What Is Making My Eyes Dry?

There are two basic problems that can be causing your eyes to become dry and lack the usual tears: either you're not making enough tears, or the tears you're making aren't as good as they used to be. Occasionally dry eyes may be caused by a third problem: the eye itself can't get the tears where they need to go.

Perhaps your eyes don't make enough tears. This condition, called KCS (for keratoconjunctivitis sicca), usually occurs in both eyes but can be worse in one eye than the other. One of the most common causes of tearing deficiency is simply age. Like skin and hair, our tears tend to "dry up" slightly as we get older; we just make fewer tears. For most of us this decrease isn't terribly noticeable, but for some people tear production can drop off significantly - enough to produce the classic dry-eye symptoms of irritation, redness, grittiness, burning, or eye fatigue. (KCS is also more common in older women than in other
groups, probably because of the hormonal changes that occur with age.)

Other health problems can hamper tear production. One of these is injury to the lacrimal glands, from infection or trauma; the effect of the injury may be temporary or permanent. Another is Bell's palsy, a condition that affects the facial nerves; its effects too may be either temporary or permanent. People with this ailment are often unable to close one eye or blink on one side of the face, and that eye also produces fewer tears. As you may imagine, the combination of not being able to blink and making fewer tears causes major problems with dryness.

Autoimmune disorders can impede tear production. Sjogren's syndrome is the miserable trio of symptoms - dry eyes, dry mouth, and joint pain - that may be associated with other autoimmune disorders, such as rheumatoid arthritis, systemic lupus erythematosus, and scleroderma. (The term secondary Sjogren's syndrome is used to describe dry eyes associated with any other disease.) Other systemic ("whole body") diseases, such as sarcoidosis, leukemia, lymphoma, and chronic thyroid problems, often diminish tear production, as well.

Occasionally medications decrease the tear-making ability in some people. For instance, as you may already know too well, antihistamines and decongestants for allergies and colds dry out everything - eyes in addition to sinuses. Diuretics, taken to lower blood pressure and ease water retention, may decrease tear production. Hormone replacement therapy and even birth control pills also can lead to dry eyes. Other potentially eye-drying medications include certain eye dilators, motion sickness inhibitors, antidepressants, oral acne medications, and opiate-based pain medications.

Even if your tear production is just fine, your eyes can still be dry if the quality of tears is poor. Remember the ingredients in each tear; they're all important, and when the balance of them is off, your tears (and your eyes) may suffer as a result. Diseases in the eye or body can cause a drop in either the mucin or the lipid portion of tears.