Color Vision in Blue Cone Monochromacy: Outcome Measures for a Clinical Trial

PURPOSE: Blue cone monochromacy (BCM) is an X-linked retinopathy due to mutations in the OPN1LW/OPN1MW gene cluster. Symptoms include reduced visual acuity and disturbed color vision. We studied BCM color vision to determine outcome measures for future clinical trials. METHODS: Patients with BCM and normal-vision participants were examined with Farnsworth–Munsell (FM) arrangement tests and the Color Assessment and Diagnosis (CAD) test. A retrospective case series in 36 patients with BCM (ages 6–70) was performed with the FM D-15 test. A subset of six patients also had Roth-28 Hue and CAD tests. RESULTS: All patients with BCM had abnormal results for D-15, Roth-28, and CAD tests. With D-15, there was protan-deutan confusion and no bimodal tendency. Roth-28 results reinforced that finding. There was symmetry in color vision metrics between the two eyes and coherence between sessions with the arrangement tests and CAD. Severe abnormalities in red-green sensitivity with CAD were expected. Unexpected were different levels of yellow-blue results with two patterns of abnormal thresholds: moderate elevation in two younger patients and severe elevation in four patients ≥35 years. Coefficients of repeatability and intersession means were tabulated for all test modalities. CONCLUSIONS: Given understanding of advantages, disadvantages, and complexities of interpretation of results, both an arrangement test and CAD should be useful monitors of color vision through a clinical trial in BCM. TRANSLATIONAL RELEVANCE: Our pilot studies in BCM of arrangement and CAD tests indicated both were clinically feasible and interpretable in the context of this cone gene disease.