Color

You have two different type of nerve cells in your eye: rods and cones. The cones let us see color, and the rods are very sensitive to shades of brightness. These cells, however, are not located in the same places in the eye. In the center of the retina, there are only cones, and no rods. Around the edges of the retina, there are less cones and more rods. The part of your eye that gives you the sharpest image is the center of the retina. So, if you see something out of the corner of your eye that you want to see more clearly, you need to turn your eye. If you stare at complimentary colors for a long time, your retina becomes tired with that color and causes optical illusions. The best examples of this is after images. To find out more about this type of illusion, click here.