SAM3.8: Vitreous, Retina, and optic n.

Vitreous is

a transparent hydrogel that takes up 80% of globe volume.

Primary Pathological rxns of the vitreous (3)

Liquefaction.

Scar tissue.

Infection/inflammation.

Persistent hyaloid a. is

a remnant of hyaloid a. attached to optic n. head or lens.

Vitreous development (3)

Primary - vascular hyaloid system.

secondary - forces primary to become hyaloid canal.

tertiary - becomes suspensory lgmt for lens.

Persistent hyperplastic primary vitreous (PHPV) (2)

White/fibrovascular plaque on posterior lens capsule/anterior vitreous.

Genetic in Dobies.

Vitreous Opacities (floaters) include (6)

Asteroid hyalosis (calcium opacities fixed in vitreous).

Synchysis scintillans (cholesterol moving w/in liquified vitreous).

Traction bands.

Anterior vitritis.

Vitreous haze from retinitis/optic neuritis.

Vitreous hemorrhage.

Anterior hyalosis is a

degenerative condition where opacity is seen in the vitreous due to calcium phospholipid fixed in vitreous.

Anterior vitritis (pars planitis) may be seen w/

uveitis in cats - may lead to lens luxation due to damage of zonular fbs.

Seeing vitreous in the anterior chamber is concerning for

lens luxation.

Vitreous hemorrhage etiology (7)

Trauma.

Hypertensive retinopathy.

Collie eye anomalies.

Detached retina.

Uveitis.

Clotting disorder.

Intraocular Sx.

Vision is tested by (4)

menace reflex (may need to wait until 4m of age).

Tracking responses.

Maze performance.

Visual tracking.

Subalbinotic funduse

normal - seen in dogs that lack pigment in the back of the eye.

Looks like hemorrhage (is not!), but you are just seeing choroid vessels and sclera .

Retinal dysplasia can present w/

folds or geographical detachment.

Retinal dysplasia genetic prediposition

Labradors - will also see forelimb/skeletal abnormalities.

Collie eye anomaly - in order of severity less to most(3)

Choroidal hypoplasia.

Retinal detachment - can see retinal folds.

Optic n. coloboma.

Collie eye anomaly - the dogs can have

one or multiple of the anomalies associated w/ dz.

Choroidal hypoplasia can only be

seen when they are puppies - are masked when they get older and can only Dx w/ genetic test.

Equine Stationary night blindness (2)

rods of the retina are abnormal which affects night vision.

Cones are unaffected so daytime vision is unaffected.

Progressive retinal atrophy (PRA) is seen in

canines (and occasionally cats).

PRA appearance of the eye (2)

gradual thinning of the retina and tapetum is more reflective (b/s of loss of retinal tissue).

Decreased size and diameter of vessels.

PRA: retina thins resulting in

increased tapetal reflectivity

PRA: Non-tapetal retina

changes in RPE of non-tapetal retina - may see pigment build-up.

PRA may have

secondary cataract - make sure that the retina works prior to catracts Sx.

Feline Retinal Degeneration is seen w/ (3)

Genetics.

Taurine deficiency.

Toxic - Enro (baytril).

Sudden Acquired Retinal Degeneration (SARD) is seen in

canines w/ an acute onset

CS/CP of SARD - may have (3)

PU/PD or polyphagic.

Increased ALP.

Decreased sense of smell.

Etiology of SARD

unknown - potentially autoimmune.

SARD - eye appearance (4)

Blind.

Normal appearing retina.

PLRs present but reduced.

Absent ERG (flat electroretnogram).

red light, blue light in a normal dog

will constrict w/ both

red light, blue light in a SARD dog

no constriction w/ red light.

may still respond to high intensity blue light.

Retinal lipemia may be a sign of

hyperlipidemia

Active chorioretinitis is when there is

there is active inflammation occurring

Retinal detachment def

split between neural and epithelial retina

Types of Retinal detachment (3)

Serous/Exudative.

Rhegmatogenous.

Traction.

A cause of serous/exudative retinal detachment

canine blastomycosis

Rhegmatogenous Retinal Detachment

tear in retina resulting in detachment, may become disinsertion.

Traction retinal detachment

retina pulled in different directions

Sx tx of retinal detachment

scleral buckle

laser or cryo retinopexy

Hypertensive retinopathy is seen in

older cats

Hypertensive retinopathy r/o's (4)

renal dz.

hyperthyroid.

cardiac dz.

idiopathic.

Micropapilla is

a small optic n. head, but has normal PLR and normal vision.

Optic n. hypoplasia def

small optic n. w/ decreased PLR, vision.

Optic n. hypoplasia is seen

in mini poodles.

Optic n. hypoplasia has to be differentiated from

micropapilla.

Optic. n. coloboma def

congenital absence of optic disc,

usually presnets as gap, hole, figure, notch-shaped defect

Papilledema def

edema of optic disc with normal vision

Papilledema is not

as common as optic neuritis.

Optic neuritis def

inflammation of optic disc with decreased vision.

Optic n. atrophy can be seen post (4)

trauma/proptosis.

inflammation.

optic neuritis.

orbital dz.

Optic disc cupping def

abnormal depression in optic disc (assoc w/ glaucoma)

Optic n. cupping is seen

as a sequellae to glaucoma (inc IOP can damage retinal cells)