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Original Investigation
July 9, 2020

Evaluation of Month-24 Efficacy and Safety of Epimacular Brachytherapy for Previously Treated Neovascular Age-Related Macular Degeneration: The MERLOT Randomized Clinical Trial

Author Affiliations
  • 1Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
  • 2Department of Ophthalmology, King’s College Hospital, London, United Kingdom
  • 3NetwORC UK, Central Angiographic Reading Center, Queen’s University of Belfast, Belfast, United Kingdom
  • 4Reading Center, Moorfields Eye Hospital, London, United Kingdom
  • 5Department of Ophthalmology, Maidstone Hospital, Maidstone, United Kingdom
  • 6Department of Ophthalmology, Bristol Eye Hospital, Bristol, United Kingdom
  • 7Department of Ophthalmology, Hull and East Yorkshire Eye Hospital, Hull, United Kingdom
  • 8Vitreoretinal Unit, Sunderland Eye Infirmary, Sunderland, United Kingdom
  • 9Institute of Genetic Medicine, Newcastle University, Newcastle Upon Tyne, United Kingdom
JAMA Ophthalmol. 2020;138(8):835-842. doi:10.1001/jamaophthalmol.2020.2309
Key Points

Question  Does epimacular brachytherapy reduce the number of anti–vascular endothelial growth factor injections that patients with chronic, active neovascular age-related macular degeneration require without sacrificing their visual acuity?

Findings  In this randomized clinical trial of 363 participants with neovascular age-related macular degeneration, epimacular brachytherapy did not reduce the frequency of anti–vascular endothelial growth factor injections and was associated with worse visual acuity at month 24 compared with as-needed ranibizumab monotherapy.

Meaning  These findings do not support the addition of epimacular brachytherapy to anti–vascular endothelial growth factor treatment for neovascular age-related macular degeneration.


Importance  Although anti–vascular endothelial growth factor (VEGF) treatment offers better outcomes than the natural history of neovascular age-related macular degeneration (ARMD), a less burdensome, less expensive, and more durable treatment is needed.

Objective  To assess the efficacy and safety of epimacular brachytherapy (EMB) for chronic, active, neovascular ARMD.

Design, Setting, and Participants  The Macular Epiretinal Brachytherapy vs Ranibizumab (Lucentis) Only Treatment (MERLOT) pivotal device trial was conducted at 24 National Health Service hospitals across the UK. Patients who had neovascular ARMD and received intravitreal ranibizumab were enrolled between November 10, 2009, and January 30, 2012. Eligible patients were randomized 2:1 and were stratified by lens status and angiographic lesion type to receive either EMB plus as-needed ranibizumab or as-needed ranibizumab monotherapy. Participants were followed up monthly for 24 months and then assessed at a final visit at month 36. Masking of participants and clinicians was not possible, but best-corrected visual acuity (BCVA) and imaging were analyzed by masked assessors. Analysis followed the intent-to-treat approach.

Interventions  Pars plana vitrectomy with 24 Gy EMB plus as-needed ranibizumab vs as-needed ranibizumab monotherapy.

Main Outcomes and Measures  Coprimary outcomes were the number of as-needed ranibizumab injections and the mean change in Early Treatment Diabetic Retinopathy Study (ETDRS) BCVA with a noninferiority margin of –5 ETDRS letters. Secondary outcomes were the percentage of participants losing fewer than 15 ETDRS letters and gaining 0 or more or 15 or more ETDRS letters and the mean change in angiographic total lesion size, choroidal neovascularization size, and foveal thickness on optical coherence tomography.

Results  Of 363 participants, 329 (90.6%) completed 24 months of follow-up (222 participants in the EMB group and 107 in the ranibizumab group). The mean (SD) age of the combined groups was 76.5 (7.4) years. The mean (SD) number of ranibizumab injections was 9.3 (6.7) in the EMB group and 8.3 (4.5) in the ranibizumab group, with a difference of 1.0 injection (95% CI, –0.3 to 2.3; P = .13). The mean (SD) BCVA change was –11.2 (15.7) ETDRS letters in the EMB group and –1.4 (10.9) ETDRS letters in the ranibizumab group, with a difference of 9.8 ETDRS letters (95% CI, –6.7 to –12.9). In the EMB group, 65.6% of participants (160 of 244) lost fewer than 15 ETDRS letters vs 86.6% (103 of 119) in the ranibizumab group, with a difference of 21% (95% CI, 12.4%-29.5%; P < .001). Microvascular abnormalities occurred in 20 of 207 eyes (9.7%) in the EMB group and 1 of 97 eyes (1.0%) in the ranibizumab group. These abnormalities occurred outside the foveal center, and there were no unexpected safety concerns.

Conclusions and Relevance  The MERLOT trial found that despite the acceptable safety of EMB, it did not reduce the number of ranibizumab injections and was associated with worse visual acuity than anti-VEGF treatment alone; these results do not support EMB use as an adjunct treatment for chronic, active neovascular ARMD.

Trial Registration  ClinicalTrials.gov Identifier: NCT01006538

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