Microvascular Abnormalities, Inner Retina Thinning and Sectorial Optic Atrophy after Low-dose Stereotactic Radiotherapy for Neovascular Age-Related Macular Degeneration: A Case Report

Introduction

Radiation therapy was under extensive investigation between 1996 and 2007 as a potential treatment for neovascular age-related macular degeneration (nAMD), owing to its anti-angiogenetic and antifibrotic effects [1]. Targeting the proliferating endothelial cells, the therapy aimed to slow the progression of macular neovessels associated with AMD [2], [3], [4]. However, the clinical studies on external beam radiation in nAMD have yielded inconsistent results, leading to concerns about its effectiveness and safety [5].

Years later, the development of technologies capable of providing a more targeted delivery of radiation has renewed interest in this treatment approach as an adjuvant therapy in combination with intravitreal anti-vascular endothelial growth factor (anti-VEGF) injections aiming to reduce the frequency of injections. IRay stereotactic radiotherapy (Oraya Therapeutics Inc., Newark, CA, USA) delivered a low-energy X-ray radiation over a 4-mm retinal treatment zone in a single session, thus offering more precise and safer delivery methods. The INTREPID study, a randomized, double-masked, sham-controlled study, showed a significant reduction in the number of required intravitreal anti-VEGF injections over 2 years [3]. However, one of the main concerns with applying radiation to the eye is the potential development of radiation retinopathy. For stereotactic radiotherapy (SRT), 1- and 2-year follow-up data indicated low incidences of radiation retinopathy, including retinal microvascular abnormalities (MVAs) [3], [4], [5]. However, the incidence of MVAs increased to 30% after 3 years [6]. Unfortunately, the study took place in 2011, therefore it did not include optical coherence tomography angiography (OCT-A) in the investigation plan. There is a notable absence of long-term OCT-A follow-up for patients that received radiation treatment for nAMD in the current and past literature.

Although the potential for radiation retinopathy associated with radiotherapy is well established in the medical literature, the specific adverse effects of low-dose SRT on the optic nerve and inner retinal layers are less defined. To this point, to the best of our knowledge, there have been no instances reported of optic neuropathy linked to low-dose SRT in patients treated for nAMD [2].

Publication History

Received: 27 October 2024

Accepted: 12 January 2025

Article published online:
16 April 2025

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