Eye Q: Dry Eye

What causes dry eye?


Dry eye is a low-grade inflammation of the surface of the eye resulting from a deficiency in one or more of the three components of the tear film. The tear film is composed of a water portion, an oil portion and a mucus portion. The most common deficiency is a decrease in the water portion of the tear film. While the most severe forms of this decreased water portion are associated with some systemic disorders such as Sjogren’s syndrome, mild to moderate decrease is most commonly found in post-menopausal women. The oil component of the tears comes from some small glands with openings at the margin of the eyelid just behind the lashes. When these glands produce abnormal amounts or an abnormal quality of oils, the tear film is affected by a more rapid break up on the surface of the eye following each blink. Certain skin disorders can affect these oil glands. The mucins or mucus portion of the tear film is created by all of the cells on the surface of the eye. Certain irregularities of the cells such as injuries following chemical exposure could permanently change the ability of the cells to produce this mucin or mucus layer. An abnormality in one or more of the components results in a low grade inflammation. This causes a further decrease in the stimulus for production of the water portion of the tears.


How is dry eye treated?


The initial treatment for a decrease in any of the three components of the tear film is frequent, routine, regular use of artificial tears. This added moisture to the eye, although short lived on the ocular surface, serves to reduce the cumulative effects of dryness. If the symptoms become too severe to be controlled by artificial tears alone, other treatments include methods to retain tears on the ocular surface as well as anti-inflammatory treatments. Rarely, dry eye can lead to severe vision loss. The main difficulty with mild to moderate dry eye is its high nuisance factor. By this we mean near-constant symptoms that require continuous routine treatment and the irritation and aggravation that ensue during periods of worsening.