FOVEOLAR CHOROIDAL BLOOD-FLOW IN AGE-RELATED MACULAR DEGENERATION

PURPOSE. To compare measurements of the foveolar choroidal blood circu lation in subjects with nonexudative, age-related macular degeneration (AMD) with those of control subjects. METHODS. Laser Doppler flowmetr y was used to assess relative choroidal blood velocity (ChB(Vel)), vol ume (ChB(Vol)), and now (ChB(Flow)) in the center of the fovea. Measur ements were obtained in 20 eyes of 20 subjects with 10 or more large d rusen, visual acuity of 20/32 or better, and no evidence of choroidal neovascularization. Findings obtained in these subjects were compared with those of 10 eyes of 10 age-and blood pressure-matched control sub jects with no large drusen. Foveolar choroidal blood flow measurements were obtained by asking the study participants to fixate on a probing laser beam. RESULTS. NO significant differences in average age, blood pressure, or intraocular pressure were observed between subjects with AMD and control subjects. Ln subjects with AMD, average ChB(Vol) was 0.24 +/- 0.08 (+/- 1 SD) arbitrary units (AU); this value was 33% lowe r than that of control subjects (0.36 +/- 0.11 AU; two-tailed, indepen dent Student's t-test, P = 0.005). Average ChB(Vel) conversely, was no t significantly different from normal (0.44 +/- 0.07 AU) in subjects w ith AMD (0.44 +/- 0.10 AU). Average ChB(Flow) in subjects with AMD (8. 7 +/- 3.1 AU) was 37% lower than that of control subjects (13.7 +/- 3. 5 AU) (P = 0.0005). Average blood flow pulsatility was 6% higher in su bjects with AMD (0.71 +/- 0.15) than in control subjects (0.66 +/- 0.1 4), but this difference was not statistically significant (P = 0.42). CONCLUSIONS. Average ChB(Flow) in the nonexudative stages of AMD is lo wer than that of age-matched controls, and the effect is caused mainly by a decrease in ChB(Vol). Further studies are needed to elucidate wh ether decreased ChB(Flow) plays a role in the development of choroidal neovascularization, and whether ChB(Flow) measurements may help ident ify subjects with AMD at risk for developing choroidal neovascularizat ion.