Why do your eyes roll back when you fain ?

[Liebenthal]

I noticed that some people my roll back their eyes when they faint. Why? What causes it?

[Lilesville]

Usually when you faint, your brain nerves will work in disorder which may affect your eyes nerves. Your eyes will not be controlled and will roll back. You'd better have the good rest for the eyes for the while. During that time, you need to use the eye drops to moisture the eyes. You could also use the warm compress by finding the clean cloth and hot water to make your eyes feel comfortable.

[Lime Springs]

It is normal that the eyes will roll back and the we can see the white of the eyes when people faint. This is because when people are in the state of relaxation, their pupillas are upward. For example, when people are sleeping, their white of the eyes will be exposed. And at the instant of faint, the optical nerves will get immediately relaxed, then the pupilla will turn upward too quickly for the eyelids to cover the eyeballs. Therefore, we see the fainted people roll back their eyes when they faint.