Prescription for Danger: 7 Harmful Shortcuts

You snooze in your contacts.

Most tissues in the body contain blood vessels that supply them with oxygen and nutrients. The cornea? Not so much. It has to get nourishment directly from the air, which is harder when your peepers are covered by contacts. "During the day, when your eyes are open and blinking, oxygen still passes through your contacts. It's when your eyes are closed at night that the lenses can become suffocating," says Thomas Steinemann, MD, a professor of ophthalmology at MetroHealth Medical Center and Case Western Reserve University. If you regularly doze with your contacts in, the lack of oxygen could lead to serious infec­tion and eventually scar or warp your corneas. (The exception: extended-wear contacts, which are designed to allow greater air flow at night.)

Even if you've been wearing contacts since childhood, there's a good chance you need to raise your "eye Q." A recent Optometry and Vision Science study found that almost 98 percent of lens users don't completely follow wear and care guidelines. "You may save money by wearing lenses longer than suggested, but you risk getting an infection as the old contacts become worn out," Dr. Steinemann says. Jenny Hepworth learned this the hard way. The 26-year-old New York City resident used to doze in her daily contacts at least three nights a week. "I'd get sleepy, or I'd forget about them," she says. Recently Hepworth fell asleep in her contacts and awoke with a painful infection that left her sporting glasses and squeezing prescription eye drops for a week. If you occasionally nod off with your lenses in, Dr. Steinemann suggests removing them and cleaning them with fresh disinfecting solution as soon as you wake, donning glasses for the next 24 hours to allow better air flow to the corneas, and calling your eye doctor immediately if your eyes are watering or if you notice any redness, pain, or sensitivity to light.