An incomplete set of trial lenses for visual testing for the bifocal component of an eyeglass prescription, from +0.5 diopters to 3.25 diopters. Each lens measures 2 cm. in diameter, set within a secondary lens measuring about 4 cm. in diameter. The set is housed in a leather covered wooden case, with velvet covered inserts.
Subject (Name):
Bernard Kosto, M.D. and Yale University. School of Medicine.
