DeZeng Refractometer

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An optometer was used to measure a person’s refractive error (strength of eye glasses needed). This was determined by having the person view an object through the eyepiece then rotating the dials until the object was most clear. The main problem was that the natural ability of the eye to focus (accommodation) could throw off the result. These days, very few of these are ever offered and can be considered a highly prized collectible for those interested in the field of optometry and/or ophthalmology.
The main viewing barrel is approx. 9″ in length with an extended height on the adjustable cast iron or metal tripod of approx. 20″. Behind the eyepiece is a rotating wheel of lenses of various powers. There is a graduated dial on the side with adjustments for myopia and hyperopia.
Marked on the barrel is:
De Zeng’s Refractometer
Spencer Lens Co.
Bausch & Lomb Optical Co.
Rochester, NY & New York City