Radiation Maculopathy
Overview
Radiation maculopathy is a condition causing vision loss due to radiation therapy, often a delayed complication of treating <uveal melanoma or <head and neck cancers. It involves microvascular damage to the retina’s macula, leading to symptoms like macular edema, intraretinal hemorrhages, and capillary nonperfusion. While symptoms like visual distortion or blurring can occur, the most common initial finding is macular edema. Treatment primarily focuses on managing macular edema with <anti-VEGF agents and <steroids, but preventing the condition is the best strategy, and treatment outcomes are often modest or temporary.
Symptoms
Symptoms of radiation maculopathy include blurry or distorted central vision (metamorphopsia), where straight lines appear wavy, and dark spots or blind spots in your field of vision. Other signs, often detected by an eye doctor, can include leakage and fluid buildup (edema) in the macula, hemorrhages, microaneurysms, and other changes to the retinal blood vessels and surrounding tissue. These symptoms typically appear gradually, often months or years after radiation therapy.
Causes
Radiation maculopathy is caused by high-energy ionizing radiation exposure to the eye during cancer radiotherapy for tumors like uveal melanoma or head and neck cancers. The radiation damages endothelial cells in the retinal blood vessels, leading to inflammation, vascular closure, macular edema (swelling), and vision loss. Factors like a higher radiation dose to the macula and preexisting diabetes mellitus increase the risk of developing the condition.
Prevention
Radiation maculopathy prevention involves minimizing radiation exposure to the eye through techniques like ocular shielding and optimized radiation delivery, along with prophylactic medical treatment using anti-VEGF agents (like bevacizumab or ranibizumab) and steroids (such as triamcinolone) to reduce macular damage. Strategies like panretinal photocoagulation (PRP) and the potential use of vitreous substitutes during plaque radiotherapy have also been explored
Diagnosis
Radiation Maculopathy (RM) is diagnosed by ophthalmic examination for signs like macular edema, retinal hemorrhage, and hard exudates, but imaging tests are crucial for early and comprehensive diagnosis. Optical Coherence Tomography (OCT) is particularly valuable for detecting early macular edema, even before symptoms appear, and for grading its severity. Fluorescein Angiography (FA) and Indocyanine Green Angiography (ICGA) can show vascular changes and perfusion issues, while OCT-Angiography (OCT-A) offers detailed insights into retinal vessel integrity.
Prognosis
The prognosis for radiation maculopathy varies, but early diagnosis and treatment with anti-VEGF injections or steroids can improve vision and prevent further decline. While initial vision may stabilize or improve, many patients still experience significant vision loss, with a substantial percentage of eyes falling below 20/200 after plaque radiotherapy. Prognosis is influenced by the tumor’s size and location, patient age, and the presence of pre-existing conditions like diabetes.
Treatment
Treatment for radiation maculopathy primarily involves anti-VEGF drugs (like bevacizumab, ranibizumab, and aflibercept), which are given via intravitreal injections, and sometimes intravitreal corticosteroids like triamcinolone or dexamethasone. Other options include focal laser photocoagulation, though this is less common now, and in some cases, steroid implants or a combination of therapies (polypharmacy). The specific treatment regimen depends on the severity of the radiation damage.