Johns Hopkins Health Alert
What Causes Dry Eye?
Do you have dry eye? Dry eye syndrome is a condition in which your eye produces too few tears or poor quality tears. Although it rarely causes blindness, it can affect the quality or sharpness of your vision. Left untreated, dry eye syndrome can make it difficult to read or drive, for instance, producing a significant adverse effect on your quality of life. What causes dry eye? Here’s an explanation, in brief.
Age is often the culprit behind dry eye. As we age, our bodies -- especially those of females -- produce less oil. At age 65, for instance, we make 60% less oil than we did at age 18. Without oil to seal the watery layer of the eye, the tear film evaporates more quickly, leaving dry spots on the cornea.
Aging also decreases the amount of tears we produce. And in women, menopause and its hormonal shifts also bring less tear production. Moreover, aging can be associated with several alterations in the eyelid position, which produce structural problems that may cause the lower eyelid to turn out (ectropion) or turn in (entropion).
In both cases, the eyelids do not close properly, leaving them exposed to the air, which may exert a drying effect. Tear ducts, too, can have structural problems that can cause dry eye, although these are not associated with aging.
Other causes of dry eye syndrome include:
- Medications. Some medicines interfere with the secretions of eye glands, leading to or exacerbating dry eye.
- Environmental factors. Sunny, dry, or windy weather; high altitudes; heaters; smoke and other air pollutants; hair dryers; air travel; and air conditioners can all dry out the tear film covering your eye. Logging in a lot of TV, computer, driving, and reading time can dry out this film as well, because during these activities, you blink less, priming you for dry eye.
- Contact lenses. As the lenses lose moisture when you wear them, they absorb tear film, leading to dryness.
- Diseases. Dry eye is associated with thyroid disease, rheumatoid arthritis, and systemic lupus. Some people who have skin conditions, such as psoriasis, eczema, and rosacea, also may be at risk. Dry eye is also prevalent among people who have Sjögren's syndrome, a condition that dries the mouth and mucous membranes.
- Blepharitis. An inflammation of the edges of the eyelids, this condition occurs when eye glands don't produce enough oil, a common cause of dry eye.
- Refractive eye surgery. Eye surgeries, such as laser-assisted in situ keratomileusis (LASIK), that correct near- and farsightedness and astigmatism can sever the nerves that stimulate tear production. But the resulting dry eye generally improves as the eye heals.
Posted in Vision on January 8, 2010
Reviewed January 2011
Medical Disclaimer: This information is not intended to substitute for the advice of a physician. Click here for additional information: Johns Hopkins Health Alerts Disclaimer
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