The human eye is one of the most valuable and sensitive sense organs in the human body.
STRUCTURE OF THE EYE
On average, the human eye is very small, about 2.5 cm. Let me go to tell you about the various parts of the eye.
PUPIL
The inner aperture that we can see in the centre of the eye is known as the pupil. The pupil is like a hole through which light enters the eye.
IRIS
It is the coloured part of the eye and is involved mainly in controlling the size of the pupil. The iris increases and decreases the size of the pupil to regulate the amount of light that enters through the pupil.
SCLERA
The white part of the eye that we can see is known as the sclera. It is filled with a clear watery fluid. It is an opaque, fibrous, protective, outer layer of an eye containing collagen and elastic Fibre. The sclera is also known as the white of the eye.
CORNEA
It is a thin transparent tissue that covers the front of the eye. The cornea is the transparent spherical membrane covering the front of the eye. Light enters the eye through this membrane.
RETINA
Just behind the eyeball is a lining called the retina. The retina is sensitive to light and has receptors called rods and cones. These rods and cones respond to light and generate impulses that can be read by the brain. The brain then sends back messages that tell us what we have seen.
CILIARY MUSCLES
These control the focal length of the eye lens. Ciliary muscles help in modifying the curvature of the lens.
LENS
It is a transparent tissue between the pupil and the retina. The lens helps in focusing the light that passes through the pupil into the eye. This helps in focusing the image on the retina by bending the light rays.
OPTIC NERVE
It connects the eye to the brain and carries impulses to and from the brain. The optic nerve transmits visual information from the retina to the brain.
BLINDSPOT
There is a portion on the retina where the nerve fibres enter the optic nerve. This portion does not have any rods and cones, and images falling on this portion of the retina cannot be ‘seen’. This spot is called the blind spot.