They can only perceive images with their mind’s eye. When the dream is about being blind, the message is of a psychological and spiritual nature. Blindness in a dream suggests that the dreamer may be unwilling to see some aspect of his life. There may be a blind spot in the mind, heart and/or soul.
The dreamer is threatened by the unconscious material being processed by the dream, and he cannot bring it to his conscious attention.
The good news is that dreams are cyclical in nature. A message that cannot get through at the current time will repeat itself at a future date. The very central point of dreams is to make us aware of all aspects of ourselves and our lives.
Enlightenment and integration of unconscious and conscious components take time and desire. What you cannot see in a dream currently will become visible when you are more able to effectively cope with the message. This definition also applies to darkness and sleep as dream symbols.