Business Segments and Geographical Information - Schedule of Revenue Information by Product (Details) - USD ($) $ in Thousands		12 Months Ended
		Jan. 02, 2021	Dec. 28, 2019
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues		$ 36,347	$ 43,447
G6
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues		11,272	13,070
Retina
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues		18,088	22,879
Other
Entity Wide Information Revenue From External Customer [Line Items]
Total revenues	[1]	$ 6,987	$ 7,498

[1] Other includes service contract revenues of $1,263 and $1,363 recognized during fiscal years 2020 and 2019, respectively. Other also includes revenues from paid service, royalty, freight and legacy G probes.