Page 60 - Miracle in the Eye

(Figure 2.2). In order for you to see a bird in
flight, first the lens has to focus its image.
That image falls, inverted upon the retina at
the back of the eye. Here, millions of pho- 2
toreceptors split the image, and analyze the RETINA
Next the photons activate
bird's color, shape and movement as pho- the retina's photorecep-
tons, which are rapidly transformed into tors—the cone and rod
tiny electrical signals. This total encoding is cells. Cones determine the
image's color; the rods let
far faster than a computer's processing us see in the dark. Great
speed. These signals are then transmitted ganglion cells then process
to the brain, where they are decoded and the information about the
bird's movement and outer
the picture interpreted. Scientists continue shape, while the smaller
to be fascinated by this amazing system ganglions encode informa-
and have not yet fully figured out the true tion about the bird's smaller
details and colors. The sig-
nature of perception. nals emerging from these
cells are sent to the optic
nerves.

ing brightness. The beams
then pass through the
changed by relevant mus-
1
THE EYE – CAMERA lens, whose shape is
cles to focus the image
Light waves reflecting off
the bird pass through the
clearly on the retina.
cornea and the pupil,
which the iris muscles
have already adjusted in
accord with the surround-