More than 16 million Americans report that they suffer from a condition called dry eye, and the total number may be as high as 30 million. Women are twice as likely as men to endure this often-painful condition, with symptoms including irritated, scratchy, or burning eyes, a feeling of something in the eyes, excess watering, and blurred vision.

Why is dry eye more common in women? One reason is that computer use, makeup and contact lens wear can exacerbate the condition, explains John D. Sheppard, M.D., M.M.Sc., President of Virginia Eye Consultants.

The hormonal changes associated with menopause and pregnancy may also adversely affect the eyes. And the incidence of dry eye rises with age.

A key root cause of many cases of dry eye is the dense population of bacteria growing on the eyelids and lashes. These bacteria can block glands in the eyelids that produce an oil that keeps our tear film from evaporating, Dr Sheppard explains. Without enough oil, the eyes dry up and become painful.

The bacteria also release toxins that cause inflammation and produce an enzyme that compromises this crucial oil layer.