Thread by @EricLawson90

#Tweetorial time! A little late this week as I’ve been busy on inpatient. Transitioning to #CommonNeuroConsults and this week will start with a #stroke and #ophthalmology topic @DGlaucomflecken @MedTweetorials #meded #medstudenttwitter

“Transient Monocular Vision Loss”
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You may also hear this called “amaurosis fugax” and can be due to an ocular cause, a vascular cause, or an optic nerve head problem!
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Let’s start with a brief review of ocular and oculovascular anatomy!

Your optic nerve is cranial nerve 2. This is the nerve that transmits visual information from the retina to the visual cortex.
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Ophthalmic artery is a branch of the internal carotid. It supplies the optic nerve via 2 main branches, the central retinal and posterior ciliary arteries.

Posterior ciliary artery branches into the short posterior ciliary arteries to supply optic nerve head
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After our ophthalmology colleagues like @DGlaucomflecken rule out a direct ocular cause such as dry eyes or angle closure glaucoma #Neurology or #Neuroopthalmology @NANOSTweets are involved
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History as always is important!
-what was time and duration
-Associated HA, scalp tenderness, jaw claudication?
-Neck pain?
-Additional focal neurologic deficits?
-Occurs with eye movement?
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Vascular transient monocular vision loss can be due to emboli, hypoperfusion, vasculitis, vasospasm, or venous congestion and is often painless!
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Emboli into the central or branch retinal artery (CRAO or BRAO) is likely due to embolic material from ipsilateral carotid artery.

Presents with a dark shade coming down across visual field for a few minutes.

Needs stroke workup/carotid artery imaging.
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Hypoperfusion of the eye can be due to severe or critical carotid stenosis. This can cause retinal or choroidal hypoperfusion.
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Vasculitis (most commonly giant cell arteritis) is a commonly missed diagnosis. Occurs in age >50 and is due to inflammation of short ciliary arteries supplying the optic nerve head. Exam can be normal or present with disc edema.

Requires immediate high dose steroids
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Giant cell arteritis can be evaluated with ESR/CRP and a temporal artery biopsy. Can result in anterior ischemic optic neuropathy or a CRAO.
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Without treatment or workup any of these conditions can progress from transient to actual visual loss so they are considered emergencies similar to a TIA.
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A completed CRAO will have a characteristic cherry red spot at the fovea (due to underlying intact perfusion of choroid at the relatively thin fovea).

A BRAO can sometimes be diagnosed by visualizing a sector of pale retina with an associated emboli seen on retinal exam

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Giant cell arteritis can cause an arteritic anterior ischemic optic neuropathy. This is different than a nonarteritic anterior ischemic optic neuropathy or NAION which occurs in younger patients with a crowded disc (small cup to disc ratio) or “disc at risk”
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There are MANY causes of emergent vision loss, I tried to do a brief overview of some of the painless, often vascular causes of vision loss that are seen by #Neurologists
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I know there is a lot to expand on here so I hope my #Ophthalmology and #Neurology colleagues will join me in helping teach this important topic to #Medtwitter #medstudenttwitter #meded
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@MonicaDhakar @SitaraKoneru @sallywilliamsmd @DGlaucomflecken @Tracey1milligan @AaronLBerkowitz @aartisarwal @Nirav_r_bhatt @NANOSTweets @aao_ophth @AANMember @NMatch2021 @WNGtweets @EmoryNeurology @Oga_DoctorBlue @VizcarraJA @ShaerQasem @MedTweetorials @doclockery
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