Retina and Optic Nerve Flashcards
what are cones responsible for?
bright light
color
acuity
what forms the optic nerve?
axons of ganglion cells
what do ganglion cells receive signal from?
interneurons
what provides outer retinal nutrition?
retinal pigment epithelium
choroid
what are the functions of the retinal pigment epithelium?
outer retinal nutrition
blood-retinal barrier
photopigment regeneration
waste disposal
thermal protection
what does the tapetum do?
increases light capture
decreases acuity
is magnification in direct or indirect ophthalmoscopy greater?
direct
what should your scope be set to for small animal indirect?
28D
when should you do fundoscopy?
screening for inherited diseases
suspect retinal or optic nerve disease
systemic disease
what are the etiologies of retinal dysplasia?
inherited
in utero infection
syndromic
what are the features of collie eye anomaly?
choroidal hypoplasia
colobomas
retinal detachment
intraocular hemorrhage
does retinal degeneration look similar at the end regardless of etiology?
yes
who does progressive retinal atrophy occur in?
mostly dogs
rare in cats
when is progressive retinal atrophy genetic testing helpful?
breeding
working dog programs
what is sudden acquired retinal degeneration syndrome?
photoreceptor apoptosis
unknown cause
what is case presentation of sudden acquired retinal degeneration syndrome?
acute bilateral vision loss
poor menace, PLR, dazzle
commonly cushinoid
normal fundic exam
what is electroretinography?
electrical test of outer retinal function
what is feline fluoroquinolone toxicity from?
abnormality in transporter protein
what infectious diseases can cause chorioretinitis?
systemic fungal disease
viral
rickettsial
protozoal
what is chorioretinitis?
inflammation of choroid to retina
what percentage of hypertensive dogs have ocular lesions?
62%
what are the types of retinal detachment?
rhegmatogenous
exudative
tractional
what breeds are predisposed to to get rhegmatogeenous retinal detachment?
shih tzu
boston terrier
italian greyhound
what are exam findings in rhegmatogenous retinal detachment?
tapetal hyper-reflectivity
absent retinal vessels
grey veil over optic nerve
out of focus
what happens in exudative retinal detachment?
retina is pushed out of place
what can cause bullous/exudative retinal detachment?
systemic hypertension
infectious
inflammatory/autoimmune
neoplasia
is the optic nerve a true nerve?
no
white matter tract of brain
what is optic neuropathy?
progressive death of retinal ganglion cells and their axons
what is interrupted in retinal detachment?
photopigment regeneration
what nutrition do retinal vessels provide?
inner retinal nutrition
what happens in retinal detachment?
neural retina (photoreceptors) separates from retinal pigmented epithelium
what is the tapetum like in carnivores and herbivores?
cellular in carnivores
fibrous in herbivores
what can you use to dilate the pupil for a fundic exam?
tropicamide
not atropine
can the tapetum be present or absent depending on coat/eye color?
yes
what is the fundus like in a cat?
tapetum, RPE pigment variable
no venous circle over optic nerve head
optic nerve head lacks myeline
conus common
what are the clinical presentations of retinal dysplasia?
multifocal retinal dysplasia
geographic retinal dysplasia
complete or total retinal dysplasia
what dogs can get collie eye anomaly?
collie
border collie
australian shepherd
shetland sheepdog
others
what can cause inherited retinal degenerations?
progressive retinal atrophy
what does retinal degeneration look like?
mydriasis
decreased to absent menace, dazzle, PLR
tapetal hyper-reflectivity
thin to absent retinal vessels
what causes progressive retinal atrophy?
genetic mutations
how is sudden acquired retinal degeneration syndrome treated?
no proven treatment
what is electroretinography used for/
sudden acquired retinal degeneration syndrome
early progressive retinal atrophy
retinal function with cataracts prior to surgery
what does feline taurine deficiency cause?
degeneration of retina starting dorsolaterally
what is treatment like of chorioretinitis?
variable
where is the retina attached?
around optic nerve head
ora ciliaris retinae
what is presentation of optic neuritis?
vision loss
anisocoria, mydriasis
other neurologic signs
what is glaucoma?
optic neuropathy: progressive death of retinal ganglion cells and their axons
