the anatomy of the human eye

2. By
Isaac koomson
Nkansah Thomas
Gerald marquaye
Larbi Papa Kwasi
Emmanuel Addai
Bridget Fobie
Mathias Domlan

3. • INTRODUCTION AND ANATOMY OF THE EYE
• PARTS OF THE EYE AND THEIR FUNCTIONS
• BLOOD SUPPLY TO THE EYE
• INNERVATION OF THE EYE
• EYE PATHOLOGIES AND VISION PROBLEMS
• RADIOGRAPHIC APPEARANCE OF THE EYE
• IMAGING PROCEDURES OF THE EYE

4. • 70% of all sensory receptors are in the eye.
• The human eye can differentiate between 10
million colours and is possibly capable of
detecting a single photon.
• The human eye is a sense organ that allows
vision.
• Human eyes help to provide three
dimensional, moving image, normally
coloured in daylight

5. Includes
• bony orbit
• eyelids
• eyelashes
• fat glands
• extra ocular muscles
• conjunctiva

7. • Sclera: outer white layer; maintains the shape of
the eye; muscles attached control eye movement
• Choroid : contains blood vessels
• Retina : innermost light-sensitive membrane
covering the back wall of the eyeball.

10. • The eye is not shaped like a perfect sphere. It is a fused two-piece unit,
composed of the anterior segment and the posterior segment.
• The anterior segment is made up of the cornea, iris and lens. The cornea is
transparent and more curved, and is linked to the larger posterior
segment, composed of the vitreous, retina, choroid and the outer white
shell called the sclera.
• The cornea is typically about 11.5 mm (0.3 in) in diameter.
• The cornea and sclera are connected by an area termed the limbus. The
iris is the pigmented circular structure concentrically surrounding the
center of the eye, the pupil, which appears to be black.
• The size of the pupil, which controls the amount of light entering the eye,
is adjusted by the iris' dilator and sphincter muscles.

12. • The eye is divided into anterior and posterior chambers by the iris.
• Anterior portion is filled with aqueous humor where as the posterior is fi
lled with vitreous humor.
• Aqueous humor:
-clear liquid
-inflates eye (intraocular pressure).
-Nourishes cornea and lens
-Provides clear medium for passage of light
• Vitreous humor:
-Clear, gel-like mass of water and proteins.
-Gives shape to the eye.
-Holds retina in place against choroid.
-Allows easy passage of light.

13. There are four
rectus and two
oblique muscles
• Lateral rectus
• Medial rectus
• superior
rectus
• Inferior rectus
• Inferior
oblique
• Superior
oblique

14. Rods and Cones
• rod cells: light sensors
– 120 million
– Functions in less intense light
– Used in peripheral vision
– Responsible for night vision
– Detects black, white and shades of
grey
• cone cells: detects colour
– 7 million
– Highest concentration at fovea
centralis
– Functions best in bright light
– Perceives fine details
– 3 types of cone cells, each sensitive
to one of the
three primary additive colours: red,
green, and blue

15. • transparent covering of the
front of the eye
• Allows for the passage of light
into the eye and it also focuses
the light

16. the hole where light
enters into the eye

17. (coloured part)
 coloured part of eye
 controls the amount of light
entering the eye

18. • SCLERA – a tough white
skin (made of tissue)
that covers all of the
eyeball except the
cornea

22. • On retina where optic nerve
leads back into the brain
• No rod or cone cells
• Other eye compensates for
this area

23. • The arterial input to the eye is
provided by several branches
from the ophthalmic artery,
which is derived from the
internal carotid artery in most
mammals.
• Venous outflow from the eye
is primarily via the vortex veins
and the central retinal vein,
which merge with the superior
and inferior ophthalmic veins
that drain into the cavernous
sinus, the pterygoid venous
plexus and the facial vein.

24. • It is a system of
protective features
that keeps blood
borne particles
from upsetting the
control and stable
environment for
the proper
functions of the
optic nerves.
• The two
components are
• Retina vessels and
the choroid.

25. • Sensory innervation is from the trigeminal
(fifth) cranial nerve, via the ophthalmic
division (upper lid) and maxillary division
(lower lid).
• The orbicularis oculi is innervated by the
facial (seventh) nerve.
• The levator muscle in the upper lid is
supplied by the oculomotor (third) nerve

26. • The optic nerve II: enters the orbit through the optic
foramen and passes to the light receptor cells in the retina.
• It allows the movements of the eye and is covered by
meninges that it acquired during its development.
• The Oculomotor nerve III: control the movement of the eyeball. it
enters the orbit through the orbital fissure.
– Supply: inferior, medial, Superior Rectus muscle
– inferior oblique muscle
• The abducens nerve VI: enters through the orbital foramen and
innervates most of retractor bulbi and lateral rectus muscles.

27. • Parasympathetic fibres to the lacrimal gland
pursue a complex course, passing with the
facial nerve and then following the maxillary
division of the trigeminal.
• The sensory and parasympathetic nerve
fibres reach the eyeball via the short and
long ciliary nerves which pierce the sclera
posteriorly.

28. • Age-Related Macular Degeneration
• Bulging Eyes(proptosis)
• Cataracts
• CMV Retinitis
• Color Blindness
• Crossed Eyes (Strabismus)
• Diabetic Macular Edema
• Glaucoma
• Keratoconus
• Retinal Detachment
• Uveitis
• Eyelid Twitching

29. • Myopia (near sightedness)
• Hyperopia (far sightedness)
• Presbyopia
• Astigmatism

30. • inability of the eye to
focus light from distant
objects
• see close objects clearly
• image focuses in front of
the retina
• Develops in childhood
and progressively
worsens
• Tends to stabilize in
adulthood
• Has a genetic component
• Affects a major part of the
population

31. Cause:
• Distance between lens
and retina is too long
(long eyeball)
• Cornea & lens converge
light too strongly
• (strong refractive
power)
• Corrected with a
diverging lens

32. • inability of the eye to focus light from
near objects no difficulty seeing distant
objects
• Babies are born slightly hyperopic. As
eye grows, condition fixes itself.
• image focused behind retina
Cause:
• Distance between lens and retina is too
small (short eyeball)
• Cornea & lens is too weak (doesn’t
Diverge rays enough)
• Corrected with converging lens

35. • X-RAY
• ULTRASONOGRPHY
• CT SCAN
• MRI

36. • Not commonly used nowadays
• A three-dimensional structure is
seen in two dimensional plane, giving
rise to disturbing superimposition.
• Moreover, its sensitivity to small
differences in the attenuation is low,
i.e., its contrast resolution is poor
Positions in imaging
• WATERS VIEW
• CALDWELL’S VIEW
• LATERAL VIEW
• SUBMENTOVERTEX VIEW
• RHESE VIEW

37. ADVANTAGES:
• BONY DETAILS /CALCIFICATION
• STRUCTURES LIKE EOM, OPTIC
NERVECAN BE VISUALISED
• IN ORBITAL TRAUMA FOR
DETECTING
DISADVANTAGES
• INABILITY TO DISTINGUISH
BETWEEN
PATHOLOGICAL SOFT TISSUE
MASS
WHICH ARE RADIOLOGICALLY
ISODENSE
• RADIATION INDUCED CATARACT

38. Advantages of MRI
Excellent soft tissue details
• Entire course of optic nerve
well studied
• No exposure to radiation
• Disadvantages:
• Less sensitive for detecting
bony abn. And calcification.
• Fat saturation artifacts can
mimic pathology.
MRI in retinoblastoma
&cavernous hemangioma

39. • Non invasive
• Well tolerated
• Safe
technique
Perineural inflammation of optic nerve

40. THANK YOU