Business Segments - Schedule of Revenue Information by Product (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jul. 03, 2021	Jun. 27, 2020	Jul. 03, 2021	Jun. 27, 2020
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues		$ 13,426	$ 6,219	$ 25,385	$ 15,240
Cyclo G6
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues		3,599	2,113	6,948	5,036
Retina
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues		7,575	2,608	14,235	6,742
Other
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues	[1]	$ 2,252	$ 1,498	$ 4,202	$ 3,462

[1] Includes service contract revenues of $375 and $311 and $674 and $627 recognized during the three and six months ended July 3, 2021 and June 27, 2020, respectively. Includes $111 recognized revenue related to the exclusive distribution rights during the three and six months ended July 3, 2021. Other also includes revenues from paid service, royalty, freight and legacy G probes.