Operations and Basis of Presentation - Additional Information (Detail) $ in Thousands, Surgery in Millions	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2019 USD ($) Product _People Case	Dec. 31, 2018 USD ($) Surgery	Jan. 01, 2019 USD ($)
Operations [Line Items]
Number of products approved | Product		2
Cash and cash equivalents	$ 31,760	$ 31,760	$ 45,261
Accumulated deficit	454,876	454,876	408,493
Working capital	36,700	36,700
Operating Lease, Liability	3,489	3,489
Operating Lease, Right-of-Use Asset	3,186	3,186	$ 0
Accounting Standards Update 2018-11 [Member]
Operations [Line Items]
Operating Lease, Liability				$ 3,700
Operating Lease, Right-of-Use Asset				$ 3,500
At-the-Market Offering [Member]
Operations [Line Items]
Gross proceeds from issuance of common stock	$ 2,600	$ 2,600
YUTIQ [Member]
Operations [Line Items]
Number of new cases of blindness every year | Case		30,000
YUTIQ [Member] | Minimum [Member]
Operations [Line Items]
Number of people affected by posterior segment of eye in U.S. each year | _People		55,000
YUTIQ [Member] | Maximum [Member]
Operations [Line Items]
Number of people affected by posterior segment of eye in U.S. each year | _People		120,000
DEXYCU [Member]
Operations [Line Items]
Number of cataract surgeries performed in U.S. | Surgery			4.8
Estimated annual growth rate of cataract surgeries performed in U.S.		8.00%