Disaggregation of Sales, Geographic Sales and Product Sales - Net Sales by Products and Services (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 03, 2020	Mar. 29, 2019
Product Information [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 5,847	$ 4,797
Total net sales	35,187	32,583
ICLs [Member]
Product Information [Line Items]
Revenue from contract with customer, excluding assessed tax	29,340	27,786
IOLs [Member]
Product Information [Line Items]
Revenue from contract with customer, excluding assessed tax	3,994	4,017
Other surgical products [Member]
Product Information [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 1,853	$ 780