Verteporfin occludes choriocapillaris, leaves nerve vessels alone, study finds

ERLANGEN, Germany — Photodynamic therapy with verteporfin induces selective occlusion of physiological choriocapillaris without affecting deeper choroidal, retinal and optic nerve vessels, according to a small study. The overlying retinal pigment epithelium also is not affected, authors said.

Researchers here studied one eye from each of three patients that had large malignant melanomas of the uvea destined for enucleation. The eyes had received photodynamic therapy (PDT) using verteporfin. Two light doses (one at 50 J and one at 100 J) were applied in unaffected chorioretinal areas.

A “rather selective” occlusion of the choriocapillary layer was observed in the 50 J area. The 100 J area also had closure of deeper choroidal vessels and focal alterations of the retinal pigment epithelium. Overlying neurosensory retina, including photoreceptors and retinal capillaries, was well preserved in all PDT areas, researchers said.

Electron microscopy showed that alterations of the choriocapillary endothelium comprised swelling, shrinkage and fragmentation of endothelial cells. Electron microscopy also showed detachment from the basement membrane up to complete degeneration of the endothelial lining. This led to platelet aggregation, degranulation and thrombus formation, authors said.

The study is published in Graefe’s Archive for Clinical and Investigative Ophthalmology.