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A Tong, D Hauser, A Barak, B Leigh, Z Goldberg, D Kubo, J Earle, JT Handa, LS Morse; Stereotactic External Beam Radiation Treatment in Eyes With Age-Related Subfoveal Choroidal Neovascular Membrane — A Two-Year Follow-up . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1221.
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Purpose: Stereotactic external beam radiation (St-EBR) has been an experimental modality in treating subfoveal choroidal neovascular membrane (CNV). Compared to conventional radiation therapy, St-EBR allows energy to be delivered to a smaller and more defined area. Last year, we presented the safety and efficacy results for 12-month. This paper presents 24-month and longer follow up. The aim of this study is to compare the visual outcome of various radiation dosages (20-24Gy, 28-32Gy, and 36-40Gy), and to evaluate the progression of cataract and radiation retinopathy from St-EBR. Methods: Patients had clinical and angiographic signs of subfoveal CNV from age-related macular degeneration (ARMD), with visual acuity (VA) between 20/40 to 20/400. Radiation was delivered by 6 MV proton beam with a 15mm in diameter. Dosages varied from 20-40Gy and were applied daily at 2Gy. Results: Out of 81 patients originally included in the study, 37 patients were followed for 24 months or more (range 24-49, average 31+7). There was no radiation retinopathy detected in any of the patients treated. Cataract changes were not statically significant in eyes treated with St-EBR compared to contralateral eyes (p=0.86). Among all patients, pre-radiation VA was 0.67 logMAR value, 12-month was 0.66 (p=0.25), 18-month was 0.71 (p=0.07), 24-month was 0.85 (p=0.02), and last visit (average 31 months) was 1.04 (p<0.05). The two subgroups that received 20-24 Gy and 36-40 Gy showed similar course. Patients who received 28-32Gy showed VA of 0.71 (p=0.46) at 24-month, and VA of 1.06 (p=0.02) at the last visit exam. Among all patients at 24-month, 42% of the patients gained vision or stayed stable, 15% lost <3 lines, 22% lost 3-6 lines, and 19% lost ≷6 lines. Conclusion: St-EBR seemed to be a safe procedure at all studied dosages for the treatment of ARMD related subfoveal CNV. At radiation dosages of 20-24Gy or 36-40Gy, St-EBR appeared to stabilize visual acuity until 12-18 months post-treatment, at which time the effect of radiation began to cease. At a dosage of 28-32Gy, vision tended to stabilize for a longer period (at least 24 months). None
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