OCT determined macular thickness in diabetic retinopathy and relation to colour vision deficiency patterns.

Background: Diabetic retinopathy is the most common cause of blindness in industrialised nations and the incidence of diabetes is expected to rise over the next 10 years. Early treatment of proliferative diabetic retinopathy and diabetic maculopathy improves visual outcome and with effective screening, blindness could be reduced. Patients suffering from diabetes mellitus show alterations in their colour perception. Colour vision testing provides a sensitive, non-invasive method to assess macular damage in diabetic retinopathy and any deterioration in colour vision often precedes changes in other clinical measures such as visual acuity and morphological changes. Optical coherence tomography (OCT) provides cross-sectional images of the retina, information concerning internal retinal structure as well as reproducible measurements of retinal thickness. Aims & Objective: This study was intended to examine the relationship between macular thickness on OCT (Optical coherence tomography) and colour vision deficiency patterns in diabetics. Material and Methods: A total of 100 patients with established diabetic retinopathy visiting hospital were examined and a detailed history of diabetes, duration and inability to differentiate colours 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: 21% (21 out of 100) of patients under study showed a gross deficiency of red green pattern of colour blindness. The colour vision deficiency increased with increasing macular thickness. Macula thickness on OCT in subjects varied from 188 to 462 microns. The average macular thickness of patients with total colour vision deficiency was 290 microns that with red green was 274 micron and those without any colour vision deficiency was 228. Prevalence of colour vision deficiency increased with duration of diabetes and severity of retinopathy. Conclusion: Higher prevalence of red green colour blindness was observed in patients of diabetes with macular oedema. Impaired colour vision was more in patients with macular thickness above 228 micron.

Serum homocysteine as a risk factor in diabetic with colour vision deficiency and for developing retinopathy.

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.