An anomaloscope is a test device for diagnosis of congenital color vision deficiencies using a 2° 10' circular bipartite target for color matching. The test subjects perform tasks involving color matching between mixed red (670nm) and green (545nm) light in the upper half of the circular target and yellow light (588nm) in the lower half of the target. Dichromats can perform color matching completely between the two halves, because the red, green and yellow lights are selected from the spectral loci where the confusion color lines of type 1 and type 2 color defectives are parallel. In this report, the chromaticity diagram, confusion color lines and fundamentals of an anomaloscope are presented. A single-view anomaloscope is proposed to prevent chromatic adaptation, which is the biggest problem of a conventional anomaloscope.
The purpose of this study was to clarify the characteristics of color discrimination in mesopic vision by analyzing error scores of the Farnsworth-Munsell 100-hue test under several retinal illuminance conditions, which were at the mesopic luminance level. The retinal illuminance conditions were 0.07, 0.35, 0.71, 3.53, and 7.07 td. The results were as follows.: 1) Under the retinal illuminance conditions of 0.07∼0.35 td, the characteristics of color discrimination in scotopic vision became dominant. 2) When retinal illuminance was kept relatively high in mesopic vision, color discrimination along the yellow-blue confusion axis was reduced. 3) Color discrimination along the rod confusion axis markedly reduced correspondence with retinal illuminance toward scotopic luminance levels. These results suggest that rod signals directly affect S-cone mediated chromatic discrimination, and that scotopic brightness cues are equal to weak S-cone-mediated hue signals.