Geographic atrophy is an advanced form of macular degeneration. Unlike wet ARMD, there are no signs of choroidal neovascularization and anti-VEGF injections or laser are not helpful.
Age-related geographic atrophy can cause slowly progressive, but severe visual loss. This geographic atrophy affects the retina, the part of the eye that sends visual information to the brain and enables sight.
Geographic atrophy (GA) is a chronic disease that leads to vision loss that makes it difficult to read, recognize faces, and drive.
Effects on Photoreceptors
The atrophy affects the photoreceptors in the retina. There are two main types of photoreceptors—rods and cones. The rods and cones are specialized photoreceptors neurons that convert light into electrical signals and send those signals through the optic nerve to the visual cortex of the brain for visual processing. The retina, which is the size of a thumbnail, is filled with approximately 150 million of these light-sensitive photoreceptors neurons.
The rods and cones are in the outermost layer of the retina. The rods produce night-time vision and the cones are responsible for our daytime vision. In geographic atrophy, areas of these rod and cone photoreceptors degenerate and no longer function, or they are completely reabsorbed and disappear entirely.
Signs and Symptoms of GA
- Vision becomes less sharp or detailed
- Colors seem dull or washed out
- A dark spot appears in the central or peripheral (side) vision
- Seeing in the dark becomes difficult
Cause of Geographic Atrophy
The cause of geographic atrophy is not well understood. One hypothesis is that oxidative stress that takes place in the cells when they convert chemical energy from oxygen molecules, along with environmental stressor such as cigarette smoke, trigger inflammation that leads to the atrophy and loss of photoreceptor cells.
Recent studies indicate that geographic atrophy may be due to deficiencies in blood flow in the capillary bed that is next to the outer retina and is part of the oxygen delivery system to the photoreceptors.
Risk factors for Developing GA are:
- Age (most common in those over age 70)
- Genetics (family history of age-related macular degeneration)
- Heart disease
- Race (more common among Caucasians
- Smoking (nearly doubles the risk)
Treatments for Geographic Atrophy
There are currently no treatments available to slow the progression of geographic atrophy, but clinical trials to find a treatment are underway.
There are some diet and lifestyle changes that are recommended that may potentially slow down the rate of photoreceptor atrophy.
The National Eye Institute recommends that those at risk of developing GA eat a diet that includes green leafy vegetables, whole fruits, nuts, and omega-3 fatty acids—all of which may help to keep the photoreceptor cells healthy by reducing inflammation and providing antioxidants. Regular exercise and keeping your weight within a normal range are also recommended.