This complete trial lens set with glass window case is one of the most visually impressive instruments in any collection of ophthalmic antiques — a magnificent mahogany case measuring 59 x 37 x 15 cm and weighing 10.8 kg, housing a complete spherocylinder lens set of 342 lenses arranged in perfect order behind a glass viewing window that allows the full glory of the collection to be appreciated without opening the case.
The trial lens set is the foundational instrument of clinical refraction — the process by which an ophthalmologist or optometrist determines a patient’s precise spectacle prescription. Each lens in the set represents a specific optical power, and by systematically placing lenses in a trial frame in front of the patient’s eye and asking them to compare different combinations, the examiner could determine the exact spherical and cylindrical correction needed for clear vision. A complete set of 342 lenses provided the full range of spherical powers, cylindrical powers, and axes needed to correct virtually any refractive error encountered in clinical practice.
The magnificent mahogany case with its brass fittings and glass window lid transforms a purely functional clinical instrument into an object of genuine beauty. Cases of this type were made to impress as well as to protect — displayed in the consulting rooms of prominent ophthalmologists and opticians, a complete trial lens set in a fine wooden case communicated the professional’s commitment to the highest standards of ophthalmic care. Finding a complete set of 342 lenses in their original mahogany case with glass window in this condition is exceptionally rare, making this one of the most significant pieces in this collection.
