14 Things Your Eyes Say About Your Health

Looking someone 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.

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 brows (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.

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.

Bumpy yellowish patches on the eyelid

What it means: Xanthelasma palpebra, the medical name for these tiny yellow bumps, are usually a warning you 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.

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.