Approximately 70% of all sensory input fibers to the brain begin in the eye. This is more than twice the neural input of all the other senses combined. For perspective, the auditory nerve contains 30,000 neurons compared to the 1,000,000 neurons in the optic nerve. While a routine ophthalmic exam typically looks normal in most patients with TBI, new imaging technologies like Optical Coherence Tomography can demonstrate anatomical changes in the visual system following TBI, chiefly a thinning of the inner retinal layer and the optic nerve where it is most pronounced in the ganglion cell layer (1A) than in the retinal nerve fiber layer (1B),