If you’re one of the 41 million contact lens wearers in the United States, then there’s a 99 percent chance you’re doing something that could leave you looking like Mad Eye Moody from Harry Potter. According to a national survey conducted by the Centers for Disease Control and Prevention, more than 99 percent of respondents reported at least one bad habit that could cause infection.

The most common risky behaviors include keeping contact lens cases for longer than the recommended three months, mixing new solution with old and sleeping in lenses. These typical, and seemingly innocent actions, can have major consequences.

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Last week, Detroit News Station WDIV featured local woman Lisa Stone, who developed a rare fungus in her eye due to improper contact lens care.

"It was stabbing, debilitating pain," Stone tells the station of the experience. "I was literally in my house in a dark room just in agony, truly in agony."

The damage was so bad Stone needed a corneal transplant to fix the problem.

According to the CDC, one in five contact lens-related eye infections lead to eye damage, reports WDIV.

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Although rare, eye-eating amoebas have also caused a stir after a teen girl with acanthamoeba keratitis, basically a parasite, appeared on Animal Planet’s Monsters Inside Me. The cause of her infection? Sleeping in contact lenses. If we haven’t scared you enough, then consider last year’s story of a British man who had his eye removed following the same parasitic infection.

Thankfully, you can avoid terrifying consequences with these tips for maintaining proper eye care:

1. Always wash your hands before touching lenses

2. Carefully rub contact lenses with your fingers for a thorough cleanse. Be sure to rinse with solution

3. Replace your case every three months and be sure to clean the case after every use

4. Completely empty your case and store lenses in new solution

5. Don’t wear contacts when swimming or showering as exposure to water can leave you vulnerable to harmful microorganisms

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