Contact lenses are thin lenses that sit on top of the cornea (the clear outer layer of the eye). They correct refractive errors to make your vision clearer — just like eyeglasses.

About 45 million Americans wear contact lenses. If you use them the right way, they can be a safe and effective alternative to eyeglasses.

If you have a refractive error, like being nearsighted or farsighted, your eye doctor can prescribe contact lenses to help you see clearly. Learn more about refractive errors.

When to get help

When you’re choosing contact lenses, there are 3 main things to know: whether they’re soft or hard, how long you can wear them, and how often you need to replace them.

Soft or hard

• Soft contact lenses are much more common than hard lenses. Because they’re soft and flexible, they can be more comfortable and easier to get used to.
• Hard contact lenses can make your vision crisper than soft lenses, and they’re less likely to tear. But they may take longer to get used to, and they can be harder to clean and take care of than soft lenses.

Daily wear or extended wear

• You keep daily wear contact lenses in all day and take them out at night. You need to clean and disinfect daily lenses every night. It’s not safe to sleep in daily lenses — it can put you at risk for serious eye infections.
• You can leave extended wear contact lenses in overnight. Depending on the brand, you can wear them for as long as 30 days and nights before taking them out. Extended wear lenses can be convenient — but they may also make it more likely that you’ll get a serious eye infection.

Single use or reusable

• You wear single-use contact lenses for one day, then throw them away at night. The next day, you put in a brand new pair. You don’t need to clean or disinfect single-use lenses.
• You take reusable contact lenses out at night, clean them, and wear them again the next day. Depending on the brand, you’ll need to replace them with a new pair after 7 to 30 days.

Some less common types of contact lenses fix specific vision problems or treat eye conditions. 

Some people prefer to wear contacts instead of eyeglasses.

Contacts stay in place and improve peripheral (side) vision, so they can be easier to wear when being active or playing sports. They don’t fog up the way glasses do, so they may also be more convenient for people who work or spend a lot of time outdoors in cold weather — or indoors in places that are very cold, like a walk-in refrigerator or freezer.

If you wear contacts, you can wear non-prescription sunglasses to protect your eyes from UV rays. You can also wear contacts with UV protection built into the lenses.

Contact lenses are not risk-free. If you don’t use them the right way, you can get serious eye conditions, including corneal ulcers (sores) and infections.

You can lower your risk by:

• Disinfecting and storing your contacts correctly — every time
• Only wearing your contacts for the amount of time your doctor recommends
• Taking out your contacts before you shower, swim, or go in a bath or hot tub

The best way to prevent complications is to take good care of your contacts. 

Most people use multipurpose contact lens solution to clean, disinfect, and store their contact lenses. Follow these steps to keep your contacts — and your eyes — clean and safe.

Every time you take out your lenses:

• Rub and rinse them with contact lens solution
• Store them in fresh solution in your contact lens storage case

Every time you put your lenses in your eyes:

• Rub and rinse the case with fresh solution
• Dump out the solution and dry the case with a clean tissue
• Store the case upside down on a clean tissue — leave the case open with the caps off

Some people use different systems to take care of their contacts. Talk to your eye doctor about which lens care system is right for you. 

Your eye doctor can prescribe eyeglasses or contact lenses as part of a dilated eye exam. The exam is simple and painless. Your doctor will ask you to read letters that are up close and far away. Then, they’ll give you some eye drops to dilate (widen) your pupil and check for other eye problems. 

If you want to use contact lenses, your eye doctor will also put some trial lenses on your eyes to see how they fit and test your vision while wearing the lenses.

If you wear contacts, get an eye exam at least once a year — that way your eye doctor can make sure you’re still seeing clearly.

“Courtesy: National Eye Institute, National Institutes of Health (NEI/NIH).”