Visualizing The Future
Vision
Why humans have two eyes and not one or three is not understood
despite hundreds of years of scientific inquiry. But then
again, there's much science doesn't understand. We do know
that vision involves the nearly simultaneous interaction of
the two eyes and the brain through a network of neurons, receptors,
and other specialized cells.
The first steps in this sensory process are the stimulation
of light receptors in the eyes, conversion of the light stimuli
or images into signals, and transmission of electrical signals
containing the vision information from each eye to the brain
through the optic nerves.
The human eye is equipped with a variety of optical components
including the cornea, iris, pupil, aqueous and vitreous humors,
a variable-focus lens, and the retina. Together, these elements
work to form images of the objects that fall into the field
of view for each eye.
When an object is observed, it is first focused through the
convex cornea and lens elements, forming an inverted image
on the surface of the retina, a multi-layered membrane that
contains millions of light-sensitive cells.
In order to reach the retina, light rays focused by the cornea
must successively traverse the aqueous humor (in the anterior
chamber), the crystalline lens, the gelatinous vitreous body,
and the vascular and neuronal layers of the retina before
they reach the photosensitive outer segments of the cone and
rod cells. These photo sensory cells detect the image and
translate it into a series of electrical signals for transmission
to the brain.
Color blindness, a disruption in the normal functioning of human
photopic vision, can be caused by host of conditions, including
those derived from genetics, biochemistry, physical damage,
and diseases. Partial color blindness, a condition where the
individual has difficulty discriminating between specific
colors, is far more common than total color blindness where
only shades of gray are recognized.
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