Abstract
Abstract: :
Purpose:The vascular theory for age related macular degeneration (ARMD) embraces sub-foveal hypoperfusion as the principal risk factor for ARMD. However, atherosclerotic changes in normal senescence may stiffen major ocular arteries to reduce the amount and quality of global choroidal blood flow (ChBF). Consequently, the pulsatile ocular blood flow (POBF), derived from the choroid as a whole, is predicted to be affected in patients with or without maculopathy in the same way. To test this hypothesis, we evaluated the discriminating ability of POBF in older normals, and matched patients with wet and dry ARMD. Methods:Forty-four volunteers over 60 years of age had their POBF measured twice in each eye with a UK-OBF tonometer in 3 subject categories: 1) Normals (mean age: 72.4 ± 6.0 yrs), 2) Patients with dry ARMD (age: 75.1 ± 6.4 yrs) and 3) Patients with wet ARMD (age 74.4 ± 6.3 yrs). Any statistical significance in group averaged data sets was identified by ANOVAs. Results:The POBF did not differ between the right and left eyes within the normals (p= 0.6928); subjects with dry ARMD in both eyes (p= 0.9469); and subjects with dry ARMD in one eye and wet ARMD in the other (p= 0.1732). Comparisons across subject categories showed that the POBF did not differ (p= 0.628) between normal eyes (711.2 ± 37.3 µl/min), nor eyes with dry (827.4 ± 45.2 µl/min) or wet ARMD (854.5 ± 72.6 µl/min). Conclusion:The data confirmed the hypothesis that the POBF cannot differentiate normals from patients with ARMD. Since the POBF varies with age, variable atherosclerotic changes in the ocular vessels may have obscured small differences across the test groups. Alternatively, focal vascular damage in ARMD may be too small to be detected reliably by POBF measurements. A more profitable approach may involve regional Laser Doppler Flowmetry measurements of sub-foveal hemodynamics in patients with risk factors for ARMD.
Keywords: 308 age-related macular degeneration • 345 choroid • 331 blood supply