Millions of Americans agree: Whether for cosmetic, practical or health-related reasons, contact lenses fit their lifestyles. Contacts are an especially good match for college students, providing clear vision in relative comfort for long hours of studying, working and playing sports.

But despite their popularity, contact lenses can cause a variety of problems for their wearers.

Aaron Olson, senior in psychology, initially chose to wear contacts during high school so he could play sports without worrying about eyeglasses getting in his way.

“For me, they are my life. I’m used to contacts and not having something in your face. I pretty much wear them every hour of the day,” he said.

Olson’s contacts have landed him in the emergency room before, causing scratches in his cornea. He also experiences occasional eye irritations.

“I keep [the contacts] in longer than I should,” Olson said.

Lauri Dusselier, health promotion supervisor at the Thielen Student Health Center, said the health center sees a number of students coming in with eye problems caused by contact lenses.

“If they’re simple problems we’re able to take care of them here,” she said. “We take those problems very seriously, because it can cause worse problems for their eyes.”

Vision changes, redness, swelling, discomfort and abnormal tearing are symptoms indicating contact problems, according to the Food and Drug Administration. If left unchecked, these symptoms can lead to corneal infections and ulcers, which could result in blindness.

The risks are greatest in extended wear lenses, which are worn overnight. Certain types of contacts, especially rigid unpermeable ones, allow less oxygen to reach the eye, increasing the chances for an infection, and sometimes reshaping the cornea.

Bacteria can also find a foothold under contacts.

“You should be particular about cleaning your contacts on a daily basis,” Dusselier said.

Soft contacts, which are gas permeable, are preferred by 82 percent of users. These let more oxygen reach the eye and cause less corneal molding.

Some of these are disposable, and are thrown out every day or week, depending on the style.

Regardless of the lens type, the Contact Lens Council cautions wearers to follow safe procedures. Contact users should be aware that makeup and birth control or other medications can interfere with lenses, rendering them less effective. Chemicals can also permeate the lenses, making them a bad choice for some laboratory workers.

For optimum wear, contact lenses should be cleansed and disinfected after each use, using a commercial saline solution, never a homemade solution or water, to prevent protein buildup.

Lenses should never be moistened with saliva, exchanged with another person or left in while sleeping or napping unless specifically designed to be worn while asleep.

Lenses are tailored for an individual’s use, and can be worn only after getting a prescription. They should be inspected regularly for breaks or tears, and should be removed at the first sign of trouble.

Andrea O’Rourke, freshman in biology, wears her lenses between 12 and 15 hours a day, and removes them when she feels stressed.

“I know when I’ve had my contacts in for too long because my eyes feel dry and very tired,” O’Rourke said. “My eyes don’t itch, but I do notice that they are reddened. When I notice all this, I usually take out my contacts and lay down for a nap because that’s usually what my body needs anyway.”