Simulating Color Vision Deficiencies on Clinical Tests with a Blue Light

Teaching color vision testing can be challenging when all (or nearly all) of the students in the class have normal color vision. Colored filters or computer simulation can be used to simulate color vision deficiencies, but both have some drawbacks. As an alternative, we used a blue compact fluorescent lamp to illuminate various clinical color vision tests. The results from 20 students showed that the illumination produced typical responses made by individuals with congenital red-green defects on the Ishihara, Standard Pseudoisochromatic Part 1, Standard Pseudoisochromatic Part 2, and Ishihara Compatible color vision plate tests. Although the majority of errors on the other plate tests were along the red-green axis, some blue-yellow and scotopic errors also occurred. The results on the arrangement tests were more variable with deutan-scotopic defects as the most common patterns. Even though the blue light illumination did not produce responses that are typical of individuals with red-green color vision defects on all color vision tests evaluated, it did provide students a reasonable approximation of their responses and the experience of making decisions based on minimal differences in color.