IMPAIRMENTS OF L-CONE/M-CONE AND S-CONE–MEDIATED COLOR DISCRIMINATION IN MACULAR TELANGIECTASIA TYPE II

To characterize red–green and tritan color discrimination in eyes with macular telangiectasia Type II (MacTel). METHODS: Color discrimination was assessed by metameric matching methods using an Oculus MR Anomaloscope. Red–green color discrimination was assessed using the Rayleigh equation, and tritan color discrimination was assessed using the Moreland equation. Results were expressed as anomalquotient (AQ) and tritanomalquotient (TAQ) units, respectively. RESULTS: Seventeen eyes with MacTel were compared with 16 control eyes with normal vision. Twelve eyes with MacTel demonstrated abnormal color matches; except for two eyes with red-shifted Rayleigh matches, the primary abnormality evident was reduced color discrimination. On average, Rayleigh matching ranges were significantly widened in MacTel (0.518 ± 0.066 AQ units) compared with normal (0.14 ± 0.03 AQ units; P < 0.0001). Similarly, Moreland matching ranges were significantly wider (0.794 ± 0.109 TAQ units) than normal control subjects (0.204 ± 0.070 TAQ units; P < 0.0001). Losses in color discrimination did not correlate significantly with the best-corrected visual acuity, although Moreland matching ranges were significantly correlated to Rayleigh matching ranges. CONCLUSION: MacTel results in a combined acquired red–green and tritan color vision deficiency. A minority of eyes demonstrated red-shifted Rayleigh matches, consistent with decreases in cone photopigment optical density.