Evaluation of the visual system in multiple sclerosis. II. Colour vision.

A study of colour vision (CV) in 65 patients with multiple sclerosis (MS), (30 patients had had previous optic neuritis) and 51 controls was carried out with Ishihara's pseudoisochromatic plates (I-test), Farnsworth's panel D-15 test (F-test), and Lanthony's desaturated 15-hue test (L-test). CV defects were classified as to type and severity. Error scorings were calculated by Bowman's computerized method and our own simple proposal for scoring, which was found of equal value. Results were compared with pattern-reversal (black/white) visual evoked potentials (PR-VEP) (80% of eyes abnormal). The I-test (56% of eyes abnormal) was a more sensitive indicator of demyelination than the L-test (47%) and F-test (26%). In 14 eyes CV defects (10 blue-yellow, 4 red-green) were only revealed with the L-test. Abnormal CV, mostly blue-yellow defects, occurred in 16 patients (19 eyes) having normal VEP latencies; 29 patients were re-tested within one week. It is proposed that the performance of the I-test, which showed the highest reproducibility, could be improved by adding more cards, particularly blue-yellow, to the test.