We just learned about the Myokymia.
Another part of how the eye works is a Refractive Error.
Some people have better vision than others and can see farther, closer or more clearly.
The reason some people have problems seeing is because the shape of the eyeball is not perfect, or because a person is old and their eye muscles aren't working as well as they used to.
The eye needs to be able to focus on things far away or up close, and switch between the two.
If you use a camera sometimes you can see that it is blurry at first and then focuses.
Refraction means how the eye changes the direction and size of the light coming into the eye.
All of the different parts of the eye have to work together to get the picture right and send it to your brain.
If one of them is not right, then your eyes have a refractive error and you can wear glasses to see better.
(from: wikipedia - refractive error)
Kid Facts - Blast from the past: Philtrum
