Transscleral delivery of Nd: YLF laser at 1,047 nm causes vascular occlusion in experimental pigmented choroidal melanoma.

Purpose: The aims of this study were to determine the scleral attenuation of focused neodymium: yttrium-lanthanum-fluoride laser at 1,047 nm applied transsclerally and whether transscleral delivery can close the vascular supply at the base of experimental choroidal melanoma in rabbits.

Methods: Fifty-two New Zealand albino rabbits were included. Scleral laser attenuation was measured across fresh sclera. B16F10 melanomas were established in the subchoroidal space of 49 rabbits. Twenty-one animals were killed immediately after transscleral treatment, 14 were followed for 2 weeks to 4 weeks, and 14 were followed without treatment. Ophthalmoscopy, fundus photographs, and fluorescein angiography were performed before treatment, immediately after, and weekly during the follow-up. Eyes were examined by light microscopy.

Results: Sclera attenuated laser energy by 31% ± 7%. Immediately after treatment, angiography showed diffuse hypofluorescence in 71% (15 of 21 rabbits). Light microscopy showed vascular occlusion extending at least two thirds of the tumor thickness from the base. Seven of the 14 tumors followed for 15 days ± 8 days were eradicated. There was no correlation between tumor height and eradication.

Conclusion: Rabbit sclera attenuated 31% ± 7% of laser energy. A single transscleral treatment causes tumor vascular closure at the base and may serve as an adjuvant therapy to ensure destruction of deep and intrascleral tumor cells.