vision loss/neuro exam Flashcards
what is responsible for dim light vision
rods
PRA loses this first
animal is blind but has a dazzle and PLR
visual cortex disease
PLR and dazzle absent
immediately rule out cortex disease. think optic nerve or retina
what does ERG do
assess the retina. we expect to see peaks.
if this lesion is unilateral and the owner notes that the dog is running into things. where are we thinking
visual cortex disease. causes unilateral visual field loss which can severely affect ambulation.
optic nerve damage right sided, what would you expect to see: menace? PLR? pupil size?
absent menace on the right
pupil slightly larger right because consentual PLR isnt as good as true PLR
normal left eye
cortex lesion on the right side
left side: absent or decreased menace. normal PLR
right side: normal
difference between PLR and menace
menace is at the occipital cortex and PLR is at the brain stem.
what innervates the iris musculature
PS: constrit
Sym: dilation
where does sympathetic innervation to the iris arise
Thoracic vertebrae
sympathetic denervation causes what to the iris
miosis
dog with negative menace, positive but reduce PLR and reduced dazzle. normal exam. what do you do
likely retinal or optic nerve due to decreased PLR. do ERG to assess retina
sudden acquired retinal degeneration syndrome SARDS- what other clinical signs
cushings like signs, acute vision loss
negative menace, severely diminished dazzle, negative PLR
localize to retina or optic nerve. perform eye exam for retinal health and maze test
likely PRA
completely negative menace, dazzle and PLR, decreased IOP, aqueous flare
likely optic neuritis due to complete loss of reflexes
