Gamma knife treatment of subfoveal, classic neovascularization in age-related macular degeneration: a pilot study

Object. Age-related macular degeneration (AMD) is the leading cause of seve re vision loss in people older than age 65 years in the western world. The visual acuity loss usually results from the ingrowth of new vessels from th e choroid capillaries, so called choroidal neovascularization (CNV). The ai m of this pilot study was to investigate the effect of a single-fraction ga mma knife radiosurgery (GKS) on visual acuity and the growth pattern of CNV in patients with AMD. Methods. Ten patients with a mean age of 75 years and with a subfoveal, cla ssic CNV due to AMD were enrolled in this study. All patients were treated with GKS in one fraction with a prescription dose of 10 Gy. The treatment t arget was the CNV located in the macula. Computerized tomography scans of t he globe were obtained. After a follow up of 1 year visual acuity was stable in six patients and de creased in four. The size of the CNV could be stabilized in four patients, and in six an enlargement of these neovascular complexes was shown. No side effects, such as cataract formation, development of radiation-induced reti nopathy, or optic neuropathy, have been observed so far. Conclusions. Gamma knife radiosurgery seemed to have a beneficial effect on visual acuity in patients with AMD, but it failed to control growth of CNV in six patients. A longer follow up, a larger study population, and a rand omized and controlled study are necessary for a final conclusion.