Cardiovascular disease & its effect on vision Flashcards Preview

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Flashcards in Cardiovascular disease & its effect on vision Deck (92):

what is a transient ischaemic attack known as

a temporary disruption go blood supply (that results on no long term damage)


what can a transient ischaemic attack be the result from

an embolism (such as a circulating fragment of an atheromatous plaque) temporarily blocking a vessel, the function of the area supplied by the vessels in impaired


what happens when the embolism moves on in a transient ischaemic attack

function returns


name an example of a specific TSA associated with the eyes

amaurosis fugax (fleeting darkness/blindness)


what is amaurosis fugax

a painless unilateral loss of vision resulting from a transient retinal ischaemia caused by an embolism in the retinal vasculature


what is the loss in vision described as by a patient, of amaurosis fugax

vision goes dark, like a curtain descending or ascending on the eye for a short period of time, which then vision goes back to normal


what do the inner 5 layers of the retina receive oxygenated blood from

central retinal artery


what is the central retinal artery a branch off

ophthalmic artery


what does the ophthalmic artery arise from

carotid artery (a branch off the aorta)


what happens in the ophthalmic artery as a result of amaurosis fugax

a dislodge is stuck in the ophthalmic artery, patient goes blind as the retina becomes ischaemic & stops functioning, then the blood clot breaks up and resolves itself whereby patient can see again


what may form a transient occlusion of a retinal vessel

an atheromatous plaque in the carotid artery which may disintegrate


what may emboli of an atheromatous plaque in the carotid artery which may form a transient occlusion of a retinal vessel be made of

various materials such as:
cholesterol crystals
platelet aggregates


instead of an emboli (which is most common), what else can be the cause of transient ischaemic event

vasopastic events such as:
unusual narrowing of vessels (artery contracts itself)
haematological causes such as:
abnormalities in blood constituents e.g. sickle cell anaemia


why is the CNS particularly susceptible to infarction

it needs a continuous supply of oxygen & CNS tissue does not regenerate


what are cerebrovascular accidents CVAs most commonly know as, and what causes it

blood supply to vessels which supply the brain become blocked so it becomes non functional (infarct)


what are the two sources which supply the brain with oxygenated (arterial) blood

- 2 internal carotid arteries
- 2 vertebral arteries


which part of the brain do the 2 internal carotid arteries supply



which areas do the 2 vertebral arteries supply

poster brain & spinal chord


what do the 2 vertebral arteries merge to form

basilar artery


what are the internal carotid & basilar arterial supplies united by

anterior & posterior communicating arteries at the circle of willis (found at the base of the brain)


why does the brain have two blood supplies

if one blood supply is impaired, the other can supply the brain


which three arteries arise fro the circle of willis

anterior cerebral artery
middle cerebral artery
posterior cerebral artery


what area of the brain does the anterior cerebral artery supply



what area of the brain does the middle cerebral artery supply



what part of the brain does the posterior cerebral artery supply



what are the two types of stroke

- hemorrhagic
- occlusive (ischaemic)


what is a hemorrhagic stroke caused by

a ruptured aneurysm or an AVM
(blood comes/leaks out & that area of the brain does not receive oxygen from the vessel & that part of the brain stays dead forever)


what % does a hemorrhagic stroke account for from all strokes



what is an occlusive (ischaemic) stroke caused by

a thrombosis (blood clot) on an atheromatous plaque


how many % of strokes does an occlusive ischaemic stroke account for



which type of stroke will be helped by medication

occlusive (ischaemic)


how does medication treat an occlusive (ischaemic) stroke

by unblocking the vessel


why is medication not suitable for hemorrhagic strokes

medication can make it worse (if for stopping clotting)


what is a result of both hemorrhagic and occlusive (ischaemic) strokes

brain tissue at one part of the brain to die


how does a CVA effect vision

by effecting one of the 30 visual areas of the brain (different parts of brain deal with different aspects of vision)


what does the early part of the visual pathway consist of

projections from the retina, along the optic pathway, via the LGN to v1 (area 17 or striate cortex)
can have a stroke at any of these areas


which part of the brain is the striate cortex located

occipital lobe/back of the brain


what supplies the occipital lobe/back of brain

posterior cerebral artery


what can a blockage of the PCA e.g. from a thrombosis result in

death of cells in v1 and patient will become blind in that hemifield (bilateral hemianopia) BUT with macular sparing


what is the reason for macular sparing of a patient who has had a blockage of their PCA which resulted in the death of v1 cells

the posterior part of the occipital cortex, which subserves macular vision, also receives blood supply from the MCA (so lose most vision in that field due to blocked PCA, except macula)


what type of attribute do v1 cells do for an image

basic attributes


what does stroke to a particular area of extra striate cortex cause

a particular attribute of vision loss i.e. specific agnosias


what does a lesion to area v4 result in

achromatopsia (form vision normal etc)
(not due to loss of visual pigment, things actually look black & white)


what can a lesion to area v5 result in

disturbed motion detection - akinotopsia (won't see cars moving or pouring of tea will look like frozen glacier)


what can a lesion/damage to the temporal lobe by a stroke result in

inability to distinguish faces, even familiar ones - prosopagnosia


what can also impair visual function, apart from a hemorrhagic or occlusive stroke

an aneurysm


where do 80-90% of aneurysms occur

in the circle of willis


where do aneurysms most often form and why

where vessels branch, as they are the weakest here


what happens to the BV from an aneurysm

BV bulges out and presses on things


what can an aneurysm of the internal carotid artery compress

the lateral aspect of the chiasm


what does the lateral aspect of the chiasm house

uncrossed temporal fibres from the ipsilateral eye


what will a lesion to the uncrossed temporal fibres from the ipsilateral eye (from internal carotid aneurysm) result in

disruption of the temporal retina of the ipsilateral eye, causing nasal field loss (ipsilateral nasal hemianopia)


as well as an aneurysm compressing the visual pathway, what can it also affect which can affect vision

compressing a cranial nerve


what other type of aneurysm of the carotid is there, as oppose to one causing damage to the chiasm

damage to the wall of the cavernous sinus (where the carotid also lies near)


how many % do intracavernous carotid aneurysms account for of all intracranial aneurysms

2-3% rare


what are the unique set of symptoms of an intracavernous carotid aneurysm based on

arrangement of cranial nerves and symptoms are largely ocular


what does the carotid artery lie within

the walls of the cavernous sinus


what system is the cavernous sinus a part of

venous drainage system of the brain


which wall of the cavernous sinus does the internal carotid lie within

medial wall of cavernous sinus


of which arteries is the blood pressure highest

in the major arteries nearest the heart


why is venous pressure much lower than arterial

they are far from the pump of the heart and due to elasticity nature of veins


when can an aneurysm within the artery wall compress the sinus

as the pressure in the internal carotid artery exceeds that of the cavernous sinus


what will a compression of the cavernous effect

the cranial nerves that lire within the walls of the sinus, which will impact several ocular structures


what can damage to the oculomotor CN 3 cause

damage to fibres which go to:
- ciliary muscle - effects/impairs accommodation
- iris sphincter - impairs pupil constriction
- levator palpebrae - impaires eyelid to open/raise causing ptosis
- 4 EOMS - MR, SR, IR, IO - impaires eye movements


what can damage to the trochlear CN 4 cause

loss of innervation of superior oblique EOM


what can damage to the ophthalmic division of the trigeminal CN 5 cause

loss of sensation of anterior eye e.g. cornea


what can damage to the abducens CN 6 cause

loss of innervation of lateral rectus EOM


list the CNs which disrupt eye movements

- oculomotor 3rd
- trochlear 4th
- abducens 6th


why are pupil anomalies complex

as both parasympathetic fibres in the 3rd CN and sympathetic fibres from the SCG are associated with the cavernous sinus, so both may be affected, therefore the pupil may be sluggish and smaller than usual/not normal


what is a fistula

any connection between two structures which shouldn't be connected


what can there be a fistula of, as a direct result of ruptured aneurysms

cavernous venous sinus & carotid artery


what type of people are connections/fistula of the cavernous sinus and carotid artery in

middle ages females or caused by head trauma (75%)


what does the cavernous sinus do

takes deoxygenated blood from the eye


due to higher pressure in the arterial system, what will fistula od the cavernous sinus and carotid artery result in

the sudden onset of many of the symptoms associated with a carotid artery aneurysm such as ophthalmegia (paralysis of intra and extra ocular muscles)


as the cavernous sinus receives venous blood from the eye, what can happen in a case of an accident such as whiplash & which mainly occurs in women

ocular vessels become engorged i.e. blood goes in the opposite direction in the vein


what things can severe engorgement result in

- chemosis
- exophthalmus/pulsatile proptosis


what is chemosis (as a result of severe engorgement)

bulba conjunctiva full of blood, cornea is fine


what is exophthalmus/pulsatile proptosis, (as a result of severe engorgement)

as the heart pumps, the eye pushes out


what can an aneurysm of the posterior communicating artery in the circle of willis present

- a sudden onset of full 3 CN palsy - ptosis, abnormal eye position, dilated and fixed pupil
- a severe unilateral frontal headache


what is cranial arteritis

inflammation of the medium to large arteries coming off the aorta, (most notably those associated with the carotid system)


what actions should be taken is cranial arteritis is detected

ocular emergency, immediate referral


what part of the BV/artery gets inflamed in cranial arteritis

lots of inflammatory cells within the tunica interna of artery leading to its fragmentation & among these are giant multinucleate cells & one of those inflammatory cells is a huge macrophage


what leads to the occlusion of the vessels as a result of cranial arteritis

lots of inflammatory cells within the tunica interna of artery leading to its fragmentation & among these are giant multinucleate cells & one of those inflammatory cells is a huge macrophage, & the proliferation of cells within the tunica interna


what are the major symptoms of a cranial arteritis

headache & tenderness of the scalp


why is headaches & tenderness of the scalp symptoms of cranial arteritis

due to involvement of the superficial temporal arteries and pain of the jaw when eating


how can cranial arteritis also result in severe visual defects

as the ophthalmic artery (which arises from the internal carotid) is also affected & as this artery supplies to most of the eye, its disruption can result in a large number of ocular symptoms


which branch of the ophthalmic artery is particularly effected in cranial arteritis

posterior ciliary arteries (which form a circle around the ONH)


what do the posterior ciliary arteries supply

the circle of Zinn-Haller


what do the circle of Zinn-Haller supply

nutrients to the ONH


what does the disruption of the ciliary arteries cause

anterior ischaemic optic neuropathy (neuropathy of the anterior part of the optic nerve) can cause blindness in that eye


which other artery which supplies the retina can also be effected by cranial arteritis

central retinal artery


which artery is thought to be associated with the sudden blindness that results from cranial arteritis

disruption to the posterior ciliary arteries affecting the ONH (circle of Zinn-Haller)