Itchy eyes. Tired eyelids. The feeling that something is stuck in your eye. These are all symptoms of dry eye, a condition that affects more than 3.2 million women over age of 50 in the U.S., according to a 2003 study in the American Journal of Ophthalmology. And that number may even be too low when it comes to the eye condition also known as dry eye syndrome, says Lauren Blieden, MD, an ophthalmologist with The University of Texas Health Science Center at Houston and the Memorial Hermann-Texas Medical Center. “I bet there are a lot of people who don’t know they have it,” she says. (One name you might recognize—Jennifer Aniston—also had dry eye for years without realizing it.)

In fact, plenty of Blieden’s dry eye patients don’t complain of ‘dryness,’ per se. “They usually say that their eyes are ‘heavy,’” she explains. “A lot of people assume it’s due to fatigue, but once you examine them, you realize the cause.”

That was exactly what happened to Linda, 56, of Chattanooga, Tennessee. She first noticed that she had eye fatigue in 2009, when she was studying for her undergrad degree. “It got so bad I could not see the words in my books,” she told Health. “I went to get a stronger [glasses] lens, thinking that would correct my problem, but [my eye doctor] was quick to give me artificial tears."

Also known as keratoconjunctivitis sicca (KCS), dry eye occurs when your eyes aren’t producing tears correctly. Tears aren't just something you shed when you're feeling sad—they are super important for your eye health. Tears contain electrolytes, nutrients, and antibodies that protect your eye against infections and after an injury. Without the right treatment, people with dry eye could eventually have scarring, pain, and vision loss. 

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The tears themselves contain three different layers: an outer, oily layer; a middle, watery layer; and an inner, mucous-y layer. Some people experience a type of dry eye called aqueous tear-deficient dry eye—a condition that occurs when a person’s glands don’t produce enough of the ‘watery’ part of the tears. The other type of dry eye is called evaporative dry eye, and that occurs when people have trouble producing the ‘oily’ part of the tears. Without the right amount of oil, the tear evaporates too quickly.

The symptoms of dry eye vary—some people feel a stinging, or burning sensation, while others feel like there’s something stuck in the eye itself. Another common complaint is feeling like you have "tired eyelids," as is blurry vision. And in fact, watery eyes or a flood of tears can also be a sign of dry eye. Because the root cause is abnormal or inadequate tear production, the eye may respond with a flood of watery tears that are unable to relieve the underlying lubrication problem.

The risk for dry eye increases as we get older, and people with rheumatoid arthritis, diabetes, and blepharitis (inflammation of the eyelid) are more likely to experience the symptoms. There are also certain medications that can increase the risk of dry eye because they reduce the rate of tear production, including antihistamines, oral contraceptives, decongestants, blood pressure medications, and antidepressants.

If a certain medication is triggering your dry eye, your doctor can help you decide whether you should switch to a different type. On the other hand, if you have an underlying medical condition that’s responsible for your itchy eyes, you’ll want to start treating the condition itself.

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If you have a mild type of dry eye—for example, you notice it after you’ve been staring at a computer monitor for 8 hours—you could try using artificial tears, which adds moisture to the eye to relieve irritation, says Dr. Blieden. (Remembering to blink can also help, though that’s easier said than done.)  Artificial tears can be purchased over-the-counter at the pharmacy and have names like Thera Tears (Amazon, $9), Tears Naturale Tears Naturale Free Lubricant Eye Drops (Amazon, $20), and Systane Ultimate Lubricant Eye Drops (Amazon, $13). These are not the same as "red eye" products, like Visine, which contain medication that constricts the blood vessels of the eye. Overusing red-eye products can lead to dependence, meaning that if you use them more often than suggested, your eyes could stay bloodshot unless you use the drops. This is not true for artificial tears. However you should carefully follow the product’s instructions and recommendations for use. Some contain preservatives or can’t be used with contact lenses, so check with your doctor as to how and when to use the drops.

If artificial tears aren't helping or you’re experiencing more uncomfortable symptoms, you can ask your doctor about taking a prescription medication like cyclosporine (Restasis) or lifitegrast (Xiidra). Your doctor might also recommend blocking off the inner corner of your eye (where the tears drain) with punctal plugs, although the American Academy of Ophthalmology recommends trying other solutions first, like hot, moist compresses and artificial tears.

As for Linda, wearing bifocals and using artificial tears have helped. She currently takes diuretics for a medical condition, which can increase the risk of dry eye, and says that, “admittedly, sometimes I do not drink as much water as I should.” When she does, however, it makes a tremendous difference.