Common Diseases
Dry Eye

What is 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.  The oily layer smoothes the tear surface and reduces evaporation of tears.  The watery layer cleanses the eyes and washes away any foreign particles or irritants.  The innermost layer, consisting of mucus, allows the watery layer to spread evenly over the surface of the eye and helps the eye to remain wet.

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.  Patients with dry eyes may also have difficulty wearing contact lenses, which normally float on top of the tear film.  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 of the eyes is also a symptom of dry eyes, as excess tears are produced in response to irritation.  However, these excess tears are "crying tears" which consist mostly of water.  The excess tears lack the oil necessary to keep them from evaporating and, therefore, do not function to lubricate 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.  Since these medications are often necessary, the dry eye condition may have to be tolerated or treated with "artificial tears."

How are dry eyes diagnosed?
Often a simple eye examination is all that is required to detect dry eyes.  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.

Treatment
Replacing natural tears with artificial tears is the most common 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.  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 are placed under the lower eyelid and gradually release lubricants during the day are also beneficial to some people.

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 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 the 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 dyers, 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, because the ointment can cause temporary blurring of vision.

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

• Floaters
• Ptosis
• Dry Eye
• Refractive Errors