Eye structure
Lesson objectives

To explore the features of visual
perception.
Amazing facts about eyes
We analyze the world with the help
of sense organs.
Sense organs include the:
eyes
 ears
 nose
 mouth
 skin

The sense organ that animals use to
sense light is the eye.
The eye has three layers:
 the sclera
 the retina
 the choroid
1) The sclera
the outer layer of eye
 it is white layer (in front part it is
transparent)
 maintains its shape
 point of attachment for muscles that
move the eye
 Protects from damages

Light enters the eye through the
cornea, a tough transparent layer of
sclera
2) The choroid
the middle layer of eye
 rich in blood vessels
 In front part of the eye it becomes iris

Iris
disk like structure
 colored part of the eye

Pupil
a small opening in the middle of the iris
 muscles in the iris adjust pupil size to
regulate the amount of light that enters
the eye

In dim light, the pupil becomes larger.
 In bright light, the pupil becomes smaller.

Lens
just behind the iris
 lens change its shape to adjust focus to
see near or distant objects.

Ciliary body
are the muscles attached to the lens
change its shape to adjust focus to see
near or distant objects.
 holds the lenses

3) The retina
is the inner layer of eye
 contains photoreceptors.

There are no photoreceptors where the
optic nerve passes through the back of
the eye, which is called the blind spot.
 The impulses leave each eye by way of the
optic nerve. Optic nerves carry impulses
to the brain.
 The brain interprets them as visual images
and provides information about the
external world
