The human eye is a sensory organ whose primary function is vision. They eye has a spheroidal shape and is structured in 3 layers: a supporting outer fibrous layer, a middle vascular layer, and an inner neural layer. The eye can also be subdivided into 3 compartments: the anterior, posterior, and vitreous chambers. Surrounding the eyeball itself are the extraocular muscles, the lacrimal apparatus, various nerves and vessels, and the bony structure of the orbit. Light travels through the compartments of the eye to focus on the retina, which is the location where photoreceptors convert the stimulus into a neural impulse that is carried by the optic nerve to the brain.