ppt

1. OPHTHALMOLOGY FOR
MEDICAl STUDENTS
Demoze Delelegn, MD
Ast. Professor of Ophthalmology

2. Course outline
I. Basic anatomy & physiology of the eye
II. Examination of the eye ---History taking & physical
examination
III. Diagnosis and management of ocular disorders
3.1. Diseases of the orbit
3.2. Diseases of eye lids and lacrimal Apparatus
3.3. Diseases of the conjunctiva
3.4. Diseases of the cornea
3.5. Diseases of the sclera
3.6. Diseases of uveal tract
3.7. Diseases of the lens

3. Course outline
 Diagnosis & mgt of ocular disorders
3.8. Diseases of retina and optic nerve
3.9. Squint
3.10. Glaucoma
3.11. Vitamin A deficiency
3.12. ocular manifestation HIV/AIDS
3.13. Ocular trauma
3.14. Refractive errors
IV. Preventive ophthalmology

4. Basic Anatomy & physiology of the eye
 Orbital Anatomy
 Ocular appendages
- Eyebrows
- Eyelids
- conjunctiva
- Lacrimal Apparatus
 The eye ball
- cornea - Lens
- sclera - vitreous
- uveal tract - Retina
 Visual pathway - Nerve & blood supply of the eye
 EOM

6. ORBITAL CAVITY
 The orbital cavities are a pair of
large bony sockets that contain
eyeball, EOMs, nerves, vessels
& orbital fat, and most of the
lacrimal apparatus.
 Each cavity is pear-shaped and
its apex is directed
posteriorly,medially, and slightly
upward; the stalk of pear lying
within optic canal.
 The medial wall runs
anteroposteriorly parallel to
sagital plane.
 The lateral wall diverges at
angle of 45.

7. Bony orbit
 Seven bones make up the bony orbit:
- Frontal -Sphenoid
- Zygomatic - Lacrimal
-maxillary - Palatine
-Ethmoidal
 Orbital roof
- made up of 2 bones: 1. orbital plate of frontal bone
2. lesser wing of sphenoid
 Medial wall ----- very thin wall
1.Frontal process of maxilla
2.Lacrimal bone
3.orbital plate of ethmoid
4.Lesser wing of sphenoid

8.  Orbital floor
1.maxillary
2.palatine
3.orbital plate of zygomatic
 Lateral wall
1. zygomatic bone
2. greater wing of sphenoid

9. The paranasal sinuses
 The paranasal sinuses are cavities in the interior of the maxilla
,frontal , sphenoid and ethmoidal bones
 Lined with mucoperiosteum & filled with air , they communicate with
nasal cavity through small openings
 Function:
-to act as resonators to voice
- to reduce weight of the skull
 4 sinuses:-1.maxillary sinus
2.frontal sinus
3.sphenoidal sinus
4.Ethmoidsal sinus
 Sinusitis – infection of the paranasal sinuses

10. The ocular Appendages
 The eye brow
 lie at the junction of forehead
and upper eyelid
 the hairs are thick and directed
horizontally laterally
 several musles of facial
expressionare inserted into
the skin , permitting movement
of eye brows.
 contraction of the frontalis
musle  raising of eyebrow
 contraction of orbital part of
orbitalis m lowering

11. The eyelids
 The eyelids protect the eye from injury and excessive light by their
closure.
 They also assist in distribution of tears over the anterior surface of
the eye ball
 The palpebral fissure ,the elliptical opening b/n eyelids, is the
entrance into conjunctival sac
 When closed the upper eyelids completely covers cornea
 When open & looking striaght ahead,upper lid just covers upper
margin of cornea & lower lid lies just below cornea
 Eyelashes are short,curved hairs,present on margins of eyelids.
upper lids: curve upward
lower lids: curve downward

12. The eyelids
 Structure of Eyelids
 From superficial to deep each
eyelids have:
1.skin
2.subcutaneous tissue
3.straited musle fibers of
orbicularis oculi
4.orbital septum & tarsal plate
5.smooth musles
6.conjunctiva
upper eyelid also receives
insertion of levator palpebrae
superioris musle

13. The eyelids
 Tarsal plate
- fibrous tissue which keeps
eyellids rigid, &contains
meibomian glands which secretes
lipid layer of tear film
 Orbicularis muscle
- supplied by CN VII (facial nerve)
- when contracted closes the eyelids
- important for tear drainage into lacrimal
apparatus
 Levator muscle
- attached to tarsal plate of upper eyelid
- supplied by CN III ( oculomotor )
- Opens the eyelids
 Muller’s musle –inervated by
sympathetic nerve
- raises upper lids

14. The conjunctiva
 Thin mucous membrane that lines eyelids and eye balls
 3 parts of conjunctiva:
1. Palpebral conjunctiva firmly attached to tarsal plate
2. Bulbar Conjunctiva
lies in contact & loosely attached to eyeball
3. Conjunctival fornix
 The junction b/n tarsal and bulbar conjunctiva
Limbus the line along which fusion of conjunctiva to
cornea occurs

15. The conjunctiva
 The main function of conjunctiva is to protect cornea
 Supplies some of its oxygen and metabolic needs
 Lubricates cornea with tears
 Protect s exposed part of the eye from infection
 Conjunctival secretion contains lysozme,antibody
and lymphocytes

16. Lacrimal Apparatus

17. Lacrimal Apparatus
 Main lacrimal gland
produce aqueous
 Accessory lacrimal glands of
krause & Wolfring 10% of
total lacrimal secretory mass
 Lacrimal excretory system
- upper & lower punctum
- canaliculi common
canaliculus ( 90%)
- Lacrimal sac
- Nasolacrimal duct

18. Lacrimal Apparatus,cont’d
 Tear film
 3 layers of tear film on the cornea:
1.Lipid layer  secreted by meibomian glands &
glands of Zeis
2. Aqueous layer
 secreted by main lacrimal gland &
accessory lacrimal glands of Krause and wolfring
3.mucin layer
 coats corneal epithelium and secreted by Goblet
cell of conjunctiva

19. Functions of tear film
 Contribute to optical property of tear film
 Supplying oxygen to avascular corneal
epithelium
 Providing an antibacterial and antiviral defense
 Retard evaporation
 Washing away debris
 Moistens eyeball and lubrication of eyelids
 Traps exfoliated surface cells,foreign particles
and bacteria

20. THE EYE BALL
The normal adult AP diameter of the globe is b/n 21 &
26mm (average=24mm)
 Consists of 3 layers of
tissues:
1. Outer ( protective) layer :
cornea, sclera
2. Middle vascular layer :
iris, ciliary body, choroid
3. Inner (light sensitive)
layer: Retina

21. Cornea
 Transparent and avascular
layer
 Important refractive power of
the eye(4/5)
 Has 5 histologic layers:
1.Surface epithelium
2.Bowman’s layer
3.Stroma
4.Desmet’s membrane
5.Endothelium
 Has high sensory innervation
from CN V.

22. Sclera
 Covers the posterior 4/5th of surface of the globe with
anterior opening for cornea & posterior opening for optic
nerve
 Opaque and thick layer made up of collagen fibres
 Sclera is thinnest (0.3mm) at the insertion of rectus
musles and thickest ( 1.0mm) at the posterior pole

23. Uveal Tract

24. Uveal Tract
 This middle layer is called the uvea( which means grape in Latin), &
consists of 3 parts: iris, CB , and choriod.
 The main vascular compartment of the eye.
 All three parts contain many pigment cells which absorb the light .
The iris
 Consists of smooth muscles,pigmented epith.cells,blood vessels &
connective tissue.
 Sphincter musle of iris is arranged circularly,supplied by
parasympathetic n. of CN III ( oculomotor) ,& constricts pupil.
 Dilator m. arranged radially,supplied by sympathetic n.,
& dilates the pupils.

25. Uveal Tract
The ciliary body
 Consists of ciliary epithelium and ciliary musle
 2 parts: pars plana & pars plicata
 Suspensory ligament pass from ciliary process to the
equator of the lens
 Function:
- Aqueous humor formation ( by ciliary epithelium)
- Lens accommodation ( by ciliary musle )

26. Uveal Tract
The choroid
 Consists mainly of blood vessels and pigment cells
 Functions:
- The choroidal circulation supplies 2/3rd of O2 needs
of retina ( nourishes outer portion of retina )
- The pigment cells absorb light inside the eye & so
prevent unwanted reflections.

27. The inner layer of the Globe - Retina

28. The inner layer of the Globe
The Retina
 Light sensitive membrane at
the back of the eye.
 The cells of the retina are
specialized & have a very
complex arrangement.
 Cell connections from outer to
in side of retina:
RPE Rod & cones
Bipolar cells Ganglion
cells axons of GC forming
opic nerve

29. Retina

30. The 10 histologic layers of retina

31. Retina
 Photoreceptor cells (
rods & cones )
 The rods are very sensitive in
dim light & found in the
periphery of the retina
 The cones are more sensitive
in bright light , & found towards
the center.
 The very center of retina is
called macula( consists of
closely packed cone cells )

32. Retina

33. The Lens
 The lens is a biconvex structure located behind posterior
chamber and pupil
 Attached to fibers of suspensary ligaments
 Provides 1/5th of refractive( focusing ) power of the eye
 4/5th by cornea
 Parts: - capsule
- epithelium
- cortex
- nucleus

34. Chambers of the eye
 Anterior chamber

35. The vitreous humor
 The vitreous cavity occupies 4/5th of the volume of the
globe.
 Its volume is close to 4 ml.
 Contains innert ,transparent jel-like structure:
- 99% water
- hyaluronic acid
- fine collagen fibrils
- hyalocytes
 Function: maintains the shape of the globe of the eye

36. The visual pathway
 The visual pathway connects the optic n. with part of
brain concerned with vision ( occipital part of cerebral
cortex – visual cortex )
 Components of visual pw:
Retinaoptic nerve  optic chiasm 
optic tract lateral geniculate body  optic
radiation  visual cortex

37. The visual pathway
 Optic nerve  1.2 million nerve fibers
 When both optic nerves meet at chiasm, all the fibers
from nasal part of each retina cross over to the opposite
site and fibers from the temporal side pass through
chiasm to the same side without crossing.
 Every thing in the left half of the field of vision in each
eye is seen on the right side of each retina and by the
right side of brain and viceversa.
 A few fibers in the optic nerve regulate the pupil size.

38. Pupillary light reflex pathway
 Light stimulates
RetinaON optic
chiasm(fibers from nasal side of
retina cross to opposite side of
brain)  optic tract 
Pretectal nucleus 
Edinger-westphal
nucleus(some fibers cross to
opposite side )
 parasympathetic fibers to
CN III  ciliary genglion 
short ciliary nerves supply
pupillary sphnicter musle

40. Extraocular musles
 There are six EOMs which control eye movement.
 They form a cone which passes backwards from the eye
to the apex of the orbit. Nerve supply
 4 rectus musles: - superior rectus …… CN III
- Inferior rectus …… CN III
- Lateral rectus …….. CN VI
- Medial rectus …….. CN III
 2 oblique Ms : - Inferior oblique …….. CN III
- Superior oblique …….. CN IV

41. Extraocular musles
 Origin
The 4 rectus musles and superior oblique musle originate from apex of the orbit.
The inferior oblique m. originate from the periosteum of the maxillary bone behind
lacrimal fossa
 Insertions
 MR : 5.5 mm from medial limbus
 LR : 6.9mm from lateral limbus
 SR : 7.7mm from superior limbus
 IR : 6.5 mm from inferior limbus
 SO : posterior to equator in superotemporal quadrant
 IO : macular area (temporally )

43. Anterior view

44. Eye movements( ocular motility)
 Monocular eye movements (Ductions )
1. Adduction  eye moves nasally
2. Abduction  ‘’ ‘’ temporally
3.Elevation  ‘’ ‘’ upward
4.Depression ‘’ ‘’ downward
5.Intorsion  nasal rotation of superior portion of
vertical corneal meridian
6. Extorsion  temporal rotation of superior portion of
vertical corneal meridian

45. Ductions

46. Binocular eye movements
 Versions-when binocular eye mov’ts are conjugate and the eyes move in
the same direction
 When the eye movements are disconjugate and eyes move in the opposite
directions , such mov’ts are known as vergences ( e.g. convergence &
divergence )
 Versions:
1.Right gaze ( dextroversion )
2.Left gaze ( levoversion )
3.Elevation or up gaze( sursumversion)
4.Depression or down gaze ( deorsumversion)
5.Dextrocycloversion both eyes rotate so that superior portion of vertical
corneal meridian moves to patients right.
6.Levocycloversion  mov’t of both eyes so that superior corneal meridian
rotates to patients left.

47. Versions

48. vergences

49. Actions of EOMs
Defn.:
 Primary position of gaze is when the eye is directed straight ahead
and head is also straight.
 The primary action of a musle is its major effect on the position of
the eye when the musle contracts while the eye is in primary
position.
 The secondary and tertiary actions of a musle are the additional
effects on position of the eye in primary position.

50. Actions of EOMs
EOM Primary action Secondary action Tertiary action
LR Abduction None None
MR Adduction None None
SR Elevation Incyclotorsion Adduction
IR Depression Excyclotorsion Adduction
SO Incyclotorsion Depression Abduction
IO Excyclotorsion Elevation Abduction

51. Summary of Actions of EOMs
 The horizontal muscles(LR & MR) have only primary
actions( abduction or adduction)
 The vertical muscles(SR & IR) adduction
 The oblique muscles(SO & IO) abduction
 The superior muscles(SR & SO) incyclotorsion
 The inferior muscles(IR & IO)excyclotorsion

52. Blood and nerve supply of the eye
 Blood supply
 Arterial supply
 From anastomosing vessels from internal and external
carotid arteries
 venous drainage
 From anterior and posterior uveavortex v.orbital
vcavernous sinus
 Lymphatic drainage
 No lymphatic vessels in the globe
 From medial eye lidssubmandibular LN
 Lateral side lidspreauricular LN

53.  Innervation
 Motor
 CN IIIMR,SR,IR,IO
 CN IV SO
 CN VI LR
 CN VII orbicularis oculi
 Sensory
 CN V
 CN II
 Autonomic
 Sympatheticmuller m. and dilator pupilae
 Parasympathetic ciliary m and sphincter pupilae

54. Thank you!