En español | Q. I have severe dry eye and take Restasis, which my insurance doesn't cover. What else can I take? If I don't use it, my eyes are so gritty and itchy that I am miserable.

A. I sympathize with you. Severe dry eye, which encompasses several conditions, including keratoconjunctivitis sicca and xerophthalmia, is a common problem among older people.

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Are you using Restasis as a treatment for dry eye? It may not be as effective as you think. — Getty Images

Dry eye occurs when your tear ducts don't produce enough tears or your tear film (the coating that nourishes the eyes and keeps them moist) evaporates too rapidly, leaving your eyes irritated, inflamed and uncomfortable. Without treatment, dry eye can even lead to vision problems.

In addition to the natural aging process, dry eye can be caused by:

• an imbalance in your tear-flow system;

• exposure to dry air;

• antihistamines, tranquilizers and antidepressants, among other medications;

• diseases that affect your ability to make tears, such as Sjogren's syndrome and rheumatoid arthritis;

• a vitamin A deficiency.

Restasis is an ophthalmic emulsion whose active ingredient is cyclosporine, an immunosuppressant. The eyedrops enhance tear production in some patients whose condition is thought to be associated with keratoconjunctivitis sicca.

Cyclosporine is frequently given, orally or by injection, to organ or bone-marrow transplant patients to prevent their bodies from rejecting the transplant. It's also used to treat some autoimmune disorders, including rheumatoid arthritis.

But in my judgment, Restasis should not be a first-line treatment for your condition.

First, Restasis is not that effective as a treatment for chronic dry eye. When the FDA approved the drug in 2002, it noted that in a clinical trial, funded by Allergan, the manufacturer of Restasis, that the eyedrops "increased tear production in 15 percent of patients, compared with 5 percent of patients in the placebo group." That means just one in 10 patients received benefit from the drug, if you net it out.

And like all drugs, its use carries risks. Your eyes are the part of your body most openly exposed to bacteria, viruses and foreign materials. So when you use a drug in your eyes that lowers your defenses against such invaders, you are putting yourself at risk for a range of ocular problems. Patients with active eye infections should not use Restasis.

When administered systemically, cyclosporine carries eight "black box" warnings — the strongest safety warnings mandated by the Food and Drug Administration (FDA) — and it can elevate your blood pressure, which increases your risk of a stroke or other cardiovascular event if you are being treated for blood pressure problems.

Granted, this side effect has only been documented in patients who are getting larger doses of cyclosporine by mouth or injection. But it underscores the importance of talking with your doctor about potential risks and benefits.

I recommend that you ask your doctor to fully examine the factors that may be causing your condition. If, say, the dry eye is a side effect of an anticholinergic medication, such as an antihistamine, it makes no sense to add another drug to the patient's regimen when the problem can be resolved simply by discontinuing or changing the antihistamine.

Methylcellulose eyedrops (Refresh, Tears Naturale, TheraTears, Visine Tears, etc.) work well to lubricate the eye but require repeated applications throughout the day.

My favorite over the counter treatment is ketotifen fumarate ophthalmic solution, which is available under several brand names, including Alaway and Zaditor. Use of the ketotifen fumarate drops in each eye twice a day, along with vitamin A (15 to 25 thousand units by mouth daily), makes for a very safe and effective treatment — at a much lower cost than Restasis and without the risks that may be posed by cyclosporine.

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