Dryeye

What Are Dry Eyes?

Some people do not produce enough tears to keep the eye wet and comfortable. Stinging, burning, scratchiness, stringy mucus, and excess irritation from smoke are the usual symptoms. Dry eyes can make it difficult or impossible to wear contact lenses.

Surprisingly, increased tearing may be a symptom of dry eyes. If the basic tear secretion is below normal, excess tears are produced by the lacrimal gland in response to irritation. Even though the eye is basically dry, overflow tearing can occur, masking the dryness which caused the tears in the first place.

What Is the Tear Film?

Tears run from our eyes when we cry or when our eyes are irritated. But tears have a much more important everyday function. A film of tears, spread over the eye by a blink, makes the surface of the eye smooth and optically clear. Without our tear film, good vision would not be possible. The tear film consists of three layers: an oily layer, a watery layer, and a layer of mucus.

The outer oily layer of the tear film is produced by small glands at the edge of the eyelid, called meibomian glands. The main purpose of this oily layer is to smooth the tear surface and reduce evaporation of tears.

The middle watery layer, the largest of the three layers, makes up most of what we ordinarily think of as tears. This watery layer is produced by small glands scattered through the conjunctiva, the delicate membrane lining the inside of the eyelid and covering the eyeball, and by the major tear gland, the large lacrimal gland. This layer cleanses the eye and washes away foreign particles or irritants.

The innermost layer consists of mucus produced by other cells in the conjunctiva. This layer allows the watery layer to spread evenly over the surface of the eye and helps the eye to remain wet. Without mucus, tears would not adhere to the eye.

What Are the Different Kinds of Tears?

There are two kinds of tears: those which lubricate the eye and those which are produced as a response to irritation or emotion. Tears which lubricate the eye are produced around the clock. Excessive tears occur when the eye is irritated by a foreign body or when a person cries.

What causes dry eyes?

Tear production normally decreases with age. Although dry eyes can occur in both men and women at any age, women, especially after menopause, are most often afflicted. Dry eyes can also be associated with arthritis and accompanied by a dry mouth. People with dry eyes, dry mouth, and arthritis are said to have Sjogren's syndrome.

Drugs and medications can also cause dry eyes by reducing tear secretion. Since these medications are often necessary, the dry eye condition may have to be tolerated or treated with "artificial tears." A list of drugs that can cause dry eyes appears at the end of the brochure.

How Are Dry Eyes Diagnosed?

Often an ophthalmologist is able to diagnose dry eyes by simply examining the eyes. Sometimes tests which measure tear production may be necessary. One widely used test, the Schirmer tear test, involves placing filter-paper strips under the lower eyelids to measure the rate of tear production under various conditions.

Treatment

Replacing the tears

Replacing natural tears with artificial tears is the basis of treatment. Artificial tears are available without a prescription and are used as eye drops to lubricate the eyes and replace the missing moisture. There are many brands of artificial tears on the market, and many people try several different brands to find one which suits them best. The tears may be used as often as necessary, only once or twice a day, or as often as several times an hour. Solid inserts that gradually release lubricants during the day are also beneficial to some people.

Conserving the tears

Conserving the naturally produced tears is another approach to keeping the eyes moist. After bathing the eye's surface, tears enter a small opening in each lid, the Sanctum, and drain through a small canal, the canaliculus, into the lacrimal sac and down the naso-lacrimal duct into the nose.

These channels may be closed temporarily, or permanently, by your ophthalmologist. The closure creates a reservoir of tears which allows the eyes to stay moist for longer periods of time.

Other Methods

Preventing the evaporation of tears can also prove helpful. In winter, when the heat is turned on, a humidifier or a pan of water on the radiator adds moisture to dry air. Wrap-around glasses (illegal to wear while driving in some states) may cut down evaporation of eye moisture due to wind. Anything that adds to dryness such as an overly warm room, hair dryers, windy days, or anything that adds an irritant to the air will make a person with dry eyes more uncomfortable. Smoking is especially bothersome.

Some people with dry eyes complain of "scratchy eyes" upon awakening. This symptom can be treated by using an ointment at bedtime. Use the smallest amount of ointment necessary for comfort, since the ointment can cause temporary blurring of vision.

Although ointments containing vitamin A seem to be of some benefit to people with severe dry eye due to scarring from Stevens-Johnson syndrome or pemphigoid, vitamin A does not seem to help people with ordinary dry eye.

Who Can Treat Dry Eyes?

A person suffering from dry eyes may only need over-the-counter artificial tears, but since extreme dryness can cause serious damage to the eye, an examination and diagnosis by your ophthalmologist is suggested.

An ophthalmologist is the medical doctor (MD or osteopath) who is educated, trained, and licensed to provide total care of the eyes. Total eye care includes performing comprehensive medical eye examinations, prescribing corrective lenses, diagnosing diseases and disorders of the eye, and using the appropriate medical and surgical procedures necessary for their treatment. Only an ophthalmologist can provide total eye care.

The following drugs may cause dry eyes. Brand names may be different from the generic or clinical names listed.