Few 40-year-olds' to-do lists include "Be proactive about not going blind," so you might have to play catch-up. Age 40 really is the time to start protecting your eyes against serious diseases such as glaucoma and macular degeneration, neither of which has symptoms in the early stages. (That's in contrast to the loss of close-focus vision that forces 45-year-olds into bifocals but doesn't threaten blindness.) "Patients may go to the drugstore and get these over-the-counter reading glasses and think, 'Hey, I've fixed my eyes,' " says Andrew Iwach, an ophthalmologist who is executive director of the Glaucoma Center of San Francisco. "Yet they may be unaware that they can be silently losing vision."
The best defense: a comprehensive eye exam that screens for glaucoma, macular degeneration, diabetic retinopathy, and cataracts. (And no, passing your driver's license retest doesn't count.)
Glaucoma and macular degeneration are more insidious conditions; by the time you know you're a victim, vision has often been lost forever. In glaucoma, the optic nerve becomes damaged, and vision loss usually starts at the side. Most people with glaucoma have increased pressure inside the eyeball, and although it's unclear how that pressure affects the optic nerve, medications that lower the pressure are effective at slowing damage.
With age-related macular degeneration, the macula, a spot in the center of the retina that provides clear central vision, is damaged by abnormal blood vessel growth or slow loss of light-sensitive cells. High doses of supplements, including vitamins C and E and beta carotene and the mineral zinc, have been found to slow the progression of AMD in several trials. But because some studies have linked high doses of beta carotene and vitamin E to cardiovascular risks, ophthalmologists advise against taking supplements as a preventive measure unless they're doctor-prescribed. It's impossible to get that quantity of antioxidants and zinc in food alone, but some studies have found that people who eat a lot of dark-green leafy vegetables have a lower risk of AMD. Smoking increases the risk of macular degeneration, so there's one more reason to quit.
People with diabetes have added reason to worry: Diabetic retinopathy affects some 40 percent of people with the disease, with 8 percent of all diabetics facing significant vision loss. Keeping your blood sugar levels under control reduces the risk of harm.