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.
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