Business Segments - Schedule of Revenue Information by Product (Details) - USD ($) $ in Thousands		3 Months Ended
		Apr. 03, 2021	Mar. 28, 2020
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues		$ 11,959	$ 9,021
Cyclo G6
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues		3,349	2,923
Retina
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues		6,660	4,134
Other
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues	[1]	$ 1,950	$ 1,964

[1] Includes service contract revenues of $299 and $315 recognized during the three months ended April 3, 2021 and March 28, 2020, respectively. Other also includes revenues from paid service, royalty, freight and legacy G probes.