Optometry Eye Training Stereoview Keystone View Co. EC 10 1920s Curved Mount For Sale

Discover this unique antique stereoview card from the Keystone Stereoscopic Service, designed for eye comfort and depth perception training. This particular card, identified as EC 10, features a detailed natural scene of a river or stream flowing over rocks and through lush foliage, with various points (1-10) marked for visual focus. The card explicitly states, "The Human Body is Strengthened by Proper Exercise—The Eyes are no Exception," indicating its purpose as an optometrist's tool for visual exercises.The reverse side provides further instructions and context, detailing "THE KEYSTONE EYE COMFORT AND DEPTH-PERCEPTION SERIES" and its aim "For the Development of Comfortable Vision and a High Degree of Depth Perception." It specifies that "Changing Fixation from 7 to 1 requires 8½ prism diopters of Fusional Convergence." This black and white stereograph is presented on a curved mount, typical of early 20th-century stereoviews, and was produced by the renowned Keystone View Company, with studios and factory located in Meadville, PA, U.S.A. This fascinating piece offers a glimpse into historical vision therapy and is a valuable addition for collectors of stereoviews, medical history, or optometry artifacts.