Anatomy of an Eye
At the front of each eye lies the cornea, a rounded bulge that allows light inside. That light passes through the pupil, a
transparent space in the center of the colored iris. Behind the pupil is the lens, which is connected to the zonules (ligaments
that tighten and slacken to focus). Light goes through the lens and hits the retina, the tissue at the back of the eye, which
sends a message through the optic nerve to the brain, telling it what you’re looking at.
From Birth Through Your 30s
When you are born, the lenses inside your eyes are generally crystal clear and flexible, and the zonules connected to them
are strong. With age, the lenses become less flexible, and the zonules are not as effective. Your eye shape, which is genetically
determined, may mean that you need corrective lenses. If your eyeballs are too long, you’re nearsighted. If they are somewhat
short, you’re farsighted. Whenever you notice a change in your vision, schedule an appointment with an ophthalmologist or
In Your 40s
“This decade is when we begin to lose our ability to focus up close, which is called presbyopia,” says Andrew Iwach, M.D.,
a spokesperson for the American Academy of Ophthalmology and the executive director of the Glaucoma Center of San Francisco.
Thank those thicker, harder lenses and weaker zonules. The remedy? Reading glasses. (Don’t feel bad―everyone needs them eventually.)
How quickly you develop presbyopia depends on where your vision started. If you have always had perfect eyesight, you’ll probably
need reading glasses in your early 40s. Nearsighted people have an edge and often won’t notice a change until their late 40s,
says Jill Koury, an assistant professor of ophthalmology at the Duke University Eye Center, in Durham, North Carolina. If
you’re farsighted, you’ll probably need those specs in your late 30s. This is also the time to schedule a comprehensive baseline
eye exam (aim to go in at age 40 if you haven’t already). Among other things, a doctor will test the pressure inside your
eyes and look at the optic nerves to be sure they are intact.
In Your 50s and Beyond
The lenses continue to harden, and you may find you need stronger corrective lenses or even bifocals, which are lenses that
have two prescriptions built into them (they are now available in contact lenses, too). You are also at greater risk of developing
the following eye diseases.
- Cataracts. These form when the lenses of the eyes become cloudy. More than 20 million Americans have cataracts, and everyone, if he
or she lives long enough, will develop them. Age is the number one culprit, says Carol L. Karp, a professor of clinical ophthalmology
at the Bascom Palmer Eye Institute, at the University of Miami Miller School of Medicine, in Florida. Smoking and sun exposure
are also contributors.
- Glaucoma. This disease affects more than 2 million people in the United States and is typically associated with pressure building up
in the eyes, resulting in damage to the optic nerves, says Emily Bedrick Graubart, an assistant professor of ophthalmology
at the Emory Eye Center and the Emory University School of Medicine, in Atlanta. Glaucoma causes peripheral-vision loss and
can eventually lead to blindness. It’s one of the most common reasons worldwide why adults lose their sight.
- Macular degeneration. If the macula (a part of the retina) deteriorates due to heredity or environmental factors, the central line of sight becomes
impaired. Blurred vision is often the first sign. Macular degeneration affects almost 2 million people in the United States
and is the leading cause of vision loss in Caucasians over the age of 65. Ultraviolet (UV) light can speed its development,
as can smoking.