5. Fair Value Measurements

Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. The fair value hierarchy distinguishes between (1) market participant assumptions developed based on market data obtained from independent sources (observable inputs) and (2) an entity’s own assumptions about market participant assumptions developed based on the best information available in the circumstances (unobservable inputs). The fair value hierarchy consists of three broad levels, which gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). The three levels of the fair value hierarchy are described below:

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Level 1: Quoted prices (unadjusted) in active markets that are accessible at the measurement date for assets or liabilities.

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Level 2: Directly or indirectly observable inputs as of the reporting date through correlation with market data, including quoted prices for similar assets and liabilities in active markets and quoted prices in markets that are not active. Level 2 also includes assets and liabilities that are valued using models or other pricing methodologies that do not require significant judgment since the input assumptions used in the models, such as interest rates and volatility factors, are corroborated by readily observable data from actively quoted markets for substantially the full term of the financial instrument.

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Level 3: Unobservable inputs that are supported by little or no market activity and reflect the use of significant management judgment. These values are generally determined using pricing models for which the assumptions utilize management’s estimates of market participant assumptions.

In determining fair value, the Company utilizes valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible, as well as considers counterparty credit risk in its assessment of fair value.

The carrying amounts of the Company’s financial assets and liabilities, including cash and cash equivalents, accounts receivable, accounts payable, and accrued expenses as of September 30, 2017 and December 31, 2016, approximate fair value because of the short maturity of these instruments.

As of September 30, 2017 and December 31, 2016, financial assets and liabilities measured and recognized at fair value on a recurring basis and classified under the appropriate level of the fair value hierarchy as described above were as follows:

	As of September 30, 2017								As of December 31, 2016
	Fair Value Measurements								Fair Value Measurements
(in thousands)	Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3		Total
Assets:
Money market funds	$	22,149	$	—	$	—	$	22,149	$	8,270	$	—	$	—	$	8,270
Liabilities:
Earn-out liability	$	—	$	—	$	524	$	524	$	—	$	—	$	694	$	694

The Company’s Level 1 financial assets are money market funds whose fair values are based on quoted market prices. The Company does not have any Level 2 financial assets or liabilities. The fair value of the earn-out liability arising from the acquisition of RetinaLabs, Inc. is classified within Level 3 of the fair value hierarchy since it is based on significant unobservable inputs. The significant unobservable inputs include projected royalties and discount rates to present value the payments. A significant increase (decrease) in the projected royalty payments in isolation could result in a significantly higher (lower) fair value measurement and a significant increase (decrease) in the discount rate in isolation could result in a significantly lower (higher) fair value measurement. The fair value of the earn-out liability is calculated on a quarterly basis by the Company based on a collaborative effort of the Company’s operations, finance and accounting groups as additional information becomes available. Any change in the fair value adjustment is recorded in the statement of operations of that period.

The following tables present quantitative information about the inputs and valuation methodologies used for our fair value measurements classified in Level 3 of the fair value hierarchy as of September 30, 2017 and December 31, 2016.

As of September 30, 2017	Fair Value (in thousands)		Valuation Technique	Significant Unobservable Input	Weighted Average (range)
Earn-out liability	$	524	Discounted cash flow	Projected royalties (in thousands)	$1,719
				Discount rate	10.89% (10.89% - 27.00%)

As of December 31, 2016	Fair Value (in thousands)		Valuation Technique	Significant Unobservable Input	Weighted Average (range)
Earn-out liability	$	694	Discounted cash flow	Projected royalties (in thousands)	$2,154
				Discount rate	11.22% (11.22% - 27.00%)

A reconciliation of the changes in the Company’s earn-out liability (Level 3 liability) for the nine months ended September 30, 2017 and October 1, 2016 is as follows:

	Nine Months Ended
(in thousands)	September 30, 2017			October 1, 2016
Balance as of beginning of the period	$	694		$	1,005
Payments against earn-out		(292	)		(313	)
Change in fair value of earn-out liability		122			86
Balance as of the end of the period	$	524		$	778

The earn-out liability is included in accrued expenses and other long-term liabilities in the condensed consolidated balance sheets. Any change in the fair value adjustment is recorded to other expense in the condensed consolidated statements of operations.