Light onto the retinas induces changes in six primary pathways of the brain, three in each hemisphere. These are the hypothalamic pathways, accessory optic tracts and geniculostriate pathways. Visual axis misalignment as simple as a phoria can produce functional vestibular asymmetry. This can be recognised with simple examinations and addressed with in-clinic and at-home exercises. With appropriate care, remarkable improvements in multiple systems throughout the body and brain can be obtained.