Diabetic retinopathy and colour discrimination under various illuminants

25 patients suffering from diabetic retinopathy, examined with the aid of 100-hue test, show an acquired tritan-like deficiency. Colour discrimination impairment is found to run parallel to visual acuity deterioration. When tested under illumination produced by an Hg source, relatively poor of energy in the short wavelength range, an improvement in colour discrimination (decrease in total score) compared to C illumination is found.