Area where optic nerves cross over, located just above the pituitary gland, which can be compressed by pituitary tumors and hinder eyesight.

At the optic chiasm, nerve fibers from half of each retina cross over to the opposite side of the brain. The fibers from the other half of the retina travel to the same side of the brain. Because of this junction, each half of the brain receives visual signals from the visual fields of both eyes.