Disaggregation of Revenues, Geographic Sales and Product Sales - Revenue from External Customers by Products and Services (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 28, 2018	Sep. 28, 2018	Jun. 29, 2018	Mar. 30, 2018	Dec. 29, 2017	Sep. 29, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 28, 2018	Dec. 29, 2017	Dec. 30, 2016
Product Information [Line Items]
Revenue from contract with customer, excluding assessed tax									$ 22,872	$ 22,286	$ 23,321
Total net sales	$ 31,186	$ 31,770	$ 33,905	$ 27,093	$ 24,852	$ 23,473	$ 21,936	$ 20,350	123,954	90,611	82,432
ICLs [Member]
Product Information [Line Items]
Revenue from contract with customer, excluding assessed tax									101,082	68,325	59,111
IOLs [Member]
Product Information [Line Items]
Revenue from contract with customer, excluding assessed tax									16,193	17,258	19,706
Other surgical products [Member]
Product Information [Line Items]
Revenue from contract with customer, excluding assessed tax									$ 6,679	$ 5,028	$ 3,615