Looking people straight in the eye may or may not reveal their honesty-but the eyes *can* tell you about cholesterol, liver disease, or diabetes, if you know what to look for.
"The eye is a unique window into health," says ophthalmologist Andrew Iwach, spokesperson for the American Academy of Ophthalmology (AAO) and executive director of the Glaucoma Center of San Francisco. "It's the only place in the body where, without surgery, we can look in and see veins, arteries, and a nerve (the optic nerve)."
The eyes' transparency explains why common eye diseases such as glaucoma, cataracts, and macular degeneration can be detected early with regular eye exams.
"Unfortunately, people get busy and delay not only eye exams but regular physicals. That's why eye doctors sometimes discover other issues, like diabetes or high blood pressure," Iwach says. Especially vulnerable, he says: People like caregivers, who worry about others around them while neglecting care for themselves.
Keep your eye out for these 14 problems.
1. Red flag: Disappearing eyebrows
What it means: Shaved eyebrows are a fad (or fashion, if you will) in some circles. But when the outer third of the brow (the part closest to the ears) starts to disappear on its own, this is a common sign of thyroid disease-either hyperthyroidism (overactive thyroid gland) or hypothyroidism (underactive thyroid gland). The thyroid is a small but critical gland that helps regulate metabolism, and thyroid hormones are among those critical to hair production.
More clues: Brows tend to thin with age naturally. But with thyroid disease, the brow-hair loss isn't evenly distributed; it's a selective dropout on the ends. There's usually a loss of hair elsewhere on the body, too, but the brows are so prominent, it's often noticed here first. Early graying is a related sign of a thyroid problem. Women are more often affected than men, and hyperthyroidism especially strikes women in their 20s and 30s.
What to do: Mention this symptom to a dermatologist or your regular doctor. Most other symptoms of both hyper- and hypothyroidism are notoriously broad and general. Before you see a doctor, make note of any other changes you've noticed, possibly concerning weight, energy levels, bowel or menstrual regularity, mood, or skin changes.
2. Red flag: A stye that won't go away
What it means: The vast majority of the time, a small, raised, often reddish bump along the inner or outer eyelid margin is just an unsightly but innocuous stye (also called a "chalazion"). But if the spot doesn't clear up in three months, or seems to keep recurring in the same location, it can also be a rare cancer (sebaceous gland carcinoma).
More clues: Actual styes are plugged-up oil glands at the eyelash follicle. Fairly common, they tend to clear up within a month. A cancerous cyst that mimics a stye, on the other hand, doesn't go away. (Or it may seem to go away but return in the same spot.) Another eyelid cancer warning sign: Loss of some of the eyelashes around the stye.
What to do: Point out a persistent stye to an ophthalmologist (a medical doctor who specializes in the eye). A biopsy can confirm the diagnosis. The stye is usually removed surgically.
3. Red flag: Bumpy yellowish patches on the eyelid
What it means: Xanthelasma palpebra, the medical name for these tiny yellow bumps, are usually a warning that you may have high cholesterol. They're also called "cholesterol bumps"-they're basically fatty deposits.
More clues: Sometimes people mistake these bumps for a stye, but with xanthelasma, there tends to be more than one bump and they're quite small.
What to do: See your doctor or a skin or eye specialist. A diagnosis can usually be made by sight. An ophthalmologist can also examine the eye and see deposits; for this reason, in fact, sometimes high cholesterol is first diagnosed during a routine eye exam. The problem usually isn't serious and doesn't cause pain or vision problems. A physician will also evaluate you for other signs of coronary artery disease.
4. Red flag: Burning eyes, blurry vision while using a computer
What it means: You might be a workaholic, and you definitely have "computer vision syndrome" (CVS). The eyestrain is partly caused by the lack of contrast on a computer screen (compared with ink on paper) and the extra work involved in focusing on pixels of light. What's more, by midlife the eyes lose some of their ability to produce lubricating tears. Irritation sets in, adding to blurriness and discomfort.
More clues: Does the problem worsen in the afternoon (when the eyes tend to become drier)? Is it worse when you're reading fine print (more eyestrain)? People who wear glasses or contacts tend to be bothered more by CVS. "Sometimes the problem is made worse by a fan positioned so it blows right in the face," the AAO's Iwach adds, noting that the air further dries tired eyes.
What to do: Reduce glare by closing window shades, investing in a computer hood, or checking out antireflective coating for your glasses (if you wear them). Simply tinkering with the contrast of your screen can help, too. White areas should neither glow brightly like a light source nor appear gray. Flat-panel LCD display screens (like those on laptops) cause less eyestrain than older models. Keep reference material close to the same height as your monitor, giving your eyes a break from having to refocus so much.
5. Red flag: Increasing gunk in the eye
What it means: Blepharitis-inflammation of the eyelids, especially at the edges-can have several causes. Two of them, surprisingly, are conditions better associated with other body parts: scalp dandruff and acne rosacea (which causes flushed red skin, usually in the faces of fair-skinned women at midlife).
More clues: The eyes may also feel irritated, as if specks have gotten in them. They may burn, tear, or feel dry. The crusty debris tends to gather in the lashes or the inner corners of the eyes, or even on the lids.
What to do: With clean hands, apply a warm, damp washcloth to the eyes for about five minutes at a time to loosen debris and soothe the skin. See a doctor, who may prescribe an antibiotic ointment or oral antibiotics, as well as artificial tears.
6. Red flag: A small blind spot in your vision, with shimmering lights or a wavy line
What it means: An ocular migraine (also called an "ophthalmic migraine," "optical migraine," or "migraine aura") produces this disturbed vision, with or without an accompanying headache. Changes in blood flow to the brain are thought to be the cause.
More clues: The visual distortion starts in the center of the field of vision. It might appear as a bright dot, dots, or a line that can seem to move and disrupt your ability to see properly, as if you were looking through a pocked or cracked window. It's painless and causes no lasting damage. Individuals seem to have different triggers (ranging from chocolate, caffeine, and alcohol to stress). A headache, possibly severe enough to cause nausea, sometimes follows.
What to do: If you're driving, pull over until the phenomenon passes (usually within an hour). Do have an eye specialist check it out if vision impairment lasts more than an hour or so, to rule out serious problems such as a retinal tear; or if you also experience other symptoms elsewhere that could indicate stroke or seizure (such as fever, loss of muscle strength, or speech impairment).
7. Red flag: Red, itchy eyes
What it means: Many things can irritate eyes, but itchiness accompanied by sneezing, coughing, sinus congestion, and/or a runny nose, usually screams "I'm allergic!" When the eyes are involved, the trigger is usually airborne, like pollen, dust, or animal dander.
More clues: An eye allergy can also be caused by certain cosmetics or ointments. Some people, for example, are allergic to the preservative in eye drops used to treat dry eyes.
What to do: Staying away from the allergic trigger is the usual treatment. Antihistamines can treat the itchiness; those in eye-drop or gel form deliver relief to the eyes faster. If the problem turns out to be an allergy to eye drops, look for a preservative-free brand.
8. Red flag: Whites of the eye turned yellowish
What it means: Two groups of people most often show this symptom, known as jaundice: Newborns with immature liver function and adults with problems of the liver, gallbladder, or bile ducts, including hepatitis and cirrhosis. The yellow in the white part of the eye (the sclera) is caused by a buildup of bilirubin, the by-product of old red blood cells the liver can't process.
More clues: "Other tissues of the body would have the same look, but we can't see it as clearly as in the whites of the eye," says ophthalmologist Iwach. (Skin can also turn yellowish when a person consumes too much beta carotene-found in carrots-but in those cases the whites of the eyes remain white.)
What to do: Mention the symptom to a doctor if the person isn't already under care for a liver-related disease, so the jaundice can be evaluated and the underlying cause treated.
9. Red flag: A bump or brown spot on the eyelid
What it means: Even people who are vigilant about checking their skin may overlook the eyelid as a spot where skin cancer can strike. Most malignant eyelid tumors are basal cell carcinoma. When such a tumor appears as a brown spot, then-as with any other form of skin cancer-it's more likely to be malignant melanoma.
More clues: Elderly, fair-skinned people are at highest risk. Look especially at the lower eyelid. The bump may look pearly, with tiny blood vessels. If the bump is in the eyelash area, some eyelashes may be missing.
What to do: Always have any suspicious skin spots or sores checked out by a dermatologist, family physician, or eye doctor. Early detection is critical, before the problem spreads to nearby lymph nodes.
10. Red flag: Eyes that seem to bulge
What it means: The most common cause of protruding eyes is hyperthyroidism (overactivity of the thyroid gland), especially the form known as Graves' disease. (First Lady Barbara Bush had it.)
More clues: One way to tell if an eye is bulging is to see whether there's any visible white part between the top of the iris and the upper eyelid, because normally there shouldn't be. (Some people inherit a tendency toward eyes that bulge, so if the appearance seems to run in a family, it probably isn't hyperthyroidism.) The person may not blink often and may seem to be staring at you. Because the condition develops slowly, it's sometimes first noticed in photos or by the occasional visitor rather than by someone who lives with the person every day.
What to do: Mention the symptom to a doctor, especially if it's present in tandem with other signs of Graves' disease, including blurry vision, restlessness, fatigue, increase in appetite, weight loss, tremors, and palpitations. A blood test can measure thyroid levels. Treatment includes medication and surgery.
11. Red flag: Sudden double vision, dim vision, or loss of vision
What it means: These are the visual warning signs of stroke.
More clues: The other signs of stroke include sudden numbness or weakness of the arm or leg or face, typically on just one side of the body; trouble walking because of dizziness or loss of balance or coordination; slurred speech; or bad headache. In a large stroke (caused by a blood clot or bleeding in the brain), these symptoms happen all at once. In a smaller stroke caused by narrowed arteries, they can occur across a longer period of minutes or hours.
What to do: Seek immediate medical help by calling 911.
12. Red flag: Dry eyes that are sensitive to light
What it means: Sjogren's (pronounced "show-grins") syndrome is an immune system disorder. It impairs the glands in the eyes and mouth that keep them moist.
More clues: Sjogren's usually affects women over age 40 with autoimmune disorders such as rheumatoid arthritis or lupus. Usually the eyes and mouth are affected together. The person may also have vaginal dryness, dry sinuses, and dry skin. Because of a lack of saliva, it can be difficult to chew and swallow.
What to do: A doctor can diagnose Sjogren's through testing. Artificial lubricants (such as artificial tears) are usually necessary to protect the eyes, as well as to improve eating. Drinking plenty of water also helps.
13. Red flag: Sudden difficulty closing one eye, inability to control tears in it
What it means: Bell's palsy is an impairment of the nerve that controls facial muscles (the seventh cranial nerve), causing temporary paralysis in half the face. It sometimes follows a viral infection (such as shingles, mono, or HIV) or a bacterial infection (such as Lyme disease). Diabetics and pregnant women are also at higher risk.
More clues: Half of the entire face, not just the eye, is affected. Effects vary from person to person, but the overall effect is for the face to appear droopy and be weak. The eyelid may droop and be difficult or impossible to close, and there will be either excessive tearing or an inability to produce tears. The effects tend to come on suddenly.
What to do: See a doctor. Most cases are temporary and the person recovers completely within weeks. Rarely, the condition can recur. Physical therapy helps restore speaking, smiling, and other tasks that require the facial muscles working in unison, and it also helps avoid an asymmetrical appearance. Professional eye care can keep the affected eye lubricated and undamaged.
14. Red flag: Blurred vision in a diabetic
What it means: Diabetics are at increased risk for several eye problems, including glaucoma and cataracts. But the most common threat to vision is diabetic retinopathy, in which the diabetes affects the circulatory system of the eye. It's the leading cause of blindness in American adults.
More clues: The changes linked to diabetic retinopathy tend to show up in people who have had the disease for a long time, not those recently diagnosed. The person may also see "floaters," tiny dark specks in the field of vision. Sometimes diabetes causes small hemorrhages (bleeding) that are visible in the eye. There's no pain. People with poorly controlled blood sugar may have worse symptoms.
What to do: Someone with diabetes should have a dilated eye exam annually to catch and control the earliest stages of retinopathy, glaucoma, cataracts, or other changes-before they manifest as changes you're aware of.