The three nerves that control eye movement and pupil diameter are:
- Oculomotor Nerve
- Trochlear Nerve
- Abducens Nerve
The human eye is equipped with a variety of optical components including the cornea, iris, pupil, aqueous and vitreous humors, a variable-focus lens, and the retina (as illustrated in Figure 1). Together, these elements work to form images of the objects that fall into the field of view for each eye. When an object is observed, it is first focused through the convex cornea and lens elements, forming an inverted image on the surface of the retina, a multi-layered membrane that contains millions of light-sensitive cells. In order to reach the retina, light rays focused by the cornea must successively traverse the aqueous humor (in the anterior chamber), the crystalline lens, the gelatinous vitreous body, and the vascular and neuronal layers of the retina before they reach the photosensitive outer segments of the cone and rod cells. These photosensory cells detect the image and translate it into a series of electrical signals for transmission to the brain.