How Age-Related Macular Degeneration Becomes Geographic Atrophy

Medically Reviewed by Whitney Seltman, OD on February 19, 2023
4 min read

If you have dry age-related macular degeneration (AMD), you might develop geographic atrophy (GA). Here’s what happens and what to expect.

It’s an age-related eye disease that leads to blurring in your central vision.

As you get older, your macula, which is the part of your eye that controls sharp, central vision, gets damaged. This can lead to vision loss. You may have trouble doing close-up things like reading, driving, cooking, or seeing faces.

There are two kinds of AMD. If you have dry AMD, your macula slowly gets thinner over time. If you have wet AMD, which is less common, abnormal blood vessels grow in your eye and lead to damage. With wet AMD, you may have faster and more severe vision loss. About 10%-15% of people with dry AMD will go on to develop the wet form. 

It’s usually a severe form of dry AMD, but you can also develop it if you have wet AMD. It happens in an advanced stage of AMD and causes vision loss in your central vision. 

It starts with dim or blind spots in your central field of vision. Your central vision is what you see in front of you. You may lose more of your vision over time and you may have permanent vision loss. It may happen in only one eye, but it’s common to have it in both eyes.

AMD affects your macula, which is in the back of your eye. Your macula is the central part of the inside lining of your eye, which is called the retina. It’s the clearest part of your vision.

When you develop GA, cells and blood vessels in your retina waste away and die. The retina layers in this area get thin. This is called atrophy. The areas or patches of dead and dying cells look like a map, which is why it’s called geographic atrophy.

To find out if you have GA, your doctor will give you an eye exam and take pictures of the back of your eye with special imaging technology. If your doctor sees a patch of your retina that’s missing dark pigment, it means you have GA.

Inside your eye, you have cells called the retinal pigment epithelium (RPE). These cells are in the deepest part of your retina. They help keep your rods and cones, or retinal photoreceptor cells, healthy. Your rods and cones are triggered when light sets off a series of electrical chemical reactions, which help your brain understand what your eye sees.

With GA, your RPE cells start to die off. That causes rods and cones to die too. That’s why it leads to vision loss. Your eye has a layer of capillaries underneath your retina called the choriocapillaris. When your choriocapillaris breaks down, it also leads to central vision loss.

Experts think it starts when large deposits of fats and proteins, called drusen, develop under or near your macula and turn into something called hyperpigmentation. Next, your drusen regress and your RPE cells start to die. That’s when you may get patches of dead cells in your retina and choriocapillaris. This is when it’s considered GA.

This can take years to develop.

When you have AMD, you have an overactive complement system. Your complement system is part of your natural immune system that fights off bacteria and other germs. An overactive complement system may be a factor in the inflammation leading to your RPE dying off. Researchers are studying this to learn more.

Certain things make it more likely that you’ll get GA.

You may have a higher risk of GA if you:

  • Have low levels of physical activity 
  • Have a family history of macular degeneration
  • Smoke or used to smoke
  • Are Caucasian
  • Spend a lot of time in the sun
  • Are obese
  • Are over 60 years old
  • Have a diet high in fat or low in nutrients and antioxidants
  • Have eyes that are light-colored
  • Have high blood pressure 

There are certain things you can do to keep your eyes healthy and lower your risk of GA.

Make healthy choices. Stop smoking. Eat a nutritious, antioxidant-rich diet with fruits and vegetables, including dark leafy greens. Wear sunglasses. Exercise regularly.

Consider vitamins. Your doctor may recommend vitamins called AREDS to lower your risk of dry AMD. They don’t cure AMD, but they may help. Talk to your doctor before taking any vitamins or supplements.

Visit your eye doctor often. If you have AMD, your eye doctor will recommend regular office visits so they can do an exam to see if your AMD is progressing to GA. Make sure you go to all scheduled visits.

Monitor yourself at home. Use an Amsler grid every day. This is a test that helps you see if you’re developing problems in your central vision. It’s made of horizontal and vertical lines that are straight. If you look at them and you see wavy or broken lines, call your doctor. You can also ask your doctor for a home-monitoring device or program to help you keep an eye on your vision loss between visits.