Photodynamic therapy of pigmented choroidal melanomas of greater than 3-mm thickness.
The purpose of the study is to determine the effect of photodynamic therapy in the destruction of experimental pigmented choroidal melanomas > or = 3 mm in thickness using a liposomal preparation of benzoporphyrin derivative, verteporfin. Pigmented choroidal tumors were established in 32 New Zealand albino rabbit eyes. Animals were treated with daily injections of cyclosporine, and tumor growth was followed by serial fundus examinations and ultrasonography. When a tumor exceeded 3 mm in thickness (tumor height ranged from 3.1-4.6 mm), the authors administered benzoporphyrin derivative intravenously (1 mg/kg) and irradiated the tumor at 692-nm through an argon-pumped dye laser at different total light doses ranging from 60 to 120 J/cm2. Control animals were treated with light or benzoporphyrin derivative only. Each animal then was followed-up for 4 to 6 weeks by fundus photography, fluorescein angiography, and ultrasonography. All animals treated with benzoporphyrin derivative and light at fluences of > or = 80 J/cm2 showed complete tumor arrest. In contrast, both control groups showed continuous tumor growth in all animals with tumors filling most of the vitreous cavity by 3 weeks. Histologic examination results of tumors treated with dye plus light immediately after treatment showed prominent vascular closure. No vascular changes were noted in the control eye treated with light or dye alone. Examination results of the eyes that showed tumor regression after a 4-week follow-up period showed tumor necrosis and extensive infiltration of mononuclear cells and pigment-laden macrophages at the tumor site. These data suggest that photodynamic therapy may have a role in the management of pigmented choroidal melanomas.