Most people that are born blind still have their optical receptors or whatever they're called so they can imagine shapes and textures in their mind. People who develop blindness later in life can lose/damage their optical receptors and go through the painful experience of not only being blind but living in complete darkness as well without the power of imagining a picture in your mind. While people who lose their sight mid-life are traumatized, people who lose their optical receptors are said to be living a life of tortured hell