Visual process of the eye

Visual process of the eye


in this nugget we will learn about
Visual Process the fundamental effect that light has is
that it enables us to perceive the world around us the role of light in our contact with
the environment can hardly be overestimated and this is
possible because have an extremely delicate sense
organ the human eye in fact more than eighty percent of the information we
received from the outside world passes through our eyes let us understand the Visual Process Our eye
functions in roughly the same way as a traditional camera with a lens that
projects and inverted image of the scene onto a light-sensitive inter film in the eye this film is replaced by the
retina and consists of light sensitive nerve
endings the iris in front of the lens can open or
close like the diaphragm other camera to control the amoun of light that
enters the eye the opening in the center of the iris is
called the pupil when more light is incident on the eye the
pupil size becomes smaller and again like with a camera the Depth or
focus or the distance over which we see sharp
images becomes greater here the lightest transformed via a
photochemical process into an electric current and transmitted
through the nerve into the brain that interprets it as
visual information human eye has the unique properties of
sensitivity towards different lighting levels and the ability to distinguish between
different shades of colors these properties are obtained through
the division of work between millions of highly specialized
light sensitive nerve endings known as cones and rods the rods are highly light-sensitive and
are principally responsible for the detection of rough
shapes and movement cones on the other hand are less
sensitive to light but can distinguish colors in case of low lighting level vision is
by rods only some hundreds of rods connect to a
common nerve fiber that goes into the brain however because
of this grouping the exact position of the light source
is not known resulting in a rather blurred vision at higher lighting levels the cones take
over completely each individual cone unlike rods
connects to the brain via a single nerve fiber visual acuity or resolving power with cone vision is
therefore far better resulting in sharper images now let us understand the adjustment
mechanisms of the eye the first mechanism is accommodation focussing at different distances is
achieved by changing the refracting power or
focal length of the lens the lens of the eye can
contract under muscular control making it more
convex thus shortening the focal length, this
process is called accommodation the second mechanism we will learn is
convergence we use both eyes to look at one and the
same target to achieve this we unconsciously rotate our eyes in our eye socket we
call this convergence when we look at an object the lines of sight of the two eyes will intersect at the target point the
closer the object the greater is the inward rotation of
the eyes the required amount of rotation is a
measure of the object distance as noted by our
brain thank you

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