Chromatic perception test: a computer-based approach

The analysis of luminance visual defects (i.e. obtained with white stimuli on a black background) in the central area of 200-300 around the fovea provide a valuable tool in neuro-ophthalmological diagnosis. In fact, distribution and depth of monochromatic visual defects reflect disease or damage to specific portion of the brain along the visual pathway. Concerning chromaticity tests, it is well known that they improve the diagnosis of many neurological diseases, such as multiple sclerosis, optic neuritis, diseases due to vitamin deficiency, etc. A new automatic technique for testing chromaticity within the Central Visual Field (CVF) by means of a PC has been developed. According to the ICO-1979 recommendation for perimeter standardization, the coloured light stimuli were isoilluminant with a 12 Lux white background. Stimuli differed from the background for hue (red, green, blue) and saturation (two levels each: one corresponding to 30% of the Maximal Saturation (MS) and the other to 10% of MS). The new test proved to be accurate and rapid. It also achieved high sensitivity, because it classified mild defects of color vision of which subjects were unaware. This pilot study on patients with multiple sclerosis proved that the test achieved significantly greater sensitivity than standard luminance visual field analysis.