Dry Eye Syndrome
Symptoms and Causes
Dry eye syndrome or dry eye disease (DED) is one of the most common eye conditions worldwide and a primary reason for visits to the Optometrist. Risk factors for dry eye syndrome included advanced age, female sex, and computer use. Dry eye syndrome is caused by a chronic lack of sufficient lubrication and moisture on the surface of the eye. Consequences of dry eyes range from subtle but constant eye irritation to significant inflammation and even scarring of the front surface of the eye.
In addition to being called dry eye syndrome, dry eye disease, or simply “dry eye,” alternative medical terms used to describe dry eyes include:
- Keratitis sicca: Generally used to describe dryness and inflammation of the cornea.
- Keratoconjunctivitis sicca: Used to describe dry eye that affects both the cornea and the conjunctiva.
- Dysfunctional tear syndrome: Used to emphasize that inadequate quality of tears can be just as important as inadequate quantity.
Dry eye symptoms & causes
Symptoms of dry eyes and dry eye syndrome include:
- Burning sensation
- Itchy eyes
- Aching sensations
- Heavy eyes
- Fatigued eyes
- Sore eyes
- Dryness sensation
- Red eyes
- Blurred vision
Another common symptom is something called a foreign body sensation, which is the feeling that grit or some other object or material is “in” your eye. As odd as it may sound, watery eyes also can be a symptom of dry eye syndrome because dryness on the eye’s surface sometimes will over-stimulate production of the watery component of your tears as a protective mechanism. This “reflex tearing” does not stay on the eye long enough to correct the underlying dry eye condition. In addition to these symptoms, dry eyes can cause inflammation and (sometimes permanent) damage to the surface of the eye. Dry eye syndrome also can affect the outcomes of LASIK and cataract surgery.
What causes dry eye syndrome?
An adequate and consistent layer of tears on the surface of the eye is essential to keep your eyes healthy, comfortable and seeing well. Tears bathe the eye’s surface to keep it moist and wash away dust, debris and microorganisms that could damage the cornea and lead to an eye infection.
A normal tear film consists of three important components:
- An oily (lipid) component
- A watery (aqueous) component
- A mucous-like (mucin) component
Each component of the tear film serves a critical purpose. For example, tear lipids help keep the tear film from evaporating too quickly and increase lubrication, while mucin helps anchor and spread the tears across the surface of the eye.
Each tear component is produced by different glands on or near the eye:
- The oily component is produced by meibomian glands in the eyelids.
- The watery component is produced by lacrimal glands located behind the outer aspect of the upper eyelids.
- The mucin component is produced by goblet cells in the conjunctiva that covers the white of the eye (sclera).
A problem with any of these sources of tear film components can result in tear instability and dry eyes.
Factors Associated with dry eye
A number of factors can increase your risk of dry eyes. These include:
- Computer use: When working at a computer or using a smartphone or other portable digital device, we tend to blink our eyes less fully and less frequently, which leads to greater tear evaporation and increased risk of dry eye symptoms.
- Contact lens wear: Though it can be difficult to determine the exact extent that contact lens wear contributes to dry eye problems, dry eye discomfort is a primary reason why people discontinue contact lens wear.
- Aging: Dry eye syndrome can occur at any age, but it becomes increasingly more common later in life, especially after age 50.
- Menopause: Post-menopausal women are at greater risk of dry eyes than men of the same age.
- Indoor environment: Air conditioning, ceiling fans and forced air heating systems all can decrease indoor humidity and/or hasten tear evaporation, causing dry eye symptoms.
- Outdoor environment: Arid climates and dry or windy conditions increase dry eye risks.
- Frequent flying: The air in the cabins of airplanes is extremely dry and can lead to dry eye problems, especially among frequent flyers.
- Smoking: In addition to dry eyes, smoking has been linked to serious eye problems, including macular degeneration, cataracts and uveitis.
- Health conditions: Certain systemic diseases — such as diabetes, thyroid-associated diseases, lupus, rheumatoid arthritis and Sjogren’s syndrome — contribute to dry eye problems.
- Medications: Many prescription and nonprescription medicines — including antihistamines, antidepressants, certain blood pressure medications and birth control pills — increase the risk of dry eye symptoms.
- Eyelid problems: Incomplete closure of the eyelids when blinking or sleeping — a condition called lagophthalmos, which can be caused by aging or occur after cosmetic blepharoplasty or other causes — can cause severe dry eyes that can lead to a corneal ulcer if left untreated.
Also, LASIK and other corneal refractive surgery can sometimes cause dry eyes. In most cases, however, dry eye discomfort after LASIK is temporary and resolves within a few weeks of the procedure.
If you have dry eyes prior to LASIK, your eye doctor may recommend a dry eye treatment regimen before your procedure to insure the best possible LASIK results.
Dry eye treatment and prevention
Thankfully, there are effective treatment options if you suffer from chronic dry eye. In many cases, routine use of artificial tears and minor behavioral modifications (taking frequent breaks during computer use, for example) can significantly reduce dry eye symptoms. In other cases, your eye doctor might recommend prescription eye medications and in-office procedures to help your body create and secrete more tears and to decrease eye irritation and inflammation. The only way to know for sure if you have dry eyes is to see an Optometrist for a comprehensive eye exam.