Whether they see visual imagery or not, depends on when they went blind.
We all dream as we live in life, so for people blind from birth or early on in life ( congenital blindness) their dreams are without visual content because this has never been a part of their world.
Blind people dream as they live in life just like sighted people do. They don’t see in dreams because they have no visual images to base their dreams on. Their dreams are rich with the senses from their world being primarily audio, emotional and sensory in nature.
Interestingly blind people do not seem to show much eye movement in REM sleep.
People who went blind later on in life appear to be able to dream visually, having experienced at some point in their life the visual images of the world around them.
A critical period between ages five and seven determines whether a person will dream with visual imagery. People who’ve been blind from birth, or who lose their sight before age five, generally won’t have a visual component to their dreams. But people who lose their sight after age seven will.
After this critical period, memory and imagination both play a role in dreams. Adults who lose their sight after age seven can retain memories of things they saw before they lost their sight. These memories, along with constructed images, will form part of the dream experience.
Hellen Keller who became blind at the age of 2 reported in her famous book “The Story of my Life” having very few visual dreams.
In this extract from her book she explains the changing of her dreams over time and gives some valuable insight into how blind people dream:
"My dreams have strangely changed during the past twelve years. Before and after my teacher first came to me, they were devoid of sound, of thought or emotion of any kind, except fear, and only came in the form of sensations. I would often dream that I ran into a still, dark room, and that, while I stood there, I felt something fall heavily without any noise, causing the floor to shake up and down violently; and each time I woke up with a jump. As I learned more and more about the objects around me, this strange dream ceased to haunt me; but I was in a high state of excitement and received impressions very easily. It is not strange then that I dreamed at the time of a wolf, which seemed to rush towards me and put his cruel teeth deep into my body! I could not speak (the fact was, I could only spell with my fingers), and I tried to scream; but no sound escaped from my lips. It is very likely that I had heard the story of Red Riding Hood, and was deeply impressed by it. This dream, however, passed away in time, and I began to dream of objects outside myself.”
Even though sighted and blind people dream differently, Many studies seem to suggest that all our dreams share the same narrative style.
Source(s): realmeaningofdreams.com, earthsky.org