Defining optical instruments to aid vision

"Other instruments to aid vision" are optical glasses and ophthalmic instruments as aids to vision, which are lenses, therapeutic devices or other appliances from given formulas intended to be used for the aid and correction of visual or ocular anomalies of the eye; and include optical systems of lenses or combination of lenses assembled into a supporting structure which, when viewed through, are aids to vision, and which are sold as optical stock-in-trade articles of merchandise, i.e., magnifiers, readers, microscopes, field glasses, binoculars, telescopes, transits or articles of similar type which are largely produced by optically grinding glass to form ulas based upon the laws of optics.