Depending on its location and severity, a TBI can affect your vision by damaging parts of the brain involved in visual processing and/or perception (e.g., cranial nerves, optic nerve tract or other circuitry involved in vision, occipital lobe).
Imagination, also called the faculty of imagining, is the ability to form new images and sensations in the mind that are not perceived through senses such as sight, hearing, or other senses.
Creativity comes from the impetus to find a different way. Let's think of the definition of creativity. There are many definitions and I'm going to use this one for this answer. Creativity is expressed as the act of having done something in a way that the audience has not seen before or will not hear of elsewhere.