How the eye works?
The eyeball is roughly a sphere of about one inch in diameter. The main components of the
eye include: – The cornea – the cornea is the transparent
front part of the eye. The cornea refracts light and accounts for about two-thirds of
the eye’s total focusing power. – The iris – the iris is the pigmented part
of the eye that makes up the eye color. The iris regulates the amount of light that enters
the eye by adjusting the size of the pupil – an opening in the center of the iris.
– The lens – the crystalline lens is a clear biconvex structure located behind the pupil
and helps to focus light further. – Light refracted by the cornea and the lens
creates an image of the visual object on the retina. The retina is a light-sensitive tissue
lining the inner surface of the eye. Within the retina, optical information is converted
into neural action potentials which are then transmitted to the visual cortex of the brain
through the optic nerve. – The fovea is the central part of the retina
where the sharpest central vision is achievable. In the normal eye, light rays converge right
on the retina. This results in sharp vision. In myopia, or nearsightedness, a condition
in which the eyeball is too long, light rays converge before they reach the retina. The
focal plane is located in front of the retina resulting in blurry vision. This happens when
the person is looking at faraway objects. In hyperopia, or farsightedness, a condition
in which the eyeball is too short, light rays have not yet converged when they reach the
retina. The focal plane is located behind the retina resulting in blurry vision. This
happens when the person is looking at nearby objects.