Abstract
Purpose :
Computer-based color contrast sensitivity (CS) tests diagnose type and severity of hereditary color vision deficiency (CVD) and acquired CVD in various diseases. These tests are predicated on saturation discrimination but provide no information about hue and color naming. Our purpose was to develop a clinically expedient test of cone CS which includes a color naming score (cone contrast naming test; CCNT).
Methods :
26 color vision normals (CVNs, mean age ± SD: 26 ± 5) and 20 hereditary CVDs (CVDs, age 32 ± 12) confirmed by Ishihara, anomaloscope, and cone CS participated after written informed consent. Test distance was 3 ft. in a dark room (Microsoft Surface display). Single letters on a grey background stimulated only L, M or S cones or luminance (Lum). Weber contrast varied from 1%-16% in 2X steps for L, M, Lum; S cones: 8%-128% in 2X steps. On each trial a single letter appeared within a crosshair for 5 sec. Subjects identified the letter and named its color. Letter types (L, M, S, Lum) were presented twice at each of five contrasts and both letter type and contrast were randomized in each session. CS and color naming was based on the number correct using a scale of 100.
Results :
CVN CCNT CS correlated with Innova Systems, Inc. cone CS (r2 = 0.3 P < .001) as did CVD CCNT CS (r2 = 0.8 P < .001) validating CCNT CS. Sensitivity of CCNT cone CS for detecting type and severity of hereditary CVD was 100% (mean CVN CS: 84, mean CVD CS: 28, P < .001). Specificity in CVDs for confirming normal color vision in the normal cone type was 100% (mean CVN and CVD CS: 84, P > .89). Mean CVD CS scores were 6.1 standard deviations below CVD norms (P < .001). CVDs showed significant decrements in color naming for the deficient cone, normal cone, and luminance stimulus (mean 39) compared to CVNs (mean 82, P < .001). CS alone showed non-repetitive distinct scores in 30% of CVDs and CVNs while a composite score (mean of CS and CN) showed distinct scores in 70% of CVDs (P < .001) and in 46% of CVNs (P < .002) indicating that the composite score better discriminates between levels of performance in both CVDs and CVNs.
Conclusions :
The CCNT combines cone CS with color naming to include both thresholds and color identification in a single, clinically expedient test. The composite score better discriminates levels of color ability important for matching CVDs with occupational needs and identifying the impact of acquired CVD on performance.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.