Abstract
Abstract: :
Purpose: Ocular melanoma regrowth can result from residual viable intrascleral tumoral cells. Trans–scleral treatment may better target tumor cells near the base of thick tumors. This study aims to determine the degree of attenuation of 2 laser lights by the rabbit sclera and to evaluate whether experimental pigmented choroidal melanomas can be destroyed via a trans–scleral approach. Methods: Experimental choroidal melanomas were established in rabbit eyes as described before by our group (Retina 1994;14:264–9). When tumors reached 2–4 mm in thickness, they were treated with either 1047 nm light (Provectus Pharmaceuticals, Inc.) or with standard photodynamic therapy using Visudyne (2 mg/kg) at fluences of 400–500 J/cm2, based on our previous results. Scleral attenuation of laser energy was measured across 1.0 cm2 sections of fresh sclera. Treatment beam with Nd:YLF laser at 1047 nm (Provectus Pharmaceuticals, Inc.) was applied in a stepwise mode using a rectangular 3x3 mm raster pattern so highly focused light was covered throughout the desired treatment area. For 689 nm light, diode laser was used (Coherent, Inc.) and 1 mm spots were applied via a fiberoptic probe (CeramOptec Industries, Inc.) covering the whole tumor. Results: Fresh sclera attenuated the 1047 nm laser energy by 40%, and 689 nm laser by 90%. Acute histological analysis of tumors treated with 1047 nm light revealed extensive vascular engorgement throughout the full thickness of the tumor consistent with vascular closure. In contrast, tumors treated with PDT showed only vascular congestion near the base of the tumor, and the penetration in the tumor was related to the amount of delivered energy. Conclusions: Our data show more effective vascular closure of tumors with trans–scleral Nd:YLF 1047 nm laser than with PDT. These data suggest that the near–infrared 1047 nm laser light may be useful in the treatment of thick choroidal melanomas.
Keywords: melanoma • tumors • laser