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3. INTRODUCTION TO NURSING
EDUCATION
STRUCTURE OF EYE
BIJUKUMAR V
8TH BATCH PBBSc. NURSING
GOVT. COLLEGE OF NURSING
THIRUVANANTHAPURAM

4. INTRODUCTION
 The eye or the organ of sight is situated in
the orbital cavity of the skull
 It is well protected by bony walls of the orbit
Orbit also contains muscles of eyeball, their
nerves, blood vessels, and lacrimal gland
Each eyeball is similar to a camera and which
produces images

5. STRUCTURE OF THE EYEBALL
1. Wall of eye ball
2. Light transmitting media (or)
refractive media

6. WALL OF THE EYEBALL
:
 OUTER LAYER (FIBROUS COAT) : SCLERA AND CORNEA
 MIDDLE LAYER (VASCULAR COAT) : CHOROID ,CILIARY-
BODY AND IRIS
 INNER LAYER (NERVOUS COAT) : RETINA

7. WALL OF EYEBALL
OUTER LAYER
(TUNICA EXTERNA OR
TUNICA FIBROSA)
CORNEA SCLERA
MIDDLE LAYER
(TUNICA MEDIA OR
TUNICA VASCULOSA)
CHOROID CILIARY BODY IRIS
INNER LAYER
(TUNICA INTERNA OR
TUNICA NERVOSA)
RETINA
(LAYERS OF RETINA,
ROD,, CONES, LAYER OF
NERVE FIBERS Etc.)

8. OUTER LAYER (OR) TUNICA EXTERNA (OR)
TUNICA FIBROSA
This gives shape of eyeball and contains sclera
and cornea

9. MIDDLE LAYER (OR) TUNICA MEDIA (OR) TUNICA
VASCULOSA
This layer comprises of three structures:,
•Choroid
•Ciliary body
•Iris
The choroid, ciliary body and iris
together form the uveal tract.
This layer contains blood vessels
Pupil is the small opening in
front of it

10. INNER LAYER (OR) TUNICA INTERNA (OR)
TUNICA NERVOSA (OR) RETINA
Retina is the light sensitive membrane

11. SCLERA AND CORNEA
- Sclera or the “white of the eye” forms the
outermost layer of the eyeball
- The anterior one sixth part of the sclera is
transparent and is known as cornea.
- The cornea is described as the “window of the
eye”
- Light rays pass through the cornea to reach the
retina.

12. FUNCTIONS OF SCLERA
• It provides protection to the delicate structure
within the eye
• It resists intraocular pressure
• It maintains shape of the eyeball
• The smooth external surface allow easy eye
movement

13. CHOROID
Choroid is a thin pigmented membrane, dark
brown in color which is situated in between sclera
(externally) and retina (internally)

14. CILIARY BODY
Ciliary body is the continuation of choroid
consisting of smooth muscle fibers, i.e., the ciliary-
muscle

15. Contd….
• Ciliary body contains suspensory ligament for
attaching the lens in position
• The ciliary muscles help in accommodation
by adjusting the thickness of lens

16. IRIS
• Iris is the pigmented membrane surrounds
the pupil
• It arises from the margin of ciliary body and
forms a dark centered opening called pupil
• The space between cornea (in front) and the
lens (behind) is the anterior segment

17. Contd…
• It is again divided into two parts by the iris;
• The space between the iris and cornea is the
anterior chamber
• The space between iris and lens is posterior
chamber
• They are filled with a clear fluid, the aqueous
humor

18. RETINA
• Retina is the inner most layer of the eyeball
• It is a thin delicate layer continuous posteriorly
with optic nerve
• The outer surface of the retina, formed by
pigment cells, is attached to choroid
• Its inner surface is in contact with the hyaloid
membrane of the vitreous
• The small area of retina where the optic nerve
leaves the eye is the optic disc or the blind spot.
It has no light sensitive cells (Rods or Cones)

19. The retina has three parts:
* OPTIC
* CILIARY
* IRIDIAL
 The optic part contains nervous tissue and it is
sensitive to light
 It extends from the optic disc to the ciliary body
The thin, non nervous, non sensitive layer covers the
ciliary body and iris is called ciliary and iridial part of
retina
Contd….

20.  Lateral to the optic disc a depression called macula
lutea (due to its yellow color)
 The center of macula is again depressed to form the
fovea centralis
 It contains cones only and is the site of maximum
acuity of vision
 The rods and cones are the receptors of light and sight
These cells contains photosensitive pigments (Rods-
Rhodopsin, Cones – Iodopsin) involved in the conversion
of light rays into nerve impulses
Contd…….…

21. BLOOD SUPPLY
 Arterial blood is supplied by branches of ophthalmic
artery (ciliary arteries &central retinal artery)
 Venous drainage a number of veins including the
central retinal vein

22. 2.LIGHT TRANSMITTING MEDIA (OR)
REFRACTIVE MEDIA
•Aqueous humor
•Vitreous humor
•Lens

23. AQUEOUS HUMOR
• Aqueous humor is a clear
fluid fills the space between
cornea and lens
• It is secreted by capillaries
of ciliary process
• From here the fluid reaches
to the anterior chamber
which finally reaches to the
canal of schlemm

24. Contd…..
 Interference with drainage of aqueous humor
results in an increase of intraocular pressure
(glaucoma)
(Normal IOP 10 to 20 mmHg)
 This leads to atrophy of the retina, leading to
blindness

25. FUNCTIONS
• It helps to maintain
intraocular pressure and
thus maintains the shape
of eyeball
• It is rich in ascorbic acid,
glucose and amino acids
and nourishes the cornea
and lens

26. VITREOUS HUMOR
 Vitreous humor or
vitreous body is a
colorless, transparent,
jelly-like substance which
fills the posterior segment
of the eye (i.e., behind the
lens).
 It is enclosed in a
delicate hyaloid membrane

27. FUNCTIONS
It helps to preserve the spherical shape of
the eyeball and to support the retina

28. LENS
 The lens of the eyeball is crystalline in nature
 It is situated behind the pupil
 It is biconvex, transparent, and elastic in structure
 Lens refracts light rays and helps to focus the image of
the object on retina
 Lens is supported by suspensory ligaments (Zonular
fibers) which are attached with ciliary bodies

29. ACCESSORY ORGANS OF THE EYE
 EYEBROWS
 EYELIDS & EYELASHES
 LACRIMAL APPARATUS
 CONJUNCTIVA

30. CONCLUSION
 Eye is the
organ of the
sense of sight,
situated in the
orbital cavity.
 It is a delicate
organ and which
is protected by
several
structures.