Ocular Disease: Dry Eye Syndrome

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Dry eye syndrome (or Keratitis Sicca) is one of the most common problems observed and treated by eyecare physicians. This condition occurs due to insufficient quantities of oil and mucus in the tear film of the eye.

The most common cause of this condition is simply the natural process of aging. The tear film is composed of three layers and is responsible for maintaining proper health of the cornea. The mucin layer is the bottom layer that coats the surface of the cornea and acts to adhere the upper two layers of the tear film to the surface of the eye. The middle layer (aqueous layer) provides water, oxygen, and nutrients to the cornea. The top lipid layer is composed of oils that act as a sealant that helps to both maintain the integrity of the tear film as well as to prevent evaporation.

As we age, out bodies produce less and less oil. This prevents the lipid layer from properly sealing the tear film, allowing moisture to evaporate from the eye and results in dry areas on the cornea.

The lack of proper tear film also presents other possible health issues. The tear film is vital to maintaining the health of the eye. It helps fight infection, provide nourishment, and create a smooth surface on the cornea that helps keep vision clear.

• Irritation
• Itching
• Blurred vision
• Burning sensation
• Excessive tearing - this may seem counter-intuitive, however, these tears do little to help the eye regain its moisture. Reflex tears, as they are called, are normally produced in response to injury or emotion and are mostly composed of water. They lack the oil and mucus necessary to maintain the tear film and keep the eye moist.

The most significant risk factor for this condition is age. As mentioned above, since our bodies produce less oil as we get older, the integrity of the tear film diminishes as well. The diminished tear film then cannot prevent evaporation from the corneal surface resulting in dry areas on the eye. Women also tend to experience this condition more often than men because of their tendency for dryer skin.

Other potential factors include:

• Environmental factors - living in hot, dry or windy climate, or at high altitude. Also, air conditioning and cigarette smoke may increase the chance of developing this condition

• Contact lenses - the lenses absorb the tear film causing the formation of protein deposits on the lenses

• Excessive amounts of reading and computer work - these activities cause us to blink less and tears are not replenished

• Certain medical conditions - menopause, thyroid conditions, vitamin A deficiency, Parkinson's disease, etc.

• Certain medications - a very common example is antihistamines

• Dehydration

May consist of artificial tears or lubricating ointment. Blocking the tear ducts with punctal plugs may also be necessary to prevent drainage of the tears.