Choriocapillaris degeneration and related pathologic changes in human diabetic eyes.

OBJECTIVES: To measure the extent of choriocapillaris degeneration (CCD) in diabetic choroids and to study the association of CCD with choroidal neovascularization and pathologic changes in Bruch's membrane-like basal laminar deposits.
MATERIALS AND METHODS: Human choroids from 10 postmortem subjects (diabetic, 5 [group 1]; nondiabetic, 5 [group 2]) were incubated for the histochemical demonstration of alkaline phosphatase and nonspecific esterase activities, permitting analysis of the choroidal vasculature and polymorphonuclear leukocytes, respectively. The tissue was then flat embedded and sectioned for structural analysis. Areas of CCD were measured in the flat perspective by computer-assisted image analysis and verified in cross-sections of flat-embedded tissue.
RESULTS: The CCD in choroids from subjects with diabetes (group 1) appeared in 2 patterns: diffuse (partial loss of alkaline phosphatase activity in a poorly defined area, ie, degeneration of some capillary segments) and focal (complete degeneration of choriocapillaris or loss of alkaline phosphatase activity in a relatively well-defined area). The mean+/-SD percentage of the choroid with focal CCD in group 1 was 5.08%+/-1.13% of the total choroidal area vs 1. 16%+/-0.35% in group 2 (P<.001). Focal CCD in group 1 was more prominent in the posterior pole than in the peripheral choroid. Choroidal neovascularization was associated with some areas of diffuse CCD in group 1. Pathologic changes in Bruch's membrane-like basal laminar deposits were often associated with CCD; the thickness of the deposits was greater in group 1 than in group 2 and greater in areas with focal CCD than in areas with diffuse or no CCD.
CONCLUSION: The percentage of choroid with focal CCD in group 1 choroids was more than 4-fold greater than that in nondiabetic choroids. The presence of CCD was related to basal laminar deposits and, in some cases, to choroidal neovascularization.