• Color thresholds in a series of patients with local or systemic diseases were determined by a chromagraph method and subjected to computer analysis. When compared with normal persons, those with optic nerve disease (multiple sclerosis, optic neuritis, and optic atrophy) showed an overall weakness for all colors (enlarged neutral areas), with an additional specific defect in the orangecyan (greenish blue) axis. Those with the two retinal diseases studied (macular degeneration and retinitis pigmentosa) also showed threshold elevation for all colors, but with a special defect in the yellow-blue axis. The general elevation was greater for patients with retinitis pigmentosa than for those with macular degeneration, regardless of the visual acuity. In patients undergoing treatment for systemic lupus erythematosus and rheumatoid arthritis, there was a mild elevation of the color threshold, especially for yellow.
Chu FC, Reingold DB, Cogan DG, Hunt SMJ, Young DH. Clinical Studies of Color Vision With Gunkel's Chromagraph. Arch Ophthalmol. 1983;101(8):1232-1235. doi:10.1001/archopht.1983.01040020234015