Abstract

Background: Diabetic retinopathy causes vascular complications of retina causing blindness. Macular edema is the crucial cause of visual impairment and may occur at any stage of diabetic retinopathy. Patients suffering from diabetes mellitus can show alterations in their colour perception. Colour vision testing provides a sensitive method to assess macular damage. Deterioration in colour vision often precedes changes in other clinical measures such as visual acuity and morphological changes. Elevated homocysteine levels play a causative role in inducing vascular endothelial cell damage and causing retinopathy in diabetics.

Aims & Objective: This observational study was intended to examine if serum homocysteine is a risk factor for developing colour vision defects in diabetes and worsening of retinopathy.

Material and Methods: A total of 92 patients with established diabetic retinopathy and having colour vision defects visiting hospital were examined and a detailed history of duration of diabetes was taken. Retinal examination for evidence of diabetic retinopathy and colour vision patterns on Ishihara colour vision chart were noted. OCT was performed on these patients.

Results: 92 of patients with diabetic retinopathy under study had a gross colour vision deficiency. The average macular thickness on OCT of patients with total colour vision deficiency was 279 microns. Prevalence of colour vision deficiency increased with duration of diabetes and severity of retinopathy. The average serum homocysteine level in these patients was 21.98 μM/L which was above the normal range. Serum homocysteine levels ranged from 11.0 μM/L to 30.2 among males and 11.1to 41.0 in females.

Conclusion: Higher prevalence of colour blindness was observed in patients of diabetes with macular oedema and high circulating serum homocysteine levels. Impaired colour vision was more in patients with average macular thickness of 228 micron and raised homocysteine levels thus suggesting it could be a possible risk factor.

Key words: Colour Vision; Diabetic Retinopathy; Serum Homocysteine