Geographic atrophy

What is geographic atrophy (GA)?

Geographic atrophy (GA) is a late stage of dry age-related macular degeneration estimated to affect about five million people worldwide. Areas of atrophy (cell death) in the retina resemble a map, which gives the condition its name. These areas can expand and lead to central vision loss.

Age-related macular degeneration (AMD) is a common condition that affects people over the age of 50. It is currently the leading cause of central vision impairment in the country. About  30% of people with dry AMD progress to geographic atrophy. The condition typically occurs as a late stage of dry AMD but may also occur after wet AMD has developed. Individuals with GA can also develop wet AMD. 

Geographic atrophy is estimated to impact nearly one million people in the United States. 

Early symptoms include increased difficulty with reading, cooking, driving and vision in dim light. As the condition progresses, blind spots, distorted vision and loss of central vision can occur. 

The risk of developing GA increases with age. Additional risk factors include family history, UV exposure, tobacco use, previous cataract surgery and chronic health conditions such as obesity, diabetes, high cholesterol and heart disease. 

The FDA approved pegcetacoplan (Syfovre™), the first treatment for geographic atrophy, in early 2023.

Causes

Geographic atrophy is an advanced stage of dry age-related macular degeneration. Dry AMD is caused by age-related thinning and degeneration of the macula, resulting in decreased central visual acuity.

The macula is the central part of the retina, the light-sensitive tissue that lines the back of the eye. This central area of the retina is responsible for your sharpest vision, providing fine detail when looking straight ahead. Damage to the macula from AMD can lead to a severe loss of visual function.

There are two types of AMD, dry and wet. This condition is further classified into stages — early, intermediate and advanced — per the guidelines of two landmark AMD studies, the Age-Related Eye Disease Study known as AREDS and AREDS2. 

Dry AMD and geographic atrophy

In dry (nonexudative) AMD, the macula becomes thinner with age. Small clusters of proteins, called drusen, accumulate under the retina and around the macula. With the development of GA in the advanced stage of AMD, these proteins enlarge, blocking nourishment to the retina and causing cell death (atrophy) in areas of the retina. These areas of atrophy are called “lesions” and have clear boundaries that resemble a geographic map, hence the name “geographic atrophy.” 

When these areas of atrophy expand into the macula, it leads to significant vision loss and blurry, missing spots in central vision. Peripheral vision typically remains unaffected in GA and AMD.

Dry AMD is classified as:

• Early – Small drusen and changes in the pigment can be seen in the retina during a dilated eye exam. Many people do not progress beyond this type. It has minimal symptoms.

• Intermediate – Vision begins to get blurry, and blank spots may appear in straight-ahead vision. Straight lines may look warped.

• Advanced (late stage) – Severe vision impairment, warped vision and missing spots in central vision are common. Difficulty seeing in and adapting to low light conditions can also occur. This stage is considered geographic atrophy.

Most (about 80%-90%) of people with AMD have the dry type, and about 45% of overall advanced cases of macular degeneration are the dry type.

Wet AMD and geographic atrophy

This type of AMD is called “wet” or exudative because blood and fluid leak from abnormal blood vessels that have begun to grow under the retina — a process known as neovascularization. Scarring and tissue damage progress rapidly, resulting in faster vision loss than with the dry form of AMD. 

According to the American Macular Degeneration Foundation:

• About 10%-15% of patients with dry macular degeneration progress to wet macular degeneration. 

• Up to 37% of wet AMD patients develop geographic atrophy within two years. 

• By seven years, 98% of patients with wet AMD develop geographic atrophy.

Wet AMD is also classified as early, intermediate and advanced. Advanced wet AMD accounts for about 55% of overall advanced cases of AMD. Treatments for wet AMD are available and focus on slowing the growth of abnormal blood vessels and the damage from fluid leaks and scars. 

READ MORE: Choroidal neovascularization (CNV): Symptoms and treatments

Symptoms of geographic atrophy

When the macula is damaged, severe vision impairment can result. Symptoms of geographic atrophy are most often noticeable when looking directly at an object. Vision changes resulting from geographic atrophy include:

• Blurry/missing areas in central vision 

• Dark spots in central vision 

• Poor vision in dim light

• Colors appearing dull

While AMD and geographic atrophy do not cause total blindness, they can significantly impact daily life. Common difficulties include:

• Recognizing faces

• Reading and writing, sewing and crafting

• Using a computer or phone

• Driving 

• Preparing meals

Risk factors for geographic atrophy

People with GA in one eye are at a higher risk of developing it in the other, typically within seven years. Additional risk factors include:

• Being age 60 or older

• Family history of macular degeneration

• UV exposure

• Opacities in the crystalline lens

• Previous cataract surgery

• Tobacco and alcohol use

• Unhealthy diet

• Obesity

• High cholesterol

• High blood pressure

• Heart disease

• Diabetes

• Caucasian ethnicity

• Light-colored eyes

In general, if someone is highly overweight, has uncontrolled high blood pressure, or is a smoker, they have a two to three times higher risk of advanced AMD.

Beginning at age 50, the prevalence of geographic atrophy quadruples every 10 years.

READ MORE: 15 ways heart disease affects eye health

Diagnosis 

Geographic atrophy is diagnosed based on a patient’s symptoms, a dilated eye exam and diagnostic imaging results. These tests include:

• Optical coherence tomography (OCT) – This procedure provides 3D cross-sectional images of the macula and retina. It does not require an injection and can be used to obtain a high-resolution retina scan. 

• Fundus autofluorescence imaging – This procedure provides imaging by taking advantage of blue light and the fluorescent properties of a pigment in the retina called lipofuscin.

Geographic atrophy treatment

Treatment for GA can include routine injections of a drug, taking supplements and lifestyle changes. Home monitoring for vision changes is also recommended. 

Syfovre™

There is currently one FDA-approved drug for GA treatment, pegcetacoplan (Syfovre™). It is given as an injection and has been found to reduce the rate of disease progression. According to Apellis, the drug’s manufacturer, Syfovre™:

• Has a dosing frequency of 25 to 60 days

• Reduces the lesion growth rate by up to 36% with monthly injections 

• Has the greatest benefit at 18 to 24 months

• Is currently not used to treat early AMD

AREDS2 supplements

Eye doctors also recommend certain supplements identified during the AREDS 2 study. These supplements can slow the progression from intermediate AMD to advanced forms, such as geographic atrophy:

• Vitamins C

• Vitamins E

• Lutein (an anti-oxidant)

• Zeaxanthin (an anti-oxidant)

• Zinc

Formulations of these vitamins can be found at pharmacies. If you have been diagnosed with AMD or geographic atrophy, consult your eye doctor about whether these dietary supplements would benefit you.

Lifestyle changes

In addition to medical treatments, certain diet changes and lifestyle changes are recommended:

• Stop smoking and drink alcohol in moderation.

• Wear sunglasses to reduce UV exposure. 

• Maintain a healthy weight.

• Develop a healthy, balanced diet with green, leafy vegetables and omega-3 fatty acids such as from fish oil.

Home monitoring

An Amsler grid, which looks like graph paper, is helpful for individuals with AMD and geographic atrophy to monitor changes in their vision. Each eye is tested individually to check for new areas of warped lines, blurriness or dark spots. If any changes are noted, an eye doctor should be contacted immediately.

Another tool for home monitoring is the ForeseeHome Monitor® from Notal Vision®. It is an FDA-cleared device for patients with dry AMD to help detect changes in the eye before symptoms become apparent. 

When to see a doctor

An individual with the beginning stages of AMD may not experience any symptoms. This is why scheduling routine comprehensive eye exams, particularly for individuals over 50, is important.

Early detection of geographic atrophy is crucial for early treatment. This can help slow down the progression of the disease and preserve useful sight. An eye doctor can monitor any changes in your eye health and provide treatment and strategies to slow down the progression of this condition.

Genetic testing for AMD is also available. This test can help determine who may be at higher risk of developing the advanced form of the disease, such as geographic atrophy, and predict the risk of progression.

Potential treatments are in clinical trials and can be found at antidote.me or clinicaltrials.gov.

If you have been diagnosed with geographic atrophy or AMD, follow your doctor’s recommendations regarding home monitoring, supplements and follow-up visits.

Page published on Thursday, December 7, 2023

Page updated on Tuesday, December 12, 2023