Eye Flashcards
What can causes diplopia, unilateral ptosis, drooping of one eyelid, fixed pupil, eye in the out position, and normal visual acuity?
Aneurysm of the posterior communicating artery - CN III courses bw PCA and superior cerebellar arteries.
Ipsilateral
MC site of berry/saccular aneurysm
acomm and ACA
Causes subarachnoid hemorrhage
Contralateral upper extremity and facial hemiparesis, sensory deficits
rupture of MCA
Bitemporal hemianopsia (compressed optic chiasm), contralateral lower extremity hemiparesis, sensory deficits
anterior communicating artery aneurysm
constricted pupil
miosis
dilated pupil
mydriasis
MS patient with diplopia. Images are horizontal on lateral gaze. Dec adduction bilaterally during lateral conjugate gaze. Most likely location of a demyelinating plaque causing the diplopia?
medial longitudinal fasciculus (allows for crosstalk bw CN6 and CN 3 nuclei to coordinate horiz gaze) located in the dorsal pons
this patient has internuclear ophthalmoplegia
Left homonymous hemianopia (cant seen on left in both eyes) is due to lesion where?
RIGHT optic tract (just posterior to the optic chiasm) (pg 489 FA)
Note this is CONTRALATERAL to side of visual defect
Left hemianopia with macular sparing (normal visual acuity) is due to what?
PCA infarct (occipital lobe) (pg 489 FA)
central scotopa (ie blind in one eye in the center) is due to what?
macular degeneration (pg 489 FA)
Left upper quadrantic anopia (ie pie in the sky) is due to lesion where?
Meyer loop (right temporal lesion, MCA) - outer tract (pg 489 FA)
Left lower quadrantic anopia is due to lesion where?
right parietal lesion, MCA - inner tract (pg 489 FA)
Glaucoma damages what cells in the eye, which can result in blindness and no bilateral constriction in response to light?
retinal ganglion cells
Timolol and other nonselective BB work by diminishing the secretion of aqueous humor by targeting what structure?
Ciliary epithelium (Acetazolamide, a carbonic anhydrase inhibitor also uses this mechanism)
Prostaglandin F2a (e lantaoprost, travoprost) and cholinomimetics (pilocarpine, carbachol) decrease intraocular pressure how?
Increase outflow of aqueous humor
Elevating or depressing the eye from the abducted position tests what EOM and nerve?
Superior and inferior rectus (CN III)
Note: CN III innervates the SKELETAL mm of the levator palpebrae superioris as well. Sympathetics innervate the SMOOTH mm of the levator and can also cause ptosis
Elevating or depressing the eye from the adducted position tests what EOM and nerve?
Inferior (CN III) and superior oblique (CN IV)
How does central retinal artery occlusion present?
sudden onset, painless and permanent monocular blindness.
CHERRY RED macula and pale retina
How does diabetic retinopathy present?
Blurry vision, black spots, floaters, “cotton wool spots”, dec peripheral vision.
Neovascularization and flame-shaped hemorrhage seen
This is a microangiopathy. Cotton wool spots can be seen with hypertensive retinopathy as well
How does amaurosis fugax present?
Painless, transient, monocular vision loss - small embolus of OPHTHALMIC artery
Doesn’t last for more than a few sec
Key feature of peripheral vascular disease
What mediates direct and consensual pupillary light reflex?
Where is this located?
Edinger-Westphal nuclei –> CN III
Upper MIDBRAIN
Nerves responsible for afferent and efferent Pupillary light reflex ?
Afferent - CN II
Efferent - CN III (also causes ptosis, down and out)
Grey subretinal membrane and subretinal hemorrhage is sign of wet age related macular degeneration. Treatment?
Stop smoking VEGF inhibitor (ranibizumab, bevacizumab)
Lesion of what nerve results in vertical diplopia? (eg walking downstairs or up close reading)
Trochlear nerve. Superior oblique mm
Note: abducens n palsy results in horizontal diplopia
