The key arteries supplying the visual pathway include the internal carotid artery, posterior cerebral artery, anterior cerebral artery, ophthalmic artery, and posterior ciliary arteries. The central retinal artery supplies the retina. The optic nerve receives blood supply from the posterior ciliary arteries and branches of the ophthalmic artery. The optic chiasm, tract, lateral geniculate body, and visual cortex are supplied by branches of the internal carotid, anterior cerebral, and posterior cerebral arteries. Venous drainage is primarily through the central retinal vein, ophthalmic veins, basal veins and internal cerebral veins.
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BLOOD SUPPLY OF VISUAL PATHWAY
1. D R . P R A T E E K V I S H W A K A R M A
D N B O P H T H A L M O L O G Y
BLOOD SUPPLY OF VISUAL
PATHWAY
2. Introduction
Arteries of Brain :
Circle of willis
Circle of willis :
Lies in interpeduncular fossa
at the base of brain.
Encircles the pituitary stalk
provides important
communications between the
blood supply of the forebrain
and hindbrain
3. Formed by:
Anterior communicating art
Ant cerebral art
Post communicating art
Post cerebral art
Basilar art
Basically a free anastomosis
bertween 2 ICA and 2 VA
4. Vertebral Artery
Enter post cranial fossa
through foramen magnum
Ascends upward, forward
and medially on
medulla oblongata
unite at lower border
of pons to form
BASILAR Artery.
5. Br. Of Cranial part of Vertebral artery:
1. Meningeal br
2. Post spinal art
3. Ant Spinal art
4. Post inferior cerebellar
art
5. Medullary art
6. Basilar Artery
Ascends in groove on anterior surface of pons and at
upper border divides into two PCA.
Br. Of Basilar art:
1. Ant Inf cerebellar art
2. Sup cerebellar art
3. Labyrinthine art
4. Pontine art
5. Posterior Cerebral Art:
7. Posterior Cerebral Art
1.visual cortex
2.posteromedial aspect of LGB
3.post region of optic radiation
Calcarine artery: whole of
Visual cortex and posterior
portion of Optic Radiations
Posterior choroidal artery:
post medial aspect of LGB
Posterior choroidal artery
9. Internal carotid artery
Enters middle cranial fossa through carotid canal
Passes through foramen lacerum
Runs in cavernous sinus
Emerge from anterior part of its
roof
Lies lateral to OC
10. Cerebral Part:
(Mn: CAMP Off)
Ophthalmic art
Choridal art:
chaisma,
optic tract (post aspect),
LGB (ant and lateral aspect) and
commencement of optic radiations.
11. Ant Cerebral:
upper aspect of chiasma,
intra cranial part of optic nerve.
Middle Cerebral: largest branch
superolateral aspect of cerebrum,
inferolateral aspect of chiasma,
optic radiation,
small part of visual cortex
Post Communicating Art: joins Post Cerebral art to form
part of C.O.W.
12. Ophthalmic Artery
Br of ICA (after it leaves the roof of cavernous sinus)
At origin: inf to ON
Pass through the Optic
canal within dural sheath
of ON
13. At the apex of Orbit: lateral to ON and medial to occulomotor and
abducent nerve and
14. Runs forward and upwards
over Optic nerve ,below
Superior rectus and then comes
to lie medial to ON
Ends by dividing into:
dorsal nasal art
supra trochleaar art
The ophthalmic artery and its
branches are tortuous to
accommodate for the
movements of the eyeball.
15. Branches of Ophthalmic Artery:
1. Central retinal art
2. Long and Short posterior Ciliary art
3. Muscular art: Ant ciliary art
4. Lacrimal art: Lateral palpebral art
5. Medial palpebral art
6. Supra orbital art
7. Anterior ethmoidal art
8. Posterior ethmoidal art
9. Recurrent meningeal art
10. Dorsal nasal art (terminal br.)
11. Supra trochlear art(terminal br.)
16. Long and Short Posterior Ciliary Artery
Two long post ciliary art : arise from ophthalmic art below ON
10-20 Short ciliary arteries: forms part of choroidal circulation
18. Blood Supply Of Retina
Outer four layers: Choriocapillaris
Inner six layers: Central retinal artery
Outer plexiform layer: Watershed area
It gets blood supply from both,
the central retinal artery
and choriocapillaris.
20. In the optic nerve head:
Superficial in the nasal part of
the cup
Covered by a thin layer of glial tissue
(meniscus of Kuhnt, which separates
the vessels from the vitreous)
Divides into superior and
inferior branches
at disc margin: sup and inf br. Divide into nasal and temporal br.
21. In the retina: The four terminal branches divide
dichotomously and end without anastomosis
22. One of the capillary plexuses is
in the superficial zone
(nerve fibre layer)and the other
one is at the junction of
inner nuclear and outer plexiform
layer.
23. Macula
Superior and inferior temporal branches of central retinal
artery
Cilioretinal artery:
It is seen in some individuals.
It is a branch of ciliary system of vessels.
Supplies macula
It helps to retain the central vision
in the event of CRAO.
Fovea: Avascular area (500 µm)
Mainly supplied by choriocapillaris
24. CRAO
Nearly always at the lamina cribrosa
Generally, due to an embolus, there may be
associated arteriosclerosis, hypertension or
Buerger disease
Sudden and complete blindness, opaque and milky
white retina, cherry red reflex at the fovea
25.
26. Venous drainage of retina
Central retinal vein and its branches follows same
pattern as CRA
Empties into sup and inf ophthalmic veins
Which drains into Cavernous sinus
27. CRVO
Presentation : sudden, u/l blurred vision.
Fundus: tortuosity and dilatation of all branches
with Dot/blot and flame shaped
hemorrhages in all 4 quad most
numerous at periphery
cotton wool spots ,
macular edema
28. Blood Supply Of The Optic Nerve
Differ significantly depending upon which segment is
considered
Intraocular
Intraorbital
Intracanalicular
Intracranial
31. AION
Defect in the blood supply of anterior part of the
optic nerve by posterior ciliary artery - AION
It produces a postlaminar infarct.
Can be inflammatory (arteritic) or Non-
inflammatory (non arteritic)
32. Intraorbital
Intraorbital optic nerve is 3cm
long while the entry of the
central retinal artery is
5-15.5mm behind the globe.
So, the optic nerve here, is
divided into two segments,
proximal and distal.
Distal segment:
Axial supply, in addition
Proximal segment:
Centripetal branches of pial network
formed from br. Of PCAs
33. Periaxial system of vessels:
1. Ophthalmic artery
2. Long posterior ciliary arteries
3. Short posterior ciliary arteries
4. Lacrimal artery
5. Central retinal artery
6. Circle of Zinn
Axial system of vessels:
1. Intraneural branches of central retinal artery
2. Central collateral arteries from central retinal artery
34. PION
Disorders affecting small pial vessels supplying the
intraorbital part of the optic nerve
Vision loss with afferent pupillary defect.
No visible ophthalmoscopic abnormality
It can occur in disorders with vasculitis and
conditions producing acute systemic hypotension.
35. Intracanalicular
Lies in a watershed zone
Anteriorly from collateral br of Ophthalmic art
Posteriorly from pial vessels from
-ICA and
-Superior hypophyseal arteries.
As opposed to Intraorbital part of ON, which moves
freely as the eye moves, the intra canalicular part is
tightly fixed to optic canal, making it vulnerable to
shearing injury in # skull
36. Intracranial
Exclusively supplied by the periaxial system of
vessels
Pial plexus:
1. Direct branches of internal carotid artery OR
Recurrent branch of anterior superior hypophyseal artery:
They supply to the inferior aspect of the optic nerve.
2. Branches from anterior cerebral artery:
They supply to the superior aspect of the optic nerve
3. Recurrent branches from the ophthalmic artery
4. Twigs from the anterior communicating artery
37. Venous drainage of optic nerve
central retinal vein (primarily) and
pial plexus of veins
ophthalmic vein.
The intracranial part is drained by anterior
cerebral and basal veins.
38. Optic chiasma
Mainly derieved from br of Ant cerebral and Internal
carotid art.
Superiorly: Anterior cerebral and anterior communicating
arteries
Inferiorly: Internal carotid artery, anterior superior
hypophyseal artery and posterior communicating artery
A branch of the ophthalmic artery supplies the antero-
inferior margin of the chiasma.
43. Occlusion of Anterior choroidal artery produces
produces an upper- and lower-sector field defect.
44. Occlusion of Posterior choroidal art produces a
homonymous horizontal sectoranopia
45. Optic radiations
Anterior
part of optic
radiations
Middle part
of optic
radiation
Perforati
ng br. Of
MCA
Posterior
part of optic
radiations
Venous
drainage:
Basal vein
and middle
cerebral
vein
46. Visual cortex
calcarine branches of PCA
Anterior end of the calcarine sulcus: Middle cerebral artery
At the occipital pole of the cortex, there is an anastomosis between
posterior and middle cerebral arteries. Therefore, in thrombosis of
posterior cerebral artery, macula is spared.
Internal occipital vein › Great cerebral vein of Galen & straight sinus
Inferior cerebral vein › Cavernous sinus