Structure & Function of Eye

Following points are explain in this article:
Introduction of eye
Eyelids & tears
Morphology of eye-ball
Components of eye
Functions of eye parts
Diagrams

1. Structure & Function of Eyeball Prepared By: RIZWAN ASHRAF RIZWAN ASHRAF 1

2. Eye: Organ of sight. It react to light & pressure. We interpret the shapes, color, & dimensions of object in the world by processing the light they reflect. It contain the photoreceptors; rods & cones located in retina. RIZWAN ASHRAF 2

3. Eyelids & Tear Eyelids: Protect the eyeball from foreign particles coming in contact with its surface. Cutoff the light during sleep. Contains sensory hair cells called cilia . Upper eyelid contain 100 to 150 & lower eyelid contain 50 to 75 cilia. They prevent the dust particles from reaching the eyeball. Tear: It is the hypertonic fluid . Due to is continuous washing & lubrication, conjunctiva is kept moist & protected from infection. RIZWAN ASHRAF 3

4. Morphology Eyeball (Bulbus oculi) Approximately globe shaped. 24 mm diameter. Walls of the Eyeball 1) Outer layer (Fibrous tunic) Consist of sclera & cornea 2) Middle layer (Vascular tunic) Consist of iris, choroid and ciliary body Inner layer (Nervous tunic) Consist of retina RIZWAN ASHRAF 4

5. Components of Eye The components of the eye include Sclera Cornea Iris Pupil Lens Retina Macula Optic nerve Vitreous Choroid Ciliary body RIZWAN ASHRAF 5

6. 1) SCLERA Tough white fibrous outer layer Cover the posterior wall of eye 2) CORNEA Clear front window of the eye Allows for the passage of light into the eye & it also focuses the light. 3) IRIS Colored part Help to regulate the amount of light that enters. 4) PUPIL Black circular opening in the iris It determines how much light is let into the eye. RIZWAN ASHRAF 6

7. 5) LENS Transparent structure inside the eye It focuses light rays onto the retina 6) Retina: Internal Membrane Converts light waves to electric signals that travel through the optic nerve to brain 7) Macula Small central area in the retina It contain special light-sensitive cells & allows to see clearly. 8) OPTIC NERVE Connects eye to the brain It carries the electrical impulses formed by the retina RIZWAN ASHRAF 7

8. 9) VITREOUS Jelly like substance that fills the middle of the eye 10) Choroid Thin vascular layer Lying between the connective tissue 11) Ciliary body Composed by ciliary muscles Covers the inner part of the anterior segment of the eye coating Controls the shape of the lens RIZWAN ASHRAF 8