Threshold and Suprathreshold Deficits in Color Vision in Optic Neuritis

Abstract

Disturbances of color vision are frequently reported by patients following an attack of optic neuritis (see MACKARELL [1] for an illustrated account of the symptoms of optic neuritis, and FOSTER [2] for a recent review of color vision anomalies in optic neuritis). For example, typical comments of our subjects have been that colors look duller, paler or less glossy with their affected eye: reds have been reported as pink, and greens as grey. Occasionally the subject will report an apparent hue change, such as calling red orange, or green yellow. Color anomalies such as these were first described in the literature just over one hundred years ago by NETTLESHIP [3]. Subsequently, in 1897, GUNN and BUZZARD [4] reported that frequently colors cannot be recognized around absolute scotomas in optic neuritis. They considered that deficits to red and green were chiefly involved, and this type of observation is embodied in KOLLNER’s rule [5] which holds that deficits to red and green but not blue are characteristic of optic nerve disorders. The introduction of pseudoisochromatic plates into neuro- ophthalmic testing by SLOAN [6] emphasized the usefulness of color vision testing in addition to visual acuity and visual field examination in optic nerve disease. Tests such as the Ishihara test and the Farnsworth-Munsell 100 hue test are particularly sensitive indicators of a previous attack of optic neuritis, even when visual acuity has returned to normal [7,8].