Michels S. M., Schmidt-Erfurth U.

Augenklinik der Universität Lübeck, Ratzeburger Allee 160, 23538 Lübeck

Objective: Evaluation of early vascular changes in choroidal neovascularisation (CNV) and physiological choroid after Photodynamic Therapy with Verteporfin (PDT).
Methods: 20 patients with predominantly classic CNV received standard photodynamic therapy. Fluorescein (FLA) and indocyanine green (ICG) angiography were performed before PDT, at 5 hours, one day and one week after treatment. A quantitative evaluation was done for CNV size, leakage area and area of choroidal hypofluorescence. A low energy scanning laser system (Heidelberg Retina Angiograph) was used with a calculated light dose far below the phototoxic threshold.
Results: Large parts of the CNV membrane were still visible five hours after treatment. The CNV size was most reduced at one day after PDT (FLA: 20%; ICG 31% of initial CNV size) and showed no significant increase at one week. Up to one day after PDT a major increase of leakage from CNV and the sourrounding treated choroid was seen (FLA:148%;ICG:378%). The leakage area was similar to baseline at one week after treatment. A slowly progressive increase of the choroidal hypofluorescent area indicating vascular hypoperfusion was seen up to one week, reaching a maximum size consistent with the treatment spot.
Conclusion: PDT induces dynamic vascular changes with a characteristic appearance. No immediate CNV occlusion is induced by PDT. The slow progression of the choroidal hypoperfusion within the first week after PDT in contrast to the faster occlusion of the CNV explains the stabilized or improved visual acuity.

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