The Choroidal Preferential Drainage Route is an Anatomical Risk Factor for the Visual Loss Due to the Diabetic Macular Edema

Abstract

Abstract: : Purpose: It has been believed that four vortex veins locate at each quadrants of the eye forming watershed at its border both horizontal and vertical. Recently we have reported that the choroidal veins arrange asymmetrically in half of normal individuals. Eventually it was demonstrated that presence of a preferential drainage route for macular region with obscured watershed in a majority of normal human subjects. The purpose of this study is to demonstrate the role of choroidal drainage system in the development of the diabetic macular edema. Methods: The subjects were 35 consecutive non-insulin dependent diabetic patients (71 eyes) with or without macula edema. Eyes with other clinical pathologies insulting visual acuity except macular edema were excluded from this study. ICG angiography was performed with a modified Topcon fundus ICG camera. Montage images using venous phase flames were prepared to evaluate the venous vascular pattern of the choroid in a wider view and correlated to visual acuity. Results: Log MAR of the eyes with the preferential choroidal drainage route was significantly higher than that of eyes without preferential route (p = 0.025). Eyes with 2 or more lines visual loss after pan-retinal photocoagulation were 8 of 28 eyes with preferential choroidal drainage route, and were 4 of 43 eyes without preferential choroidal drainage route. There was a significant difference between these groups with or without preferential drainage route (p = 0.034). Conclusions: The choroidal preferential drainage route is an anatomical risk factor for the visual loss induced by macular edema in diabetic patients with or without pan-retinal photocoagulation. This result suggests that choroidal vascular circulation may play a role in the pathogenesis of diabetic macular edema.

Keywords: imaging/image analysis: clinical • choroid • anatomy