Computer colour tests for the major causes of blindness using an inexpensive PC system

Abstract

Background: Computer‐graphics methods of assessing acquired losses of colour vision are superior in many ways to all others. They can employ briefly flashed stimuli, that can be presented in the retinal periphery; any luminance signal can also be masked by dynamic random luminance noise; and chromaticity can be varied very precisely. We have devised a program that is designed to detect and quantify disturbances in the three major blinding conditions (glaucoma, ARM and diabetes).Methods: The tests can be performed very rapidly, using standard PCs.Results: Normal results from age‐matched groups prove prominent tritan losses in all 3 three conditions. In diabetes, relatively large abnormalities can be detected before the appearance of mild background retinopathy, and worsen with the appearance of microaneurysms. In suspected glaucoma, abnormalities can be detected when conventional perimetry is ambiguous. There is a good correlation with minor changes on the Heidelberg Retinal Tomograph (HRT). The loss is related to IOP. In ARM, even with normal visual acuity, very large losses of tritan contrast sensitivity can be seen. Although patients can see the colours on the monitor screen, the targets (small optotypes) cannot be recognised, apparently because of the presence of very small tritan scotomas, which can be demonstrated when the target is flashed briefly.Conclusions: Colour vision testing permits rapid screening of patients at risk of developing sight‐threatening disorders, and thus is potentially of considerable use in health‐care programmes.