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42 Cards in this Set
- Front
- Back
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What is a central scotoma?
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It is an area of depressed vision that corresponds with the point of fixation and interferes with central vision
It suggests a lesion between the optic nerve head and the chiasm |
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What are some possible causes of a central scotoma?
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unilateral or asymmetrical bilateral scotoma
Methyl alcohol (symmetrical bilateral scotoma) Vascular lesions - unilateral gliomas of the optic nerve - unilateral |
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If you have a bitemporal hemaniopia where is the lesion and what visual loss do you experience?
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Lesion is at the optic chiasm and you lose the input from the 2 nasal retinas so you lose peripheral vision on both sides
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Where is the lesion in homonoymous hemianopia and what visual loss do you experience?
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You will lose vision from one visual field
Lesion is after the optic chiasm |
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If you have lost vision in the superior visual field what is this called and what has been damaged?
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Quadrantanopia
Meyer's loop has been cut (inferior radiation - takes superior visual field) |
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What causes monoocular visual loss i.e. one eye
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a lesion of the retina
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What are some common causes of monoocular visual loss?
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retinal infarcts
amaurosis fugax haemorrhage degeneration or infection |
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What can cause enlargement of the blind spot? What symptoms might the patient present with?
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papilloedema which can produce visual blurring due to enlargement of the blind spot
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If the lateral geniculate nucleus is taken out by tumours, infarcts, haemorrhage, infection what finding might you see?
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contralateral homonomous hemianopia
Takes out the oppostie visual field |
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Which artery territory covers optic radiations and what visual finding might you see if they are taken out?
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Contralateral quadnatanopias (supioer/inferior)
MCA inferio division - tempral lobe (superior visual loss) superior division - parietal lobe (inferior visual loss) |
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If you have a lesion affecting the visual cortex what visual finding might you see?
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Macular sparing - vision at the fovea is spared so you see contralateral homonoymous hemianopia with central vision spared
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What does amaurosis fugax mean?
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transient loss of vision in one or both eyes
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What visual finding is highly suggestive of retinal ischaemia?
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Transient visual loss descending over the field of vision like a curtain or shade
very uncommonly reported |
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What are some common causes of transient monovular visual loss?
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Ischaemia - most common
- atherothrombosis, embolus, dissection - carotid artery disease (thromboembolism or hypoperfusion) Papilloedema Optic neuropathy (MS) Ocular disease (glaucoma, hyphema = haemorrhage within anterior chamber) Giant cell arteritis |
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What are some causes of transient binocular visual loss?
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migraine
seizure veretbrobasilar ischaemia |
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What is the aetiology of central retinal artery occlusion?
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emboli from carotid arteries or heart
thrombus temporal arteritis |
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What features do you present with central retinal artery occlusion?
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sudden, painless, severe monoocular loss of vision
relative afferend pupillary defect |
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What fundoscopy findings suggest central retinal artery occlusion?
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cherry red spot at centre of macula
retinal pallor narrowed arterioles, boxcarring cotton wool spots cholesterol emboli (Hollenhorst plaques) usually located at arteriole bifurcation |
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How do you manage central retinal artery occlusion?
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Occular emergency - must attempt to restore blood within 2 hours
massage globe to dislodge embolus decrease intraocular pressure (topical beta blockers, inhaled O2, CO2, mixture), carbonic anhydrase inhibitor, mannitol anterior chamber paracentesis |
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What role does the inferior oblique have?
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Extorsion and elevation
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What role does the superior oblique have?
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Down/intorsion/abduction
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How does a 4th nerve palsy present?
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eye will be extorted and upward deviated
diplopia when they look down and in |
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What is internuclear ophthalmoplegia
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on gaze away from size of lesion 1) adduction of ipsilateral eye is impaired, contralateral eye can abduct but with nystagmus
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What is INO due to?
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lesion in medial longitudinal fasciculus which disrupts coordination between VI in pons and contralateral CNIII in midbrain - disrupts conjugate horizontal gaze
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How does a third nerve palsy present?
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ptosis
eye is down and out (i.e. SO functioning) mydriasis can get pupil sparing |
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When do you get pupil sparing third nerve palsy?
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Pupillary constrictor fibres are on the peripheral aspect of CNIII so infarction (affecting centre of nerve) will cause pupillary sparing
Anuerysms - painful CNIII palsy + pupil involvement Diabetic neuropathy - pupils usually spared |
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How does a CNVI palsy present?
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Inability to abduct eye on affected side
horizontal diplipia, worse on ipsilateral gaze |
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Common cause of VI palsy?
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Raised ICP
Infection, head trauma neoplasm inflammation aneurysm cavernous sinus thrombosis |
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Common cause of IV palsy?
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Congenital
Traumatic Idiopathic |
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What is nystagmus?
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rapid, involuntary, small amplitude movements of the eyes that are rhythmic in nature
Jerk: slow drift in one direction with a corrective jerk in the opposite direction Pendular: slow ossilations to and fro |
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How do you define the direction of nystagmus?
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It's defined by the rapid component of the eye movement
i.e. direction of the fast phase |
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What is the difference between peripheral and central nystagmus?
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Peripheral is unidirectional with the fast phase opposite the lesion and tinnitus or deafness often present
Central is unidirectional or bidirectional and tinnitus or deafness is often absent with the fast phase in the direction of the lesion |
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What is the cause of most jerk nystagmus?
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result of an asymmetry in vestibular inputs in either the central or peripheral nervous system
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What are the factors that make up Horner's syndrome?
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misosis
Anhydrosis ptosis hypochromicheterochromia (irides of different colour) |
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Describe the relative afferent pupillary defect (Marcus Gunn pupil
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Caused by an incomplete optic nerve lesion or severe retinal disease
Light stimulus to the disease pupil evokes a weak response in both eyes but stimulus to the normal eye evokes a brisk response So when you swing to the abnormal eye after the normal eye the pupils dilate after constricting because they are perceiving less light then there actually is |
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What is an afferent pupillary defect
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it is caused by a complete optic nerve lesion
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What is the most common cause of RAPD?
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optic neuritis - most common
optic nerve compression large retinal detachment central retinal artery/vein occlusion advanced glaucoma |
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Difference between two types of macular degeneration
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both have central scotomas
dry: d for drusen = yellow spots on Bruch's membrane, caused by geographic atrophy wet: exudative, choroidal neovascularisation. Leakage of serous fluid and blood can subsequently result in a rapid loss of vision. Carries worst prognosis |
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Risk factors for macular degeneration
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Risk factors
* age: most patients are over 60 years of age * smoking * family history * more common in Caucasians * high cumulative sunlight exposure * female sex |
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Rx for dry macular degeneration
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nothing
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Rx for wet macular degeneration
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* photocoagulation
* photodynamic therapy * anti-vascular endothelial growth factor (anti-VEGF) treatments: intravitreal ranibizumab |
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Difference between uveitis and acute angle glaucoma
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both red...
* glaucoma: severe pain, haloes, 'semi-dilated' pupil * uveitis: small, fixed oval pupil, ciliary flush |
