Top Causes of Vision Loss and Blindness
What to know about macular degeneration, glaucoma and other eye problems
En español | One undeniable fact of aging: We’re more at risk for a range of eye problems as the years pass. When we reach our 40s, we are likely to begin to experience minor vision issues, such as difficulty reading the newspaper (a condition known as presbyopia), and our eyes may become drier and more sensitive to light and wind. Floaters — tiny specks that float across our field of vision — are also more common when we get older.
The good news is that major vision loss is not a natural part of aging, although our risk for it does rise. The leading causes of blindness — macular degeneration, diabetic retinopathy, glaucoma and cataracts — are primarily age-related. And the number of older Americans with vision impairment is large and growing. About 12 million U.S. adults age 40 and over have vision impairment, including 1 million who are blind, according to the Centers for Disease Control and Prevention. That number is projected to more than double by 2050, as the population ages and more people develop diabetes and other chronic conditions.
But some causes of vision loss can be prevented or treated successfully before damage progresses: “It’s really a matter of catching things early,” says Mitchell Brinks, M.D., an assistant professor of ophthalmology at the Oregon Health & Science University School of Medicine.
Here’s what to watch for.
Macular degeneration, also known as age-related macular degeneration, or AMD, is a leading cause of vision loss among Americans over age 50. More than 10 million Americans have AMD, and about 2.2 million have advanced vision-threatening cases.
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In the “dry” form of this disease, small deposits called drusen dry out the macula — the part of the eye that gives us our central vision and allows us to see in great detail and in vivid color. In the more damaging “wet” form, abnormal blood vessels grow under the macula, causing them to leak fluid or bleed.
AMD may not cause complete blindness, but it can lead to the loss of central vision and make it harder to see faces, drive and do other tasks. Some vitamins and minerals, especially those found in leafy green vegetables, may mitigate its effects.
Diabetic retinopathy — a complication of diabetes — is extremely common: More than 2 in 5 people with diabetes develop diabetic retinopathy, according to the National Institutes of Health’s National Eye Institute; older Hispanic people are at especially high risk.
This disease occurs when blood sugars block vessels in the retina — the light-sensitive tissue at the back of the eye. It progresses through four stages and can eventually eliminate vision. It’s treated with injections, laser treatment and surgery; controlling blood sugar levels is the best way to reduce risk.
More than 2.7 million Americans over 40 have glaucoma, but only half are aware of it, according to the American Academy of Ophthalmology. People over 60 (or over 40 for people of color), smokers and those with a family history of glaucoma face higher risk.
Glaucoma damages the nerve that transmits visual information to the brain. In most U.S. cases, the eye doesn’t drain fluid well, which puts pressure on the optic nerve. In others, the iris blocks fluid drainage, increasing eye pressure.
The more common form of the disease (open-angle glaucoma) progresses slowly and without obvious symptoms at first, but can eventually cause blindness if left untreated — that’s why it’s known as the “silent thief of sight.” Treatments can’t restore lost vision but can prevent it from getting worse. Regular exercise may also help, says Brinks. He points to one study that had people with glaucoma use an exercise bike three times week for 45 minutes each time, “and the eye pressure dropped significantly. It was a home run.”
Cataracts are the most common eye disease in the United States, afflicting more than 25 million Americans; by age 80, most people either have cataracts or have had surgery to correct them. Cataracts develop when eye proteins break down and clump together, forming a cloudy area on the lens — much like fog on a window. They blur and dull vision, making reading, driving and other activities more difficult.
They are the leading cause of blindness worldwide, but are less likely to cause blindness in this country, thanks to highly successful treatments and relatively easy access to them. “It’s almost completely reversible,” says Brinks, who calls it “a success story of medicine.”
Two other major causes of vision impairment — amblyopia (aka “lazy eye”) and strabismus, an imbalance in eye positioning — develop during infancy or childhood. Common “refractive errors” like nearsightedness, farsightedness and astigmatism (distorted vision at all distances) also impair vision, especially as we age, and can be a major problem for those without access to eye care. “Just basic refractive error is a public health concern in this country,” says Jeff Todd, president and CEO of Prevent Blindness, an eye health and safety organization.
Prevention and treatment
Not all vision loss can be prevented, and some diseases are hard to treat. But regular eye exams can protect eye health, Todd says, allowing for critical early intervention if problems arise.
Wearing protective glasses and taking other safety precautions also protect vision. And regular exercise, a healthy diet and quality sleep are also essential. “Taking care of your body is taking care of your eyes,” Todd says.
Brinks and Todd also recommend “screen timeouts,” especially as we log more time on computers during the pandemic. They cite the “20-20-20” rule: Every 20 minutes, look at least 20 feet away from your computer screen for at least 20 seconds. “It’s good to get out and about and let your eyes rest along with the rest of your body,” Todd says.
On a more systemic level, we can advocate to improve and advance access to health care and for more support for telehealth and vision health research. “If you’re lucky enough to live old enough, you’re going to experience changes in your vision,” Todd says. “That doesn’t mean there’s nothing that can be done about it.”