Owner's Manual: Listen to Your Eyes

With more than a million parts in each peeper, there's a lot to take care of. Focus on these pointers to keep your vision sharp.

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Get to Know the Parts of the Eye

Cornea: Directs light onto the lens and does most of the focusing for you.

Pupil: Like a camera aperture, it opens and closes to let in the right amount of light.

Retina: It's the tissue at the back of your eye, which includes rods and cones that convert light into signals your nerves can read.

Iris: Your iris has a pattern utterly unique to you — that's why there has been so much interest in iris scanners as security tools.

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Lens: Converges light to be passed to the retina. When light goes through a convex lens, the image gets flipped. Technically, you see things upside down, but your brain turns them right side up.

Vitreous: This is your eyeball's transparent, gel-like filling. It carries light to the retina.

Optic Nerve: Sends signals from the retina to the brain via more than a million fibers. That's why an entire eye can't be transplanted; it's impossible to surgically attach all those connections.

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Your Eyes Love Greens

They crave two little plant nutrients you don't hear much about — lutein and zeaxanthin — along with the mineral zinc. A huge study from the NIH's National Eye Institute found that taking them may slow the progression of age-related macular degeneration (AMD) if you catch it early — especially if you're low in these nutrients to begin with. That's a big deal, since AMD is a major cause of vision loss. Lutein and zeaxanthin are easy to eat up (and everyone should); a cup of cooked kale delivers double what the study used. Also possibly helpful: healthy amounts of vitamins C, D, and E. The 25 mg of zinc is more than most people eat (unless you're a big oyster fan), so if you're at higher risk of AMD — family history, smoking, obesity, and high cholesterol can raise it — consider a multivitamin or talk to a doc about supplements.

There's a Reason Why…

…A scratch hurts so much. The cornea is laced with pain-transmitting nerve cells that tell you to remove a foreign body quickly before it causes damage.

…Your contacts bother you. A new CDC survey found that almost every single contact lens wearer does at least one thing that puts her at risk of an uncomfortable or harmful eye infection. Three dirty habits: sleeping in lenses, using a lens case for longer than three months, topping off solution.

…You get "sleepers," those crusty little globs that form overnight. When you're awake and blinking, particles of oil, mucus, dust, and skin cells naturally wash away, explains Ivan Schwab, MD, a professor of ophthalmology at the University of California Davis School of Medicine. Not so during shut-eye.

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Use the Right Drops

The drugstore has shelves upon shelves devoted to them. Let us help.

If your eyes are red, itchy, or watery during allergy season, try antihistamine eyedrops, which block the allergic reaction in your eyes. Help prevent symptoms by using the drops daily in allergy season, recommends Angie Wen, MD, of the New York Eye and Ear Infirmary of Mount Sinai.

If they're dry and tired now and then, artificial tears, also known as lubricant drops, can keep natural tears from evaporating. If you use these more than four times a day, experts suggest steering clear of the kind with benzalkonium chloride, a preservative that can be irritating. Beware of redness reducers; frequent use can leave eyes more bloodshot than ever.

If they're dry and scratchy 24/7 and artificial tears aren't helping, you may have dry eye syndrome: Tears evaporate too quickly, or you're not making enough. You might want prescription drops; or some people opt for a minor surgical maneuver to fill the "drain" in each eye with a tiny silicone plug that keeps moisture around longer.

Prevent Tired Eyes

Screens make your eyes work extra hard. Relieve them with the 20-20-20 rule: For every 20 minutes of screen time, look about 20 feet away for 20 seconds.

Additional Sources: Emily Chew, MD, deputy clinical director, the NIH's National Eye Institute; Robert F. Melendez, MD, clinical assistant professor, University of New Mexico Health Sciences Center; Jonathan D. Trobe, MD, professor of ophthalmology and visual sciences, University of Michigan Kellogg Eye Center

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