Tears normally coat the surface of the eyes to keep them moist and comfortable. When tears are poor in quantity or quality, it causes dry eyes. Dry eyes usually present with gritty sensation, burning, redness and discomfort in the eyes. Ironically watering of eyes is also a symptom of dry eyes. This occurs because the dry surface of the eyes stimulates the nerves to cause tearing.
Normally when we blink, the eyelids close and replenish the normal tear film by draining away the old tear film. Also on blinking, around 30 to 40 glands located in the eyelids secrete oily secretions to stabilize the tear film. The average blink rate in an infant is around 8 to 12 blinks a minute and as we age the blink rate drops to around 4 to 6 blinks per minute. In between blinks, when the eye remains exposed to the atmosphere, the tear film dries up resulting in symptoms of dry eyes.
When viewing any object with interest, subconsciously the blink rates further decrease to 1 to 2 times a minute. This results in poor blinking or habitual “half blinking”. This worsens symptoms of dry eyes and also retains the secretions of the gland. This in the long run results in poor functioning of the glands. This is called Meibomian Gland Dysfunction. This accounts for 86% of the causes for dry eyes.
Normally, our eyes are more comfortable looking down to read a book, than, to look at a computer monitor at or above eye level, exposing more surface area of the eye to the atmospheric environment contributing to dry eyes. In an air-conditioned environment, the eyes dry up faster.
Computer users are prone to dry eyes due to prolonged hours of usage. It is mandatory that all computer users are evaluated for dry eyes and Meibomian gland dysfunction.