Why it happens: When you're young, your tears have the right components to coat the eye completely. As you get older, your tears may lose their ability to fully lubricate the eye.
"Tears have three layers: a protein layer, a fat layer, and a water layer," says Tanchel. "If any of those layers are not working as well as they should, we call that dry eye."
Eyes may feel dry and scratchy, or they may water excessively to compensate for a tear imbalance. Blood pressure medicines, antihistamines, diuretics, hormone replacement therapy, and some antidepressants could be to blame, as could the use of a ceiling fan.
Postmenopausal women also tend to develop meibomian gland dysfunction. The meibomian glands, located in the eyelids, create the oily, fat layer of tears. If that oil is diminished, the patient experiences dry eyes.
"It's pretty common for women past 40 to have dysfunction of the meibomian glands or blepharitis — inflammation of the eyelids," says Jen Galbraith, O.D., an optometrist in Harrisburg, Pennsylvania. "Another kind of dry eye I see misdiagnosed is lagophthalmos, which happens when the patient doesn't blink completely." These patients often sleep with their eyes cracked slightly open, so the eyes dry out. "It's often missed," says Galbraith, " but easy to treat."
How to Fix it: Experiment with over-the-counter artificial tears. If that doesn't work, consider Restasis, a prescription drop that helps you make your own tears. If your dry eye is caused by medication, switching meds may help. Tetracycline-based antibiotics can also be used to treat dry eyes, says Cory M. Lessner, M.D., medical director and owner of Millennium Laser Eye Center in Sunrise, Florida. A final option is punctal occlusion, which involves placing tiny plugs in the tear duct, so tears drain more slowly.
Red Flag: Sudden dry eyes might signify a damaged tear gland or blocked tear duct, which can be caused by an infection, a tumor, or scarring or swelling from a blow to the eye. Treatments range from massaging the area (your eye doctor can show you how), to a probe procedure that opens the duct, to surgery.