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 (ChB Vol), and flow (ChBF low) in the center of the fovea.
Results: We found a significant inverse relationship between total drusen area and ChB Vol or ChB Flow. For every 1-mm2 increase in total drusen area, ChB Vol decreased by 0.0061 arbitrary units (P = 0.03) and ChBF low decreased by 0.23 arbitrary units (P = 0.049). Average druse area was also significantly inversely related to ChB Vol and ChBF low. For every 0.01-mm2 increase in average druse area, the ChB Vol decreased by 0.0149 arbitrary units (P = 0.001) and the ChB Flow decreased by 0.4951 arbitrary units (P = 0.003). Adjustment for age weakened the significance, although it remained strong for average druse area versus ChB Flow (P = 0.017) and ChB Vol (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 ChB Vol and ChB Flow. This suggests the presence of ischemia and possibly the reason why patients with high-risk drusen are prone to advanced disease.