The eye in systemic disease Flashcards
How does a defect in eye movements present?
double vision
What would a lesion in the 6th nerve cause?
a lateral rectus palsy and inability to abduct
What is the number one cause of 6th nerve palsy?
microvascular disease
Why is the 6th nerve susceptible to ICP?
curves over the petrous tip so can be pushed against it in increased pressure
What should you look for if a patient presents with headache, vomiting and a convergence squint?
papilloemea
What are the functions of SO?
medial rotation (intorsion); looking down when adducted
What would be the sign of an SO palsy when the patient is looking straight ahead?
one pupil is slightly higher than the other (so superior oblique isnt balancing it)
What are the features of bilateral trochlear plasy?
torsion and chin depression
What causes bilateral IVth palsy?
blunt head trauma
What are the causes of 4th nerve palsy?
congenital decompensated; microvascular; tumour
What are the sighsn of a 3rd nerve palsy?
ptosis; dilated pupil; pupil down and out- only SO and LR working
What is a 3rd nerve palsy caused by until proven otherwise?
circle of willis aneurysm
What is more likley to be the cause if the pupil is not involved in a 3rd nerve palsy?
microvascular
Why are hte parasympathetic fibres sometimes not involved?
they lie on the outside of the nerve
What is the inter-nuclear pathway called?
medial longitudinal fasciculus
What can cause problems with inter-nuclear ophthalmoplegia?
MS- demyelination; vascular
What does the optic radiation pass through?
temporal and parietal lobes
What can cause problems with the optci nerve?
ischaemic optic neuropathy; optic neuritis; tumours
What are the sings of optic neuritis?
progressive visual loss (unilateral); pain behind eye esp. on movements
What follows optic neuritis?
atrophy of the nerve
What are the sings of optic atrophy?
pale and featureless disk
What tumours can affect the optic chiasm?
pituitary tumour; craniopharyngioma; meningioma
What can cause probelms in the occipital cortex?
vascular disease; demyelination
What causes diabetic retinopathy?
chronic hyperglycaemia–glycosylation of protein/basmemnt membrane– loss of pericytes–microaneurysm (outpouching of capillary wall) which causes leakage and ischaemia
What are the signs of non-proliferative retinopathy?
microaneurysms/ dot and blot haemorrhages; hard exudates; cotton wool patches; abnormalities of venous calibre- venous bleeding; intra-retinal microvascular abnormalities
What happens as the basemenet membrane thickens?
hypoxia so body makes new vessels to compensate- prolferative retinopathy
Why do new vessels leak?
not surrounded by pericytes
How can you tell the difference bewteen new vessels and nomral vessels?
new vessels dont have a “purpose” or go somewhere
What causes the loss of visiion in diabetic retinopathy?
retinal oedema affecting fovea; vitreous haemorrhage scarring
What causes scarring in diabetic retinopathy?
new vessels are associated with fibrous tissue formation
What are the features of hypertensive retinopathy?
attenuated blood vessels- copper or silver wiring; cotton wool spots; hard exudates; retinal haemorrhage; optic disc oedema
What layer becomes swollen during central retinal artery occlusion?
retina nerve fibre layer
Why is there a cherry red spot CRAO?
the fovea has no ganglion cells to swell up and so obscure the choroid and pigmented epithelium
What are the signs of CRAO?
sudden painless loss of vision; pale retina except from fovea
What is the visual loss in papilloedema?
none- except increased blind spot
Why does hypertension increase risk of CRVO?
artery adn vein share same exit so hypertensive/ atherosclerotic artery presses on vein
What are hte extra-ocular isgns of thyroid eye disease?
proptosis-swelling of extraocular muscles and orbital fat; lid retraction, oedema, lag and pigmentation; restrictive myopathy- difficulty moving eye and diplopia
What are the ocular features of thyroid eye disease?
chemosis; injection; glaucoma; optic nerve swellign
What happens in GCA to the eye?
massive infarction of optic nerve head
What are teh eye features of RA?
keratoconjunctivitis sicca (dry eyes); scleritis; corneal melt
What are the triad of features of sjogrens ?
keratoconjunctivitis sicca; xerostoma; arthritis
What causes the dry eyes in Sjogrens?
infiltration of lacrimal glands
How does Marfans affect the eyes?
affects the zonules of the eye ( suspensory ligamnet of the lens)
What can occur as a result of conjuncitivits in stevens-johnson syndrome?
symblepharon- adhesion of eyelids to eyebal
