Cone contrast test-HD: sensitivity and specificity in red–green dichromacy and the impact of age

Abstract

We report normative cone contrast sensitivity values, right–left eye agreement, and sensitivity and specificity values for the cone contrast test-HD (CCT-HD). We included 100 phakic eyes with color vision normal (CVN) and 20 dichromatic eyes (10 with protanopia and 10 with deuteranopia). The CCT-HD was used to measure L, M, and S-CCT-HD scores, and the right and left eyes were evaluated for agreement using Lin’s concordance correlation coefficient (CCC) and Bland–Altman analysis to investigate the sensitivity and specificity of the CCT-HD based on diagnosis with an anomaloscope device. All cone types were in moderate agreement with the CCC (L-cone: 0.92, 95% CI, 0.86–0.95; M-cone: 0.91, 95% CI, 0.84–0.94; S-cone: 0.93, 95% CI, 0.88–0.96), whereas the Bland–Altman plots showed that the majority of cases (L-cone: 94%; M-cone: 92%; S-cone: 92%) fell within the 95% limits of agreement and showed good agreement. The mean±standard error L, M, and S-CCT-HD scores for protanopia were 0.6±1.4, 74.7±2.7, and 94.6±2.4, respectively; for deuteranopia, these were 84.0±3.4, 40.8±3.3, and 93.0±5.8, respectively; and for age-matched CVN eyes (mean±standard deviation age, 53.1±5.8 years; age range, 45–64 years), these were 98.5±3.4, 94.8±3.8, and 92.3±3.4, respectively, with significant differences between the groups except for S-CCT-HD score (Bonferroni corrected α=0.0167, p<0.0167). The sensitivity and specificity of the CCT-HD were 100% for protan and deutan in diagnosing abnormal types in those aged 20 to 64 years; however, the specificity decreased to 65% for protan and 55% for deutan in those aged >65 years. The CCT-HD is comparable to the diagnostic performance of the anomaloscope in the 20–64-year-old age group. However, the results should be interpreted cautiously in those ≥65 years, as these patients are more susceptible to acquired color vision deficiencies due to yellowing of the crystalline lens and other factors.