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what is RAPD due to commonly?
optic neuritis
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what is an argyll robertson pupil a sign of? and what does it mean?
- sign of neurosyphilis
- pupil is small and irregular
- can accommodate
- but not react to light
- usually bilateral
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give 2 causes of optic disc swelling? how can u tell which one it is?
- 1. papilloedema
- 2. local inflammatory processes involving optic nerve near the retina - optic neuritis
- papilloedema - visual acuity is preserved until late
- optic neuritis: early loss of acuity and get central scotoma
- optic neuritis is usually unilateral
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when would you get homonymous hemianopia with macular sparing?
lesion of visual cortex sparing the occipital pole where the macular region is represented
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which condition can give enlargement of the physiological blind spot?
papilloedema - increased ICP, but preserved visual acuity
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which ophthalmological disease can cause tunnel vision?
glaucoma
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what is perimetry used for?
visual field testing
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what is tonometry used for?
measure IOP
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what are common causes of optic atrophy?
- 1. infection/inflammation: optic neuritis (MS), syphilis, sarcoid
- 2. vascular: compression by carotid aneurysm, ischaemic optic neuropathy
- 3. DM, b12 def
- 4. glaucoma, retinal probs
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how can you tell between a medical and surgical 3rd cranial nerve palsy?
- surgical: pupil is fixed and dilated
- medical: pupil is spared
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what is the common cause of 4th CN palsy?
minor head trauma
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what does the pt usually complain of in 4th CN palsy?
diplopia going down the stairs
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which test can be done to check superior oblique paralysis?
cover test
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which nerve palsy can appear as a convergent squint at rest?
6th nerve palsy due to unopposed action of medial rectus
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when do you get diplopia in 6th CN palsy?
when look towards affected side, with horizontal separation of images
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what are the causes of isolated 6th CN palsy?
damage to nerves bld supply - vasa nervorum due to DM or HTN
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which CN palsy can be a false localising sign of raised ICP and why?
- 6th CN palsy
- because the nerve has a long and tortuous INTRACRANIAL course
- so it is vulnerable to the general effects of increased pressure, arising from an intracranial mass which need not necessarily directly compress the nerve
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which 2 nerves contribute to elevating eyelid?
- 1. sympathetic fibres (Horners)
- 2. 3rd CN
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what is amblyopia ?
poor vision in an otherwise physically normal looking eye
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what is amblyopia due to?
- no or poor transmission of the visual stimulation through the optic nerve
- to the brain for a sustained period
- its a developmental problem in the brain
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what causes amblyopia in childhood? vision obstructing disorders eg
- congenital cataracts
- strabismus - misaligned eyes
- anise metropia (different degrees of myopia or hypermetropia in each eye)
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what symptom does adult onset strabismus give?
diplopia as the 2 eyes are not fixated on same object
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what is an apparent strabismus?
pseudosquint - eg epicentral fold - so can see less of the sclera on that side, looks like a convergent squint
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give an example of an acquired strabismus?
3rd nerve palsy
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what is an intermittent strabismus?
happens when child becomes tired
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what is Hirschberg's test? and use?
- corneal reflex, screening test to see if person has strabismus (ocular misalignment)
- go obliquely to the child, shine a light into their eye,
- observe where the light reflects of the corneas
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what is a normal hirschberg test?
- normal ocular alignment: light lands on centre of both retinas
- abnormal: based on where the light lands on the cornea - exotropia (eye turned out), esotropia (in), hypertropia (higher), hypotropia (lower)
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