Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Assumptions Used to Compute Share-Based Compensation Costs for Stock Options Granted

The assumptions used to compute the share-based compensation costs for the stock options granted during the years ended December 31, 2020 and 2019, using the Black-Scholes option pricing model, were as follows:

	Year Ended December 31,
	2020			2019
Weighted average grant date fair value of    stock options	$	2.93		$	1.84
Assumptions
Risk-free interest rate (weighted average)		0.44	%		2.36	%
Expected dividend yield		—			—
Weighted average expected life (years)		6.2			6.2
Volatility (weighted average)		80.8	%		78.7	%
Forfeiture rate		12.0	%		26.0	%

F-22

Assumptions Used Estimate Fair Value of Employee Stock Purchase Plans

Following is a schedule of the shares purchased, the fair value per share, and the Black-Scholes model assumptions for each offering period:

	September 30,			March 31,			September 30,			March 31,
Offering Period Ended	2020			2020			2019			2019
Shares purchased for offering    period		4,184			1,536			2,195			2,112
Fair value per share	$	1.75		$	2.28		$	1.07		$	0.96
Assumptions
Risk-free interest rate (average)		0.29	%		1.84	%		2.44	%		2.29	%
Expected dividend yield		—			—			—			—
Weighted average expected life    (years)		0.5			0.5			0.5			0.5
Volatility (average)		86.8	%		86.3	%		51.7	%		54.3	%

Non-Cash Stock-Based Compensation Expenses

Non-cash stock-based compensation expenses related to stock options, restricted stock grants and the ESPP were recorded in the financial statements as follows (in thousands):

	Year Ended December 31,
	2020		2019
Selling and marketing	$	549	$	247
Research and development		559		278
General and administrative		1,956		969
Total non-cash stock compensation expense	$	3,064	$	1,494

F-23

Summary of Outstanding Stock Options and Related Activity

A summary of the Company’s stock options outstanding under the 2015 OEIP and 2005 Plan as of December 31, 2020 and the activity during the years ended herein are as follows (in thousands except per share amounts):

	Shares			Weighted Avg. Exercise Price		Wtd. Avg. Remaining Contractual Life (Yrs)		Aggregate Intrinsic Value
Outstanding as of December 31, 2018		158		$	4.88		5.9	$	—
(121 options exercisable at a weighted average    exercise price of $5.64)
Granted		65		$	2.65			$	—
Exercised		(13	)	$	3.81			$	28
Canceled / expired		(13	)	$	7.81			$	22
Outstanding as of December 31, 2019		197		$	4.03		6.3	$	171
(112 options exercisable at a weighted average    exercise price of $5.16)
Granted		22		$	4.25			$	—
Exercised		(13	)	$	2.14			$	39
Canceled / expired		(1	)	$	42.04			$	—
Outstanding as of December 31, 2020		205		$	3.95		5.6	$	341
Exercisable as of December 31, 2020		135		$	4.35		4.1	$	183
Vested and expected to vest at December 31, 2020		181		$	3.77		5.5	$	304

Summary of Outstanding Restricted Stock Awards and Related Activity

A summary of the Company’s restricted stock awards outstanding under the 2015 OEIP and 2005 Plan as of December 31, 2020, and the activity during years ended therein, are as follows (in thousands):

				Weighted average
	Number					grant date
	of shares					fair value
Unvested at December 31, 2018		1,007			2.01
Granted		1,250			2.00
Vested		(673	)		2.06
Canceled and forfeited		(25	)		1.97
Unvested at December 31, 2019		1,559			1.98
Granted		1,000			6.40
Vested		(857	)		2.99
Canceled and forfeited		—			—
Unvested at December 31, 2020		1,702			4.07

F-24