Imagine no longer being able to see the expression on a loved one's face, the road ahead or even the words on this page.
Age-related macular degeneration takes away the sharp central vision needed to do these tasks, and the Centers for Disease Control and Prevention estimates that 7.3 million Americans are at risk for the disease. No cure exists, but early detection and therapies can slow its progression.
What is age-related macular degeneration? Simply put, it is the deterioration of the eye's macula, the area in the retina that allows for clear sight of what is straight ahead. As the body ages, the macula degenerates -- more quickly for those with specific risk factors. The disorder most often occurs after age 60 but can develop earlier and is a leading cause of vision loss for those 50 and older.
"All otherwise-healthy people over the age of 50 should have an eye exam at least every two to three years," said Dr. Richard Lewis, an ophthalmologist and professor with the Cullen Eye Institute at Baylor College of Medicine in Houston. He stressed the importance of dilation as part of the exam, as it allows for the detection of drusen, deposits underneath the retina. When drusen are found in significant quantity, Lewis recommends seeing an ophthalmologist for more testing.
Stages and available treatments
The size and amount of drusen indicate the stage of age-related macular degeneration. The presence of medium-size drusen -- still only the width of a human hair -- show early degeneration, for which there is no treatment.
Large drusen are a sign of the disorder's intermediate stage. Patients generally would take a formula of high-dose vitamins and minerals developed by researchers at the National Eye Institute created and tested the formula, which can delay the onset of late age-related macular degeneration and help slow vision loss in late-stage patients. Lewis advises those who have not reached this stage to save their money on the supplements, as research also shows that the combo has no impact on the disorder before then.
Late-stage brings with it large drusen and macular damage. There are two forms of this stage: geographic atrophy (dry) and neovascular (wet). Dry progresses slowly, but the wet form can cause rapid and severe damage as it involves abnormal growth of blood vessels underneath the retina that leak fluid and blood. Treatments for the wet form include monthly injections of anti-vascular endothelial growth factor into the eye to block the abnormal growth. Laser therapy and surgery also are potential options to slow and even potentially prevent later vision loss.
Implantable miniature telescope
One of the newer procedures available to patients with late-stage dry AMD is the Implantable Miniature Telescope. The size of a pea, it sits behind the iris and renders an enlarged central image onto healthy retinal areas surrounding the degenerated macula, reducing the area of the blind spot and making images recognizable again. Dr. Nan Wang, an ophthalmologist with The Robert Cizik Eye Clinic and affiliated with Memorial Hermann-Texas Medical Center, is trained to perform the procedure. "It allows the damaged eye to magnify, leaving the other as the scanning eye," she said. "The combination can overcome the deficit. Vision is not perfect, but much better."
Wang has yet to implant the telescope, an outpatient procedure that takes an hour, because of the criteria patients must meet. They must be 75 years of age or older and also must be a candidate for a certain level of cataract surgery.
Dr. Ron Adelman, an ophthalmologist and director of Yale Retina Service at Yale University School of Medicine, agreed. He said doesn't perform the telescope procedure, but knows there are some doctors in the state who do. Adelman said he has recommended some patients for the surgery, but that's rare. Like Wang, he said modern medicine has prevented the disease from progressing in most people to the stage where they would need this procedure. "There are just not that many people who would benefit from it," he said.
Pamela Mitchell is a freelance writer living in Houston.
Staff writer Amanda Cuda contributed to this report.