Color vision defects in pigmentary retinal dystrophy

Abstract

Color vision was studied, using the Farnsworth Panel D-15 test, in 72 patients (115 eyes) with primary pigmentary retina dystrophy of autosomal recessive inheritance, and the results were correlated with the visual acuity and visual field. The incidence of color vision defects and the degree of disturbance increased as the visual acuity and the visual field deteriorated. However, even in cases with the visual acuity better than 0.7, type III acquired blue-yellow defect was found in 22% of the cases. This type of color vision defect was also found in 52% of the cases with the visual acuity between 0.4 and 0.6. In the group with the visual acuity of 0.1 or less, total achromatopsia was found in 64% of the cases. The increment thresholds of the blue and green cone mechanisms in the fovea were determined by the two-color threshold technique of Stiles in 12 patients with the visual acuity better than 0.8. The thresholds of the blue cone mechanism (pi 1) and of the green cone mechanism (pi 4) were found to be elevated over the normal values. The increases in the former and the latter thresholds were correlated linearly with the slope of the regression of 0.64. The increase in the threshold of the blue cone mechanism was more pronounced than that of the green cone mechanism. Due to the difference in the density of both cones in the fovea, this result does not necessarily support the hypothesis that the blue cone mechanism is affected preferentially more than the green cone mechanism.