Severity of colour vision loss in diabetes

Abstract

AbstractPurpose Vascular and structural changes in the retina are used to grade progression in diabetic retinopathy (DR) and this is often taken as an indicator of the severity of vision loss. Changes in visual function may, however, precede detectable structural damage. Red‐green (RG) and yellow‐blue (YB) thresholds were measured in patients with DR and related to their clinical grading classification.Methods 66 patients diagnosed with diabetes were examined. DR was graded according to ETDRS severity scale as no retinopathy, mild, moderate, severe DR and presence/absence of macular oedema. Colour thresholds were measured using the CAD test (Expert Rev.Ophthalmol. 6:409‐420, 2011) together with other patient‐specific information: VA, duration of diabetes, HbA1c and central subfield (CSF) thickness, and response of macular oedema to Ozurdex intravitreal implant injection.Results All diabetic patients showed loss of chromatic sensitivity (with mean RG and YB thresholds exceeding six times normal values). The clinical grading of disease progression showed negligible correlation with either RG (r2=‐0.0004) or YB thresholds (r2=0.052). Patients with no DR often exhibited normal visual acuity (~ 1 min arc), but showed significant loss of colour vision. Ozurdex treatment was associated with significant initial improvement in colour thresholds.Conclusion RG and YB colour thresholds provide a sensitive measure of functional change in diabetics that does not relate well to observed vascular and structural changes. These preliminary findings also suggest that measurement of colour thresholds can be used to monitor the efficacy of treatment in diabetic macular oedema.