Eye Disease of the Month: Severe Dry Eye
Tears are essential to the health of our eyes. Tears moisturize, lubricate, nourish and clean the eye. The moisture prevents the cornea from drying, while the lubrication makes blinking smooth and comfortable. Tears also provide nourishment to the eye by supplying oxygen and removing carbon dioxide. Tears wash away foreign particles and help protect the eye from infection. Without adequate tears, the cornea can become damaged, which can lead to pain, blurred vision, and even blindness.
Tears are comprised of 3 components, oil, mucus (also called mucin) and watery tears. The innermost layer of tears is the mucus layer which coats the surface of the cornea and allows the tear film to adhere to the eye. The middle layer is the watery tears which provide moisture and supply oxygen and other nutrients to the cornea. The outer layer is composed of oil that seals the tear film and slows the evaporation of tears from the surface of the eye.
Tears are formed in several glands around the eye. The watery tears are produced in the lacrimal gland, while several smaller glands produce the oil and mucus layers. With each blink, the eyelids sweep tears across the eye. Excess tears flow into drainage ducts.
Dry eye is a result of a reduction in the quality or quantity of natural tears. Insufficient tear production can lead to irritation, pain, and scarring of the cornea (the front covering of your eye). Over 50 million Americans suffer from dry eye symptoms. One of the most common causes of eye dryness is the normal aging process. Over time, your body produces less oil – 60% less at age 65 than at age 18. With less oil to seal the watery layer, the tear film evaporates much faster, leaving eyes feeling dry, gritty, and irritated. According to some estimates, as many as 75% of people over age 65 will experience severe dry eye.
Dry eye symptoms, which include itching, burning, irritation, redness, blurred vision that improves with blinking, excessive tearing, increased discomfort after periods of reading, watching TV, or using a computer, can also be triggered by environmental factors including low humidity environments (such as airplanes, deserts, high altitudes, and windy climates), indoor heating and air conditioning, and exposure to cigarette smoke. Poor blinking habits coupled with prolonged computer use or reading can all result in pain and irritation in the eyes.
In addition, certain diseases and medications can lead to severe dry eye. Over 10 million Americans suffer from Dry Eye Syndrome, a chronic condition that can impact the way they live and sleep. According to Sjogren’s Syndrome Foundation, about 4 million Americans suffer from Sjogren’s syndrome, a chronic, autoimmune disease characterized by dry eyes, dry mouth and arthritis. Many other diseases such as rheumatoid arthritis, lupus, scleroderma and thyroid disease can also cause severe dry eye. And many medications inhibit tear production including antihistamines, antidepressants, oral contraceptives and some heart medications.
People who wear contact lenses have an increased risk of developing Dry Eye Syndrome, as contact lenses absorb the tear film and increase the evaporation of tears.
There is no cure for dry eye. If left unattended, dry eye can lead to scarring of the cornea and even vision loss.
