A recent study found almost 1-in-13 soft contact lens wearers had eye problems severe enough to lead to infections and other difficulties. And more than half of the 500 people in the study had signs of mild abrasions on at least one eye.

These abrasions are called corneal staining, something that happens to everyone from time to time, whether or not they wear contact lenses, the Ohio State University researchers say. But people who wear contact lenses may be particularly susceptible to corneal staining if they don't regularly clean and replace their lenses.

The surface of the cornea regenerates much like skin -- old cells slough away to make room for new cells. But sometimes too many cells are shed and that provides an opening for bacteria, viruses and other microorganisms to enter the eye.

Anything that causes friction on the surface of the eye -- rubbing, blinking and wearing contact lenses -- can cause corneal cells to slough off.

The study, which was published in the Optometry and Vision Science journal, found that people who didn't clean their lenses properly were almost three times as likely to have moderate to severe corneal staining.

Contact lens power also played a role in moderate to severe corneal staining. Farsighted people and those with moderate to high nearsightedness were more likely to have severe corneal staining.

More information

The Food and Drug Administration's office of consumer affairs has a wealth of information on contact lenses.