You pop them in, you take them out.

Chances are, you don't think twice about your contact lenses throughout the day.

Some researchers say soon we’ll be taking medicine, checking our blood sugar, and even watching television or computer screens using our contact lenses. But doctors say all of that could be pretty dangerous. And without proper care, those dangers that could leave you blind.

Roughly 41 million people in the world wear contacts, according to the CDC. Those reports state between 40-90 percent of contact wearers don't use them correctly.

Bacterial infections and fungus in the eye are just a few problems UC Davis optometrist Melissa Barnett says she deals with in her patients who probably had no idea a small bad habit could be devastating to their vision.

"Unless contact lenses are advised to sleep in, they're not recommended to sleep in your contact lenses," Barnett says.

CDC reports say sleeping in contacts increases your risk of infection sixfold. Barnett added that sleeping in them could lead to eye pain, eye irritation, sensitivity to light, and vision loss. You could need a corneal transplant or have to replace the surface of the eye.

But popping contacts out before sleeping isn't the only problem. Here's something to think about before you jump in a pool.

"Within twenty four hours my eye was swollen shut. I was in the hospital and the infection was so bad it was hard to know whether a contact lens was in my eye," Kaci Fisher, who now has an ulcer on her eye after she slipped into a pool of chlorine and salt water, said.

"If someone really needs to go swimming with them wear goggles that don't allow water in. But it's really important to avoid water around contact lenses," Barnett recommends, adding she would avoid wearing them in the shower and bathtub, as well.

Other things to think about?

  • Don't hang on to that storage case for too long. Change it out every three months.
  • Don't reuse solution. Change it out every night and don't top it off.
  • And remember, contacts are medical devices and need a prescription. Buying them online from unauthorized websites or from costume shops is dangerous.