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Blood supply of the eye
Dr. Amer A. Shamsulddin
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Arterial blood supply:
• Internal carotid artery:
• External carotid artery:
Note:
(eyelids and conjunctiva from both internal and external carotid arteries)
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Internal carotid artery:
• First intracranial branch of the internal carotid justas the artery exits from the cavernous sinus
• optic foramen below and lateral to the optic nerve
• Pass over the optic nerve to its medial side
• Between the MR and SO
• Terminates by dividing into dorsonasal andsupratrochlear
Ophthalmic artery:
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Branches of ophthalmic artery:• Central retinal a.
• Supra-orbital artery
• Posterior ciliary artery– Long posterior ciliary a. (2 arteries)
– Short post. Ciliary a. (10-20 arteries)
• Muscular arteries – Anterior ciliary a. (7 arteries)
• Lacrimal artery (terminate into zygomatic branches)
• Ant. And post. Ethmoidal arteries
• Superior and inferior palpebral arteries
• Dorsonasal artery
• Supratrochlear artery
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Central retinal artery
• pierces the dural sheath of the opticn. 12 mm behind the globe
• It gives off small meningeal branchesto supply the pial sheath of the opticnerve.
• It’s functionally as end artery.
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1. ophthalmic artery.2. central retinal artery3. ciliary arteries (on each side of the
optic nerve). These vessels divideinto 2 long posterior ciliaryarteries(#4 in Figure) and ~20 shortposterior ciliary arteries (#5 inFigure) that enter the eyeimmediately adjacent and around theoptic nerve . The short posteriorciliary arteries directly supply thechoroid and the long posterior ciliaryarteries travel in the suprachoroidalspace anteriorly (#6 in Figure) thensupply the choroid anteriorly viarecurrent branches.
posterior (#7 in Figure) and anterior (#8in Figure) ethmoidal vessels.
The superior oblique muscle is shown fororientation ( #9 in Figure).
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Ciliary arteries• Long post, short post. And ant. ciliary aa. are the major blood supply to the
globe
• Long post. Ciliary aa:
– Paired arteries that pierce the sclera outside the circle of Zinn snd
– travel forward in the suprachoroidal space to the ciliary body,
– Gives recurrent branches that supply the choroid anterior to the equator and anastomose with short post ciliary aa.
• Short post. Ciliary aa:
– 10- 20 branches pierces the sclera around the optic n
– This anastomotic circle of Zinn supplies the optic n. head (optic disc)
– Supplies the choroid to the equator
• Ant. Ciliary aa:
– 7 arteries 2 for each rectus m. exept LR m. only 1
– Supply the sclera and conjunctiva and the iris
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External carotid artery:
• External maxillary artery (facial artery)
– Angular artery
• Superficial temporal artery
• Internal maxillary artery
– Middle meningeal artery
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Blood supply of the eyelids• The main arterial blood
supply:– Lat. Palpebral a. (from
lacrimal artery)– med. Palpebral a. ( from
ophthalmic artery)
• These palpebral aa. (frominternal carotid a.)anastamose with facial artery(external carotid) and itsbranch (zygomatico-temporal a.and angular a.) at the lat.aspect of the lid and form theMarginal and peripheralpalpebral arcades
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Venous drainage:
• Medially: to ophthalmic and angular vv.
• Latrally: to superficial temporal v.
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Lymph drainage
• Lat. 2/3 of upper and lower lidssuperficail parotid nodes (pre-auricular nn.)
• Medial submandibularnodes
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Nerve supply:
• Lower lid:– infra-orbital (from V2)
– Med. Aspect infra-trochlear n. (V1)
• Upper lid: – Supra-orbital n.
– Supra-trochlear n.
– Lacrimal n. (v1)
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Blood supply to the conjunctiva
• Palpebral conjunctivamarginal and peripheral arcades (from med. And lat. Palpebral aa.)
• Limbal conjunctiva ant. ciliary art.
• Venous drainage:The conj. veins sup. and inf. ophthalmic vv.
• Nerve supply: Bulbar conj. long ciliary nn. (nasocialiary of ophth. n.)
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Blood supply of the ACLong post. ciliary aa. anastomose with ant. ciliary aa.
– Major arterial arcade (ciliary stroma)
– Minor arterial arcade (At the collarete of the iris)
• They are the major blood supply to the iris and ciliary body
• Iridial vessels are non-fenestrated (endothilial tight junctions)
• Vessels in the ciliary body are fenestrated and no tight junctions
• Blood-aqueous barrier tight junctions in the ciliary epithelium
• Venous drainage: follow the aa. minor venous circle directly into the vortex veins (not into the corresponding major circle)
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retinal blood supply:
• The outer plexiform layer isthe watershed region
• Outer to this layer(neuroreceptors and RPE) choroidal circulation bydiffusion
• Inner 2/3 central retinala. directly
• Retinal aa. run in the nervefiber layer with 4 branchesfor each quadrant
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• Retinal capillaries are concentrated in the maculabut are absent from the fovea centralis (FAZ)
• In 20% of people there’s cilioretinal a. (from post.
ciliary a.) supplies the macula
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Blood retinal barrier• Inner BRB:
– Tight junctions between the endothelial cells or retinal blood vessels
• Outer BRB:
– Tight junctions between
RPE cells
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Blood supply to the visual pathway
• Intra-ocular optic n. short post. ciliary aa. That form the circle of Zinn.
• The central retinal a. pierces the dural sheaths of the orbital optic n. but doest supply it, it’s supplied by pial plexus of vessels
• Intracraneal optic n. is supplied by the superior hypophyseal and ophthalmic aa.
• A rise in the ICP may compromise blood flow to these vessels papilloedema
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• Optic tracts pial arteries (from ant.Choroidal and post. Communicating aa)
• Lat. Geniculate body and post. aspect ofoptic radiations the middle cerebral a. withthe post. Cerebral a.
• Visual cortex:
– Most of its blood supply post. Cerebral a.
– Occipital pole (macular area)Middle cerebral a.(causing macular sparing in some of occipital lobestrokes)
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Venous drainage of the eye
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• There 4 vortex veins
(2 on each side)
exit the eyeball
post. to the equator.
• Sup. Vortex vv. and central retinal v. Superiorophthalmic v. (which is from supra-orbital and facial vv.)
• Inferior vortex vv. Inf. Ophthalmic v. which:
– may drain to the sup. Ophthalmic v or directly tocavernous sinus
– communicates with the pterygoid venous plexus (andbecause of the reason the inf. From this plexus may reachcavernous sinus cavernous sinus thrombosis)
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Cavernous sinus• Extends from the sup. orbital fissure ant.ly to
the apex of petrous bone (temporal bone)
• Floor dural coverings of greater wing of sphenoid
• Med body of sphenoid and pitiutary fossa
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• Internal carotid a. grooving the medial wall of the sinus then pierces its roof.
• The abducent nerve (VI) travels within it
(first nerve to damage by cavernous
sinus thrombosis)
• Its lat. Wall encloses III, IV, V1 & V2 nerves.
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