[Photodynamic therapy of pigmented choroidal melanomas in rabbits]

Abstract

Objective: To evaluate the effect of photo-dynamic therapy in the destruction of experimental pigmented choroidal melanoma using a liposomal preparation of benzoporphyrin derivative (BPD), verteporfin.

Methods: Pigmented choroidal tumors were established in 44 New Zealand albino rabbit eyes. Animals were treated with daily injections of cyclosporine. Funduscopic examinations and ultrasonography were used to follow the tumor growth. When the tumor exceeded 2 mm in thickness (tumor height ranged from 2.0 - 4.6 mm), the rabbits were divided into three groups. In the 10 rabbits in the control group, 6 were treated with laser 120 - 150 J/cm(2) for tumors with the height range of 2.1 - 3.0 mm without photo-dynamic therapy, and 4 were not treated at all. The benzoporphyrin derivative was injected intravenously (1 mg/kg) for the rabbits in treatment group I (14 rabbits) and II (20 rabbits), and 692 nm argon-pumped dye laser at different light doses 60 - 150 J/cm(2) was used to irradiate the tumors. After the treatment for 4 - 6 weeks, the rabbits were sacrificed and the therapeutic results were observed.

Results: In treatment group I, the irradiation dose was 60 - 80 J/cm(2) and the tumor height was < 3 mm, in comparison with that of the control group the difference being very significant (P < 0.001). In the treatment group II, the thickness of the tumor was 3.0 - 4.6 mm and the irradiation dose was > 80 J/cm(2) (P < 0.001, companed with the control group). In contrast, the tumor grew continuously in all the animals in the control group and filled most of the vitreous cavity by 2 - 3 weeks.

Conclusion: These data suggest that photodynamic therapy have a role in the management of pigmented choroidal melanomas.