Diagnosing Geographic Atrophy

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

If you think you may have geographic atrophy (GA), your eye doctor can run tests and do an exam to find out.

Here’s what to look for and how to find out if you have it.

If you have an advanced stage of dry age-related macular degeneration (AMD), you might develop GA. With this condition, changes in your eye’s retina create blind spots in the center of your vision.

 When you have GA, cells and blood vessels below your retina start dying and thinning your retina. This process is called atrophy. If your doctor looks at your retina, it may look like a map with certain regions of atrophy. That’s why it’s called geographic atrophy.

Signs and symptoms include:

  • A dim or dark spot in or near the center of your vision
  • Trouble recognizing people’s faces
  • A hard time seeing a difference in two shades of a similar color or the same color
  • A hard time seeing in low light or when there’s a glare
  • Problems seeing when you read, do crafts, cook, or drive
  • Seeing bright colors as dull or washed-out 
  • Seeing things less clearly or sharply
  • Vision loss in the center of your vision

 Talk to your eye doctor if you notice any of these.

You may be more likely to develop GA with AMD if you have certain risk factors.

Those include:

  • A diet that’s high-fat or low in nutrients and antioxidants
  • A family history of macular degeneration
  • Light-colored eyes
  • You smoke or used to smoke
  • Spending a lot of time in the sun
  • Being Caucasian
  • You’re not active
  • Obesity
  • Being older than 60

 If you have wet AMD, it’s also possible to have GA. You can develop GA at any point before, after, or during AMD.

If you already have AMD, your eye doctor will want to see you regularly for checkups and to see if it’s becoming GA.If you notice signs, make an appointment with your eye doctor.

Your eye doctor will do an eye exam and run tests to look for signs of GA.

They may start with a dilated exam. This is where they use eyedrops to widen your pupils. It helps them see the back of your eyes, which includes your retina and macula.

Your doctor may test your vision by using an eye chart. They’ll ask you to read it, then see how clearly you can see.

Your doctor may also use imaging techniques to see what’s happening in your eyes. They may include:

  • Retinal fundus photography
  • Optical coherence tomography (OCT)
  • OCT angiography
  • Autofluorescence imaging
  • Scanning laser ophthalmoscopy

They’ll look for changes in your macula, which is at the back of your eye. They’ll look for yellow deposits under your retina, which are called drusens. They’ll also look for a patch of your retina that’s missing its normal dark melanin pigment. That’s how they’ll know if you have GA.

Recent advances in cameras, computers, optics, and software have made a big difference in how doctors diagnose GA. Now there are retinal imaging techniques to help them see how your vision is changing and if it’s developing GA.

You may have images taken during every visit. Your eye doctor may use a few different types of imaging techniques to get the best picture of your eyes.

Optical coherence tomography (OCT). This imaging technique is the biggest advancement in how doctors diagnose GA. It creates pictures in just a few seconds, without any bright flashes that may be uncomfortable.

An OCT uses infrared light reflections off your retina to get a picture of it. The reflections create a cross-sectional view that your doctor can see on the computer. They can measure the layers of your retina and see how thick the layers are. If any regions of your retina are thinning, it’s a sign of GA.

An OCT also shows if your retina has pockets of fluid or drusen, which is a small deposit under your retina.

OCT angiography. This is another advanced technique. It shows your eye doctor what’s happening with your blood vessels. Through rapid imaging, it can see how your blood flows.

They can see if it’s normal or if there’s something that needs attention.

Before this technique was developed, your doctor could only see your retina’s blood vessels in detail by injecting dyes like fluorescein or indocyanine green through an IV. That method uses injections and involves 15-30 minutes of light flashes. Your doctor may still use this technique to get a full, detailed picture.

Retinal fundus photography. This is a technique that shows your doctor a color picture of your retina.

It detects:

  • Blood, drusen, or lipids that leak out of abnormal blood vessels
  • Places where your retinal cells are gone from atrophy
  •  Scar tissue

 This procedure is relatively quick. You can do it in about a minute. You may see a few bright flashes.

Autofluorescence Imaging. This technique helps your doctor see a view of your retinal pigment epithelial cells (RPE). Those are cells that help your retina stay healthy by protecting it, nourishing it, and getting rid of waste. If you have GA, these cells die.

Your doctor will use the imaging to see what your RPE cells look like. If they’re bright, they’re alive. If it looks like a dark patch, it means they’ve worn away and died.

The test is quick and involves a few flashes of light.

Scanning laser ophthalmoscopy. This technique gives your doctor a sharper image of RPE cells by using a scanning laser ophthalmoscope (SLO). It sends blue, green, and red wavelengths through the layers of your retina. It’s more complicated, so it takes longer and uses more equipment.

In some research labs, experts may use a higher form of SLO called adaptive optics-SLO (AO-SLO). This uses high-resolution telescopes to create views of individual cells in your retina.