Modern environmental conditions such as air conditioning, computer use and pollution can make symptoms and signs noticeable even in people with relatively normal tear volumes.

Tear secretion is largely controlled by a balanced hormone production and it is for this reason that women are more susceptible to dry eyes at different times in their lives such as pregnancy (many female contact lens wearers report their lenses feel dry and irritable in the later stages of pregnancy) and the menopause.

Studies have shown that the volume of tear production reduces with age and, unsurprisingly as we all live longer, dry eyes effect more of us in our 40’s, 50’s and 60’s.

Other factors that can contribute to dry eye include some systemic diseases such as arthritis and drugs, such as first generation antihistamines, oral contraceptives and some antidepressants.

Computer Dry Eyes

On average the eye blinks every 4-6 seconds or 10-15 times per minute. However a number of studies have investigated how the spontaneous eye blink rate varies with different tasks. Our blink rate can be as high as 23 blinks per minute when we are at rest and not concentrating on any particular visual task to as few as 7.6 blinks per minute when working on a computer.

If we consider the drop in blink rate as a percentage, the following chart shows that the blink rate declines with different visual tasks:

Blink more often!

Blinking is very important when working at a computer: it spreads tears over your eyes to avoid dryness and irritation.

When working at a computer, people blink two-thirds less frequently or about five times less than normally, according to studies. Tears coating the eye evaporate more rapidly during long non-blinking phases and cause dry eyes. Also, the air in many office environments is dry, which can increase the evaporation rate of your tears, placing you at greater risk for dry eye problems.