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Purpose: To determine which patients respond best to stereotactic radiotherapy (SRT) for neovascular age-related macular degeneration., Methods: 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., Results: 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., Conclusion: 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.

Purpose: To determine the safety and efficacy of low-voltage, external-beam, stereotactic radiotherapy (SRT) for patients with neovascular age-related macular degeneration (AMD)., Design: Randomized, double-masked, sham-controlled, multicenter, clinical trial., Participants: A total of 230 participants with neovascular AMD who received ≥ 3 ranibizumab or bevacizumab injections within the preceding year and requiring treatment at enrollment., Methods: Participants received 16 Gray, 24 Gray, or sham SRT. All arms received pro re nata (PRN) ranibizumab for 12 months, with PRN bevacizumab or ranibizumab thereafter., Main Outcome Measures: Mean number of PRN injections; best-corrected visual acuity (BCVA); loss of <15 Early Treatment of Diabetic Retinopathy Study letters; change in optical coherence tomography central subfield thickness; and change in angiographic total lesion area and choroidal neovascularization (CNV) area., Results: At year 2, the 16 and 24 Gray arms received fewer PRN treatments compared with sham (mean 4.5, P = 0.008; mean 5.4, P = 0.09; and mean 6.6, respectively). Change in mean BCVA was -10.0, -7.5, and -6.7 letters for the 16 Gray, 24 Gray, and sham arms, respectively, with 46 (68%), 51 (75%), and 58 participants (79%), respectively, losing <15 letters. Mean central subfield thickness decreased by 67.0 μm, 55.4 μm, and 33.3 μm, respectively. Mean total active lesion area increased by 1.0, 4.2, and 2.7 mm(2), respectively. Mean CNV area decreased by 0.1 mm(2) in all groups. An independent reading center detected microvascular abnormalities in 6 control eyes and 29 SRT eyes, of which 18 were attributed to radiation; however, only 2 of these possibly affected vision. An exploratory subgroup analysis found that lesions with a greatest linear dimension ≤ 4 mm (the size of the treatment zone) and a macular volume greater than the median (7.4 mm(3)) were more responsive to SRT, with 3.9 PRN injections versus 7.1 in comparable sham-treated participants (P = 0.001) and mean BCVA 4.4 letters superior to sham (P = 0.24)., Conclusions: A single dose of SRT significantly reduces intravitreal injections over 2 years. Radiation can induce microvascular change, but in only 1% of eyes does this possibly affect vision. The best response occurs when AMD lesions fit within the treatment zone and they are actively leaking., (Copyright © 2015 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.)

Purpose: To evaluate low-voltage X-ray stereotactic radiotherapy (SRT) delivered in conjunction with intravitreal ranibizumab for the treatment of active macular polypoidal choroidal vasculopathy (PCV)., Methods: At baseline, all eyes received an intravitreal injection of ranibizumab, followed by 16-Gy X-ray SRT to the macula. Further ranibizumab injections were given pro re nata. The primary outcome measure was regression of the polyps assessed by indocyanine green angiography. Secondary outcome measures were best-corrected visual acuity (BCVA) and central foveal thickness (CFT) changes on optical coherence tomography. Local or systemic adverse events were evaluated as well., Results: We examined 12 eyes of 12 patients with PCV. At month 12, an angiographic regression of the polyps was observed in 10 of the 12 eyes. The mean BCVA improved by 7.6 letters: from 65.08 ± 11.4 to 72.7 ± 14.75 letters on the Early Treatment Diabetic Retinopathy Study (ETDRS) chart. The mean CFT decreased from 372.3 ± 79.6 to 215.9 ± 57.9 µm (p < 0.01). No local or systemic adverse events were reported., Conclusions: The preliminary data support the safety of low-voltage X-ray SRT for the treatment of macular PCV and show polyp closure, reduction in CFT and improvement in the mean BCVA. Additional research is warranted to confirm the efficacy and longer-term safety of this therapy in this population., (© 2014 S. Karger AG, Basel.)

Objective. To determine the dose response and toxicity threshold of micro-collimated X-rays delivered to porcine maculae by a stereotactic radiosurgical system after 270 days. Methods. Twelve eyes of six Yucatan mini-swine were randomized to receive up to 90Gy to the retina, using an office-based trans-pars plana delivery system. To determine the safety profile of this radiation delivery, ophthalmic examination, fundus photography, fluorescein angiography (FA), and spectral domain optical coherence tomography (SD-OCT) were obtained at multiple time points up to 270 days post treatment. Results. No abnormalities were noted on external examination. Cataracts were noted in 4 of 12 eyes. Dose and time-dependent changes were noted on fundus examination, FA, ICG and SD-OCT. No significant abnormalities were seen in the control, 16Gy or 24Gy groups using any modality. Histopathology revealed a dose response effect with no discernable lesions in the 16Gy group. Conclusion. The X-ray delivery system precisely targets the porcine retina in vivo with little effect on surrounding structures. No ophthalmic or intracranial adverse effects were noted at clinically relevant doses at 270 days following radiation delivery. [ABSTRACT FROM AUTHOR]