CLEVELAND -- Roughly 31 million people nationwide wear contacts, and according to a new study, many of them are lens abusers.

Dr. Ann Laurenzi, an optometrist from the Cleveland Clinic, has seen it all when it comes to contact lens abuse.

She said the biggest mistake is not cleaning lenses the right way.

The companies that make the cleaning solutions know this, so they have made major changes to help people out.

"The newest trend the contact lens companies have come out with is you don't even have to rub the contact lens," Laurenzi said. "You just have to use solution to put it in the case and store it overnight."

She said that means the old days of putting a lens in your mouth or running it under water to clean it are over.

"It carries bacteria," she said. "If you put that into your eye, you're going to get possibly get a serious eye infection."

Laurenzi said many people focus more on the convenience of contacts instead of what's happening to their eyes.

"Do they feel OK? Do they look OK?" she said. "If they become excessively red, excessively irritated and it doesn't go away within a few hours, you should remove the contact lenses."

She said that if that doesn't work, a person shouldn't take any chances and go to a doctor.

"A corneal ulcer -- if it's left untreated, or even if it is treated but not treated soon enough -- can cause scarring on the eye, which can cause not complete loss of vision, but it can drop the vision several lines, which could lead to potential corneal transplant," Laurenzi said.

That's why she said patients have to pay special attention to any changes in their sight or how their eyes look when they're wearing contacts.

"If the eye is irritated at all, leave the contact lens out," Laurenzi said. "You're allowing the eye to heal. You're allowing any medication that you are using to take effect and be most effective.

"The one thing you have to remember to do, which patients sometimes don't even do, is to throw that solution out every day and put fresh solution in. So I think just wearing your lenses properly and cleaning them properly are the two most proactive things you can do for your eyes to keep them healthy."

Laurenzi said that although it's added work, it's always a good idea to have an extra case to store lenses.

If their doctor didn't prescribe extended-wear contacts, patients should not assume they can wear the lenses for longer than during the day.

"There are materials now that allow oxygen flow through the contact lens to the eye that are safe to wear for an extended period of time," Laurenzi said.