The physiology of the human eye involves several key structures working together. The eye receives light stimuli which is transformed into nerve impulses along the optic nerve to the visual cortex where it creates visual sensation. The external structures include the eyelids, conjunctiva, extraocular muscles, and bony orbit. Internally, the eye contains the iris, pupil, lens, vitreous humour, retina, aqueous humour, optic nerve and blood vessels which work to focus light, transmit signals to the brain and provide nourishment to the eye. The retina in particular contains light-sensitive rod and cone cells that convert light energy into electrical signals.

1. Presented by:
Haider Zaman
THE PHYSIOLOGY OF HUMAN EYE

2. THE EYE
• Eye is the gift of the creator
• Eye give us the sense of light
• They are pair in numbers
• Eye receive light stimulus and transforms
It into nerve impulse. which runs along the
Optic nerve reaching the visual cortex and
gives rise to visual sensation

3. EXTERNAL STRUCTURE OF EYE:
• Includes bony orbit, eyelids,
• eyelashes
• Tears
• Fat glands
• Extra ocular muscle
• conjunctiva

4. EXTERNAL STRUCTURE OF EYE:
• Includes bony orbit:
the anatomical space that contains the eye
• Eyelids:
These cover the orbits interiorly.
• Extra ocular muscle:
These muscles are separate from the eye.
• They are responsible for the movement of
• the eyeball and superior eyelid.

5. PARTS OF EYE

6. PARTS OF EYE:
• Aqueous Homour:
It is clear watery fluid in the interior chamber
Function:
Nourishes the lens & cornea
Helps refract light onto the retina

7. VITREOUS HUMOUR:
• A clear, gel like fluid in the posterior chamber
• Support the lens & retina and keeps the eye from
collapsing.

8. RETINA:
• Innermost, sensitive layer of the eye
• A delicate membrane containing photoreceptor and
associated neurons
• Transforms light energy to electrical signals
• two main kind of photoreceptor (cone & Rods)

9. CONE:
• Sensitive to bright light
• Cluster near the center of retina
• Distinguish colours
• 5 million cones in the retina

10. RODS:
Sensitive to dim light
125 million rods in the retina
Allow dim light vision
Black: consBlack: cons
Bright: rodsBright: rods

11. LENS:
• The lens sits directly behind the pupil. This is a clear
layer that focuses the light the pupil takes in. It is held in
place by the ciliary muscles,
• Function: allow the lens to change shape depending on
the amount of light that hits it so it can be properly
focused.

12. OPTIC DISC:
• The point where optic nerve enter to retina
Choroid:
The choroid lies between the retina and the sclera,
Function:
provides blood supply to the eye.
disk opticdisk optic

13. IRIS
The iris is the area of the eye that contains the pigment
which gives the eye its color.
Function:
This allows the eye to take in more or less light depending
on how bright it is around you.

14. OPTIC NERVE
• The bundle of over one billion nerve fibers
that carry visual message from retina to the
brain.
• 1.3mm place where
• 26billion optic nerves are
Passed.

15. MECHANISM
• Eye
• Optic nerve
• Lateral Geniculate nucleus
• Visual cortex

16. RETINAL BLOOD VESSELS:
• Arteries transmit oxygen & nutrients
• veins carry deoxygenated blood from the eye

17. SCLERA
• The sclera is commonly referred to as the "whites" of the
eye. This is a smooth, white layer on the outside, but the
inside is brown
• Function
• The sclera provides structure and safety for the inner
workings of the eye.

18. CORNEA
• The cornea is the outer covering of the eye. This
dome-shaped layer
• Function:
• protects your eye from elements that could cause
damage to the inner parts of the eye.

19. PUPIL & CONJUNCTIVA GLANDS
• The pupil appears as a black dot in the middle of the eye.
• Function: This black area is actually a hole that takes in
light so the eye can focus on the objects in front of it.
• Conjunctiva Glands:
• These are layers of mucus which help keep the outside
of the eye moist.