Human eye is a sense organ that helps us to see this beautiful world. But few of
us are not able to see things around us properly because of some defect. Explore
the two main types of defects in our vision . Find out their differences and how
they can be corrected. Write a short note on these defects, causes, and their cure.
You can also draw diagrams if possible. Referring to some books is more
appreciable. Mention the reference at the end. ( one page in A4 sheet )
Answers
Answer:
Every day you ‘see’ beautiful things around you. You don’t just ‘see’ things you observe them, analyze them and then you either keep staring or choose to ignore. What enables us to look at things around us? What makes human eye so wonderful and essential? Yet, if on one hand, our eyes enable us to have a look at the world around us; it also carries some defects. Let us know more about the human eye and its defects below.
Explanation:
Human Eye’ is the organ of vision of the human body that enables us to see. The human eye(s) are located in the specialized sockets carved out in the human skull. Each human eye sizes for approximately 2.5 cm in diameter. The main parts of a human eye are:
Sclera
The white outer region of our eye which protects the internal parts of our eyes is known as ‘sclera‘. Its made up of fibrous tissues. It’s continuous with the cornea.
Cornea
The transparent portion of our eye that allows the light to enter our eye is known as the ‘cornea’ and is made up of transparent tissue. The cornea covers the pupil, anterior chamber, and the iris. Along with the anterior chamber and lens, cornea refracts light and accounts for two-thirds of the eye’s total power. Usually, the refractive power of the cornea is approximately 43 dioptres.
Iris
A circular, thin structure made up of contracting and relaxing muscles in the eye that controls the size of the pupil and the light reaching the retina are known as the ‘iris’. Iris defines a person’s eye color. If we define the human eye as a camera then the iris becomes aperture of the eye.
Pupil
The part of the eye located in the center of the iris allowing light to reach the retina. The pupil appears black in color since the eye tissues absorb or diffusely reflect the light entering the pupil. Iris controls the pupil.
Lens
The lens is a biconvex, transparent structure present in the eye behind the pupil. The lens along with the cornea refracts the light, so as to focus it on the retina. By changing its shape, the lens is capable of changing the focal distance of the eye.
Retina
The retina is a light-sensitive tissue in the inner coat of the eye that sends electrical signals after converting them from light to the brain for processing. Rods and cones are the two light-sensitive types of cells present in the retina. Rods help us for night-time vision and cones help us see colors.
Optic Nerve
The optic nerve sends electrical impulses from the retina, at the back of the eyes to the brain.