Neuro-Ophthalmology Flashcards
what does pupillary light reflex involve?
photoreceptors
retinal ganglion cells
what can make a PLR be absent in a visual pet?
medications/toxins
fear
iris atrophy
synechiae
what toxins can cause vision loss?
ivermectin
fluoroquinolones
ethylene glycol
what is anisocoria?
pupils asymmetrical in size
what conditions do you need to rule out with anisocoria with the abnormal pupil being miotic?
corneal ulcers
uveitis
posterior synechiae
what are the four signs of horners?
miosis
enophthalmos
ptosis
third eyelid protrusion
what can large forebrain lesions lead to with CN III?
loss of inhibitory tone
what should you rule out with bilateral mydriasis?
bilateral glaucoma
optic neuritis
retinal detachment, degeneration
iris atrophy
what supplies the orbicularis oculi muscle?
facial nerve
what is strabismus?
rotational misalignment of eyes
what are the two types of strabismus?
restrictive
pareetic/plegic
what does the parasympathetic division of the oculomotor nerve (CN III) do?
constricts pupil
what does CN IV control?
dorsal oblique
whaat does normal eye position require to be normal?
inner ear
vestibular nerve
cranial nerves controlling extraocular muscles
extraocular muscles
what cranial nerves can be affected for external ophthalmoplegia?
III
IV
VI
where does vision loss usually localize to?
eyes
why might a patient have an absent menace but be able to see?
age
species
fear
inability to blink
cerebellar disease
can you have complete photoreceptor loss and still have PLRs?
yes
what things can mimic vision loss?
orthopedic disease
neurologic disease
behavioral/psychological
what nerve causes the pupil to dilate?
sympathetic trunk
what nerve causes the pupil to constrict?
CN III
can mild anisocoria be normal in heterochromic animals?
yes
blue eye slightly dilated
what do you need to rule out when the abnormal pupil is miotic?
corneal ulcers
uveitis
posterior synechiae
what drug can you use to confirm horners?
phenylephrine test
denervation hypersensitivity
what is horners often caused by in dogs?
idiopathic
less often idiopathic in cats
can you see horners with trauma to brachial plexus?
yes
what do you need to rule out when the abnormal pupil is mydriatic?
glaucoma
posterior synechiae
iris atrophy
retinal detachment, optic neuritis
what can cause internal ophthalmoplegia?
idiopathic and self-limiting
trauma
large cavernous sinus syndrome or CN III lesion
what should you rule out with bilateral miosis?
ophthalmic disease- uveitis
drugs
large forebrain lesions lead to loss of inhibitory tone on CN III
what ophthalmic disease should you rule out with bilateral mydriasis?
bilateral glaucoma
optic neuritis
retinal detachment, degeneration
iris atrophy
what are the eyes like with dysautonomia?
mydriasis
third eyelid protrusion
low schirmer tear test
what is restrictive strabismus?
fibrosis or other pathology limits eye movement
what are the two division of CN III?
motor division
parasympathetic division
what does the trochlear nerve (CN IV) control?
dorsal oblique muscle
what is nystagmus in siamese cats and relateed caused by?
abnormal projection of optic nerve fibers
