Choroidal thickness and choroidal vascularity index in diabetic retinopathy and diabetic macular edema – A clinical study

Abstract

Purpose: To evaluate the choroidal thickness and choroidal vascularity index (CVI) in various stages of diabetic retinopathy and to assess its significance in diabetic macular edema. Materials and Methods: 166 eyes of 83 patients were evaluated in this study. 116 eyes were with various stages of diabetic retinopathy and 50 eyes were non-diabetic healthy controls. Spectral Domain Optical Coherence Tomography (SD OCT) was done for all patients. The choroidal thickness and the macular thickness at the fovea, 500 μm nasal, temporal, superior and inferior to the fovea were measured manually, and CVI was calculated as the ratio between the total choroidal area and the luminal area using ImageJ software. Results: The mean age of the study group was 55.95 ± 10.57 years and that of the control group was 53.33 ± 11.28 years. The choroidal thickness was significantly decreased in patients with proliferative diabetic retinopathy (p < 0.005). CVI was inversely proportional to the severity of diabetic retinopathy and was statistically significant (p < 0.01 to 0.005). In eyes with DR and macular edema a significant decrease in choroidal thickness (p = 0.019) was observed; however, the decrease in CVI was not significant (p = 0.056). Conclusion: In diabetic retinopathy, the choriodal thickness and CVI decreases as the severity of the retinopathy increases. Choroid plays an important role in disease progression. But in eyes with diabetic retinopathy associated with or without macular edema, there is no significant difference in CVI.