Eyes are the
organs of
vision. They detect
light and convert it into electro-chemical impulses in
neurons. In higher organisms, the eye is a complex
optical system which collects light from the surrounding environment, regulates its intensity through a
diaphragm,
focuses it through an adjustable assembly of
lenses to form an image, converts this image into a set of electrical signals, and transmits these signals to the
brain through complex neural pathways that connect the eye via the
optic nerve to the
visual cortex and other areas of the brain. Eyes with resolving power have come in ten fundamentally different forms, and 96% of
animal species possess a complex optical system. Image-resolving eyes are present in
molluscs,
chordates and
arthropods.
