PHOTODYNAMIC THERAPY OF OCULAR MELANOMA WITH BIS SILICON 2,3-NAPHTHALOCYANINE IN A RABBIT MODEL

Purpose. To investigate bis (tri-n-hexylsiloxy) silicon 2,3-naphthaloc yanine (SINc; 0.5 mg/kg) for photodynamic therapy of an experimental o cular melanoma in pigmented rabbits. Methods. SINc was dissolved in ca nola oil by heating, emulsified with Tween 80, and administered by ear vein. Pharmacokinetics were studied in frozen tumor sections by fluor escence microscopy using a charge coupled device, camera-based, low-li ght detection system with digital image processing at 1 and 24 hours. A Ti:sapphire laser and a microlens were used to deliver the light (77 0 nm; 40 mW/cm(2); 20 J/cm(2)). A control rabbit received light withou t SINc. Results. Localization studies of SINc showed intravascular dis tribution shifting to a tumor stromal and perivascular distribution 24 hours after treatment. Tissue thermal damage after irradiation was mi nimal in the control. Exudative retinal detachments were not observed. Tumor destruction was observed, with sharp demarcation to a depth of 3.5 mm. Conclusions. Tumor light penetration was good at 770 nm, and t hermal effects from the exciting light alone were minimal. Photodynami c therapy with SINc resulted in localized tumor destruction reflecting the light beam path without damage to adjacent tissue or intraocular complications.