People who become blind after the age of 6 can see in their dreams, whereas people who are born blind cannot.
Although, people who lose their sight at 7+ have very vivid visual imagery in their dreams 20 or 30 years down the track. The content of their dreams is more often about familiar situations, rather than new ones.
Dreaming in sound'
People who are born blind however, still dream. Their dreams, containing as much content as sighted people, are experienced by auditory imagery.
This is due to their lack of Rapid Eye Movement (or REM), which occurs in sighted dreamers, as if they are watching something in their dream. People who become blind, however have REMs of the same intensity as of sighted people.
(newscience.com)