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Photodynamic therapy of pigmented choroidal melanomas of greater than 3-mm thickness
1Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston 02114, USA.
Purpose:
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.
Methods:
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.
Results:
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.
Conclusions:
These data suggest that photodynamic therapy may have a role in the management of pigmented choroidal melanomas.
Insights
Photodynamic therapy using benzoporphyrin derivative (verteporfin) effectively arrested experimental pigmented choroidal melanomas in rabbits. This treatment shows promise for managing these eye tumors.
Area of Science:
- Ophthalmology
- Oncology
- Photomedicine
Background:
- Choroidal melanomas are malignant tumors requiring effective treatment.
- Photodynamic therapy (PDT) offers a targeted approach to tumor destruction.
Purpose of the Study:
- To evaluate the efficacy of PDT using verteporfin in treating experimental pigmented choroidal melanomas.
- To determine the optimal light dose for PDT-induced tumor destruction.
Main Methods:
- Experimental pigmented choroidal melanomas were induced in rabbit eyes.
- Tumors exceeding 3 mm thickness were treated with intravenous verteporfin and 692-nm laser irradiation.
- Control groups received light or verteporfin alone; outcomes were assessed via fundus photography, angiography, and ultrasonography.
Main Results:
- Complete tumor arrest was observed in rabbits treated with PDT at light doses of 80 J/cm2 or higher.
- Control groups exhibited continuous tumor growth.
- Histological analysis revealed vascular closure and tumor necrosis in PDT-treated eyes.
Conclusions:
- Photodynamic therapy with verteporfin demonstrates significant potential for managing pigmented choroidal melanomas.
- PDT-induced vascular closure and necrosis are key mechanisms of tumor destruction.