The eye has several key structures that allow for vision. The cornea and iris control the amount of light entering the eye. The pupil is a gap in the iris that changes size depending on lighting. Behind the pupil is the lens, which focuses light using refraction. The lens thickness changes to focus on distant or near objects. Light hits the retina, a light-sensitive layer, which sends signals through the optic nerve to the brain for vision. Some eyes have imperfections causing near- or far-sightedness.

1. 7.8- Sight
SIR. MUHAMMAD ABDEL MAGEID
VIII-Cambridge

2. Introduction
Vision is one of the most important senses .We
collect more useful information about the world
around us by looking than by any other sense

3. The structure of the eye

4. The structure of the eye
1- Cornea: the transparent front surface
2- Iris : is the coloured part of the eye
3- Pupil : - a gap at the centre of iris through which light can pass
- it can change size to control the amount of light passing into the eye
- In bright light the pupil becomes smaller and in the dark the pupil
becomes larger

5. Iris & Pupil

6. The structure of the eye
4- The lens : is behind the pupil and focuses the rays of light that pass through
it using refraction
- - When we are looking at distant objects the lens is stretched thin by small
muscles inside the eyeball .
- When we are looking at nearby objects the muscles relax and the lens
is much fatter
5- Retina : a light-sensitive layer of cells at the back of the eye
- When light falls onto these cells signals are sent to the brain through
optic nerve

7. 1- SHORT–SIGHTED
2- LONG–SIGHTED
Imperfect eyes

9. Thanks !
SIR. MUHAMMAD ABDEL MAGEID
Do you have any questions?
sirmuhammadabdulmageid@gmail.com