2. Human Eye and Colourful World
(A) Introduction
The Human eye and the colourful world. Students also study some of the optical phenomena. The nature
and the formation of the rainbow, the splitting of white light and the blue colour of the sky are also examined
in the chapter.
(B) Human Eyes
Our eyes are one of the most important sense organs in our body. They work on the refraction of light
through their convex lens to enable us to see the colourful world around us.
Figure: Human Eye
Main parts shown in the diagram: Conjunctiva, Iris, Cornea, Aqueous anterior chamber, Lens, Ciliary muscle, Vitreous
body, Visual axis, Optic axis, Fovea, Retina, Choroid, Sclera, Optic nerve and Nerve fibres.
Page 1
, Human Eye — Parts and Functions
1) Cornea: The front part of the eye, which is bulging outside, is called the cornea. The outer surface of
cornea is convex in shape. It acts like a window to eye and allows light to enter the eyes.
2) Iris: The flat, coloured ring shaped membrane, just behind the cornea, is called iris. Iris consists of
muscles and coloured pigment.
3) Pupil: Pupil is a hole in the centre of iris. It allows light to enter our eyes. Its main function is to balance
the amount of light entering our eyes to enable us to view objects clearly.
4) Eye Lens: Eye lens is present just behind the pupil. It is a crystalline double convex lens which is made
up of transparent fibrous, soft and flexible jelly-like substance.
5) Aqueous Humour: The space between cornea and eye lens is filled with aqueous humour which is
transparent, watery and viscous liquid.
6) Vitreous Humour: The space between eye lens and retina is filled with a jelly-like substance called
vitreous humour.
7) Ciliary Muscles: One end of suspensory ligament is connected to eye lens while the other is connected
to a muscular structure called ciliary muscle.
Page 2
(A) Introduction
The Human eye and the colourful world. Students also study some of the optical phenomena. The nature
and the formation of the rainbow, the splitting of white light and the blue colour of the sky are also examined
in the chapter.
(B) Human Eyes
Our eyes are one of the most important sense organs in our body. They work on the refraction of light
through their convex lens to enable us to see the colourful world around us.
Figure: Human Eye
Main parts shown in the diagram: Conjunctiva, Iris, Cornea, Aqueous anterior chamber, Lens, Ciliary muscle, Vitreous
body, Visual axis, Optic axis, Fovea, Retina, Choroid, Sclera, Optic nerve and Nerve fibres.
Page 1
, Human Eye — Parts and Functions
1) Cornea: The front part of the eye, which is bulging outside, is called the cornea. The outer surface of
cornea is convex in shape. It acts like a window to eye and allows light to enter the eyes.
2) Iris: The flat, coloured ring shaped membrane, just behind the cornea, is called iris. Iris consists of
muscles and coloured pigment.
3) Pupil: Pupil is a hole in the centre of iris. It allows light to enter our eyes. Its main function is to balance
the amount of light entering our eyes to enable us to view objects clearly.
4) Eye Lens: Eye lens is present just behind the pupil. It is a crystalline double convex lens which is made
up of transparent fibrous, soft and flexible jelly-like substance.
5) Aqueous Humour: The space between cornea and eye lens is filled with aqueous humour which is
transparent, watery and viscous liquid.
6) Vitreous Humour: The space between eye lens and retina is filled with a jelly-like substance called
vitreous humour.
7) Ciliary Muscles: One end of suspensory ligament is connected to eye lens while the other is connected
to a muscular structure called ciliary muscle.
Page 2
