Abstract
Abstract: :
Purpose: In patients with poor vision, it is not always clear whether errors on color vision testing are due to an abnormality in color vision or inadequate acuity. This study evaluates the effect of decreased visual acuity on clinical color vision tests. Methods: The right eyes of 12 healthy subjects (11 females, 1 male, mean age 38, range 20 to 61) with no history of color vision abnormality and normal visual acuity were fogged with plus lenses at the phoropter to visual acuity of logMAR 1.88 (20/1500) at near and assessed with Farnsworth D-15 hue discrimination test, Ishihara color plates, and Hardy-Rand-Rittler (HRR) color plates. Subjects were similarly tested at progressively lesser degrees of fogging, at 0.1 logMAR intervals, up to acuity logMAR 0.67 (20/94) and at baseline, logMAR 0 (20/20). For all levels of visual acuity the mean number of errors made with each color vision test was compared to baseline using the paired t-test. To compare examination devices, for each subject the worst visual acuity that the number of errors did not differ from baseline was determined for each color vision test. These acuities were averaged for each color vision test and compared using repeated measures analysis of variance. Results: The number of errors on color vision testing did not significantly differ from baseline, using the cutoff p=0.05, up to and including visual acuities logMAR 1.57 (20/750) on D-15 panel, 1.27 (20/375) on HRR plates, and 0.88 (20/150) on Ishihara plates. The measures analysis of variance on the most decreased unaffected acuity was highly significant (p<0.001). All three color vision tests were significantly different from each other (all p<0.005). Conclusion: Of the three color vision assessment techniques, Ishihara plate testing was most dependent and the Farnsworth Panel D-15 was least dependent on good visual acuity. Color vision testing was accurate up to and including acuity of logMAR 1.57 (20/750) with the D-15 panel, 1.27 (20/375) with HRR plates, and 0.88 (20/150) with Ishihara plates.
Keywords: 362 color vision • 486 neuro-ophthalmology: diagnosis • 620 visual acuity