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This vintage stereoview card from the Keystone Diagnostic Series is part of the Diagnostic B Section, specifically designed for red-green color-blind testing. The card features multiple dot-matrix numerical test plates, intended for eye-training and diagnostic evaluation using Keystone stereoscopic equipment. Each panel displays color-contrast numbers used to assess red-green differentiation, making this card both a collectible medical artifact and a functional example of early vision-testing tools.
Printed in the U.S.A., this card reflects Keystone’s long history of producing instructional and clinical stereoscopic materials. A useful piece for collectors of medical ephemera, optometry tools, or Keystone stereoview sets.
Condition:
The card shows light visible wear, including slight edge wear and minor surface marks, but overall remains in good collectible condition with clearly readable test panels.
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