STEREOTACTIC RADIOTHERAPY FOR WET AGE-RELATED MACULAR DEGENERATION (INTREPID) Influence of Baseline Characteristics on Clinical Response RETINA-THE JOURNAL OF RETINAL AND VITREOUS DISEASES Jackson, T. L., Shusterman, E. M., Arnoldussen, M., Chell, E., Wang, K., Moshfeghi, D. M. 2015; 35 (2): 194-204


To determine which patients respond best to stereotactic radiotherapy (SRT) for neovascular age-related macular degeneration.Participants (n = 230) receiving intravitreal anti-vascular endothelial growth factor injections for neovascular age-related macular degeneration enrolled in a randomized, double-masked sham-controlled trial comparing 16 Gray, 24 Gray, or Sham SRT. In a post hoc analysis, participants were grouped according to their baseline characteristics, to determine if these influenced SRT efficacy.At 52 weeks, SRT was most effective for lesions =4 mm in greatest linear dimension and with a macular volume greater than the median value of 7.4 mm. For 26% of the participants with both these characteristics, SRT resulted in 55% fewer ranibizumab injections (2.08 vs. 4.60; P = 0.0002), a mean visual acuity change that was 5.33 letters superior to sham (+2.18 vs. -3.15 letters; P = 0.0284), and a 71.1-µm greater reduction in mean central subfield thickness (-122.6 vs. -51.5 µm; P = 0.027). Other features associated with a positive response to SRT included pigment epithelial detachment and the absence of fibrosis.Stereotactic radiotherapy is most effective for neovascular age-related macular degeneration lesions that are actively leaking at the time of treatment, and no larger than the 4-mm treatment zone.

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