Gamma knife radiosurgery for uveal melanomas: an 8-year experience

Object. The authors report their experience using gamma knife radiosurgery (GKS) to treat uveal melanomas. Methods. Between 1992 and 1998, 60 patients were treated with GKS at a pres cription dose between 45 Gy and 80 Gy. The mean diameter of the tumor base was 12.2 mm (range 3-22 mm). The mean height of the tumor prominence was 6. 7 mm (range 3-12 mm). The eye was immobilized. The follow-up period ranged from 16 to 94 months. Tumor regression was achi eved in 56 (93%) of 60 patients. There were four recurrences followed by en ucleation. The severe side effect of neovascular glaucoma developed in 21 ( 35%) patients in a high-dose group with larger tumors and in proximity to t he ciliary body. A reduction in the prescription dose to 40 Gy or less and excluding treatment to tumors near the ciliary body decreased the rate of g laucoma without affecting the rate of tumor control. Conclusions. Gamma knife radiosurgery at a prescription dose of 45 Gy or mo re can achieve tumor regression in 85% of the uveal melanomas treated. Neov ascular glaucoma can develop in patients when using this dose in tumors nea r the ciliary body. It is advised that such tumors be avoided and that the prescription dose be reduced to 40 Gy.