Geographic atrophy is a condition affecting central vision, representing an advanced stage of dry age-related macular degeneration (AMD). It is characterized by the progressive and irreversible loss of retinal tissue, which can impact detailed tasks like reading and recognizing faces. This condition develops as cells in a part of the retina called the macula waste away. The name “geographic” is used because the areas of dead cells can resemble a map to an eye care professional examining the retina.
The Connection to Age-Related Macular Degeneration
Age-related macular degeneration is a common eye condition that primarily affects older adults and is categorized into two types: “wet” and “dry.” Geographic atrophy is the final and most severe stage of the dry form. This process involves the gradual breakdown of the retinal pigment epithelium (RPE), a layer of cells that supports the light-sensing photoreceptors in the retina.
As the RPE cells die, the photoreceptors they nourish also begin to degenerate, leading to a loss of function in the macula. The risk factors for developing AMD, and consequently geographic atrophy, include advancing age, a family history of the condition, and genetic predispositions. Lifestyle factors such as smoking also increase the risk of the disease’s progression.
Recognizing the Symptoms
The onset of geographic atrophy is slow, with symptoms often unnoticeable in the early stages. Individuals may experience a gradual loss of sharpness in their vision, which can manifest as difficulty reading small print or trouble seeing in dim lighting. One of the defining symptoms is the appearance of a dark or blind spot, known as a scotoma, in the central field of vision.
Another common symptom is that colors may appear washed out, dull, or less vibrant than before. While central vision is significantly affected, peripheral or side vision remains intact. The progression of symptoms can vary, with some people experiencing a more rapid decline in vision than others.
How Geographic Atrophy Is Diagnosed
The diagnosis of geographic atrophy is made by an eye care professional during a comprehensive eye exam. The process begins with a dilated eye exam, using eye drops to widen the pupils for a clear view of the retina and macula. During this examination, the specialist can identify the characteristic patches where the dark pigment of the retina has been lost.
To confirm the diagnosis and monitor the condition’s progression, several imaging techniques are used. Fundus photography takes detailed pictures of the retina to document the atrophic lesions. Optical coherence tomography (OCT) is a non-invasive test that uses light waves to create cross-sectional images of the retina, revealing the thinning of retinal layers. Another valuable tool is fundus autofluorescence (FAF), which uses a special filter to highlight the areas of dead RPE cells, making it easier to track the expansion of the atrophic areas.
Current Treatment Approaches
Until recently, management of geographic atrophy was limited to monitoring and the use of vision aids. In 2023, the first treatments for GA were approved by the FDA. These treatments are not a cure and do not reverse existing vision loss or damage to the retina. Their primary goal is to slow the rate at which the lesions grow and the disease progresses.
These new therapies are administered as injections directly into the eye. They work by inhibiting the complement cascade, a part of the body’s immune system. Overactivation of this system is believed to contribute to the inflammation and cell death that occurs in geographic atrophy. By blocking specific proteins in this pathway, these medications help reduce the rate of cell loss and slow the expansion of the atrophic areas. Patients require multiple injections over time to maintain the effect.
Adapting to Vision Changes
Living with vision loss from geographic atrophy involves strategies to maximize remaining sight. Low-vision rehabilitation services can provide valuable training and support. Specialists can recommend and train individuals on how to use vision aids, such as handheld or electronic magnifiers, to make reading and other detailed tasks easier. Using high-contrast settings on digital screens and ensuring bright, well-distributed lighting in the home can also improve visibility.
Making practical modifications at home can enhance safety and independence. This might include using contrasting colors to make objects and potential hazards more visible, such as placing dark mats on light-colored floors or using brightly colored tape to mark the edges of steps. Support from family, friends, and formal support groups is also beneficial for addressing the challenges that can accompany progressive vision loss.