A new survey from the Centers for Disease Control and Prevention has bad news for people who are careless with contact lens hygiene.

The survey found that a third of all respondents had to go to the doctor due to red or painful eyes caused by poor contact lens hygiene, and a huge amount of people are putting themselves at risk, according to an NBC News report.

Most people know how they should and shouldn’t use contact lenses, but a tremendous amount of wearers go the lazy route anyway, with half of wearers admitting that they sleep while wearing lenses, and about 55 percent acknowledging they top off the solution instead of changing it completely and rinsing the case. About 61 percent admitting to swimming with their contact lenses in.

And those are the results for adults; teenagers weren’t included in the study, and they are even more likely to not practice good hygiene.

More than 90 percent of people who had rigid or hard lenses admitted to using tap water. Tap water is perfectly safe to drink, but it is not sterile: it has microorganisms that can contaminate both the cases and the lenses, and can result in eye infections. Many of the respondents admitted that they often rinse their lenses with top water rather than using the solution.

The poor hygiene results in more doctor’s visits and more incidences of keratitis, which is an inflammation of the cornea that costs people an estimated $175 million per year in the United States. Proper contact lens hygiene can prevent keratitis.

So the CDC recommends that people remember the basics if they were contact lenses: take them out before you go to bed, take a shower, or go for a swim, don’t rinse with tap water, don’t touch them with your dirty hands, and always use disinfecting solution.