Some 45 million Americans depend on contact lenses to correct their vision, and while contacts are very safe overall, not caring for them properly can lead to serious eye infections, health experts warn.

Thatiana Medina learned that the hard way when she scratched her cornea.

"I forgot to take off my contact lens before going to bed," she said.

Falling asleep with your contacts in is a common problem.

"It can increase your chances of an eye infection by six to eight times," said Jeneen Interlandi, Consumer Reports' health editor.

Even just a nap with your contacts in can be risky.

A Centers for Disease Control and Prevention study found that 20 percent of eye infections involving contacts lead to eye damage and many of those infections were easily avoidable.

For instance, doctors say never rinse your lenses with tap water. It's rare, but the water could contain a vision-threatening parasite. For the same reason, you should not swim with contacts unless you wear goggles. And avoid wearing contacts in a hot tub.

Another bad habit that can lead to infections is wearing weeklong or monthlong lenses longer than recommended. Contacts that you use for just one day are more expensive, but Consumer Reports says they might be worth it.

"Less handling can help make single-use lenses a bit safer than those you use multiple times," Interlandi said.

Contact wearers should also take care to keep cases clean and never share lenses.

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