The Eye:
An Owner's Manual

Learn how to keep your sight keen as the years pass.

March 2016

By Lisa James

The eye’s main structures:

Sclera
The white outer coating.

Cornea
The clear front of the eye that helps focus light as it passes through.

Iris
The colored part that regulates light entering the eye by adjusting the size of
the pupil; less light under bright conditions, more under dim ones.

Lens
The clear, spherical structure that focuses light onto the back of the eye;
held in place by the ciliary body.

Aqueous Humor
A clear fluid between the cornea and the lens that nourishes both structures.

Retina
The nerve layer at the back of the eye that turns images into electrical impulses;
these impulses travel to the brain via the optic nerve.

Macula
Central part of the retina that allows fine details to be seen.

Choroid
A layer of blood vessels between the retina and the sclera.

Vitreous Humor
The clear, jelly-like substance that fills the space, known as the vitreous body,
between the lens and the retina.

Several small muscles attach the eye to its socket,
allowing it to move up and down as well as from side to side.

 

Potential Hazards:

By far the most common eye conditions are myopia (nearsightedness), in which far objects are unclear because light rays focus in front of the retina; hyperopia (farsightedness), in which near objects are fuzzy because rays focus behind the retina; astigmatism, in which corneal defects cause loss of focus; and presbyopia, the decline in fine focus that comes with aging. These conditions are correctable with lenses (glasses or contacts); myopia, hyperopia and astigmatism may also be treated with laser surgery.
Other conditions pose more serious threats to vision because they can cause blindness.

These disorders include:

Statistic #1

1
Ranking of cataract as a potentially blinding disorder, affecting nearly 24.5 million Americans

(Source: National Eye Institute)

• Age-Related Macular Degeneration (AMD)—Damage to the macula, resulting in a dark spot in one’s central vision that progresses more quickly in some people than in others. Early-stage AMD is diagnosed by the presence of yellow deposits beneath the retina called drusen, which generally enlarge as the condition advances. Late-stage AMD occurs in two major forms, geographic (dry) and neovascular (wet). In dry AMD, cells in the macula gradually break down. In the wet version, abnormal new blood vessels grow beneath the retina, which can leak to cause swelling and macular damage.

• Cataract—A cloudiness in the lens that gradually diminishes vision. It develops as proteins in the lens start clumping together.

• Diabetic Retinopathy—A diabetic complication which affects blood vessels beneath the retina. Mild forms involve small aneurysms, or balloon-like swellings, in the vessels, which can become blocked as the disease progresses. In late-stage proliferative retinopathy, new, fragile blood vessels form and may cause vision loss by leaking blood within the eye.

• Glaucoma—Damage to the optic nerve generally associated with excessive pressure within the eye. Normally, the aqueous humor between the cornea and lens drains through the angle where those two structures meet. In open-angle glaucoma, the drainage channels become partially blocked, increasing pressure. (Nerve damage can sometimes occur even if pressure doesn’t increase, a condition known as normal-tension glaucoma.) In closed-angle glaucoma, the iris bulges forward, narrowing or blocking the drainage angle.

Statistic #2

1 million+
Number of Americans
40 and older who are
legally blind

(Source: American Academy
of Ophthalmology)

Age is the major risk factor for these disorders (retinopathy becomes more common among people with diabetes as they grow older). Family history plays a role in the development of AMD, which is more common among European Americans, and in glaucoma, more common among African and older Hispanic Americans. Smoking promotes the development of AMD and cataract; risk of developing the latter also increases with the amount of time spent in the sun.

Besides causing diabetic retinopathy, diabetes also contributes to cataract risk and may promote progression of glaucoma among people who already have it. High blood pressure, which can itself damage the retina, has been linked to AMD and may be associated with glaucoma.

Damage Control:

The best way to discover eye ailments before they erode sight is to go for a full-scale eye exam every year. In addition to a visual acuity (eye chart) test to determine if corrective lenses are necessary, such an exam generally includes a glaucoma test and a thorough examination of the eye using magnification and bright light; the retina and other internal structures are examined after the pupils have been dilated. Other tests may be done as needed depending on factors such as one’s medical history and any symptoms that are present.

One of the best-known, and most effective, treatments for vision loss is cataract surgery, in which the damaged lens is removed and an artificial lens inserted. Various forms of surgery and other treatments are also available for AMD, diabetic retinopathy and glaucoma; these options should be discussed with an ophthalmologist who specializes in the disorder diagnosed.

Preventive Maintenance:

While vision problems become more common with age, it is possible to help protect eyesight naturally.

Statistic #3

3 million
Cataract surgeries
performed in the
US each year

(Source: Journal of Cataract
and Refractive Surgery)

One of the best ways to reduce the risk of developing cataract, the most common vision-robbing condition, is to wear a brimmed hat and high-quality sunglasses whenever outside—even on cloudy days. (Not smoking, another cataract risk factor, is a no-brainer.)

The American Academy of Ophthalmology recommends wraparound shades that block 100% of both UV-A and UV-B rays. And always wear protective goggles when engaged in activities that pose an eye injury risk, such as using a chainsaw or playing racquetball. (Some medications, such as statins and antibiotics, can make the eyes more sensitive to light; discuss such risks with your practitioner.)

EXPERT OPINION: Nature did not intend for humans to be exposed to so much UV light. The ozone layer in the atmosphere absorbs far-UV light, but the ozone layer has been damaged by air pollution—Robert Abel, Jr., MD, author of The Eye Care Revolution (Kensington)

Living an overall healthy lifestyle is crucial, too. Exercise has long been known to reduce blood sugar levels, which helps lower the risk of diabetic retinopathy. Some studies suggest physical activity may also reduce one’s risk of developing AMD. In addition, exercise has long been known to ease stress, an under-appreciated cause of poor eyesight.

EXPERT OPINION: Most people don’t realize that the commonest form of glaucoma is a disease of stress. An essential component in treating and preventing glaucoma is dealing with stress appropriately—Abel

Spending so much time staring at screens can lead to eyestrain. It’s a good idea to look away from computers, cell phones and such periodically to give your eyes a chance to rest and refocus.

EXPERT OPINION: One thing is obvious: The more close work we do, the greater the strain we place on our eyes—Abel

Yoga offers exercises that help work the small muscles of the eye; advocates say these movements not only help older people maintain sharp focus but also reduce tension and sharpen concentration (see the box for an example).

Diet is a crucial component of an eye-friendly lifestyle. The Age-Related Eye Disease Study (AREDS), a major clinical trial sponsored by the National Eye Institute, found that antioxidants, found abundantly in fresh produce, help protect aging eyes.

EXPERT OPINION: In every part of the world, people with poor digestion and chronic bowel problems have a fourfold higher incidence of cataracts—Abel

The two most helpful are lutein and zeaxanthin, members of the carotenoid family found in eggs, leafy greens and other foods. Concentrated in the macula, lutein and zeaxanthin help filter the high-energy blue light that promotes lens and retina damage, and have been found to reduce the risk of chronic eye disease, including AMD and cataract. (Another carotenoid, astaxanthin, has also been found to protect retinal cells.)

EXPERT OPINION: Lutein and zeaxanthin have been shown to reduce cataract formation by approximately 20%—Abel

Plant compounds called anthocyanosides appear to help protect the retina. A blueberry relative called the bilberry, which is a rich source of anthocyanosides, has long been used in traditional medicine to promote better vision.

Leafy greens contain vitamin C while nuts supply vitamin E; as powerful antioxidants they also help defend tissues within the eye against harmful free radicals. What’s more, omega-3 fatty acids—most notably found in fish and krill oils—have been found to help protect the macula in addition to reducing inflammation, a key factor in many chronic ailments.

EXPERT OPINION: The Inuit of Alaska have traditionally had a low incidence of glaucoma because of the high fish oil content of their diet—Abel

Proper vision also depends on vitamin A, which helps support cornea function and
is required for production of rhodopsin, a protein that absorbs light in the retina; vitamin A works best when paired with its mineral partner, zinc. In addition, a recent study found a link between increased AMD risk and low levels of vitamin D.

 

The Clock Exercise

This is a good way to give your eye muscles a workout: Picture a clock face in front of you and move your eyes to the 12 o’clock position while keeping your head still. Hold for a second, then look to 6 o’clock; continue this up-and-down movement 10 times. Rub your hands together to generate warmth and gently cup your palms over your eyes for a minute or two to let them relax. Then repeat the same movement from 9 o’clock to 3 o’clock, 2 o’clock to 8 o’clock and finally 11 o’clock to 5 o’clock, palming the eyes between sets. Finish with 10 full circles in each direction.

 

Keeping Kids’ Eyes Healthy

Getting your children on a regular eye care regimen now can pay health dividends in their later years.

“Children, perhaps even more than adults, require regular eye exams,” says Robert Abel, Jr., MD. “Children’s eye conditions are often diagnosed earlier than a similar condition might be in an adult, either because the child is born with the problem or because adults are playing close attention to the child.” Problems present at birth can include amblyopia (sometimes called lazy eye), in which the brain doesn’t properly process information coming from one eye; strabismus, crossed eyes; or nystagmus, shaking eyes that don’t focus properly.

An expert panel created by the National Center for Children’s Vision Health recommends that all youngsters between the ages of three and six have their eyes checked, preferably every year. To find a practitioner who specializes in child eye care, go to the American Association for Pediatric Ophthalmology and Strabismus website at aapos.org.

Problems such as nearsightedness and farsightedness often first manifest themselves in childhood. In fact, “we are experiencing an epidemic of myopia around the world,” says Abel. “Close work, TV, computers and cell phones are contributing to this in Europe, Asia and the United States.” He cites journal articles showing that spending recess time outside, as well as exposure to longer periods of daylight in general, may help slow the process that results in nearsightedness.

Children’s eyes are also vulnerable to injury, during either playtime with toys such as BB guns or sports competition. The US Consumer Product Safety Commission reports that of the 251,800 youngsters under 12 who visited emergency rooms for toy-related injuries in 2014, 44% suffered injuries to the face and head, including the eyes.

If your children do play with toys such as BB or paint guns, equip them with protective eyewear; polycarbonate lenses are less likely to damage the eye if broken. If they participate in organized sports, make sure any protective headgear is undamaged and fits properly. In one study, severe eye-related injuries among field hockey players fell 67% after a requirement for protective eyewear was adopted throughout the country.

Just like adults, kids need proper nutrition to support all bodily functions, including eyesight. Abel recommends a diet that relies on antioxidant-rich plants; as he puts it, “Children burn up huge amounts of energy, which means they are generating lots of cellular waste for their antioxidants to clear away.” Because it isn’t always easy to get children to eat healthy meals, Abel adds, “Make sure you give your child a good children’s multivitamin—and not one that’s loaded with sugar.”

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