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Dr. Paul Finger
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Radiation For "Wet" Macular Degeneration Radiation therapy can destroy blood vessels and prevent neovascularization. Radiation is used after surgery to prevent scarring of the skin (keloid) and during coronary bypass surgery to prevent stenosis (scarring). This is because radiation can kill or effect the cells which make up newly formed blood vessels, inflammatory cells which promote scarring, and cells which help create fibrous tissues. Ophthalmologists have been using radiation to treat tumors within the eye, thyroid eye disease, and more recently to treat "wet" macular degeneration. Though numerous studies have suggested that radiation might help patients with macular degeneration, many other studies have suggested that it does not. Bergink et al have provided the best evidence that radiation can delay vision loss after the onset of wet macular degeneration. He performed a prospective-randomized, controlled clinical trial comparing moderate doses of external beam irradiation to observation (no treatment). They found that 30% of treated patients and 52% of nontreated patients lost 3 lines of vision after 1 year of follow up. But the more dramatic comparison was at 6 lines of vision loss. Only 22% of the radiation treated patients suffered this severe loss of vision as compared 44% of the untreated patients at 1 year follow up. In contrast, Holz recently reported on a large multicenter trial of relatively low dose external radiation therapy. This study concluded that 16 Gy in given over 8 days resulted in the same vision in the treated and untreated patients at 1 years follow-up. Both of these studies are excellent, but Bergink's suffers from small numbers (only 75 patients), and Holz concluded that they might have used too little radiation. Other Forms of Radiation Therapy You may have heard of different forms of radiation. These may include: Proton Beam, Strontium-90, Palladium-103, Radiosurgery, and EBRT (external beam radiation therapy). The potential therapeutic effects and side-effects of these different forms of radiation differ due to their distributions of radiation to the macula and normal ocular structures. For more information: Paul T. Finger, MD. 1. Bergink GJ, Hoyng CB van der Maazen RWM, et al. A randomized controlled clinical trial on the efficacy of radiation therapy in the control of subretinal choroidal neovascularization in age-related macular degeneration: radiation versus observation. Graefes Arch Clin Exp Ophthalmol 1998;236:321-325. 2. Finger PT, Chakravarthy U. Radiotherapy as treatment for age-related macular degeneration. Arch Ophthalmol 116:1507-1509, 1998. A Summary of Clinical Trials Using Radiation Therapy
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