Preliminary experience in the treatment of choroidal melanoma with gamma knife radiosurgery

Object. The authors report their early results from an ongoing experience t reating patients with choroidal melanoma by using gamma knife radiosurgery (GKS). Methods. Between September 1998 and March 2000, 11 patients were treated fo r choroidal melanoma. Treatment was facilitated with specialized frame plac ement. Eye immobilization was accomplished with supra- and infraorbital ner ve block and tethering sutures to the periorbital tissue. Magnetic resonanc e imaging was performed to localize the tumor for treatment planning. Plugg ing patterns were used to steer fall-off radiation away from the fovea, opt ic nerve, or lens. Tumor volume, tumor location relative to critical struct ures, and dose to critical structures were determined using GammaPlan. Tumo r response was determined using ultrasonography. Toxicity was determined by clinical assessment, visual acuity testing, and ophthalmoscopy. All 11 patients successfully completed the treatment. In every case, 40 Gy was prescribed to the 50% isodose, which completely encompassed all visible tumor. Tumor height ranged from 2.9 to 7 mm. The tumor diameter ranged fro m 6 to 13 mm. The range of follow up was 2 to 19 months. No tumor has progr essed. One patient had improvement in vision because of improvement in reti nal detachment. Two patients experienced visual decline. One patient's visu al decline was due to a vitreous hemorrhage, and the other's was due to har d exudates encroaching on the macula. One patient has developed a dry eye t hat is managed effectively with topical eye lubricants. Conclusions. This preliminary experience demonstrates that GKS is a feasibl e treatment option for small- to medium-sized choroidal melanomas. Longer f ollow up and additional patients will be required to improve the assessment and the ultimate tumor control and toxicity in this ongoing series.