Dry eye syndrome occurs when eyes don’t produce enough tears, or when the quality of the tears produced is poor. Tears must maintain a precise balance of mucus, water, oil, nutrients, proteins and antibodies in order to function properly. With age, the glands in the eyelids produce less oil, which allow tears to evaporate quickly and leave the eyes too dry.
The American Academy of Ophthalmology estimates 3.2 million women age 50 and over and 1.68 million men age 50 and over are affected by dry eye syndrome.
Dry eye syndrome can be caused by any of the following factors:
- The natural aging process
- Diseases, including diabetes
- Hormonal changes, especially after menopause
- Prescription medications, including some high blood pressure medications, antihistamines, diuretics, antidepressants, sleeping pills and pain medications
- Non-prescription medications, including some cold and allergy products
- Environmental conditions such as hot, dry, windy or high-altitude climates
- Exposure to pollutants like smoke
- Activities that keep one from blinking for long periods, like reading, using a computer or watching TV
- Contact lens use
- Eye surgery, including LASIK
According to the American Optometric Association, people with dry eyes either do not produce enough tears or their tears are of a poor quality:
Tears are produced by several glands in and around the eyelids. Tear production tends to diminish with age, with various medical conditions or as a side effect of certain medicines. Environmental conditions, such as wind and dry climates, can also decrease tear volume due to increased tear evaporation. When the normal amount of tear production decreases or tears evaporate too quickly from the eyes, symptoms of dry eye can develop.
Tears are made up of three layers: oil, water and mucus. Each component protects and nourishes the front surface of the eye. A smooth oil layer helps prevent evaporation of the water layer, while the mucin layer spreads the tears evenly over the surface of the eye. If the tears evaporate too quickly or do not spread evenly over the cornea due to deficiencies with any of the three tear layers, dry eye symptoms can develop.
The most common symptoms of dry eye syndrome include:
- Excessively watery eyes
- Eyes that produce a stringy mucus-like discharge
- Red, irritated eyes that burn and itch
- Foreign body sensation in the eyes
- Vision that becomes blurred after periods of reading, watching TV or using a computer
An eye doctor can check for dry eye syndrome by examining a patient’s eyes and measuring the rate of tear production and evaporation. The doctor can also check for pinpoint scratches on the front surface of the eye caused by dryness.
The National Eye Institute identifies several approaches to relieve the symptoms of dry eye depending on the cause. An eye care professional who has examined the patient’s eyes and is familiar with his or her medical history is the best person to answer specific questions and recommend treatment.