Characterisation of choroidal morphological and vascular features in diabetes and diabetic retinopathy

Aim We aimed to characterise specific morphological and vascular features of the choroid in Indian adults with diabetes and diabetic retinopathy (DR). Methods Consecutive participants from the Singapore Indian Eye Study's 6-year follow-up examination underwent choroidal imaging using spectral domain optical coherence tomography (OCT) with enhanced depth imaging. Raw OCT images were loaded on a custom-written application on MATLAB that enabled delineation for detailed morphological and vascular analyses. Multiple linear regression analyses were performed to assess differences in choroidal characteristics by diabetes DR. Results Of the 462 recruited participants, 273 had no diabetes (mean age was 60.1 +/- 6.8 years), 100 had diabetes but no DR (61.8 +/- 7.4 years) and 89 had DR (62.4 +/- 6.0 years). In multiple regression analysis, after accounting for relevant confounders, compared with those without diabetes, participants with diabetes had significantly thinner mean choroidal thickness (CT; mean difference (MD)=-25.19 mu m, p=0.001), smaller choroidal volume (MD=-0.23 mm(3), p=0.003), more inflection points (MD=1.78, p<0.001) and lesser choroidal vascular area within the foveal (MD=-0.024 mm(2), p=0.001) and macular (MD=-0.095 mm(2), p<0.001) regions. Among the diabetic group, subjects with DR had significantly thicker mean CT (MD=25.91 mu m, p=0.001), greater choroidal volume (MD=0.24 mm(3), p=0.009), lesser inflection points (MD=-0.478, p=0.045) and greater choroidal vascular area at foveal (MD=0.016 mm(2), p=0.019) and macular (MD=0.057 mm(2), p=0.016) regions, compared with those without DR. Conclusions Choroidal morphology and vasculature were altered in Indian adults with diabetes and DR. These findings may provide insights into choroidal changes in diabetes and DR.