The Eye and Vision
The eye is a complex optical system -
very similar to a camera. Vision begins
when light enters the eye through the
cornea, a powerful focusing surface.
From there, it travels through clear aqueous
fluid, and passes through a small aperture
called the pupil. As muscles in the iris
relax or constrict, the pupil changes size
to adjust the amount of light entering the
eye. Light rays are focused through the
lens, and proceed through a clear
jelly-like substance in the center of the
eye called
vitreous, which helps give the eye form
and shape. When light rays finally land on
the
retina, the part of the eye similar to
film in a camera, they form an upside-down
image. The retina converts the image into an
electrical impulse that travels along the
optic nerve to the brain, where it is
interpreted as an upright image.
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