Clinical Classification of Degree of Deficiency in Color Defectiveness: Simulations by Changing the Total Number of Caps or Saturation of Farnsworth Dichotomous Test D-15.

Purpose: For the purpose of classification for social adaptability of color vision defectiveness, the Farnsworth Dichotomous Test D-15(Test D-15)was applied to distinguish a severe group from other cases. Following this, the Ichikawa Lantern was employed to separate a moderate from a mild group. Majima's classification has provided a convenient framework for identifying color vision defectiveness for the past several decades. However because of the discontinuity in the employment of Ichikawa's Lantern, the introduction of alternative methods is vital. New classification methods subdividing the "moderate/mild" group into separate groups were established by using simulations. Subjects and methods: Simulations of hue discrimination using the color caps of Test D-15 were carried out. Adding color caps one by one between each of the 15 color test caps of Test D-15 to a total of 30, or subtracting caps from Test D-15 to nine (P-1-3-5-7-9-11-13-15)or six(P-2-5-8-11-14) were employed to simulate the compressing of the hue circles along the color confusion lines. Simulations changing the saturation of color caps were conducted simultaneously. Results: The fewer the number of caps, the more errors occurred. Subtracting the number of caps of Test D-15 made it possible to subdivide the "moderate/mild" group into three groups. Changing the saturation of color caps of Test D-15 had no effect on the results of the Test D-15. Conclusion: Using Test D-15 and reducing the number of caps to nine or six allows for the identification of different levels of color defectiveness and the assigning of patients into separate groups.