Retina and Optic nerve

Question 1

primary vitreous
secondary vitreous
tertiary vitreous

Answer 1

• primary: vessels of hyaloid, macrophages, collagenous fibrillar material, mesenchymal cells
• seconday: primitive hyalocytes, hyaluronic acid, and monocytes. Persists in adults as formed vitrous
• tertiary: secreted by ciliary epithelium and becomes lens zonules + vitreous base

Question 2

persistant hyaloid artery

Answer 2

usually not a problem

• mittendorf’s dot: attached to posterior lens capsule
• bergmeister’s papilla: large remnant on optic disc

Question 3

persistent hyperplastic primary vitreous

Answer 3

• most commonly with Dobermans and Staffordshire
• “white pupil” is a common sign
• most frequent problems are spontaneous hemorrhage and cataract

Question 4

asteroid hyalosis

Answer 4

Ca or lipid deposition in the vitreous
not considered a problem
mostly older animals

Question 5

what are the 10 layers of the retina

Answer 5

• RPE (retinal pigmented epithelium)
• photoreceptors
• external limiting membrane
• outer nuclear layer (nuclei of rods and cones)
• outer plexiform layer (synaptic layer for photoreceptors, bipolar cells, and horizontal cells)
• inner nuclear layer (nuclei of bipolar, horizontal, amacrine and muller cells)
• inner plexiform layer (synaptic layer for bipolar and amacrine cells)
• ganglion cell layer
• nerve fiber layer(connected to optic nerve)
• internal limiting membrane

Question 6

what are the 4 retinal vascular patterns

Answer 6

• holangiotic (dog, cat, cattle, sheep, pig)
• paurangiotic (horse)
• merangiotic (rabbit)
• anangiotic (birds and reptiles)

Question 7

collie eye anomaly (CEA)

Answer 7

• autosomal recessive with no sex or coat predisposition
• only progressive if coloboma is present
• phenotypic signs include: coloboma (hole in an eye structure) , choroidal hypoplasia, retinal detachment, retinal hemorrhage

Question 8

what is progressive retinal atrophy

Answer 8

• autosomal recessive
• always bilateral
• can do genetic testing
• no treatment
• electroretinography testing at 1.5-2yrs old

Question 9

progressive retinal atrophy clinical signs

Answer 9

• rods go first, so lose night vision first
• decreased PLR so tapetal is hyperreflective
• attenuated vessels
• pale optic disc
• cataract formation
• should have some detectable ERG activity but no SARD activity

Question 10

CPRA (central progressive retinal atrophy) or RPED (retinal pigment epithelial dystrophy)

Answer 10

• usually only seen in England

- day blindness

Question 11

retinal dysplasia

Answer 11

• abnormal formation of retina (from small folds to complete detachment)
• usually present at birth with no progression
• autosomal recessive (cocker, lab, springer spaniel, bedlington, sealyham)
• can be secondary to infectious dz (FeLV, BVD, adenovirus)

Question 12

merle ocular dysgenesis

Answer 12

associated with marling gene
wide range of abnormalities
-homozygous: multiple ocular defects, predominantly white
-heterozygous: occasional ocular defects

Question 13

SARD (sudden acquired retinal degeneration)

Answer 13

• sudden complete blindness
• usually middle aged overweight females
• may be associated to Cushing’s
• no known treatment
• no ERG activity, if there is ANY then diagnosis needs to correlate with brain or optic nerve

Question 14

FCRD (feline central retinal degeneration)

Answer 14

often incidental finding
associated with Taurine deficiency
progression from grade 1-5

Question 15

______ is associated with acute blindness in cats

Answer 15

enrofloxacin (baytril)

-more associated with parenteral administration

Question 16

chorioretinitis can be____, _____, or _____

Answer 16

septicemic, viral, or fungal

Question 17

true/ false

DIC and trauma are common reasons for retinal hemorrhage

Answer 17

FALSE

common reasons: hypertension, thrombocytopenia, coagulopathy, radiation, hyperviscosity, senile

Question 18

common reasons for retinal detachment

Answer 18

hypertension
exudative/ serous
neoplasia
congenital 
traume is RARE

Question 19

4 things that can go wrong with the optic nerve

Answer 19

• hypoplasia (congenital)
• papilledema aka edema of optic disk from increased CSF pressure (still have some vision and usually normal PLR)
• coloboma
• atrophy

Question 20

optic neuritis

Answer 20

clinical signs: acute blindness, mydriatic, no PLR

• if optic nerve head is effected it may be swollen/inflammed/hemorrhagic (if retrobulbar optic nerve is affected without the head being effected, the head may appear normal )
• treat underlining cause

Question 21

if there is a large _____ mass, blindness can be associated with endocrine disease

Answer 21

pituitary mass due to being close to optic chiasm