How Do Eyeglasses Work?

I've been wearing eyeglasses for decades, but I'll admit that some of the terminology around eyes and glasses doesn't mean much to me. For instance, I know I have astigmatism, but I couldn't tell you what that meant until I watched this simple TED-Ed video on eyeglasses and how eyes work.

If you're even slightly unsure on the definitions of myopia, hyperopia, astigmatism, or presbyopia, take four minutes and learn up:

There are more resources and discussion topics from TED-Ed if you're so inclined.

Further reading from mental_floss: What Happens If I Survive the Apocalypse and Only Have One Pair of Contact Lenses? and How Do Transition Lenses Work?