life (Years)	6 years 3 months 25 days
Options Exercisable	2,452,764	1,583,749
Weighted Average Exercise Price	$ 5.44	$ 5.63
Aggregate Intrinsic Value	$ 1,472
Weighted Average Remaining Contractual Life (Years)	4 years 7 months 28 days
$0.00 - $2.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Lower Range Limit	$ 0.00
Exercise Price Upper Range Limit	$ 2.99
Options Outstanding	1,759,903
Weighted Average Remaining Contractual Life (Years)	7 years 4 months 24 days
Options Exercisable	716,893
Weighted Average Remaining Contractual Life (Years)	4 years 10 months 13 days
$3.00 - $6.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Lower Range Limit	$ 3.00
Exercise Price Upper Range Limit	$ 6.99
Options Outstanding	1,465,336
Weighted Average Remaining Contractual Life (Years)	5 years 4 months 28 days
Options Exercisable	1,012,211
Weighted Average Remaining Contractual Life (Years)	4 years 21 days
$7.00 - $8.99
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Lower Range Limit	$ 7.00
Exercise Price Upper Range Limit	$ 8.99
Options Outstanding	677,433
Weighted Average Remaining Contractual Life (Years)	5 years 18 days
Options Exercisable	568,759
Weighted Average Remaining Contractual Life (Years)	4 years 7 months 9 days
$9.00 - $20.84
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Lower Range Limit	$ 9.00
Exercise Price Upper Range Limit	$ 20.84
Options Outstanding	201,778
Weighted Average Remaining Contractual Life (Years)	7 years 9 months 3 days
Options Exercisable	154,901
Weighted Average Remaining Contractual Life (Years)	7 years 9 months 3 days

Share-Based Compensation - Summary of the Activity Related to RSUs (Details) - Restricted Stock Units (RSUs)	12 Months Ended
	Dec. 31, 2019 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Granted \| shares	1,339,300
Number of Shares, Vested \| shares	(70,000)
Non-vested units outstanding, Number of Shares, Ending balance \| shares	1,269,300
Weighted Average Grant Date Fair Value, Granted \| $ / shares	$ 0.88
Weighted Average Grant Date Fair Value, Vested \| $ / shares	1.09
Non-vested units outstanding, Weighted Average Grant Date Fair Value, Ending balance \| $ / shares	$ 0.87

Income Tax - Additional Information (Detail) - USD ($)	12 Months Ended
Income Tax - Additional Information (Detail) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Line Items]
U.S. federal tax rate	21.00%	21.00%	34.00%
Tax Cuts and Jobs Act of 2017,Provisional Income Tax Expense			$ 14,900,000
Deferred tax assets, valuation allowance	$ 56,206,000	$ 49,563,000	32,670,000
Deferred tax assets, operating loss carryforwards	$ 46,305,000	$ 41,152,000	$ 27,999,000
Operating loss carryforwards, limitations on use	Ownership changes, as defined by Section 382 of the Internal Revenue Code of 1986, as amended (the “Code”), may limit the amount of net operating losses that a company may utilize to offset future taxable income and taxes payable. Pursuant to Section 382 of the Code, an ownership change occurs when the stock ownership of 5% stockholders increases by more than 50% over a testing period of three years. It is possible that the Company has undergone an ownership change as defined by Section 382 of the Code or that the Company may undergo such a change in the future. Any such ownership change may limit the Company’s ability to utilize net operating losses.
Reserve for tax positions of prior years	$ 2,900,000
U.S. Federal or State Income Taxes
Income Tax Disclosure [Line Items]
Provision for income taxes	0
Federal
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	219,800,000
Deferred tax assets, operating loss carryforwards	$ 46,200,000
Federal \| Earliest Tax Year
Income Tax Disclosure [Line Items]
Operating loss carryforwards expiration period	2031
State
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 7,600,000
Deferred tax assets, operating loss carryforwards	$ 150,000
State \| Earliest Tax Year
Income Tax Disclosure [Line Items]
Operating loss carryforwards expiration period	2027

Schedule of Net Deferred Tax Assets (Detail) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred tax asset (liability)
Net operating loss carryforwards	$ 46,305,000	$ 41,152,000	$ 27,999,000
Non-deductible accrued expenses	422,000	245,000	248,000
Right of use asset	(138,000)
Lease liability	264,000
Deferred rent		148,000	49,000
Deferred revenue			38,000
Stock compensation expense	1,472,000	899,000	387,000
Depreciation differences	(94,000)	(125,000)	(18,000)
Disallowed interest expense	99,000
Charitable contributions	4,000	6,000	6,000
Valuation allowance	(56,206,000)	(49,563,000)	(32,670,000)
Federal
Deferred tax asset (liability)
Net operating loss carryforwards	46,200,000
Tax credits	7,249,000	6,481,000	3,437,000
State
Deferred tax asset (liability)
Net operating loss carryforwards	150,000
Tax credits	$ 623,000	$ 757,000	$ 524,000

Schedule of Statutory and Effective Income Tax Rate Reconciliation (Detail)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
U.S. federal tax rate	21.00%	21.00%	34.00%
State tax rate		(0.73%)	2.42%
Permanent difference and other	(1.33%)	(0.33%)	(2.84%)
Tax credit	2.06%	3.96%	3.97%
Valuation allowance	(21.73%)	(20.39%)	(12.42%)
ASC 740-10		(3.51%)
Impact of federal rate change			(25.13%)
Total income tax provision (benefit)	0.00%	0.00%	0.00%

Commitment and Contingencies - Additional Information (Details)	1 Months Ended			12 Months Ended
	Aug. 31, 2018 USD ($) ft²	May 31, 2018	Nov. 30, 2016 USD ($) ft²	Dec. 31, 2019 USD ($)
Commitment And Contingencies [Line Items]
Lessee, operating lease, option to extend, description				The renewal option is not included in the calculation of the right-of-use asset and the lease liabilities as the Company has not yet determined if the Alpharetta, Georgia lease will be renewed.
Incremental borrowing rate				11.00%
Operating lease, remaining lease term				3 years 9 months
Operating Lease, Cost				$ 393,000
Variable Lease, Cost				83,000
Short-term Lease, Cost				$ 20,000
Manufacturing Supply Agreement \| Gerresheimer Regensburg GmbH
Commitment And Contingencies [Line Items]
Initial term of agreement		5 years
Renewal term of agreement		3 years
GEORGIA
Commitment And Contingencies [Line Items]
Area of office leased \| ft²			20,000
Operating lease agreement term			6 years 6 months
Operating lease agreement renewal option term			5 years
Minimum monthly lease payments			$ 35,145
Percentage of increase per year			3.00%
CALIFORNIA
Commitment And Contingencies [Line Items]
Area of office leased \| ft²	3,500
Operating lease agreement term	2 years
Operating lease agreement renewal option term	1 year
Lease termination date	Dec. 15, 2019
Operating lease liability payments due	$ 0

Commitment and Contingencies - Operating Leases Included on the Balance Sheet (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Commitments And Contingencies Disclosure [Abstract]
Operating lease right-of-use asset	$ 656
Liabilities
Current portion of operating lease liabilities	360
Operating lease liabilities	897
Total operating lease liabilities	$ 1,257

Commitment and Contingencies - Future Minimum Commitments Due Under Non-Cancelable Operating Leases (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2020	$ 378
2021	392
2022	407
2023	316
Total minimum lease payments	1,493
Less imputed interest	(236)
Total operating lease liabilities	$ 1,257

License and Other Agreements - Additional Information (Detail) - USD ($)			12 Months Ended
	Oct. 29, 2019	Oct. 22, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Research And Development Arrangement Contract To Perform For Others [Line Items]
Deferred revenue			$ 5,000,000
Revenue			2,173,000	$ 30,000	$ 345,000
Other Agreements
Research And Development Arrangement Contract To Perform For Others [Line Items]
Revenue			105,000	$ 30,000	$ 325,000
Commercial Arrangement \| Maximum
Research And Development Arrangement Contract To Perform For Others [Line Items]
Pre-launch milestone payments		$ 15,000,000
Additional milestone payments		56,000,000
License Arrangement \| REGENXBIO, Inc.
Research And Development Arrangement Contract To Perform For Others [Line Items]
Option fee paid	$ 2,000,000
Proceeds from option fee previously received	500,000
Milestone payments	34,000,000
Sales-based milestone payments	$ 102,000,000
License Arrangement \| REGENXBIO, Inc. \| License
Research And Development Arrangement Contract To Perform For Others [Line Items]
Revenue			2,000,000
Bausch Lomb
Research And Development Arrangement Contract To Perform For Others [Line Items]
Upfront payment		5,000,000
First cumulative net sales of products		$ 30,000,000
Bausch Lomb \| Upfront payment
Research And Development Arrangement Contract To Perform For Others [Line Items]
Deferred revenue			$ 5,000,000

Fair Value Measurements - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Short-term investments maturity start period	90 days
Short-term investments maturity end period	365 days
Significant transfers between Levels 1, 2 and 3	$ 0	$ 0

Fair Value Measurements - Summary of Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financial Assets:
Total financial assets	$ 22,955	$ 41,238
Treasury Bills
Financial Assets:
Total financial assets		7,490
Commercial Paper
Financial Assets:
Total financial assets		25,346
Level 1
Financial Assets:
Total financial assets	22,955	15,892
Level 1 \| Treasury Bills
Financial Assets:
Total financial assets		7,490
Level 2
Financial Assets:
Total financial assets		25,346
Level 2 \| Commercial Paper
Financial Assets:
Total financial assets		25,346
Cash and Money Markets
Financial Assets:
Total financial assets	22,595	8,042
Cash and Money Markets \| Level 1
Financial Assets:
Total financial assets	22,595	8,042
Restricted Cash Money Market
Financial Assets:
Total financial assets	360	360
Restricted Cash Money Market \| Level 1
Financial Assets:
Total financial assets	$ 360	$ 360

Net Loss Per Share - Potential Common Stock Equivalents Excluded from Computation of Diluted Net Loss per Share (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	5,403,546	3,105,145	2,273,371
Outstanding Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	4,104,450	3,075,349	2,243,575
Non-vested Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	1,269,300
Stock Purchase Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	29,796	29,796	29,796

Related Party Transactions (Detail) - Private Placement	Nov. 22, 2019 $ / shares shares
Related Party Transaction [Line Items]
Shares issued, price per share \| $ / shares	$ 1.054
Hatteras venture partners IV SBIC, LP
Related Party Transaction [Line Items]
Shares, issued	1,347,629
Hatteras venture partners IV, LP
Related Party Transaction [Line Items]
Shares, issued	170,397

Quarterly Financial Information (Unaudited) - Summary of Quarterly Financial Information - (Details) - USD ($)
$ / shares in Units, $ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2019

Sep. 30, 2019

Jun. 30, 2019

Mar. 31, 2019

Dec. 31, 2018

Sep. 30, 2018

Jun. 30, 2018

Mar. 31, 2018

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

Quarterly Financial Data [Abstract]

Operating expenses

$ (4,955)

^[1]

$ (6,509)

^[1]

$ (5,662)

^[1]

$ (15,351)

^[1]

$ (21,662)

$ (23,956)

$ (20,904)

$ (16,453)

$ (32,477)

$ (82,975)

$ (58,753)

Net loss

$ (3,096)

$ (6,536)

$ (5,734)

$ (15,404)

$ (21,638)

$ (23,872)

$ (20,701)

$ (16,607)

$ (30,770)

$ (82,818)

$ (58,975)

Net loss per share of common stock — basic and diluted

$ (0.07)

$ (0.17)

$ (0.15)

$ (0.45)

$ (0.68)

$ (0.75)

$ (0.65)

$ (0.62)

$ (0.81)

$ (2.69)

$ (2.33)

[1]	Based upon final reconciliations from the CRO for SAPPHIRE and TOPAZ, the operating expenses include credits related to previously recorded expenses of $2.6 million and $2.0 million in the three months ended June 30, 2019 and December 31, 2019, respectively.

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Quarterly Financial Information (Unaudited) - Summary of Quarterly Financial Information - (Parenthetical) - (Details) - USD ($)
$ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2019

Sep. 30, 2019

^[1]

Jun. 30, 2019

Mar. 31, 2019

^[1]

Dec. 31, 2018

Sep. 30, 2018

Jun. 30, 2018

Mar. 31, 2018

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

Operating Expenses

$ 4,955

^[1]

$ 6,509

$ 5,662

^[1]

$ 15,351

$ 21,662

$ 23,956

$ 20,904

$ 16,453

$ 32,477

$ 82,975

$ 58,753

Clinical Trials | SAPHHIRE

Operating Expenses

2,000

2,600

Clinical Trials | TOPAZ

Operating Expenses

$ 2,000

$ 2,600

[1]	Based upon final reconciliations from the CRO for SAPPHIRE and TOPAZ, the operating expenses include credits related to previously recorded expenses of $2.6 million and $2.0 million in the three months ended June 30, 2019 and December 31, 2019, respectively.

Subsequent Event - Additional Information (Details) - Subsequent Event - Arctic Vision Limited $ in Millions	Mar. 10, 2020 USD ($)
Subsequent Event [Line Items]
Amount of upfront payment and development milestones payment to be received under license agreement	$ 35.5
Upfront payment	4.0
Maximum
Subsequent Event [Line Items]
Development milestone payments	$ 31.5
Threshold percentage of sales for tiered royalties	12.00%
Minimum [Member]
Subsequent Event [Line Items]
Threshold percentage of sales for tiered royalties	10.00%