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Pronunciations arthritis cholinergic conjunctivitis cyclosporine isotretinoin keratitis keratoconus keratomalacia keratopathy lacrimal lupus erythematosus systemic lupus erythematosus tretinoin

Keratoconjunctivitis sicca (dry eye) is dryness of the conjunctiva and cornea.

• Too few tears may be produced, or tears may evaporate too quickly.
• The eyes become irritated and sensitive to light and usually burn and itch.
• Tear production may be measured by placing a strip of paper at the edge of the eyelid.
• Artificial tears help relieve symptoms.

Dry eyes may be due to inadequate tear production (aqueous tear-deficient dry eyes). With this type of dry eyes, the tear gland (lacrimal gland) does not produce enough tears to keep the entire conjunctiva and cornea covered by a complete layer of tears. This is the most common type among postmenopausal women. Dry eyes are common in Sjögren's syndrome (see Autoimmune Disorders of Connective Tissue: Sjögren's Syndrome). Rarely, aqueous tear-deficient dry eyes may be a symptom of diseases such as rheumatoid arthritis or systemic lupus erythematosus (lupus).

Dry eyes may also be due to an abnormality of tear composition that results in rapid evaporation of the tears (evaporative dry eyes). Although the tear gland produces a sufficient amount of tears, the rate of evaporation is so rapid that the entire surface of the eye cannot be kept covered with a complete layer of tears during certain activities or in certain environments.

Symptoms

Symptoms of dry eyes include irritation, burning, itching, a pulling sensation, pressure behind the eye, and a feeling as if something is in the eye. Damage to the surface of the eye increases discomfort and sensitivity to bright light. Symptoms are worsened by

• Activities in which the rate of blinking is reduced, specifically those that involve prolonged use of the eyes, such as reading, working on a computer, driving, or watching television
• Drafty, dusty or smoky areas and dry environments, such as in airplanes or in shopping malls; areas with low humidity; and areas where air conditioners (especially in the car), fans, or heaters are being used
• The use of certain drugs, including isotretinoin Some Trade Names
  ACCUTANE
  and some tranquilizers, diuretics, antihypertensives, oral contraceptives, and antihistamines and other drugs with anticholinergic effects

Symptoms improve during cool, rainy, or foggy weather and in humid places, such as in the shower.

Even with the most severe dry eyes, it is rare that vision is lost. However, people sometimes feel that their blurred vision or eye irritation is so severe, frequent, and prolonged that it is difficult to function normally. In some people with severe dryness, the surface of the cornea can thicken, or ulcers and scars can develop. Occasionally, blood vessels can grow across the cornea. Scarring and blood vessel growth can impair vision.

Diagnosis

Although a doctor can usually diagnose dry eyes by the symptoms alone, a Schirmer test—in which a strip of filter paper is placed at the edge of the eyelid—can measure the amount of moisture bathing the eye. Doctors examine the eyes with a slit lamp (see What Is a Slit Lamp?) to determine if the eye has been damaged.

Treatment

Artificial tears applied every few hours can generally control the problem. Artificial tears are eye drops prepared with substances that simulate real tears and help keep the eyes coated with moisture. Lubricating ointments applied before bed last longer than artificial tears and help prevent dryness in the morning. Such ointments are not usually used during the day because they may blur vision.

Eye drops that contain cyclosporine Some Trade Names
SANDIMMUNE
NEORAL
can decrease the inflammation associated with dryness. These drops sting and take months before an effect is noticed. Inflammation can improve significantly, although the drops work only in a small number of people. Avoiding dry, drafty environments and smoke and using humidifiers can also help.

Minor surgery can be done to block the flow of tears through the tear duct into the nose. This way more tears are available to bathe the eyes. In people with extremely dry eyes, the eyelids may be partially sewn together to decrease tear evaporation.

Last full review/revision October 2008 by Melvin I. Roat, MD