The eye is the organ of sight that contains photoreceptors called rods and cones in the retina. It has three layers - an outer fibrous layer containing the sclera and cornea, a middle vascular layer containing the iris, choroid and ciliary body, and an inner nervous layer containing the retina. The eyelids and tears protect the eyeball. The components of the eye include the sclera, cornea, iris, pupil, lens, retina, macula, optic nerve, vitreous, choroid and ciliary body.

1. Structure & Function of Eyeball
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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.
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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.
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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
3) Inner layer (Nervous tunic)
– Consist of retina
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5. Components of Eye
The components of the eye include
• Sclera
• Cornea
• Iris
• Pupil
• Lens
• Retina
• Macula
• Optic nerve
• Vitreous
• Choroid
• Ciliary body
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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.
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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
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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
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