Figure 3.4 | The Path of Light Through the Eye and the Structure of the Retina | The light travels through the cornea, enters through the pupil whose size is controlled by the iris, and is focused on the retina by the lens. Here, as explained in the figure, the light waves are (1) transduced into neural signals describing the visual image; and (2) these signals are sent to the bipolar cells, which forward them to the ganglion cells whose axons bundle together to form the optic nerve, which (3) carries the signals back to the occipital lobes in the brain, via the thalamus, to be interpreted.