Though the eye itself is an incredible specialized structure devoted to “seeing images”, we would not be able to “interpret” what we see without the help of the brain. Believe it or not, we use almost half of the brain for vision-related activities, including sight and moving the eyes. More parts of the brain are devoted to sight than to any of our other senses.
The nerve that controls vision resides at the back of the eye and is called the optic nerve. The optic nerve is composed of about 1,000,000 ganglion cell axons (an axon is the output fiber of a nerve cell) and these axons are arranged in as organized a manner as possible. For example, the axons (or nerve output fibers) carrying signals from neighboring parts of the retina are next to one another within the optic nerve. The optic nerve than communicates with the visual cortex and the other parts of the brain concerned with vision.
One quick example of how the brain interprets what the eye sees is as follows: The optics resulting from the size and the shape of the eye’s cornea and lens causes the eye to “see” objects upside down. The brain then flips the images right-side up so that we don’t need to coordinate our hands and legs to an upside-down world. It is probable that for the first few days of life, babies actually see everything upside-down. As they become used to vision, their brains “learn” to flip the images so that they will see right-side-up for the rest of their lives.
Neuro-ophthalmology is a specialty involving problems of the optic nerve and the parts of the nervous system related to vision. Some of the common problems evaluated by neuro-ophthalmologists include: optic nerve disorders (such as optic neuritis and ischemic optic neuropathy), migraines and chronic headaches, visual field loss, double vision, optic nerve swelling (papilledema and pseudotumor cerebri), abnormal eye movements, thyroid eye disease, myasthenia gravis, unequal pupil size and eyelid abnormalities.
He is a board-certified ophthalmologist with additional fellowship training in neuro-ophthalmology completed at the University of Pennsylvania Medical Center (Scheie Eye Hospital, Children’s Hospital of Philadelphia and Hospital of the University of Pennsylvania). She is the former director of Neuro-Ophthalmology.