For those with less-than-perfect vision, rinsing and storing contact lenses each day might be a familiar routine. But as the American Academy of Ophthalmology (AAO) points out, few people actually clean their lenses properly.

One investigation by the Centers for Disease Control and Prevention revealed that 99 percent of people who wear contact lenses exhibit at least one behavior that puts their eyes at risk for irritation or infection. There are more than a dozen things that contact lens wearers should never do—from swimming in contacts to using the same case for months or years—but the dangers of wearing lenses that have been left to soak in old contact lens solution are often overlooked.

People who wear contacts sporadically might have a habit of keeping their lenses stored in a case for days or weeks at a time, only to pop their lenses in when they need them without ever changing the solution. Even if you rinse your lenses with multi-purpose immediately prior to inserting them, the AAO says this is still a bad idea.

"Disinfecting solutions lose their efficacy over time, leading to microbial overgrowth in the case and on the lens," the AAO said in a statement. If you're going to store your lenses for a few days, be sure to swap out the solution the night before you wear them in order to disinfect the lenses and remove all harmful bacteria. That could be as often as once a day if you wear lenses regularly.

The same guideline applies to "topping off" whatever old solution remains in your contact case with a squirt of fresh solution. It seems like a cost-saving measure, but you may end up spending more on co-pays at the doctor's office to treat an eye infection.

And yes, contact solution does go bad, so if you have any travel-sized bottles lying around, check the expiration date before you wind up with an eye infection on your next vacation.