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C.J. Pournaras, E. Logean, C.E. Riva, B.L. Petrig, S. Chamot, G. Coscas, G. Soubrane; Regulation of Subfoveal Choroidal Blood Flow in Age Related Macular Degeneration: Effect of Photodynamic Therapy . Invest. Ophthalmol. Vis. Sci. 2003;44(13):1758.
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Purpose: To study the changes of the regulation of the subfoveal choroidal blood flow (ChBF) in eyes with age-related macular degeneration (AMD) and within a neovascular tissue before and after photodynamic therapy (PDT), in response to an acute increase in systemic blood pressure. Methods: Laser Doppler flowmetry (LDF) was used to determine changes of subfoveal choroidal blood velocity (ChBVel), choroidal blood volume (ChBVol) and choroidal blood flow (ChBF) during isometric excercise. Measurements were performed, at baseline and end of exercise, in one eye of 18 young healthy volunteers (mean age 31 ± 4 years CI, CI = 95% confidence interval, group I), in one eye of 25 older healthy volunteers (mean age 69 ± 4 years CI, group II ) and in one eye of 24 subjects presenting subfoveal classic neovascularisation (mean age 67 ± 5 years CI, group III). In 10 eyes of the group III, LDF parameters were measured before and 14.8 ± 4.3 days after PDT. Results: Although the acute increase in systemic blood pressure induced a similar increase in the mean perfusion pressure (PPm) for all groups (20.0 ± 4.7 mmHg CI for group I, 19.8 ± 3.6 mmHg CI for group II, and 23.2 ± 3.9 mmHg CI for group III ; p=0.99), we did not record any significant changes of the LDF parameters of the groups I (Δ ChBVel = 3.7 ± 3.4 CI, Δ ChBVol = -2.1 ± 3.5 CI, Δ ChBF = 0.9 ± 1.5 CI ; n=18) and II (Δ ChBVel = 5.1 ± 8.3 CI, Δ ChBVol = -2.3 ± 6.6 CI, Δ ChBF = 0.5 ± 1.7 CI ; n=25). In contrast, in group III the ChBF within the neovascular tissue increased significantly (Δ ChBF = 12.1 ± 3.7 CI ; n=24). In patients of group III treated by PDT (n=10), isometric exercise induced a significant increase in PPm (18.7 ± 5.7 mmHg CI) before PDT, resulting in an increase of ChBF within the neovascular tissue (17.4 ± 13.5 CI ; p=0.04). However, after PDT, although during squatting PPm increased to 28.7 ± 11.1 mmHg CI, the LDF measurements did not change significantly. Conclusions: Similarly to normal controls younger than 45 years, the acute elevation of systemic blood pressure does not affect the ChBF in elderly subjects with non-exudative stages of AMD. Regulation of ChBF in acute elevation of blood pressure seems to be preserved in early stages of AMD. In contrast, the ChBF within the subfoveal neovascular tissue increases significantly during isometric exercise. PDT partially restores the affected regulation of ChBF.
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