Geographic atrophy (GA) is an eye condition that progressively impairs central vision, impacting millions worldwide. It represents an advanced stage of dry age-related macular degeneration (AMD), a common cause of vision loss in older adults. GA leads to a gradual decline in the ability to see clearly straight ahead, affecting daily activities such as reading, driving, and recognizing faces.
What is Geographic Atrophy?
Geographic atrophy is characterized by the progressive loss of cells within the macula, the central part of the retina responsible for sharp, detailed vision. It involves the degeneration and death of retinal pigment epithelium (RPE) cells, which support the light-sensing photoreceptor cells. As these RPE cells and photoreceptors degenerate, well-defined areas of atrophy form, resembling islands on a map when viewed by an eye care professional.
This cellular loss creates blind spots or areas of blurriness in the central visual field. The fovea, the center of the macula responsible for the highest quality vision, can eventually be affected as the atrophic areas expand. These areas of cell death enlarge over time, leading to worsening vision loss.
Identifying Symptoms and Risk Factors
Individuals with geographic atrophy experience visual symptoms that develop gradually. Blurred or distorted central vision is common, making tasks like reading or recognizing faces challenging. Many notice a dim or dark blind spot, known as a scotoma, in their direct line of sight. Seeing in dim light also becomes more difficult, and colors may appear less vibrant or washed out. Peripheral vision remains unaffected.
Several factors increase the likelihood of developing geographic atrophy. Age is the most significant risk factor, with the condition affecting those over 60 years old. Genetics also play a substantial role, as a family history of AMD elevates the risk. Smoking, both current and past, significantly increases the chances of developing GA. Race (more common in Caucasians), high blood pressure, and high cholesterol can also contribute to the risk.
How Geographic Atrophy is Diagnosed
Diagnosing geographic atrophy begins with a comprehensive eye examination performed by an ophthalmologist. During this examination, the doctor will dilate the pupils to get a clear view of the retina at the back of the eye. This allows for direct visualization of any changes in the macula, including the characteristic atrophic patches.
Specialized imaging tests provide detailed views of the retina and confirm the diagnosis. Optical Coherence Tomography (OCT) is a non-invasive imaging technique that produces cross-sectional images of the retina. OCT scans reveal the loss of RPE and photoreceptor cells, along with thinning of the retinal layers, which are hallmarks of GA.
Fundus Autofluorescence (FAF) imaging highlights areas where RPE cells are damaged or lost by detecting changes in naturally occurring fluorescent compounds (lipofuscin). These areas of decreased autofluorescence correspond directly to the geographic atrophy lesions. An Amsler grid, a simple grid of straight lines, can also be used at home to detect changes in central vision, such as wavy lines or missing areas.
Current Treatment and Management Options
Recent advancements have brought new pharmacological treatments for geographic atrophy, primarily targeting the complement system, a part of the immune response that contributes to AMD progression. Pegcetacoplan (SYFOVRE) and avacincaptad pegol (IZERVAY) are two complement inhibitor therapies approved to slow the progression of GA. These medications are administered as intravitreal injections, delivered directly into the eye. Pegcetacoplan targets complement component 3 (C3), while avacincaptad pegol targets complement component 5 (C5), both aiming to reduce the rate of GA lesion growth. Clinical trials have shown these treatments can reduce the growth rate of GA lesions by 14-35%.
Despite these breakthroughs, current treatments for geographic atrophy aim to slow the disease’s progression rather than cure it or restore lost vision. Vision rehabilitation and management strategies are a significant part of living with GA.
Low vision aids, such as magnifiers, telescopic glasses, and electronic devices, help individuals make the most of their remaining vision. Adapting to vision loss involves strategies like improving lighting, enhancing contrast, and using large-print materials. Consulting with a low vision specialist can provide tailored advice and resources to maintain independence and quality of life. Regular eye examinations monitor the disease’s course.