A clinical test to estimate chromatic thresholdsa

Abstract

A quick and relatively inexpensive colour vision test is described which estimates chromatic thresholds for representative hues of the Munsell colour space. Results suggest that the test is not as sensitive as several pseudo-isochromatic plate tests for colour vision screening. However, the test results correlate well with the anomaloscope range which indicates that the test is useful in estimating the severity of a red-green defect. Results from the screening trial also showed that there is a substantial learning or attention artefact for colour-normal observers. Approximately 36 per cent of the colour-normal subjects made at least one mistake on the test, whereas only nine per cent repeated at least one of their errors. Because these errors made by colour-normals were age-related and were clustered near the blue-yellow axis, detection of subtle blue-yellow defects in older patients will be difficult.