Ophthalmol 4th yr.txt
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what is RAPD due to commonly?
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
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
when would you get homonymous hemianopia with macular sparing?
lesion of visual cortex sparing the occipital pole where the macular region is represented
which condition can give enlargement of the physiological blind spot?
papilloedema - increased ICP, but preserved visual acuity
which ophthalmological disease can cause tunnel vision?
what is perimetry used for?
visual field testing
what is tonometry used for?
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
how can you tell between a medical and surgical 3rd cranial nerve palsy?
- surgical: pupil is fixed and dilated
- medical: pupil is spared
what is the common cause of 4th CN palsy?
minor head trauma
what does the pt usually complain of in 4th CN palsy?
diplopia going down the stairs
which test can be done to check superior oblique paralysis?
which nerve palsy can appear as a convergent squint at rest?
6th nerve palsy due to unopposed action of medial rectus
when do you get diplopia in 6th CN palsy?
when look towards affected side, with horizontal separation of images
what are the causes of isolated 6th CN palsy?
damage to nerves bld supply - vasa nervorum due to DM or HTN
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
which 2 nerves contribute to elevating eyelid?
- 1. sympathetic fibres (Horners)
- 2. 3rd CN
what is amblyopia ?
poor vision in an otherwise physically normal looking eye
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
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)
what symptom does adult onset strabismus give?
diplopia as the 2 eyes are not fixated on same object
what is an apparent strabismus?
pseudosquint - eg epicentral fold - so can see less of the sclera on that side, looks like a convergent squint
give an example of an acquired strabismus?
3rd nerve palsy
what is an intermittent strabismus?
happens when child becomes tired
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
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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