Anatomy of the Eye Organ of sight • Well protected in the bony orbit • 2.5cm in diameter • Works similar to a camera which produces images pdf

eye anatomy

1. ANATOMY OF THE EYE
DR. AKHILA WIMALASUNDERA
DEPARTMENT OF ANATOMY

2. LEARNING OUTCOMES
•At the end of this lecture you will be able to………..
•Describe the anatomical structures of the eye including; Coats of the eyeball,
Sclera & Cornea, Uveal tract, Lens, Retina / Fundus
•Describe the visual pathway
•Describe the aqeuosdrainage pathway
•Recall on anatomy of orbit and describe extraocular muscles –on moodle

3. INTRODUCTION
•Organ of sight
•Well protected in the bony orbit
•2.5cm in diameter
•Works similar to a camera which produces images

4. Introduction
•The Eye ball
•Ocular Adenexae
•Eye lid
•Lacrimal apparatus
•Exeternal ocular muscles
•Optic Nerve
•Orbit

5. EYE BALL
Wall of eye ball
Refractive media and Lens
-Inside is balck to prevent internal light reflections
-Vitreous body
-Anterior and posterior chamber

7. Wall of the eye ball
Made up of three coats
1.Outer fibrous coat or Tunica fibrosa
2.Middle Vascular coat or Tunica Vasculosa
3.Inner Nervous coat or Tunica Nervosa

8. Outer Fibrous Coat
Two spheres with different radii
Part of smaller more curved sphere -Cornea
Part of larger less curved sphere -Sclera

9. Sclera
93% of the outer coat of the eye
Whitish and Opaque can be regarded as a cup like expansion of dura.
Dense collagen fibersinterspersed with elastic fibers
Anteriorly -continuous with Cornea at corneoscleraljunction
Scleral dimensions -individual variations, thicker at posterior pole.
Thinner at coronal equator.

10. Sclera
A loose fibrovascular tissue invests the outer surface of sclera -Episcleral lamina
Anteriorly invested by the Conjunctiva -reflects on to it from posterior surface of the
eyelids
Pierced by
Optic nerve -sieve like appearance -lamina cribrosa
Anterior cillilary arteries
Vortex veins -cross sclera equatorially
Long and short cilliary nerves and arteries

11. Conjunctiva
•transparent mucous membrane that lines both the inner surface of
theeyelidsand the anterior surface of theeyeball
•Bulbar conjunctiva
•Palpebral conjunctiva
•Conjunctival fronixand conjunctival sac

12. Cornea
Window of the eye -7% ocular surface.
Light rays pass through cornea to enter the eye
Continous with the sclera -corneoscleral junction (limbus)
Its laminae of fibrous tissue are transparent.
Completely avascular and no lymph vessels-success in corneal
transplant

14. Cornea -Microscopy
Corneal epithelium-continuous with conjunctival epithelium at limbus
Stratified squamous type, about 5 cell layers
Separated by corneal stroma by Anterior limiting layer
Corneal stroma consists of 200 lamellae of collagen fibrils
Inner surface of stroma lies against the Posterior limiting layer
Corneal endothelial layer

16. Cornea -innervation
The cornea is supplied by Short and Long cilliary nerves
Corneal nerves provide the afferent arm of corneal reflex and
lacrimation reflexes
It also have a neurotrophic function.

17. Vascular coat
Intermediate coat of the eye
Frequently known as Uveal tract
Consists of Choroid, Ciliary body, Iris

19. Choroid
Can be regarded as the extension of Arachnoid and Pia mater.
Thin pigmented layer lining the inner surface of the sclera
Five-sixth of the eye posteriorly
Anteriorly -merges with Ciliary body
Pierced by the Optic N.
External surface loose connected to sclera by Suprachoroid layer
Internally -attached to Retinal

21. Choroid
At the optic disc -continuous with Pia -Arachnoid tissue around the Optic
nerve.
Four layers
Suprachoroid layer
Vessel layer (stroma)
Choriocapillaries
Lamina Vitrea

22. Choroid
Vessel layer -
Composed mainly of arteries and veins
Scattered pigment cells\melanocytes
Short posterior ciliary arteries
Veins -four to five large vortex veins, which pass through sclera

23. Ciliary body
Continuous posteriorly -Choroid body
Anteriorly-Iris
A flat ring applied to the inner surface of the sclera.
Triangular in section
Periphery of the iris is attached halfway along the short anterior base of the
triangle
Ciliary muscle -scleral surface of ciliary body
Vitreous surface -Ciliary processes -reciproca grooves on ant.surface of
vitreous body

25. Ciliary muscle
Smooth muscle
Focus lens for near vision
Outermost -Longitudinal
Innermost-Circular -near periphery of the lens
Between the two are radial fibers
Contraction --relaxation of suspensory fibers----increased curvature of lens
N. supply -Oculomotor N. ---edinger westphal nucleus---ciliary g.----short cil.N

26. Iris
Attached at its periphery to the middle of the anterior surface of the
ciliary body.
Pushed slightly forward in the form of a low cone.
In contact with the anterior surface of the lens.
Iris is perforated centrally by the pupil.
Pigmneted cells with melanin granules

28. Sphincter pupillae and Dilator Pupillae muscles
Sphincter Pupillae :
Circular band of smooth muscle
In stroma of iris at margin of the pupil
Edinger-westphal part of Oculomotor N.
Dilator Pupillae :
Radial fibers of smooth muscle
Cervical sympathetic br.

29. Nervous Coat
Consists of the Retina
Retina
Contains light receptive cells. (Rods and Cones)
Outer-attached to the choroid
Inner -vitreous body
Anterior limit -Ora serrata

31. Retina
At the entrance of Optic N---circular pale area ----Optic disc
Macula Lutea-------shallow depression, devoid of bloodvessels and no
rods in post.pole of the eye.
Foevea centralis ----shallow pit in the Macula lutea
High concentrations of cones----------area of most acute vision

32. Microscopy of Retina
10 retinal layers
Outer layer -single layer of pigmented epithelial cells
Firmly attached to the choroid
Photo sensitive cell layer
Nervous cell layers

33. Microscopy of Retina

34. Microscopy of
retina

35. Refracting Media
Aqueous Humor
Lens
Vitreous humor

36. Aqueous humor
Is a clear fluid that lies between the back of the cornea and the front of
the lens.
Anterior and Posterior chambers
Produced by ciliary processes---------posterior chamber

37. Aqueous drainage pathway
Flows to anterior chamber
Iridocorneal angle
Canal of schelmm -trabecular tissue

38. Aqueous drainage pathway

39. Aqueous drainage pathway

40. Lens and suspensory ligament
Transparent biconves body enclosed in a transparent elastic capsule
10mm in diameter and 4mm thick
Posterior surface highly convex than anterior
Anterior surface in contact with aqueous humour,pupillary margin of iris.
Lens capsule-elastic membrane
Capsular epithelium-lies anteriorly

41. Lens and Suspensory ligaments
Suspensory ligaments of the lens -Zonule
Attached to the ciliary processes and some to ciliary body
Anteriorly to the front of the lens in its periphery
In rest -tensioned -lens flattened

44. Vitreous body
Colorless, jelly like mass
Occupies the posterior four-fifths of the eyeball
99% of water and a sparse cellular and fibrous content
Hyaloid canal-remnant of embryonic hyaloid artery

45. Blood supply
Ophthalmic artery
Central artery ---Optic Nerve and retina---end artery
Posterior ciliary arteries -choroid coat of the eye
Choroidal capillaries supply the outer part of retina
Venous drainage-Superior ophthalmic and Inferior Ophthalmic vein.
No lymphatics of the eyeball

46. Ocular Adenexae

47. Eye lids and Conjunctiva
•Protects the eye.
•Distribution of tear film over the eye
•Loose skin anteriorly and adherent conjunctiva posteriorly
•Meet at lateral and medial angles-(Canthi)
•Superior and Inferior tarsal plates

48. Tarsal plates

49. •Meibomian/tarsal glands-
modified sebaceous
glands embedded in the
tarsal plates. oily
secretion to eyelid margin
•Ciliary glands-modified
sweat glands opens on
eye lid margin, between
follicles.

50. Medial and lateral palpebral ligament

51. Lacrimal apparatus

52. Lacrimal gland
Serous gland
Large orbital and small palpebral part
Orbital part ---lacrimal fossa
Palpebral part ---superior fronix of conjunctiva
Nerve supply-Scretomotor-superior salivary nucleus-pterygopalatine
ganglion ---zygomatic N.

53. Visual pathway

54. Visual pathway

56. Thank you
Please send in your questions to [email protected]