If you are one of the approximately 37 million Americans who wears contact lenses, you may wonder what happens if your contacts get old. Perhaps you are using contacts you got several years ago. Or you are trying to save money by wearing your two-week lenses over a more extended period. It may seem like a good idea, but wearing old contact lenses can damage your eye health.

How do you know if your contacts are old?

There are many kinds of contact lenses. Each comes with information about the recommended use, as well as when they should be replaced. The U.S. Food and Drug Administration regulates contact lenses and other medical devices. They conduct testing on such products to determine how long the product is considered safe for use. So before you open a new package of lenses, note the expiration date.

The experts at the American Academy of Ophthalmology advise users to replace contact lenses when recommended. This means you should wear one-month contact lenses, for example, for one month after the package has been opened. After that, you should discard them.

What’s the risk of wearing old contact lenses?

Your lenses touch your eye, so lax hygiene and replacement practices create a risk of eye infections. Some infections may cause serious damage to your vision. According to the Centers for Disease Control and Prevention, nearly a million eye infections are reported each year. Many of these are related to contact lens use.

If you decide to wear contact lenses that are several years old, remember that the lenses are resting in a solution that might have expired. The expired solution can mean a pH level change and lead to discomfort or infection. If you have a prescription for two-week lenses, you may assume that because you only wear them once a week, you can use the same lenses over a 14-week period. You may think you are saving money, but contacts that are intended to be used for 14 days should be used for 14 days from the time you open the package. After that, the lens begins to break down and can result in infection.

What happens to the contacts over time?

As you wear your contacts, germs, protein deposits, and other residues build up on the surface of the contact. Over time your eyes will become irritated by the deposit buildup.

Contact lens prescriptions usually expire in one year. It is essential to have your annual eye exam to make sure your eyes are healthy and that your prescription has not changed. If you are experiencing discomfort, vision problems, or have questions about the safe and proper use of your contact lenses, ask your eye doctor.