Geographic atrophy risk factors: What to know

Geographic atrophy (GA) is an advanced form of dry age-related macular degeneration (AMD), an eye condition that causes central vision loss. In GA, damage occurs in the macula, the part of the retina responsible for image sharpness, detail, and color intensity.

GA gets its name from how it appears during an eye examination. Damaged areas of the macula develop distinct borders that can resemble land masses on a map. As the condition progresses, many people experience permanent vision loss.

Research suggests that about 1 million people in the United States are living with GA, with an estimated 160,000 new cases occurring each year.

Some risk factors for GA cannot be changed, while others can. Understanding these risks can help people have more informed conversations with an eye care professional and make decisions about their eye health.

This article takes a closer look at the risk factors for GA.

Age is one of the most significant risk factors for GA. As people get older, natural age-related changes in the eyes can weaken their natural defenses, reduce blood flow, and slow important processes such as cellular waste removal.

As a form of AMD, GA is linked to changes in deposits in the eye called drusen. Drusen are small clumps of extracellular material that can develop even in healthy eyes. In earlier stages of AMD, drusen can build up and displace healthy retinal cells.

Over time, some drusen may regress or collapse. When this happens, they can take surrounding retinal tissue with them, leaving areas of cell loss, or atrophy. Aging can also impair the eye’s ability to manage waste and inflammation, adding to retinal stress.

While not all drusen are harmful, their size, behavior, and pattern of change can contribute to retinal damage and the development of GA.

In addition to age, genetics and family history are leading risk factors for GA.

GA is linked to changes in the complement system, a part of the immune system that helps clear damaged cells and cellular debris and directs immune responses. When this system does not function properly, it can contribute to ongoing, low-grade inflammation in the retina.

Certain inherited genetic variants affecting the complement system may increase the risk of GA. People with a family history of GA are more likely to carry variants in genes such as:

These genetic variants do not directly cause GA. However, they can contribute to chronic immune activation in the eye, which may increase the likelihood of developing the condition.

People assigned female at birth have a higher risk of developing GA and experiencing disease progression, compared with people assigned male at birth.

The exact reasons for this difference are not fully understood, but researchers believe several factors may contribute, including:

The macula relies on a dense network of small blood vessels to receive oxygen and nutrients and to remove waste products.

Cardiovascular conditions, such as high blood pressure, can damage these vessels and reduce blood flow to the retina. Over time, reduced circulation and impaired waste removal may contribute to macular degeneration and increased oxidative stress, raising the risk of geographic atrophy.

Oxidative stress happens when reactive oxygen species (ROS) overwhelm the body’s ability to neutralize them with antioxidants. ROS are oxygen-containing molecules that are highly reactive and can damage nearby cells. Antioxidants help limit this damage by stabilizing ROS.

The eye is susceptible to oxidative stress because the macula has high energy demands and relies on a steady supply of oxygen and blood. In GA, reduced circulation can disrupt this balance, allowing oxidative stress to buildup and contribute to retinal damage.

Lifestyle factors, such as diet, exercise, and environmental exposures, may also influence the risk of GA.

Smoking is one of the strongest modifiable risk factors associated with AMD, including GA.

Research suggests that people who smoke more than 25 cigarettes a day are about twice as likely to develop AMD compared with non-smokers. Former smokers may also have a higher risk than those who have never smoked. Toxic compounds in cigarettes can promote inflammation, oxidative stress, and damage to blood vessels in the eye.

Diet and physical activity can also play a role in GA risk.

Poor nutrition can limit the availability of nutrients important to eye health, such as lutein and zinc. When these nutrients are lacking, the eye may be less able to manage oxidative stress and inflammation.

Physical activity supports eye health in several ways.

Exercise helps maintain healthy circulation by improving blood vessel flexibility and function and supports a healthy body weight. Lower levels of physical activity may contribute to increased inflammation and vascular stress, which can affect the retina over time.

Long-term exposure to environmental factors, such as ultraviolet (UV) radiation from sunlight and air pollution, may damage parts of the retina, making it more vulnerable to degeneration.

Age and family history are important risk factors for GA, but lifestyle factors and overall health may also influence risk by contributing to inflammation and oxidative stress.

Having one or more risk factors does not mean a person will develop GA. However, understanding these factors can support proactive monitoring and timely conversations with an eye care professional.