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`Keratoconjunctivitis Sicca Eye Disorders Merck Manuals Consumer Version
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`Consumer Version
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`MERCK MANUAL
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`Home / Eye Disorders / Corneal Disorders
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`Keratoconjunctivitis Sicca -ˈsik-ә
`(Dry Eye; Keratitis Sicca)
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`By Melvin I. Roat, MD, FACS, Clinical Associate Professor, Wills Eye Institute,
`Department of Ophthalmology, Jefferson Medical College, Thomas Jefferson University
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`Keratoconjunctivitis sicca is dryness of the conjunctiva (the membrane that lines the eyelids and
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`covers the white of the eye) and cornea (the clear layer in front of the iris and pupil).
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`Too few tears may be produced, or tears may evaporate too quickly.
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`The eyes become irritated and sensitive to light and usually burn and itch.
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`Tear production may be measured by placing a strip of paper at the edge of the eyelid.
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`Artificial tears and punctum plugs help relieve symptoms.
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`Locating the Cornea
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`Causes
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`Dry eyes may be due to inadequate tear production (aqueous teardeficient 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 syndrome. Rarely, aqueous teardeficient
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`Keratoconjunctivitis Sicca Eye Disorders Merck Manuals Consumer Version
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`dry eyes may be a symptom of diseases such as rheumatoid arthritis or systemic lupus erythematosus
`(lupus).
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`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.
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`Drying can also result from the eyes being partly open for periods of time at night (nocturnal
`lagophthalmos) or from an insufficient rate of blinking (as can occur in Parkinson disease).
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`Symptoms
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`Symptoms of dry eyes include irritation, burning, itching, a pulling sensation, pressure behind the eye,
`and grittiness or a feeling as if something is in the eye (foreign body sensation). Damage to the surface
`of the eye increases discomfort and sensitivity to bright light. Symptoms are worsened by
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`Activities in which the rate of blinking is reduced, specifically those that involve prolonged use of
`the eyes, such as reading, working at a computer, driving, or watching television
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`Windy, 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
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`The use of certain drugs, including isotretinoin and some tranquilizers, diuretics,
`antihypertensives, oral contraceptives, and antihistamines, and other drugs with anticholinergic
`effects
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`Symptoms lessen during cool, rainy, or foggy weather and in humid places, such as in the shower.
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`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.
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`Diagnosis
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`A doctor's evaluation
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`Doctors diagnose dry eyes by the symptoms and appearance of the eyes and by doing some tests.
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`The Schirmer test—in which a strip of filter paper is placed at the edge of the eyelid—is used to
`measure the amount of tears produced during the 5minute test.
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`Doctors examine the eyes with a slit lamp to determine whether the eye has been damaged.
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`They may also measure how long it takes for the eye to become dry when the person stares (called the
`tear breakup time).
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`Keratoconjunctivitis Sicca Eye Disorders Merck Manuals Consumer Version
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`Treatment
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`Artificial tears
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`Cyclosporine eye drops
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`Punctum plug
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`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.
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`Eye drops that contain cyclosporine can decrease the inflammation associated with dryness. These
`drops sting and take months before an effect is noticed. Inflammation can lessen significantly,
`although the drops work only in a fraction of people. Avoiding dry, drafty environments and smoke
`and using humidifiers can also help.
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`An ophthalmologist (a medical doctor who specializes in the evaluation and treatment―surgical and
`nonsurgical―of eye disorders) can do a minor inoffice procedure to help people with dry eyes. During
`the procedure, an ophthalmologist inserts plugs into the puncta (the small openings at the inner
`corners of the eyelids near the nose) to keep tears from leaving the eye by blocking the flow of tears off
`of the eye surface, through the tear duct, and into the nose. This way more tears are available for
`longer to bathe the eyes. In people with extremely dry eyes, the eyelids may be partially sewn together
`to decrease tear evaporation.
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`Punctum Plug
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`Photo courtesy of Professor J. Wollensak via the Online Journal of Ophthalmology
`(www.onjoph.com).
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`© 2017 Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA
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