Why some people wear glasses?

There are different degrees of "blindness", from being totally blind to being partially blind. One eye may be better than the other. Some people are "blind enough" to be regarded as "legally blind" but can see slight shadow in one or both eyes. Others may have one eye totally blind and the other only partially, while still others can have impaired blindness where they are able to see some light or shadow but there is distortion or double-imaging. Darkened glasses stop the double-light shadow vision. Others must just prefer to wear dark glasses because blind eyes tend to look milky and they may not want to stared out.