Abstract
Abstract: :
Purpose: To evaluate the effects of low-intensity laser treatment on the choroidal circulation of age-related macular degeneration (AMD) patients participating in the Complications of AMD Prevention Trial (CAPT). Methods: This study included 30 AMD patients with bilateral drusen and visual acuity of 20/40 or better who were enrolled in the CAPT at the Scheie Eye Institute. The average age of the patients was 71 ± 6 years (mean ± standard deviation). Laser Doppler flowmetry (Oculix) was used to measure relative choroidal blood velocity (Chvel), volume (Chvol), and flow (Chflow) in the center of the fovea by asking the patients to fixate on a probing laser beam. Circulatory measurements were obtained in both eyes at baseline and three months following laser application. Laser treatment was applied in one eye and consisted of 60 light intensity 100 micron diameter spots located in a circular pattern 1500 to 2500 microns from the foveal center. Results are shown in arbitrary units (AU) as mean ± 1SD. Probability values are shown for paired, two tailed Student?s t-tests comparing choroidal hemodynamic parameters before and after laser photocoagulation therapy. Results: In comparison to baseline, no significant difference in Chvel, Chvol, or Chflow was observed three months following the application of low-intensity laser according to the CAPT protocol. In addition, no significant differences were detected in untreated eyes. Conclusions: No significant change in foveolar choroidal circulation was observed in this group of 30 AMD patients following laser photocoagulation treatment according to the CAPT protocol. Based on the variability of flow measurements in the untreated eyes, we have estimated that we have an 85% power to detect a 15% change in relative blood flow. A comparison of the circulatory changes found in the eyes that do and do not show regression of drusen after photocoagulation will be performed when the fundus photographic analysis of the patients is released by the CAPT study. Supported by NIH grants EY 12769, EY 12279, RPB, and the Vivian S. Lasko Research Fund.
Keywords: age-related macular degeneration • blood supply • choroid