Business Segments - Schedule of Revenue Information by Product (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2023	Oct. 01, 2022	Sep. 30, 2023	Oct. 01, 2022
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues		$ 12,850	$ 14,635	$ 39,411	$ 41,777
Cyclo G6
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues		3,042	3,460	10,369	10,477
Retina
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues		7,865	8,750	21,936	23,580
Other
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues	[1]	$ 1,943	$ 2,425	$ 7,106	$ 7,720

[1] (1) Includes service contract revenues of $409 thousand and $358 thousand and $1,174 thousand and $1,122 thousand recognized during the three and nine months ended September 30, 2023 and October 1, 2022, respectively. Includes $364 thousand and $351 thousand and $1,091 thousand and $985 thousand recognized revenue related to the exclusive distribution rights during the three and nine months ended September 30, 2023 and October 1, 2022, respectively. Other also includes revenues from paid service, royalty, freight and legacy G probes.