Some patients with age-related macular degeneration (AMD) will develop geographic atrophy (GA), which refers to regions of the retina where cells waste away and die (atrophy). Sometimes these regions of atrophy look like a map to the doctor who is examining the retina, hence the term geographic atrophy. The regions of atrophy result in a blind spot in the visual field. GA can affect one or both eyes, and a patient with GA in one eye is more likely to develop it in the other.
Symptoms of Geographic Atrophy
The initial symptom may be found during reading, when one or several letters in a word are “missing.” Or, when looking at faces, a small part of the face cannot be seen.
Usually, once GA starts, the region of atrophy expands slowly over several years until the central vision is lost and vision is about 20/200. It does not normally affect peripheral vision.
Wet AMD and Geographic Atrophy
Patients with another form of advanced AMD called wet AMD can sometimes also have GA before, during, or after they have the wet form of AMD. The two forms of AMD are not mutually exclusive.
Diagnosing Geographic Atrophy
How can you tell if you have geographic atrophy? GA can be diagnosed by an ophthalmologist during a dilated exam and/or with retinal imaging. In a dilated exam, GA appears as a patch of retina that’s missing its dark melanin pigment. Imaging techniques including retinal color photographs, optical coherence tomography (OCT), or autofluorescence photographs can also be used to detect GA. Read more about the eye exam for macular degeneration.
There is currently no proven treatment for GA. Patients can benefit from increased lighting, magnification and low vision devices that help with reading. Some patients may prefer an implantable miniature telescope, which is surgically inserted into the eye in place of the lens. It can help certain carefully selected patients with near or distance vision by magnifying images.
While a phase III trial by Genentech targeting the complement protein called factor D in geographic atrophy patients was not successful, a phase II trial by Apellis targeting a different complement protein called C3 showed promising results.
The Geographic Atrophy Lipoic Acid (GALA) clinical trial is testing whether a once-per-day antioxidant/iron chelator pill can slow the growth of GA.
Additional clinical trials for GA can be found at antidote.me or clinicaltrials.gov.
Cell replacement is also being tested for GA. A few patients have received stem cell treatments. The most promising of these have the cells grown on plastic sheets, which are surgically placed under the retina and unrolled into position. The cells have been well-tolerated and can survive in the recipient’s eye for at least a year.
GA robs sight, but advances in low vision therapy (by specially trained optometrists) and implantable miniature telescopes can help patients adapt to their diminished retinal function. New treatments already in clinical trials or being tested in National Institutes of Health (NIH) and/or foundation-funded labs—like those supported by Macular Degeneration Research, a BrightFocus Foundation program— bring hope for improved vision on the horizon.
Author: Joshua Dunaief, MD, PhD, Scheie Eye Institute, University of Pennsylvania