Your guide says:
Light enters the eyes through your pupils, and is focussed on the back of the eye, called the retina. The retina is covered with receivers, called photoreceptors, which
convert light
into neural
signals. A
funny thing
about the
way the
eye is constructed is that the wires carrying these signals are in front of the photoreceptors - between them and the light. This appears to be a
quirk of
evolution (evidence
that it
doesn't have
to be this way comes from octopuses ? the eyes of octopuses evolved independently
from our
lineage, and
their wires
are behind
their photoreceptors). A consequence of this wiring set up is that the wires need to leave the eye somewhere, so they can reach the visual processing areas of the rest of the brain. To achieve this there is
