Over 10 million Americans suffer from dry eye syndrome, making it one of the most common conditions seen by eye doctors. It is usually a result of a problem with the quality of tears produced that lubricate the eye. Tears are made up of 3 layers. The mucus layer coats the cornea (the white of the eye) so that tear film can adhere to the eye. The middle layer is made up mostly of water but also contains salts, proteins and other compounds. This layer moisturizes the eye and provides oxygen and nutrients important to eye health. The outer tear layer contains oils that seal tears onto the eye to prevent evaporation of tears.

Tears are made in several small glands around the eye. Lacrimal glands found under the upper eyelid form the water layer. Mucus and oil layers are made by smaller glands in the eyelids. Tears are spread over the eyes with each blink. Excess tears flow into tiny ducts located in the corner of the eyes near the nose. These ducts are connected to the nasal passages, which is why crying causes a runny nose as excess tears are drained into nasal passages. Reflex tears are produced in response to certain external stimuli such as injury, irritation or emotions; however, these tears do little to lubricate the eye, which is why someone can complain of eye irritation even though they have watery eyes.

The most common cause of dry eye syndrome is age. People produce much less oil as they age, as much as 60% less at age 65 than at 18. This is more pronounced in women as they tend to have drier skin than men. If less oil is produced in the outer tear layer, the watery layer evaporates much faster leaving eyes dry. Other causes include hot, dry climate, high altitude, air conditioning and cigarette smoke. Some people notice their eyes become drier when reading or working on the computer. In these cases, stopping regularly to blink and rest the eyes may make them more comfortable. Contact lenses absorb tear fluid which can also dry out eyes. So can certain medications, thyroid conditions, vitamin A deficiency, and diseases like Parkinson's and Sjogren's. Dry eyes can also be associated with menopause in women because of hormonal changes.

Symptoms of dry eye syndrome include itching, burning, irritation, redness, blurred vision that improves with blinking, watering eyes, and increased discomfort when watching TV, working on a computer or reading. Testing for dry eye syndrome involves measuring tear production, evaporation rate, and quality. Most sufferers experience chronic irritation but no vision loss, however, severe cases may result in damage or infection to the cornea.

The most common treatment for dry eyes involves the use of moisturizing eye drops. Sufferers should avoid eye drops that remove eye redness, as these tend to dry out eyes more. Severe cases may require the use of moisturizing eye ointments that last longer than eye drops, especially at night. Restasis is a prescription eye drop that increases tear production. In some cases the ducts that drain tears are plugged surgically to allow tears to remain on the eye longer. It is important for dry eye syndrome sufferers to stay well hydrated by drinking plenty of water.

There are a variety of effective moisturizing eye drops available over the counter that can be helpful, especially in mild cases of dry eye syndrome. Ask your pharmacist to recommend an eye drop that can help in your special case.

Reference: http://www.stlukeseye.com/Conditions/DryEyeSyndrome.asp.

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