Tunnel vision is also possible after a history of head injury, concussion, brain damage and
of color vision
can be due to diabetes
mellitus, glaucoma, cataracts, macular degeneration, Parkinson's disease, Alzheimer's disease, side effects of certain drugs, head injury, sickle cell disease and leukaemia. You need a MRI of brain, EEG studies, and blood works for diabetes, vitamin B12, thyroid disorders, kidney function, liver function and vitamin D.