From here:
http://www.brainconnection.com/topic...t/vision-anat2
The optic nerves within each eye meet in the front part of the head at a point called the optic chiasm, which functions like a cloverleaf on a highway. All the fibers from the left half of each retina turn towards the right side of the brain, and the fibers from the right half of each retina turn towards the left side of the brain. The end result of this crossing is that the left half of the brain looks at the right visual world, and the right half of the brain looks at the left visual world.
http://www.brainconnection.com/med/m...nat/990304.gif