Dry eye, a common eye problem, is caused by a lack of tear production. Tears normally keep the eyes moistened and lubricated. However, stinging, burning, dryness, and redness will result if enough tears are not produced to keep the eyes wet and comfortable. While discomfort is the primary result of dry eyes, infection and corneal scarring may occur if left untreated.
What is tear film?
Tears flow when we cry or when our eyes are irritated. But tears have a much more important everyday function. Tear film spread by a blink makes the surface smooth and optically clear, washes away foreign particles and irritants, and keeps the eye moist. Without tear film, good vision would not be possible.
What are the different kinds of tears?
There are two kinds of tears: those that lubricate the eye and those that 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 are the symptoms of dry eyes?
Patients with dry eyes often complain that their eyes feel gritty, itchy, and dry. Other common symptoms include burning, stinging, redness, stringy mucus, and sensitivity to light. Patients may experience their eyelids sticking together in the morning and have difficulty wearing contact lenses. If not enough tear film is produced, irritation and redness may result from the contact lens rubbing against the surface of the eye. Surprisingly, watering eyes is also a symptom of dry eyes, as excess tears are produced in response to irritation. However, excess tears are "crying tears," which consist mostly of water. Excess tears lack the oil necessary to keep them from evaporating and lubricating the eye.
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. Drugs and medications can also cause dry eyes by reducing tear secretion.
How are dry eyes diagnosed?
Often dry eye are detected during a simple eye examination. Sometimes tests that 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.
Replacing natural tears with artificial tears is the most common treatment. Artificial tears are available without a prescription and are used to lubricate the eyes and replace missing moisture. Tears may be used as often as necessary. Solid inserts, placed under the lower eyelid gradually release lubricants during the day, are also beneficial to some people.
Conserving the naturally produced tears is another approach to keeping eyes moist. After bathing the eye's surface, tears enter a small opening in each lid, the punctum, and drain through a small canal into the lacrimal sac and down a duct into the nose. These channels may be closed temporarily or permanently by your doctor. The closure can create a reservoir of tears, which allows the eyes to stay moist for longer periods of time.
Some patients may also find preventing evaporation of their tears beneficial. 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 may cut down evaporation of moisture due to wind.
If artificial tears alone fail to provide sufficient relief from dry eyes, soft contact lenses may be used to keep moisture on the surface of the eye. Soft contact lenses have a tendency to absorb water and other fluids and act as a bandage that protects the cornea. When used to treat the eye, soft contact lenses trap artificial tears and medicine drops on the surface of the eye, thus providing needed moisture and lubrication.
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.