Eye

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Eye

• Tanvaa Tansatit
• Anatomy, Medicine, Chulalongkorn

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Orbit

• pyramidal, bony cavity in facial skeleton
• Contains eyeball, muscles, nerve ,vessels, fat,
  lacrimal apparatus
• Lined with periorbita which forms fascial sheath
  of eyeball
• Periorbita continues with dura and periosteal of
  skull

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Orbit
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Orbit

• Four walls and apex
• Superior wall orbital part of frontal bone,
  lesser wing of sphenoid
• Fossa for lacrimal gland
• Medial wall Ethmoid, frontal, lacrimal, sphenoid
  bones
• Lacrimal fossa for lacrimal sac

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Orbit

• Four walls and apex
• Inferior wall maxilla, zygomatic, palatine bones
• Inferior orbital fissure
• Lateral wall Frontal process of zygomatic bone,
  greater wing of sphenoid
• Apex Optic canal in lesser wing of sphenoid,
  superior orbital fissure

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Orbit
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Eyelid

• Covered externally by skin and internally by
  palpebral conjunctiva
• Balbar conjunctiva adheres to cornea
• Lines of reflection onto eyeball form
  conjunctival fornices
• Tarsal plate are dense bands of connective tissue
  form skeleton
• Orbicularis oculi are superficial to tarsal plates

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Eyelid

• Tarsal glands secrete lipid secretion embedded in
  tarsal plates
• Eyelashes are in margin of lids
• Ciliary glands are large sebaceous gland
  associated with eyelashes
• Medial and lateral palpebral ligaments connect
  tarsal plates with orbital margins
• Orbital septum spans from tarsal plate to orbital
  margins

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Orbicularis oculi
Levator palpebrae
Tarsal plate
Balbar conjunctiva
Eyelashes
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Lacrimal apparatus

• 2-cm almond-shaped lacrimal glands secrete
  lacrimal fluid
• Lacrimal ducts from glands
• Lacrimal canaliculi opening at lacrimal punctum
  on lacrimal papilla conveys lacrimal fluid to
  lacrimal sac
• Nasolacrimal duct opening to inferior nasal
  meatus in nasal cavity

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Lacrimal apparatus
Lacrimal gland
Lacrimal canaliculi
Lacrimal sac
Eyeball
Nasolacrimal duct to inferior nasal meatus
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Three layers of Eyeball

• Outer fibrous layer opaque sclera and
  transparent cornea
• Middle vascular layer Dark brown choroid
  terminates in ciliary body
• Ciliary body is muscular and vascular
• Ciliary processes secretes aqueous humor
• Iris is contractile diaphragm with pupil aperture

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Three layers of Eyeball

• Inner layer retina has a light-receptive neural
  and pigment cell layers
• Optic disc or blind spot where optic nerve
  enters eyeball
• Macula lutea with photoreceptor cones
• 1.5-mm fovea centralis free of capillary network
• Ora cerrata marks termination of light-receptive
  retina
• Central retinal artery and veins supply neural
  layer except for cones and rods cells which
  receive nutrients from choriocapillary layer

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Cornea
Anterior chamber
Ciliary body
Sclera
Choroid
Retina
Macula lutea
Optic disc
Extra ocular muscle
Optic nerve
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Refractive media

• Cornea is transparent, avascular, and sensitive
  to touch
• Aqueous humor in anterior and posterior chambers
  drains into scleral venous sinus or canal of
  Schlemm at iridocorneal angle
• Lens enclosed in a capsule anchored by suspensory
  ligament to ciliary body
• Watery vitreous humor in jellylike meshes of
  vitreous body

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Cornea
Anterior chamber
Ciliary body and iris
Lens
Vitreous body in posterior chamber
Sclera
Retina
Macula lutea
Optic disc
Optic nerve
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Muscles

• Levator palpebrae superioris attach to superior
  tarsal plate
• Four recti arise from common tendinous ring
  surrounds optic canal, attach to sclera on
  anterior half of eyeball
• Superior and inferior recti do not parallel to
  axis of eyeball
• Vertical movements of eyeball requires
  synergistic work of rectus and oblique muscles
• CNIV supplies superior obloque
• CNVI supplies lateral rectus
• CNIII supplies all others

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Muscles
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Fascial sheath of eyeball

• Bulbar fascia or Tenons capsule envelops eyeball
  and extraocular muscles
• Check ligaments from medial and lateral rectus
  muscles attach lacrimal and zygomatic bones
• Suspensory ligament forms hammocklike sling from
  check ligaments to fascia of inferior rectus and
  inferior oblique muscles

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Innervation

• Branches of ophthalmic nerve passes through
  superior orbital fissure
• Lacrimal nerve passes to lacrimal gland providing
  secretomotor from zygomatic nerve
• Frontal nerve divides into supraorbital and
  supratrochlear nerves supply forehead
• Nasociliary nerve supplies eyeball
• Infratrochlear nerve from nasociliary nerve
  supplies nose and lacrimal sac
• Ethmoidal nerves from nasociliary nerve supplies
  sphenoid and ethmoidal sinuses

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Innervation
Inferior division Oculomotor n.
Short ciliary n.
Long ciliary n.
Ciliary ganglion
Nasociliary n.
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Innervation

• Short ciliary nerves from ciliary ganglion carry
  sym/parasym fibers to ciliary body
• Nasociliary nerve supplies ciliary ganglion
  between optic nerve and lateral rectus
• Long ciliary nerves from nasociliary nerve
  transmit sym to dilator pupillae and sensory
  fibers from cornea

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Vasculature

• Ophthalmic artery is main blood supply
• Central retinal artery pierces optic nerve and
  run within to optic disc
• Choriocapillary layer of posterior ciliary
  arteries supply choroid and outer retina
• Long posterior ciliary arteries pass under sclera
  to anastomose withanterior ciliary arteries
• Infraorbital artery supply inferior part of orbit

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Vasculature
Anterior ciliary a.
Short ciliary a.
Central retinal a.
Lacrimal a.
Long ciliary a.
Ophthalmic a.
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Vasculature

• Superior and inferior ophthalmic veins pass
  through superior orbital fissure enter cavernous
  sinus
• Central retinal vein enter cavernous sinus or
  ophthalmic veins
• Vorticose veins from choriod drain into inferior
  ophthalmic veins
• Scleral venous sinus encircling anterior chamber
  drains aqueous humor