The association between drusen extent and foveolar choroidal blood flow in age-related macular degeneration

PURPOSE: To investigate the relationship between drusen extent and foveolar choroidal blood flow in nonexudative age-related macular degeneration. METHODS: Total drusen area, average druse area, and total drusen number were determined using a computer program developed to quantify the extent of manually outlined drusen from fundus photographs of 157 patients (239 eyes) with nonexudative age-related macular degeneration. Laser Doppler flowmetry was used to assess relative choroidal blood velocity (ChBVel), volume (ChBVol), and flow (ChBFlow) in the center of the fovea. RESULTS: We found a significant inverse relationship between total drusen area and ChBVol or ChBFlow. For every 1-mm increase in total drusen area, ChBVol decreased by 0.0061 arbitrary units (P = 0.03) and ChBFlow decreased by 0.23 arbitrary units (P = 0.049). Average druse area was also significantly inversely related to ChBVol and ChBFlow. For every 0.01-mm increase in average druse area, the ChBVol decreased by 0.0149 arbitrary units (P = 0.001) and the ChBFlow decreased by 0.4951 arbitrary units (P = 0.003). Adjustment for age weakened the significance, although it remained strong for average druse area versus ChBFlow (P = 0.017) and ChBVol (P = 0.004). The computer-aided quantification of drusen used in this study showed high intra-and intergrader agreement. CONCLUSION: In patients with nonexudative age-related macular degeneration, there is an association between increased drusen extent and decreased ChBVol and ChBFlow. This suggests the presence of ischemia and possibly the reason why patients with high-risk drusen are prone to advanced disease.