Business Segments - Schedule of Revenue Information by Product (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jul. 01, 2023	Jul. 02, 2022	Jul. 01, 2023	Jul. 02, 2022
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues		$ 12,855	$ 13,755	$ 26,561	$ 27,142
Cyclo G6
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues		3,658	3,477	7,327	7,017
Retina
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues		6,857	7,529	14,071	14,830
Other
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues	[1]	$ 2,340	$ 2,749	$ 5,163	$ 5,295

[1] (1) Includes service contract revenues of $382 thousand and $402 thousand and $765 thousand and $764 thousand recognized during the three and six months ended July 1, 2023 and July 2, 2022, respectively. Includes $363 thousand and $357 thousand and $727 thousand and $634 thousand recognized revenue related to the exclusive distribution rights during the three and six months ended July 1, 2023 and July 2, 2022, respectively. Other also includes revenues from paid service, royalty, freight and legacy G probes.