Haematoporphyrin photosensitisation treatment of experimental choroidal melanoma

Greene amelanotic melanoma transplanted to pigmented rabbit choroid provided the experimental model for studying photosensitisation treatment of choroidal melanoma. Administration of haematoporphyrin derivative (HPD) and subsequent photoradiation with green laser light destroyed much of the melanoma with minimal side effects to normal uvea. The results of treatment were documented by fundus photography and fluorescein angiography. By 24 hours, the irradiated melanoma and surrounding retina appeared whitened and necrotic, with complete non-perfusion of the area. Over the course of one week, the clinical appearance did not alter. Histopathology at 24 hours and 8 days confirmed massive central tumour necrosis, but in all cases this was subtotal. Viable cells were evident at the periphery and also along the base of the tumour. Experimental evaluation of treatment parameters is required before this technique can be recommended for human choroidal melanoma.