Cheatography
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CN II - Anatomy + Disorders
This is a draft cheat sheet. It is a work in progress and is not finished yet.
Visual anatomy
Visual system is located in the supratentorial compartment |
Cells in back of eye that process vision are rods (night vision + Movement) + Cones (day + colour vision) |
In the Macular, rods are more prominent |
Pathway: |
Rods/Cones |
Bipolar Cells |
Ganglion cells |
Optic Disc |
Optic Nerve |
Optic Chiasm - nasal fibres cross over here |
Optic Tract |
Nasal fibres - Lateral Geniculate Body (LGB) |
Superior Colliculus |
Considerations
Impairment |
One/both eyes, total/partial visual loss, whole/partial field loss, precipitating factors? Transient/constant |
Diplopia |
Unequal eye placement - Brain receives two displaced images |
Gaze Disorders |
Hallucinations |
Field involved, Formed/Unformed |
Central loss |
Macula - <5° of visual field |
Field loss (peripheral) |
>5° of field |
Monocular Visual Loss
Single Eye lesion before optic chiasm |
Optic Neuritis
S&S |
Usually a sign of MS, but can occur in isolation |
Presents at a young age |
7-10 days of eye pain when moving the eye |
Loss of vision |
Glaucoma
S&S |
Sudden Visual Loss, Severe eye and facial pain |
Nausea, Vomiting |
Dilation |
Associated with: Diabetes, high intraoccular pressure, Genetic |
Retinal Detachment
S&S |
Associated with: Myopia, diabetes, intraoccular inflammation, surgery/trauma |
Brief flashes of light in peripheral vision |
Increase in floaters in temporal vision |
Central Retinal Artery occlussion
S&S |
Sudden Severe visual loss NO PAIN |
If branch affected, the symptoms will get better. If central artery itself is affected, symptoms will not improve |
In fundoscopy: |
"cherry red" spot in choroid |
Posterior pole retinal opacity |
Pallor |
Optic disc oedema |
Transient visual field loss - binocular/monocular
Ischaemia |
Visual symptoms without headache |
Migraine |
Aura |
Increased ICP |
Visual Loss when sitting up/standing - findings bilateral optic disc oedema, obstruction of CSF |
TIA |
Hemiplegia, Dysarthria, Nausea, Vomiting, Dizziness |
Retrobulbar Neuritis
Inflammatory condition of optic nerve + Retina |
Affects central vision (blurring/mistiness) |
Pain when moving eye |
MS - Present in ~50% of cases |
Tumour on Optic Nerve
Painful |
Increased ICP |
Affects fibres that convey red - can affect other colours too |
Red colour blind - gets worse as increased compression happens |
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