Effects of photodynamic therapy on choroidal newvessels and normal choroid. An angiographic study

Purpose: The effects of photodynamic therapy (PDT) on the CNV and the normal choroidal vasculature have not yet been completeley understood. We report here the early angiographic changes observed in the CNV and the surrounding choroid in patients with ARMD after PDT. Methods: Twenty eyes of 20 patients (mean age 76.5 ys) with ARMD and subfoveal "predominantly classic" CNV were considered. Dynamic and still-frame fluorescein angiography (FA) and indocyanine green angiography (ICGA) were carried out in all patients. Angiographic evaluations 7 days before treatment, 30 min, 1 day (only ICGA), 7 and 30 days after PDT were performed in all patients. No patients had had previous PDT or laser treatment. Results: 1) PDT effects on the CNV complex. Within 30 min after PDT CNV showed, in 3 eyes (15 %), hypofluorescence in early and late phases due to closure of the neovascular complex, while in 17 eyes (85%) CNV appeared hyperfluorescent in the early phases. One day after PDT this hyperfluorescence seemed to decrease. At 1 week all eyes showed a hypofluorescent CNV. However, within 4 weeks most CNV demonstrated a progressive reopening with increasing fluorescence intensity, quite resembling that of pre-treatment angiography. 2) PDT effects on choroidal circulation. Thirty minutes after PDT ICGA showed in 11 eyes (55%) a mid-phase hyperfluorescence on the laser spot area, followed by deep choroidal leakage of dye even beyond the boundaries of the treated area. In these eyes, at 1 day, an intense and well-delineated early hypofluorescent spot, covering the whole PDT area, was observed. A black spot of hypofluorescence over the treatment area could be observed in all eyes, 7 days after PDT. A choriocapillary loss, changes of choroidal filling with marked decrease in the overall density of choroidal vessels, was observed. Though they progressively reopen in the following days, an area of hypofluorescent choroid still persisted in all patients, as observed 1 month after PDT. Conclusions: PDT is associated to a dynamic sequence of vascular changes. It produces a strong occlusive effect on the CNV but lighter collapsing changes are also visible within the normal choroid exposed to the laser spot. These "side-effects" on normal choroidal circulation can sometimes determine closure of major vessels. Most changes on both CNV and the treated choroid are temporary, even though a residual slight hypoperfusion can be appreciated in the treatment spot. This study seems to demonstrate that PDT is only partially selective. The different impact on the surrounding choroid could influence the rate of recurrences.