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.
Key words: Diabetes; Macular Thickness; Optical Coherence Tomography (OCT); Colour Vision
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