The document summarizes key aspects of eye anatomy in 3 layers: 1) The outer coat includes the cornea and sclera. 2) The middle coat contains the choroid, ciliary body, iris, and lens. It nourishes the retina and controls eye focusing. 3) The inner coat is the retina. It also briefly describes the orbit, lacrimal system, eyelids, and extraocular muscles.

1. Eye Anatomy
Ahmed Osama Hashem
Fellow Royal College ophth
PhD,MD ,Lecturer,consultant of ophthalmology

2. Eye consists of 3 coats (Layers).
1- Outer coat.
2- Middle coat.
3- Inner coat.

3. 1- Outer coat
• The outer coat which is :
-Transparent anteriorly, is called the cornea.
-The white ,opaque and posterior coat is the sclera.

6. 2- Middle coat
• A rich middle ,vascular coat (the choroid-Uveal tissue) lines the posterior
segment of the eye and nourishes the retina at its inner surface.
-The ciliary body lies anteriorly. It contains the smooth ciliary muscle whose
contraction alters lens shape and enables the focus of the eye to be changed.
- ciliary epithelium secretes aqueous humour and maintains the ocular
pressure. The ciliary body provides attachment for the iris. (pupillary
diaphragm)
- Inflammation in this layer is called uveitis.
•The lens lies behind the iris and is supported by fine fibrils (the zonule)
running between the lens and the ciliary body.

7. Between middle and outer layer
• The angle formed by the iris and cornea (the iridocorneal angle) is
lined by a meshwork of cells and collagen beams (the trabecular
meshwork).
• In the sclera outside this, Schlemm’s canal conducts the aqueous
humour from the anterior chamber into the venous system,
permitting aqueous drainage. This region is termed the drainage
angle.

9. • Between the cornea anteriorly and the lens and iris posteriorly lies
the anterior chamber. Between the iris, the lens and the ciliary body
lies the posterior chamber (which is distinct from the vitreous body).
Both these chambers are filled with aqueous humour. Between the
lens and the retina lies the vitreous body.

11. 3-Inner Coat = Retina

18. Orbit
• The eye lies within the bony orbit
• a four-sided pyramid.
• At its posterior apex is the optic canal which transmits the optic nerve
to the brain.
• The superior and inferior orbital fissures allow the passage of blood
vessels and cranial nerves which supply orbital structures.
• On the anterior medial wall lies a fossa for the lacrimal sac. The
lacrimal gland lies anteriorly in the superolateral aspect of the orbit

19. Skull

20. Orbit

21. Orbit anatomy
• Resemble a pear whose stalk is the optic canal,,,,

22. 4 walls ---- 7 bones

23. Superior orbital wall,,,Roof
Roof:
Lesser wing of sphenoid ,
frontal
Defect
Pulsatile proptosis
Lacrimal gland fossa
laterally
Trochlea medially

24. Lateral orbital wall,,
Lateral wall 2 bones
1-greater wing of sphenoid
2-zygomatic
Only orbital wall not
related to paranasal
sinus
Anterior globe vulnerable
to lateral trauma because
the wall only protect the
posterior

25. Medial orbital wall,,
4 bones:
1-maxillary
2-lacrimal
3-ethmoid
4-sphenoid
Related to sphenoid
and ethmoid sinus
Lamina papyracea ,covers
the medial wall,very thin
For this reason: commonest
cause for orbital cellulitis is
ethmoidal sinusitis,,

26. Inferior orbital wall,,,Floor
3 bones
1-zygoma
2-maxillary
3-palatine
Posteromedial portion is
relatively weak
= blow out fracture
floor=roof of maxillary sinus
Maxillary carcinoma invading
Orbit may displace the globe
upwards,,,,

27. Lacrimal System.

28. Lacrimal System.
• Tears drain into the upper and lower puncta and then into the
lacrimal sac via the upper and lower canaliculi. They form a common
canaliculus before entering the lacrimal sac. The nasolacrimal duct
passes from the sac to the nose.
• Failure of the distal part of the nasolacrimal duct to fully canalize at
birth is the usual cause of a watering, sticky eye in a baby. Tear
drainage is an active process. Each blink of the lids helps to pump
tears through the system.

29. Eye lid

30. Eye lid function.
• provides mechanical protection to the anterior globe.
•secretes the oily part of the tear film.
•spreads the tear film over the conjunctiva and cornea.
•prevents drying of the eyes.
•contains the puncta through which the tears drain into the lacrimal
drainage system.

32. Eye lid Anatomy
1-A surface layer of skin.
2-The orbicularis muscle.
3-A tough collagenous layer (the tarsal plate) Contain Mebomian’s
glands.
4-An epithelial lining, the conjunctiva, reflected onto the globe.

33. Eye lid opening
• A flat smooth muscle arising from the deep surface of the levator
inserts into the tarsal plate. It is innervated by the sympathetic
nervous system.
• The levator muscle passes forwards to the upper lid and inserts into
the tarsal plate. It is innervated by the third nerve. Damage to the
nerve or changes in old age result in drooping of the eyelid (ptosis).

34. Horner syndrome
: Sympathetic chain
damage.
Third nerve palsy

35. Extraocular muscle

36. Thank you