By Sharon Solomon, MD, as told to Keri Wiginton
Geographic atrophy (GA) is an advanced dry form of age-related macular degeneration (AMD). Up to 20% of folks with AMD may get it. While we see GA across all populations and races, it’s more common in older folks who have a family history of AMD and those of European descent.
GA tends to progress incredibly slowly, but it can be devastating for the subset of people who get it. However, the FDA recently approved the first drug for GA. And I expect we’ll see more options down the line.
I want people to know that it’s rare to go completely blind from this condition. GA doesn’t affect your side vision, and you’ll be able to look around in the morning, get dressed, and take care of yourself.
Again, I want to reassure folks, even those with late-stage disease, that it’s possible to maintain your independence with GA. Other eye diseases may make it hard to tell the difference between night and day. This isn’t that.
What Is Geographic Atrophy?
People who have GA lose light-sensitive cells and tissue in the retina. This thinning, or atrophy, tends to occur very close to the center of the back part of your eye or macula. You use this area to read, drive, and focus directly on any fine detail.
For example, when you look at the word “the,” you use the central part of your macula called the fovea to focus on the “h” in the center. Often, geography atrophy occurs in this area.
People often tell me they can’t see letters when they try to read. As the atrophy grows, whole words may disappear. And in severe cases, they can’t read anything on the page because everything they focus on is in this blank area. We call that missing part of the visual field a scotoma.
If you have a loved one with GA, it can be hard to grasp what they’re going through. Relatives often tell me they don’t understand why their loved one says they have vision trouble. They know their mom can see because they’ve watched her pick up a pen, get dressed, or put on makeup.
I try to explain that the disease doesn’t tend to progress so much that it affects tissue outside the macula. Your loved one may navigate the world just fine with the peripheral or side vision that remains intact.
For example, I’ve treated people with GA who can walk into the exam room and seat themselves — so we know they can see — but when we ask them to read letters on a chart, they ask, “What chart?”
The whole chart goes missing because that’s how large the blank spot in the central vision has become.
What Are Some Symptoms of Geographic Atrophy?
Geographic atrophy affects everyone differently, and some people don’t notice they have it. In the early stages, you may think you have trouble reading because you need a new prescription for your glasses.
But you may have trouble recognizing faces. Some folks with GA tell me that when they look directly at people, they can’t see their eyes or nose. But they can use their side vision to see the top of someone’s head and their shoulders.
GA can affect how well someone sees contrast, and you may not be able to tell the difference between colors. That’s because your cones (the cells that control color) are in the macula. Your black and white cells are in the peripheral retina.
I’ve never had someone tell me they only see in black and white. Someone with GA can probably stand in a pasture and know that a barn is red. But they’ll tell me they’re less primed to pick up colors when they’re reading. And they may not be able to tell the difference between blue or green print, for example.
At a certain point, people with GA may have so many blind spots it’s unsafe for them to drive.
But when people don’t want to give up their keys, I explain that if you’ve lost some or all of your central vision, you may not notice or be able to react fast enough to avoid an animal or child who darts out into the road. That tends to hit home with people.
Strange Sights
People with GA sometimes get Charles Bonnet syndrome. What happens is people may see fully formed images that aren’t there, but they won’t have auditory hallucinations at the same time. They tend to see things that are familiar to them. Like dreams, these visions may be ordinary or creative. But it’s usually based on some lived experience.
This visual phenomenon happens to folks with AMD and other diseases that cause vision loss. I don’t think we know exactly what causes it, but the go-to explanation is that the brain is trying to fill in missing data.
Understandably, folks who see things that aren’t there are often afraid to speak up. But when they do get the courage to tell me what’s happening, they describe seeing things like pink fences floating around or flowers on trees in winter. A dead loved one may appear and disappear.
As described to me, these visual hallucinations tend to last seconds or minutes. It’s not like your dead friend or family member sits with you all day. And folks adapt extremely well and are tremendously reassured once I explain what’s happening and that it’s not a psychological or psychiatric issue.
That said, it’s important to tell your doctor if you see things that aren’t there. If you have a loved one with GA, ask if this happens to them. Other things can cause visual hallucinations, including medication or other health problems.
Advice for Caregivers
Sometimes family members aren’t that sympathetic, and they get frustrated because they don’t understand why their loved one with GA struggles to see only certain things.
I try to explain how GA affects someone’s fine focus. So maybe someone can drop their pen and pick it up because the pen is big, and they can see it with their peripheral vision. But those same people can still have trouble reading, driving, or paying their bills.
Sometimes I’ll have a family member come and look through the microscope with me like I would with a medical student. I’ll point out color differences that show where pieces of the retina are missing yet some areas are intact. This can be eye-opening.
Future Treatment for Geographic Atrophy
In the past, there was a big focus on how to manage wet AMD. But you can definitely see that drug companies and others are pouring research dollars into ways to treat GA.
And it’s encouraging that these new drugs have been FDA-approved. It’s good to know that they’re making medications that target the biological pathways that cause the progression of GA.
I tell people that the outlook for GA treatment is promising. Just like when our first therapy came out for wet AMD, and 5 years later we got another therapy that blew the old one out of the water, I suspect that’s what we’re going to start to see here.
Steps to Take After a GA Diagnosis
Without a cure, I always go over lifestyle changes that may help preserve the sight someone has left. And since we know that tobacco use or exposure to secondhand tobacco smoke can raise your odds of GA, I suggest people quit smoking or spend less time around smokers.
The second thing I’ll do is make sure someone with GA is on an AREDS supplement. These are a specific mix of high-dose vitamins and minerals that may slow the progression of intermediate dry AMD to late-stage disease.
Unfortunately, GA may progress to vision loss, which makes everyday life harder. But people amaze me every day with their resilience and ability to adapt.
The good news is I can refer folks to low-vision services when they need it. Visual aids like stronger glasses or magnifiers, for example, can help people to read better and function normally for a lot longer.
Photo Credit: E+ / Getty Images
SOURCE:
Sharon Solomon, MD, Katharine M. Graham professor of ophthalmology, Wilmer Eye Institute; professor of ophthalmology, Johns Hopkins University School of Medicine.
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