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This muscle changes the shape of the lens allowing accomodation
this is the center of the macula and is the region with the highest visual acuity.
The three cell layers of the retina:
- - outer nuclear layer containing photoreceptors
- - bipolar cell layer
- - ganglion cell layer
The difference between rods and cones.
- Rods: more numerous and useful for night vision. found at the periphery
- Cones: detect color. concentrated at the fovea
This produces the blind spot
photoreceptors synapse on:
bipolar cells synapse on
axons of ganglion cells form
Most common pituitary tumor
binasal hemianopia occurs because:
bilateral lateral compression of the optic chiasm. can result from calcified internal carotid arteries.
corneal reflex components
- afferent: opthalmic division of the trigeminal nerve
- efferent: facial nerve
depresses and extorts
elevates and extorts
"inferiors extort money."
optic nerve extis the skull through:
oculomotor nerve exits the skull through:
superior orbital fissure
trochlear nerve exits the skull through:
superior orbital fissure
abducens nerve exits the skull through the:
superior orbital fissure
input to the visual pathway from the optic nerve:
optic nerve-->optic chiasm-->optic tract-->lateral geniculate nucleus-->optic radiations--> visual cortex
Pupillary light reflex pathway:
optic nerve-->optic chiasm-->optic tract-->pretectal nuclei-->Edinger-Westphal nuclei-->ciliary ganglion-->short ciliary nerves
complete oculomotor palsy:
eye is down and out, ptosis and dilated nonreactive pupil.
causes of CN 3 palsy:
- - compression
- - Posterior communicating artery aneurysm
- - aneurysm at the junction of the posterior cerebral and superior cerebellar arteries as CN3 passes between these
- - transtentorial herniation
what could cause CN3 palsy with sparing of the pupil?
Diabetes as it tends to affect the central fibers and not the pupilloconstrictor fibers
This can also cause CN3 palsy with sparing of the pupil:
superior division of CN3 innervates:
superior rectus and levator
inferior division of CN3 innervates the:
inferior oblique, inferior rectus, medial rectus and pupillary sphincter
This is the longest and most slender cranial nerve.
trochlear nerve palsy
double vision worse when looking down and away from the lesion; head tilt to compensate; involved eye is elevated in primary gaze.
one major cause of CN VI palsy
Diplopia in pts with CN VI palsy is worse when:
the look laterally toward the side of the lesion.
Orbital apex lesion:
Optic nerve involvement, may have a bulging eye, also involves CN 3, 4, 6 V1
Superior orbital fissure lesion involves these CN:
Tolosa-Hunt is a cause of this:
- cavernous sinus syndrome, involves CN 3,4,6, V1, V2.
- It is a granulomatous inflammation in the cavernous sinus that results in painful opthalmoplegia. treat with prednisone.
Edinger Westphal Nucleus innervates:
pupillary sphincters and ciliary bodies.
the long ciliary nerve carries sympathetic fibers to the:
dilator of the pupil
the short ciliary nerve carries parasympathetic fibers to the
pupil constrictor and ciliary muscles.
the medial longitudinal fasciculus travels from:
the abducens nucleus to the contralateral oculomotor nucleus
left abducens nucleus lesion causes:
left gaze palsy due to the inability of the left eye to abduct and the right eye to adduct.
- caused by a lesion in the MLF which intterupts the connection between the abducens and contralateral oculomotor nucleus. causes difficulty addcuting the ipsilateral eye.
- this can be seen in MS.
INO vs CN3 palsy:
INO; eye can adduct during convergence. CN3 palsy it cannot adduct during convergence.
Brodmanns area for:
Frontal eye fields:
Primary Visual Cortex
Visual association cortex:
upper bank of the calcarine cortex is called:
lower bank of the calcarine cortex is called:
the lingual gyrus
info from the right lower visual field is projected to:
the left cuneus (upper bank)
information from the right upper visual field is projected to:
the left lingual gyrus (lower bank).
patients with cortical blindness:
have no blink to threat, no optokinetic responses but do have pupillary resonses to light.
fast conjugate eye movements used to bring a target into view. there is some voluntary control. the frontal lobe generates these through connections with the PPRF.
this allows one to view a moving object. it is not under voluntary control. the parieto-occipital cortex generates ipsilateral of these.
smooth pursuit movements.
this is important in upgaze:
this is important in downgaze:
rostral interstitial nucleus of the MLF.
causes painless vision loss of sudden onset:
anterior ischemic optic neuropathy.
this is the most common cause of persistent monocular vision loss in patients over 50 years old:
AION, may occurin in giant cell arteritis.
miosis, anhydrosis, ptosis
Horners syndrome pupil:
react to light??
dilate with 10% cocaine?
- temporary loss of vision.
- due to emboli causing temporary occulsion of the retinal artery. often described as a shade coming down.
denial of cortical blindness. cause would be bilateral PCA infarcts resulting in bilateral occipital lobe damage.
irregular, small pupil that reacts poorly to light but reacts to accomodation. associated with CNS syphillis.
balint's syndrome triad:
simultanagnosia; optic ataxia; ocular apraxia
due to bilateral parietal-occipital damage.
foster kennedy syndrome triad:
ipsilateral anosmia; ipsilateral optic atrophy; contralateral papilledema.
foster kennedy syndrome is associated with:
a mass, like a meningioma, involving the olfactory groove or sphenoid ridge. the mass compresses one optic nerve, causing optic atrophy and increases ICP resulting in papilledema in the contralateral eye.
What is the cause of Parinaud's syndrome?
lesion in the dorsal midbrain affecting the superior colliculi and pretectum.
What are the findings in Parinaud's syndrome?
- 1) paralysis of upgaze and accommodation
- 2) light-near dissociation
- 3) eyelid retraction (Collier sign)
- 4) convergence-retraction nystagmus on attempted upgaze.
a person can see moving fingers but not still fingers.
What are the characteristics of spasmus nutans?
- 1) titubation/nodding of the head
- 2) nystagmus
- 3) torticollis
decreased visual acuity assocaited with increased temperature. it is seen in optic nerve disease.
What is von Graefe sign and when can it be seen?
- - when during downward gaze there is a lag of the upper lid
- - can be seen in thyrotoxicosis.
- ipsilateral CN3 palsy and contralateral weakness.
- due to a lesion in the ventral midbrain involving CN3 and the cerebral peduncle.
This syndrome is characterized by the following triad:
- agenesis of the corpus callosum
- infantile spasms
- chorioretinal lacunae (can also see optic nerve coloboma)
What are the genetics of Aicardi syndrome?
This is a type of recurrent vasculitis and can be associated with recurrent meningoencephalitis:
What is the classic triad of Bechet disease?
- - oral ulcers
- - genital ulcers
- - uveitis
What is chronic progressive external opthalmoplegia?
- - mitochondrial disease that begins after age 20.
- - characterized by progressive bilateral ptosis and loss of eye movements.
Homocystinuria is associated with this:
downward lens subluxation
What is Kearns-Sayre syndrome?
- - mitochondrial disorder
- - can have progressive external opthalmoplegia
- - pigmentary retinopathy
- - elevated CSF protein
- - cerebellar syndrome
- - endocrine abnormalities
- - heart block
- - mitochondrial myopathy
What is Leber's Hereditary Optic Neuropathy?
bilateral optic neuropathy due to a mitochondrial DNA point mutation.
How does LHON present?
as a painless loss of central vison usually beginning in adolesence or early adulthood.
What causes locked in syndrome?
bilateral ventral pontine lesions.
What are the two things patients can do with locked in syndrome?
blink and move their eyes vertically
What is oculopharyngeal muscular dystrophy?
- ptosis and impairment of EOM without diplopia.
- starts in the 5th decade of life
- can also have swallowing difficulty
what causes oculopharyngeal muscular dystrophy?
GCG repeat expansion in the gene encoding PABP2 on chromosome 14
what does the pathology in oculopharyngeal MD show?
What is NARP?
Neuopathy, Ataxia, retinitis pigmentosa
What is the most common presentation of NARP?
What causes NARP?
mitochondrial disease. due to an ATPase point mutation
What diseases cause a cherry red spot?
- - Farbers lipogranulomatosis
- - GM1 gangliosidosis
- - Sandhoff disease
- - Sialidosis
- - Tay Sachs
- - Neimann Pick Disease Type A
What is opsoclonus myoclonus associated with?
- - childhood neuroblastoma
- - adults with anti-Ri AB which is associated with breast, gynecologic and lung cancers.
What is Susac's syndrome?
microangiopathy involving the brain, retina and cochlea that usually presents in young women.
What is the triad of Susac's syndrome?
- 1) branch retinal artery occlusions (BRAO)
- 2) encephalopathy
- 3) sensorineural hearing loss
What are the typical brain MRI findings in Susac syndrome?
multiple areas of high T2 signal, may resemble MS. involve the gray and white matter. the corpus callosum is often involved.
What is the triad that characterizes Wernicke Encephalopathy?
- 1) oculomotor palsy
- 2) ataxia of gait
- 3) confusion
What is the cause of whipple's disease?
gram positive bacillus (Tropheryma whippelii) which is PAS +
what is the classic triad of Whipple disease?
- 1) dementia
- 2) supranucelar gaze palsy
- 3) myoclonus
What is Wolfram Syndrome?
a constellation of diabetes insipidus, diabetes mellitus, optic atrophy and deafness (DIDMOAD)
What can cocaine cause in terms of eye movements?
What eye findings to ethylene glycol cause?
non reactive pupils and loss of corneal reflexes
what eye findings can ethambutol cause?
what eye findings can vigabatrin cause?
bilateral concensual visual field defects with relative temporal sparing
What eye findings can thioridazine cause?
What is Charles Bonnet Syndrome?
where patients with vision loss see things in the space where vision is lost.
What characterizes Dementia with Lewy Bodies?
- - degenerative dementia
- - fluctuating levels of alertness
- - visual hallucinations
- - parkinsonian features
- - sensitivity to neuroleptics
in patients with epilepsy, where do formed visual auras arise from?
in patients with epilepsy, where do simple, unformed visuals auras arise from? (like flashing lights)
what can nacolepsy be associated with?
hypnopompic or hypnagogic hallucinations
What are peduncular hallucinosis?
vivid images seen following midbrain injury
What is the most common genetic cause of visual impairment?
Leber congenital amaurosis
What part of the eye has the highest visual acuity?