Color Perception on Ishihara Plates with Red Lenses in Subjects with Low Vision Due to Retinal Diseases.

Purpose: This study aimed to evaluate color perception (CP) changes on Ishihara plates following red-tinted contact lenses in subjects with low vision (LV) from retinal diseases. Methods: A cross-sectional observational study without control involved 84 subjects, aged 20–70 years, having LV from retinal diseases to examine CP changes following wearing red-tinted contact lenses. The subjects viewed Ishihara plates, with each eye separately, before and after wearing red lenses in two categories: “plates 1–21” and “plates 22–25”. Change in CP with the use of a red lens was the primary outcome measure. Results: There was a significant increase in the number of plates read in both categories, that is, plates 1–21 (P = 0.002) and plates 22–25 (P = 0.032), the latter being used to diagnose the red-green defects. Although 70 eyes could read both digits on plates 22–25 and appeared to have normal color vision (CV) at baseline, this number rose to 99 eyes following the use of red-tinted lenses. There was a significant change in the type of CP (red defect/green defect/normal/undefined defect) (P = 0.022) with the application of a red-tinted lens. Conclusions: The use of red-tinted lenses caused a significant increase in the number of plates read, increased the number of subjects who appeared normal on plates 22–25, and significantly changed CP of LV subjects. These lenses can be a valuable aid for LV subjects. Although Ishihara plates can diagnose only red-green defects, further studies on CV testing techniques that detect both red-green and blue-yellow CV defects are recommended.