Intangible Assets

6 Months Ended

Jun. 30, 2021

Goodwill And Intangible Assets Disclosure [Abstract]

Intangible Assets

5. Intangible Assets

The reconciliation of intangible assets for the six months ended June 30, 2021 and 2020 was as follows (in thousands):

	June 30,			June 30,
	2021			2020
Patented technologies
Gross carrying amount at beginning of period	$	68,322		$	68,322
Gross carrying amount at end of period		68,322			68,322
Accumulated amortization at beginning of period		(43,113	)		(40,653	)
Amortization expense		(1,230	)		(1,230	)
Accumulated amortization at end of period		(44,343	)		(41,883	)
Net book value at end of period	$	23,979		$	26,439

The Company amortizes intangible assets with finite lives on a straight-line basis over their respective estimated useful lives. Amortization of intangible assets totaled $615,000 and $1.2 million for each of the three and six months ended June 30, 2021 and 2020, respectively.  

In connection with the Icon Acquisition, the initial purchase price was attributed to the DEXYCU product intangible asset. This finite-lived intangible asset is being amortized on a straight-line basis over its expected remaining useful life of 9.75 years at the rate of approximately $2.5 million per year. Amortization expense was reported as a component of cost of sales for the three and six months ended June 30, 2021 and 2020, respectively.