FIGURE 3.3 Path of Light in a Human Eye As you look at Susan’s cat Milla, light waves reflected from Milla’s brown fur and green eyes pass through your cornea, pupil, and lens. The iris controls the amount of light entering the eye by controlling the size of the pupil. The lens changes shape to focus the incoming light onto the retina. As the light strikes the retina, the light energy activates the rods and cones. Signals from the rods and cones are collected by the bipolar cells, which transmit the information to the ganglion cells. The ganglion cell axons are bundled together to form the optic nerve, which transmits the information to the brain. The optic nerve leaves the eye at the optic disk, creating a blind spot in our visual field. (For a demonstration of the blind spot, see Figure 3.4 on page 92.)
Ivan Bojanic