Reduced Choroidal Blood Flow Parameters Are a Risk Factor for the Development of Neovascular AMD

Abstract

Purpose:: In the recent years there is a significant improvement in the management of neovascular AMD. Nevertheless the trigger for neovascular AMD is not known. Recent experimental and epidemiologcal studies indicate that the development of AMD is related to inflammatory processes. By contrast, there, is currently little evidence that hypoxia, a classical trigger of ocular angiogenesis is involved in the development of AMD. In the present study we tested the hypothesis that reduced choroidal blood flow parameters are a risk factor for the development of neovascular AMD.

Methods:: The present study was an observational longitudinal 3-years follow up study. 41 patients with unilateral CNV and non-exudative AMD in the study eye were included. These patients have a particularly high risk of developing neovascular AMD in the second eye. Choroidal blood flow (CBF) measurements with a compact laser Doppler flowmeter and fundus pulsation amplituden (FPA) measurements with laser interferometry were performed when patients were included in the study. After 3 years of observation patients were divided in those who developed CNV in the study (group 1) and those who did not (group 2). Choroidal hemodynamic parameters were compared between the two study groups using a non-paired t-test.

Results:: During the 3 years observation period 17 patients developed a CNV (group 1), 20 patients did not develop a CNV (group 2) and 4 patients were lost for follow up. As compared to patients in group 2 (18.9 ± 3.74 AU), patients in group 1 had lower CBF values (16.2 ± 3.00 AU; p = 0.021 between groups). Likewise group 1 had lower FPA values than group 2 (3.58 ± 1.05 µm versus 2.96 ± 0.71 µm; p = 0.045 between groups).

Conclusions:: This pilot study indicates that patients with lower choroidal hemodynamic parameters are at an increased risk of developing CNV over a three years period. Although neither of the two methods is a direct measure of choroidal blood flow our data are consistent with the idea that choroidal hypoperfusion plays a role in the development of CNV in AMD.

Keywords: choroid: neovascularization • blood supply • hypoxia