Very simply, dry eye is an uncomfortable condition where your eyes stop making sufficient quantities of healthy tears, leading to a lack of moisture and lubrication. Millions of Americans are affected by dry eye. Fortunately, dry eye symptoms are treatable.
In the healthy eye, a thin layer of tears—it's called the tear film—coats the surface of the eye. When the eye is open, the tear film keeps the surface of the eye moist, lubricated and comfortable. With each blink, the tear film on the surface of the eye is swept away by the movement of the lids, much like a windshield wiper, and is replenished with fresh tears.
Whether it be loss or reduction of the eye's ability to produce normal tears, dry eye is one of the most frequent causes of visits to an eye care professional. A variety of factors may cause or contribute to this problem, such as working too many hours at the computer each day or an age-specific reason such as menopause.
In the normal tear film, there are three components or layers – water, mucous and oil. In the most common type of dry eye, there is a deficiency in the outermost (oily), middle aqueous (water), and inner (mucous) layers. Most commonly, people experience deficiency in the oily component of tears, leading to increased tear loss by evaporation that causes dry eye.