Describe the path of the optic nerve from the eye to the primary visual cortex
- optic nerve
- optic chiasm where nasal fibres decussate and temporal fibres don’t
- optic tract
- lateral geniculate nucleus in the thalamus
- superior radiation in parietal lobe and inferior radiate in temporal lobe
- primary visual cortex in occipital lobe
State some causes for bitemporal hemianopia, how would you differentiate between these?
pituitary tumour: superior affected worse
craniopharyngioma: inferior affected worse
anterior communicating artery aneurysm
Describe the pathophysiology of the macula sparing phenomenon and state when you’d see this
If the posterior cerebral artery and occipital lobe is damaged you lose your vision however the occipital pole which correlates to the macula and central vision is supplied by the middle cerebral artery and therefore is spared
State some causes of double vision
- Squints including extra-ocular nerve damage
- Refractive errors
- Myasthenia gravis
- Thyroid eye disease
- Stroke, SOL, RICP
- Migraine
- MS
Describe what is meant by the terms monocular diplopia and binocular diplopia
Monocular: double vision persists when the unaffected eye is occluded
Binocular: double vision is only when both eyes are open and is corrected when either eye is occluded
What are some causes of
a) monocular diplopia
b) binocular diplopia
Monocular: refractive error, cataract, retinal detachment
Binocular: Myasthenia gravis, thyroid eye disease, CN palsy
State some differentials for ptsosis
- Myasthenia gravis
- Horner’s
- Thyroid eye disease
- Stroke
- CN3 palsy
- MS
What muscles and nerves could be involved in the pathophysiology of ptosis?
Sympathetics which supply the tarsal/Mullers muscles
CN3 which supplies levator palpebrae superiorus
State some differentials for a red eye - give a defining feature of these to differentiate them
- conjunctivitis: discharge
- keratitis: ulcer on fluorescein stain
- corneal abrasion: trauma history
- episcleritis: painless wedge shaped redness
- scleritis: boring pain
- uveitis: peri-limbal redness, autoimmune history
- acute closed angle glaucoma: pain, N&V, haloes
- subconjunctival haemorrhage: well demarcated
State some differentials for a gradual loss of vision - give a defining feature of these to differentiate them
- cataract: glare, colour desaturation
- open angle glaucoma: tunnel vision
- diabetic retinopathy: central vision loss, floaters
- ARMD: central vision loss, wavy lines
- refractive error
State some differentials for acute loss of vision - give a defining feature of these to differentiate them
- stroke
- retinal artery occlusion: amaurosis fugax history
- retinal vein occlusion: on waking, hyperviscosity risk factors
- closed angle glaucoma: pain
- retinal detachment: floater history
- vitreous haemorrhage: dark floaters
Where is the lesion if a patient has a homonymous hemianopia?
contralateral optic tract
