Geographic atrophy (GA) is an advanced stage of dry Age-Related Macular Degeneration (AMD), a progressive condition affecting millions globally. This degeneration of the retina is a leading cause of severe, irreversible vision impairment in older adults. GA is characterized by a slow, relentless loss of central sight, which profoundly impacts the ability to perform daily tasks requiring sharp focus.
Defining Geographic Atrophy and the Macula
Geographic atrophy is the final stage of dry AMD, characterized by the death of specialized cells in the central part of the retina. This central region, known as the macula, is responsible for the sharp, detailed vision needed for activities like reading and recognizing faces. The condition earns its name from the appearance of the damaged areas, which are clearly defined patches of cellular loss that resemble a map when viewed by an eye care specialist.
The physical damage involves the progressive wasting, or atrophy, of the Retinal Pigment Epithelium (RPE) cells and the overlying photoreceptor cells. RPE cells are responsible for nourishing the photoreceptors, which are the light-sensing cells in the retina. When RPE cells die, the photoreceptors they support also perish, resulting in a non-functioning patch of retina. These distinct areas of cell death, or lesions, expand and merge over time, steadily encroaching on the most central point of the macula, called the fovea.
The fovea contains the highest concentration of cone photoreceptors, making it responsible for the clearest, most acute color vision. When GA lesions reach the fovea, the loss of central visual acuity accelerates significantly. This explains why the condition is so destructive to focused vision while leaving the surrounding areas of the retina intact.
Addressing the Risk of Total Blindness
A common concern for people diagnosed with geographic atrophy is the risk of progressing to total blindness. GA does not lead to a complete loss of light perception or “total blindness.” The disease primarily targets the macula, meaning the damage is confined to the central field of vision.
The condition causes a dense, permanent blind spot, known as a scotoma, directly in the center of the visual field. Although this central blind spot makes tasks requiring fine detail impossible, the peripheral, or side, vision remains functional. This preserved side vision allows a person with advanced GA to maintain mobility and navigate their environment.
Despite the preservation of peripheral sight, the extensive loss of central vision often results in the patient being classified as legally blind. Legal blindness is a designation based on a corrected central visual acuity of 20/200 or less, or a severely restricted peripheral field. The functional experience of legal blindness from GA is the inability to see objects or faces when looking directly at them, rather than living in complete darkness.
Recognizing the Stages of Vision Loss
Geographic atrophy is a slowly progressive disease, and symptoms can be subtle in the early stages, especially if only one eye is affected. One of the first symptoms often reported is difficulty adapting to changes in light levels, such as moving from a bright room into a dimly lit one. Patients may also find they require significantly brighter light to read or perform other close-up tasks.
As the lesions grow, the central vision begins to blur, and colors may appear less vivid or washed out. The central blind spot, or scotoma, then develops, making it difficult to read printed words because letters or parts of words seem to disappear. Recognizing faces also becomes challenging, as the central area of focus is obscured by the blind spot.
The disease is characterized by steady, irreversible advancement. Once GA lesions form outside the fovea, the destructive process typically takes between 1.4 and 2.5 years to spread and involve the center of the macula. Once the fovea is reached, the decline in central visual acuity accelerates.
Current Approaches to Managing Geographic Atrophy
Until recently, there were no approved medical treatments specifically designed to slow the progression of geographic atrophy. However, the landscape of GA management has significantly changed with the introduction of new therapies that target the complement cascade. Two FDA-approved treatments, pegcetacoplan (Syfovre) and avacincaptad pegol (Izervay), are complement inhibitors that work by reducing the inflammation believed to drive the cell death process.
These therapies are administered through injections into the eye, typically on a monthly or bimonthly basis, and are designed to slow the rate at which the GA lesions grow. Clinical trials have demonstrated that these treatments can reduce the progression of the atrophic lesions by approximately 18% to 35% over the first year, but they cannot restore lost vision. This slowing of the disease offers patients the chance to preserve more of their remaining sight for a longer period.
Management also involves non-medical strategies. Smoking cessation is recommended, as smoking significantly increases the risk and progression of AMD. Low-vision rehabilitation maximizes the use of remaining peripheral vision. Specialists train patients to use magnifiers, specialized electronic devices, and lighting solutions to adapt to central vision loss and maintain independence.