Proud older lady

We seem resigned to the idea that as we age, we will have trouble getting around, become hard of hearing, and begin to not see too well. Leading eye care researchers and clinicians, though, are calling for a shift in the way we think of vision and aging. The fact is, low vision can often be delayed or prevented with appropriate screening, diagnosis, and treatment.

Aging bodies

The first Baby Boomer turned 60 in 2006. Every day since then, about 8,000 Boomers have passed that milestone. More than half of them will develop an age-related eye disease. A recent survey, however, showed that older Americans are less concerned about retaining their sight than they are about shedding some extra pounds and managing their back pain. They seem unaware of what’s at stake, or perhaps they believe there’s nothing they can do to preserve their vision.

It’s nearly impossible to say what "normal" aging is. Many variables, such as lifestyle choices, genetic makeup, and exposure to chemicals and disease-causing agents, interact in unpredictable ways within any given person.

Aging eyes

Nevertheless, we can make some broad statements about how the eyes age. Most of us, for instance, become farsighted, or less nearsighted, as the case may be (see the discussion of presbyopia later in this article). As the the iris muscle and other body tissues become less elastic, pupil response slows and vision diminishes in especially dim or bright light. The eyes may become either too dry or too watery. The retina thins, and the lens of the eye becomes discolored and loses some of its transparency.

Age-related eye disorders

Several eye diseases are closely tied to the aging process and often exist in the presence of the systemic diseases we’ve just mentioned:

Cataracts. The term cataract usually refers to age-related cataracts. A cataract is a clouding of the lens, a transparent, layered structure that lies behind the iris. A cataract may begin to form as early as age 40 or 50 and at first goes unnoticed (read Overview of Cataracts). By the time a person reaches age 60, the cataract may have become advanced enough to cause low vision. In most people with cataracts, surgical treatment restores adequate vision.

Age-related macular degeneration. Age-related macular degeneration (AMD) destroys the macula (pronounced MAK-you-luh), a cluster of light-sensitive cells in the central part of the retina, the structure at the back of the eye. The macula is responsible for crisp central vision and perception of fine detail.

More than 15 million Americans have AMD, and it’s a leading cause of low vision in those age 60 and over. In fact, 20 to 30 percent of Americans age 75 and older have dry or wet AMD, and age is the most important non-modifiable risk factor for the disease. Early diagnosis and close follow-up are essential to preserving vision in people with AMD (read Dry Age-Related Macular Degeneration and What is Macular Degeneration?).

Glaucoma. Glaucoma is a group of related diseases in which the optic nerve becomes damaged by excessive fluid pressure within the eyeball. In a person with open-angle glaucoma, by far the most common type, fluid drainage fails to keep pace with output. Pressure builds on the optic nerve as the fluid level rises. This process takes place so gradually that it may be imperceptible until irreversible vision loss has occurred. Eventually the optic nerve becomes so damaged that it’s unable to transmit complete signals to the brain.

Adults over age 60 are at increased risk of developing glaucoma, and elderly adults over age 80 have three to ten times the risk of developing glaucoma as those in their 40s (see Glaucoma).

Diabetic retinopathy. The eye is supplied with its own microcirculation - tiny blood vessels that nourish the retina and other structures of the eye. In diabetic retinopathy, high blood glucose causes these fragile vessels to grow where they’re not needed. They tend to swell and burst, leaking blood and other fluids beneath the retina. This process causes inflammation and eventual scarring.

The older you are and the longer you’ve had diabetes, the more likely you are to develop diabetic retinopathy (see What is Diabetic Retinopathy?).

Dry eye. The human eye needs adequate surface hydration in order to function properly. Five percent to thirty percent of Americans over age 50 have dry eye. This condition occurs when tears evaporate too quickly, the eye doesn’t produce enough tear film, the tear fluid has an abnormal pH composition, the eyelids don’t close properly, or the person is unable to blink normally.

Watery eyes. Watery eyes can have any of several causes. A common culprit is the weakening infrastructure of muscles and tendons that supports your eyelids. As this undergirding relaxes, your eyelids may no longer be able to sweep tear film efficiently to the corners of your eyes, where it drains through tiny tear ducts called puncta. Alternatively, sometimes a blockage within the invisible drainage system of ducts and canals causes tears to pool in the eyes.

Presbyopia. The odd-sounding term presbyopia comes from a Greek word that literally means "an old man." It refers to the farsightedness that develops as the lens of the eye and its surrounding muscles lose elasticity. These taut muscle fibers become too rigid to contract or relax properly in order to change the shape of the lens. As a result, they can no longer focus light well enough to produce crisp visual images. Presbyopia is different from normal farsightedness, which is caused by a distortion in the shape of the eyeball.

Age-related farsightedness sets in at about age 40 or 45. You may begin to have trouble reading menus, prescription labels, baseball stats, recipes, and anything else printed in a small type. Presbyopia also makes it difficult to perform tasks that require sharp near vision, such as wood carving, sewing, or even painting your fingernails and applying makeup. The condition is easily corrected with reading glasses, bi- or trifocals, contact lenses, or surgery. Your eye care professional can advise you of your options.

Ptosis and blepharitis. Ptosis (pronounced TOE-sis, with a silent "p") comes from a Greek word meaning "to fall," an apt description of the droopy, hooded eyelids characteristic of the condition. If this draping effect is extreme enough to obscure vision, surgery may be in order.

A condition called blepharitis causes redness, swelling, and sometimes crusting at the margins (edges) of the eyelids. The condition is caused by bacterial overgrowth in the oil glands near the eyelashes and usually poses no threat to the eyes themselves.

Reducing your risk of age-related eye diseases

You can’t control the passage of time, but you can do a great deal to preserve your sight as you age:

  • Be aware of your risk factors. You need to know what genetic factors, lifestyle choices, diseases, and exposures place you in a higher risk category for certain diseases so that you and your vision care provider can adjust your screening intervals accordingly. For recommended screening guidelines, see Prevention
  • Have a baseline eye exam at age 40 if you are an adult with no risk factors for cataracts, glaucoma, AMD, or diabetic retinopathy. People who have no vision problems or obvious risk factors should have a baseline eye examination at age 40, to establish a standard against which future exam results can be compared.
  • Get screened earlier or more frequently screening if you have risk factors for cataracts, glaucoma, AMD, or diabetic retinopathy. If you have diabetes, high blood pressure, or a family history of eye disease, for example, or if you fall into a high-risk ethnic group, you should receive thorough eye examinations more often. Click on the links above for lists of risk factors and recommended screening intervals.
  • Cooperate with your vision care provider. This advice applies to examinations, preventive measures, treatment, and follow-up care. If you have diabetes, for example, you should have a comprehensive dilated eye examination annually. If you have glaucoma, you should use your eye drops daily as prescribed. If you have AMD and your provider has asked you to test your vision with an Amsler grid, you should do so every day. After cataract surgery, you should wear your eye shield and use your antibiotics as your provider has instructed.
  • Listen to your body and report any new symptoms promptly to your vision care provider. If your vision changes, especially if you have AMD or diabetic retinopathy, tell your provider immediately.

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