Quiz: Glasses and Contacts in Focus

American Founding Father Ben Franklin had presbyopia, an inability to focus close-up that usually happens as you age. He described their invention, which has lenses for both far and near vision, in a letter to a friend in 1784.

You might hear them called multifocal lenses or no-line bifocals. They let you see things clearly at different distances. You probably won’t need bifocals until after age 40.

Each eye has a different prescription. Plus, custom lenses are made to account for the specific distance between your eyes. Still, store-bought glasses are cheap enough that you can have several pairs. It won’t hurt to use them -- unless you’re skipping regular eye exams.

A study published in Optometry and Vision Sciencefound that women are 40% more likely than men to wear contact lenses.

After each use, rinse the case with fresh contact lens solution and leave it open to dry. Replace it every 2 or 3 months -- or right away if it’s cracked or has other damage.

Yes, extended-wear contacts are designed to be worn for several days and nights. Up to a week is a safe bet for most. But not all doctors agree. Many say not to sleep in any type of contact lenses. It can make you more likely to get an infection. If you do hit the hay with your contacts in, tell your doctor at the first sign of any eye problems -- pain, discharge, or a change in vision.

No matter what solution you use, eye doctors say to rub the lenses with your fingers first. Rinse them with solution before you soak them. 

Glasses are unique. No two people have the same prescription. Looking at the world through someone else’s lenses won’t permanently harm your eyes, but it can cause eyestrain and headaches.

Shatter-resistant polycarbonate lenses, commonly used in sports, usually come with full ultraviolet protection. So do high-index lenses, a lightweight type can help you avoid thick lenses if you have a strong prescription. But UV coating is a good idea if you get less expensive lenses made of a plastic called CR-39.

They aren’t so great for cars or airplanes. Windows block the light rays that trigger the tint to change.

Astigmatism means light doesn’t focus evenly on the back of the eye. Glasses are the simplest fix, but special soft contacts or rigid ones also work. LASIK or other surgery helps some people.

These hard lenses let oxygen flow through to the eye. They’re also more durable, and may provide clearer vision, than soft lenses.

You should seriously weigh the pros and cons of wearing contact lenses for a different look. Talk to your eye doctor -- they can supply the look you want and give you the periodic exams required for all people who wear contacts. The lenses you get from costume shops are illegal and could hurt your eyes.

Your child’s doctors will use a special tool to shine light in their eye and watch how it reflects off their retina. If they see a problem, they’ll test different lenses to see which one provides the best fix.

Saliva and tap water are unsafe. If you wear soft contacts, put the lens in saline or soaking solution as soon as you can. Then disinfect it. (If it’s damaged or irritates your eye, don’t use it.) If you wear disposables, replace the lens with a new one. If you use gas-permeable lenses, store the lens dry until you can care for it.