It depends on the causes that lead to people's blindness. In some cases, people are born to be blind and their eyes may appear as normal as others except that these blind people can not see. Then they can blink and close their just as normal people do. On the other hand, if people get blind because of trauma, hurt, cut and so on, and their eyes are broken and can not open as normal people do, then their eyes will not be able to blink. The optical muscles and nerves of their eyes are completely damaged and thus are not able to control the eyelids.