structure of eye ball,eyeball is a specialized sense organ that helps us to understand our environment. It is a sensory unit composed of three parts: receptor, sensory pathway, and a brain center The main parts of the human eye are The Conjunctiva, Sclera,Choroid, Cornea, Iris, Pupil, Anterior Chamber, Posterior Chamber, Aqueous humor, Lens, Vitreous humor, Retina,Macula and Optic nerve.

1. Basic Structure of Human Eye Ball
Md: Azizul Islam, Associate Optometrist
Oculoplasty Department
Ispahani Islamia Eye Institute & Hospital
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2. The eye is a specialized sense organ that helps us
to understand our environment. It is a sensory unit
composed of three parts: receptor, sensory
pathway, and a brain center.
Size-average AP diameter is 21-26mm
Circumference-72mm
 At birth is appox.16mm
At age of 3yrs -23mm
It reaches its maximum size 2years very little
growth there after Has 3 concentric layers
Connected to the brain by optic nerve Protected
by bony orbit and eyelids
The Eyeball

3. External Anatomy of the
Human Eye
 Orbital cavities:- Bony sockets.
 Eyelids:– folds of skin that cover the surface of the eye; close by reflex action when an
object approaches.
 Eyelashes:– secrete oils that prevent lids from sticking together.
 Eyebrows:– protect against foreign articles, perspiration, & direct rays of light.
 Muscles of eye:-
 Extrinsic muscles – muscles located outside of the eye that control certain eye
movements such as moving the eyeball from side to side or rolling the eyes.
 Intrinsic muscles – muscles located inside the eye that help hold the lens in place &
modify its shape.
 Lacrimal glands:– produce tears that lubricate & have a germicidal effect .
 The lacrimal apparatus:- Its the physiological system containing the orbital structures
for tear production and drainage.

4. External Anatomy of the Human
Eye
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5. Basic Structure of Human Eye Ball
The main parts of
the human eye are
The Conjunctiva,
Sclera,Choroid,
Cornea, Iris, Pupil,
Anterior Chamber,
Posterior Chamber,
Aqueous humor,
Lens, Vitreous
humor,
Retina,Macula and
Optic nerve.
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6.  The conjunctiva : is the clear, thin membrane that covers part of the front surface of the
eye and the inner surface of the eyelids.
 The Sclera: The tough outer coat that protects the entire eyeball.
 The Choroid: Layer of the eye behind the retina, contains blood vessels that nourish the
retina.
 The Cornea: The outer, transparent structure at the front of the eye that covers the iris,
pupil and anterior chamber; it is the eye's primary light-focusing structure.
 The Iris: The colored ring of tissue behind the cornea that regulates the amount of light
entering the eye by adjusting the size of the pupil.
 The Pupil: The adjustable opening at the center of the iris through which light enters the
eye.
 Anterior chamber: The region of the eye between the cornea and the lens that contains
aqueous humor.
Glossary of Terms:
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7. Posterior chamber: is a narrow space behind the peripheral part of the iris, and in front
of the suspensory ligament of the lens and the ciliary processes. The posterior chamber
consists of small space directly posterior to the iris but anterior to the lens.
Aqueous humor: The fluid produced in the eye.The aqueous humour is a transparent,
watery fluid similar to plasma, but containing low protein concentrations. It is secreted from
the ciliary epithelium.
Ciliary body: Part of the eye, above the lens, that produces the aqueous humor.
Lens: The transparent structure suspended behind the iris that helps to focus light on the
retina; it primarily provides a fine-tuning adjustment to the primary focusing structure of
the eye, which is the cornea.
Vitreous humor : Clear jelly-like substance that fills the eye from the lens to the back of
the eye.
Glossary of Terms:
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8. Retina: The light sensitive layer of tissue that lines the back of the eye.
Macula: The portion of the eye at the center of the retina that processes
sharp, clear straight-ahead vision.
Fovea: The pit or depression at the center of the macula that provides the
greatest visual acuity.
Optic nerve: The bundle of nerve fibers at the back of the eye that carry
visual messages from the retina to the brain.
Glossary of Terms:
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9. Vitreous
Parts Of The Human Eye
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10. The eye is made up of three layers:
 The outer layer: called the fibrous tunic,
which consists of the sclera and the
cornea;
 The middle layer: responsible for
nourishment, called the vascular tunic,
which consists of the iris, the choroid, and
the ciliary body; and
 The inner layer: of photoreceptors and
neurons called the nervous tunic, which
consists of the retina.
Layers Of The Eyeball
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11. In humans, seven bones make up the
bony orbit:
1. Frontal bone.
2. Zygomatic bone.
3. Maxillary bone.
4. Sphenoid bone.
5. Ethmoid bone.
6. Palatine bone.
7. Lacrimal bone.
The Orbital Bone in Human Eye
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12. There are six extraocular muscles
that move the globe (eyeball).
These muscles are named the
1. Superior Rectus,
2. Inferior Rectus,
3. Lateral Rectus,
4. Medial Rectus,
5. Superior Oblique, and
6. Inferior Oblique.
Extraocular Muscles Of The Eyeball
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13. The cornea consists of five distinct layers.
The outermost layer is called the epithelium which rests on
Bowman's Membrane. The epithelium has the ability to quickly
regenerate while Bowman's Membrane provides a tough,
difficult to penetrate barrier. Together the epithelium and
Bowmanâ s Membrane serve to protect the cornea from
injury. The innermost layer of the cornea is called the
endothelium which rests on Descemet's Membrane. The
endothelium removes water from cornea, helping to keep the
cornea clear. The middle layer of the cornea, between the two
membranes is called the stroma and makes up 90% of the
thickness of the cornea.
Layers Of Cornea
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14. The Retina Can Be Divided Into 10 Layers
Including
(1) The Inner Limiting Membrane (ILM);
(2) The Nerve Fiber Layer (NFL);
(3) The Ganglion Cell Layer (GCL);
(4) The Inner Plexiform Layer (IPL);
(5) The Inner Nuclear Layer (INL);
(6) The Outer Plexiform Layer (OPL);
(7) The Outer Nuclear Layer (ONL);
(8) The Outer Limiting Membrane (OLM);
(9) The Photoreceptor Layer (PL), And
(10) The Retinal Pigmented Epithelium (RPE)
Layers Of Retina
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15. Key Takeaways: The Human Eye and Vision
Light enters the eye by passing
through the transparent cornea and
aqueous humor. The iris controls the
size of the pupil, which is the opening
that allows light to enter the lens. Light
is focused by the lens and goes
through the vitreous humor to the
retina. Rods and cones in the retina
translate the light into an electrical
signal that travels from the optic nerve
to the brain.
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16. Video Eye Anatomy :1
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17. References
 Comprehensive Ophthalmology, 4th Edition, by A. K. Khurana
 Kanski's Clinical Ophthalmology,7th Edition by Jack Kanski
 Essentials Of Ophthalmology, 4th Edition by Samar K Basak
 Picture+Video : Google + Me
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19. If Any Question
Please……
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