Test 2: lecture 30 retina Flashcards
A biologic reflector system to enhance visual sensitivity in dim illumination
tapetum lucidum
tapetum in carnivores is
cellular
tapetum in herbivores is
fibrous
what kind of retinal vasculature do carnivores, primates, even toes ungulates and most rodents have
holangiotic
what kind of retinal vasculature do horses, odd-toed ungulates, guinea pigs have?
paurangiotic
what kind of retinal vasculature do lagomophs have?
Merangiotic- extend horizontally
what kind of retinal vasculature do birds, and monotremes have?
anangiotic- no vasculature in the retina, instead has a pecten in the vitrious that supplies nutrients
fovea is surrounded by the
macula
humans and NHP
fovea is an area of the eye with many —
cones- color seeing
humans and NHP
other mammals have a — instead of a fovea
visual streak
instead of a fovea dogs have
a visual streak with a small area centralis that has high number of Retinal Ganglion Cells and cones
how to do fundus exam
optic nerve head(ONH): shape, degree of myelination, vascularization
retinal vascularization (pattern, tortuosity, attenuation/thinning)
tapetal fundus (hypo or hyperreflectivity)
non-tapetal fundus (normally pigmented but can be non-pigmented).
take picture or draw diagram
— of the fundus changes with age
color
starts to form at 6 wks old and mature at 11 wks old
normal
degeneration: hyperreflectivity and loss of vasculature
what can cause this
hyporreflectivity- subretinal fluid, retinal detachment, retinal edema
perivascular cuffing →retinitis
where is the bleeding, what is the source?
subretinal- is from choroidal vessels
intraretinal and preretinal is from retinal vessels
what can cause retinal hemorrhage
Trauma
Anemia, coagulopathy, hyperviscosity
Systemic hypertension
Infectious diseases (e.g ehrlichiosis)
how to exam retina if there is a loss of transparency of cornea, aqueous humor or lens
ocular ultrasound
Useful to detect retinal detachment
how does OCT work
sends infared waves into eye to map eye
Optical coherence tomography (OCT)
(= non-invasive imaging of the retinal layers)
needs to be sedated
test to measure if rods and cones are working
ERG- Electroretinography
when to use Electroretinography
to measure if retina(cones and rods) is working
prior to cataract
early diagnosis of retinal degeneration
blind dog but everything looks normal
retinal dysplasia is caused by
genetic
maternal viral infections: herpes, panleuk
toxicities in utero
neuroretina does not attach to the RPE and folds onto itself forming rosettes
3 forms of retinal dysplasia
focal/multifocal- vision usually normal
geographic- vision depends on how big lesion is
complete retinal dysplasia with detachment- blind, skeletal dysplasia- labs and samoyeds
retinal dysplasia: Congenital, developmental abnormality of the retina where retina does not bind to RPE and folds onto itself forming rosettes
more common in dogs then cats/cattle
collie eye anomaly is caused by —
genetic (NHEJ1)
collie eye anomaly will cause
choroidal hypoplasia +/- posterior coloboma (< 10% of cases)
how to diagnosis collie eye anomaly
have to find it before RPE becomes pigmented (6-10 weeks old)
choroidal hypoplasia
inherited retinopathies are normally
autosomal recessive > XL> autosomal dominant
most common rods affected but can attack cones, rods, RPE
the most common cause of later onset progressive retinal atrophy is by a defect in — gene
PRCD
progressive rod cone degeneration
effects toy poodles, cocker, labs and many other breeds
clinical signs of inherited retinopathies
vision loss: night and day vision loss
↓ PLRs
tapetal hyperreflectivity
retinal arterioles then venules get smaller
optic disc atrophy
+/- secondary cataract
SARDS
Sudden Acquired Retinal Degeneration Syndrome
cause unknown, no treatment
dogs with acute blindness, dilated pupils, responsive to bring blue light, no response to bright red light
how to diagnosis SARDS
ERG
PLR slow
no response to bright red
responsive to bright blue light
cause unknown- suddent blindness in dogs
active retinitis/chorioretinitis will look
Borders poorly defined, hyporeflectivity, perivascular cuffing, exudative retinal detachments
inactive Retinitis/ Chorioretinitis will look
Sharp borders, hyperreflectivity, depigmentation in non-tapetal fundus
what are some causes of retinitis/chorioretinitis
Dogs: Distemper, fungi, ehrlichia, rickettsia, Prototheca
Cats: FIP, FeLV, FIV, Toxoplasmosis, fungi
Separation of the neuroretina from the RPE
retinal detachment
Rhegmatogenous
retinal tear allows vitreous to get under
neuroretina and separate it from RPE.
