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PDT induces some vascular damage, study shows
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Photodynamic therapy may induce selective vascular damage in choroidal neovascular membranes, according to a study. The authors said the effectiveness and selectivity of the treatment may be jeopardized by a rebound effect, however.
Olcay Tatar, MD, and colleagues in Germany retrospectively reviewed a case series of 50 eyes of 50 patients who underwent removal of the choroidal neovascular membranes. Neovascularization was secondary to age-related macular degeneration (AMD), the authors noted.
Photodynamic therapy (PDT) was administered to 20 patients anywhere from 3 to 655 days before surgery. Choroidal neovascular membranes were stained for CD34, CD105, Ki-67, cytokeratin 18 and vascular endothelial growth factor (VEGF). The researchers compared results to 30 choroidal neovascular membranes secondary to AMD that did not undergo any previous treatment.
Specimens without pretreatment disclosed varying degrees of vascularization, proliferative activity and VEGF expression by different cells, researchers said. On the other hand, those that had undergone PDT were “highly vascularized and proliferating,” they said. There appears to be an “impressive VEGF immunoreactivity” unique to retinal pigment epithelial cells shortly after PDT that shifted to other cells at later time points.
The study is published in the June issue of Archives of Ophthalmology.