Some people clean their contacts by putting them in their mouths, while others admit they've stored their lenses in beer.
"You're playing Russian roulette there," said optometrist Sheri McGurk.
McGurk is shocked by the results of a study from the University of Texas Southwestern Medical Center. It claims of the 30 million contact lens wearers in the U.S., 99 percent are doing something wrong.
One of the top offenses is falling asleep while wearing contact lenses. McGurk says the danger in doing that is you're cutting off oxygen to your eyes, and they can quickly develop infections and bacterial ulcers called pseudomonas.
"Pseudomonas can eat through the cornea in 24 hours," McGurk said.
Another study by Bausch and Lomb found that 20 percent of contact wearers have stored their lenses in everything from tap water to coke to baby oil.
"Tap water is terrible. There's bacteria, there's chemicals in tap water," McGurk said.
The bacteria can cause a corneal infection that's resistant to treatment. McGurk says only use contact solution to store and clean your lenses. And if it's irritating your eyes, talk to your doctor about switching brands.
Another common mistake is using two-week contacts longer than recommended.
"By the time that we can feel that they feel uncomfortable, we've gone about 4 or 5 days too long," McGurk said.
McGurk says with the right contact care, you can avoid vision-imparing problems.