Business Segments - Schedule of Revenue Information by Product (Details) - USD ($) $ in Thousands		3 Months Ended			6 Months Ended
		Jul. 02, 2022	Jul. 03, 2021	Jul. 03, 2021	Jul. 02, 2022	Jul. 03, 2021
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues		$ 13,755	$ 13,426	$ 13,426	$ 27,142	$ 25,385
Cyclo G6
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues		3,477	3,599		7,017	6,948
Retina
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues		7,529	7,575		14,830	14,235
Other
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues	[1]	$ 2,749	$ 2,252		$ 5,295	$ 4,202

[1] (1) Includes service contract revenues of $402 and $375 and $764 and $674 recognized during the three and six months ended July 2, 2022 and July 3, 2021, respectively. Includes $357 and $634 and $0 and $111 recognized revenue related to the exclusive distribution rights during the three and six months ended July 2, 2022 and July 3, 2021, respectively. Other also includes revenues from paid service, royalty, freight and legacy G probes.