Lecture 3 Flashcards
what this
iris atrophy (with cataract)
how can you tell between a persistent pupillary membrane and iris atrophy?
ppm originates from collarette
what is iris atrophy?
senile loss of iris tissue –> spontaneous progressive thinning of storm or pupillary margin
pupillary margin develops moth-eaten appearance, creating dyscoria, a scalloped appearance of pupillary portion of iris, and PLR deficit if severe
what is this?
iris atrophy
what is this
uveal cyst
- black circular mass between cornea and iris in ventral anterior chamber
what is a uveal cyst? is there breed disposition?
single/multiple, uni/bi-lateral, oval, dark/translucent mass arising from posterior iris
they are benign
goldens, labs, Bostons
how do you tx uveal cysts?
not required if vision is not impaired
laser ablation or aspirate with 27g needle
wot dis
hyphema
blood in the anterior chamber, settled blood in ventral anterior chamber
wot
hyphema
complete filling of anterior chamber with blood, blood also pooling under dorsal conjunctiva (secondary to dorsal globe rupture)
what are the causes of hyphema?
- primary ocular causes
- trauma (intraocular tumor, retinal detachment, anterior uveitis)
- systemis (blood dycrasias, clotting abnormalities, circulatory disorders)
what is this ?
iris melanoma
multifocal areas of iris hyperpigmentation
what is the most common primary intraocular tumor in cats?
feline diffuse iris melanoma
tell me about the progression of feline diffuse iris melanoma? what about mets?
starts as benign nevi on iris surface (superficial iris stroma without destruction of normal iris architecture, well circumscribed flat), then over the course of months to years, benign pigmentation may undergo malignant transformation (infiltration of iris stroma with loss of normal iris surface architecture, raised)
mets possible, but true rate unknown
what can happen with feline diffuse iris melanoma?
anterior uveitis, secondary glaucoma, ocular discomfort, and vision loss
for feline diffuse iris melanoma, who is most at risk?
- diffuse lesions >50% iris surface
- significant elevation on iris surface
- pigment cells in anterior chamber
- dyscoria
- glaucoma
how do you treat feline diffuse iris melanoma?
age of pt can dictate options
- watch + monitor
- laser ablation (can be effective in prevention progression if done early enough)
- enucleation (if glaucoma or diffuse changes)
what the heck? what is it?
iris melanoma
what dis
iris melanoma –> could laser ablate at this point
what is this
iris melanoma (diffuse) –> have to enucleate
if does not have glaucoma currently, will develop glaucoma shortly
what is happening here
glaucoma
corneal cloudiness, white lines in cornea, dilated pupil, buphthalmia
tell me about normal aqueous humor dynamics
- AH produced in ciliary body in nonpigmented epithelium
- rate of formation = outflow (resistance at outflow, otherwise anterior chamber would collapse) –> maintains IOP
- normal IOP = 15-25 mmHg (in cats and horses can be up to 30)
- pump operates at a constant rate, not sensitive to IOP
- inflow: AH flows into posterior chamber, through pupil, into anterior chamber, to iridocorneal angle (where outflow starts)
- outflow: through corneoscleral trabecular meshwork, out through aqueous collecting veins (most of it, conventional outflow), or uveoscleral into systemic circulation (non-conventional outflow, independent of IOP and by osmosis)
what is the most frequent cause of irreversible blindness in dogs?
glaucoma
what are the causes of glaucoma?
primary:
- goniodysgenesis
- congenital (rare)
secondary:
- anterior lens luxation
- anterior uveitis
- intraocular neoplasia
- hyphema
- retinal detachment (chronic)
IOP elevation is due to….?
decreased aqueous humor outflow (either primary or secondary iridocorneal angle issues)
what is goniodysgenesis?
continuous sheet of tissue bridging across iridocorneal angle –> normal pectinate ligaments and spaces b/t them fail to form
glaucoma may occur with aging in those with this (doesn’t ensure development of glaucoma)
what occurs in one eye eventually will be bilateral
there is breed predisposition, but there are a lot of them and I dont wanna remember them :)
what is this showing?
goniodysgenesis
most cases of glaucoma occur _____.
how does loss of vision occur in these cases?
acutely
destruction of ganglion cells and optic nerve
what are the effects of elevated IOP?
- ischemic damage
- compressive damage of axons (reversible if caught early)
- lamina cribosa pushed back, optic nerve cupping
- injection of episcleral vessels
- mydriasis (axon compression, ischemic/neural damage, chronic atrophy)
- corneal edema (AH into cornea, altered endothelial function)
- buphthalmia (chronic)
- Haab’s striae (chronic) (breaks in Descemet’s membrane with globe enlargement = stretch marks) (when this is noted, glaucoma is the cause)
- lens subluxation (chronic)
- pain (acute & chronic)
Ice Cream Lovers Indulge, Making Cool Blissful Happy Licks Pleasurable
what is this showing?
optic nerve cupping
how can you tell if cause of glaucoma is primary or secondary?
gonioscopy –> allows assessment of iridocorneal angle
also looking at the whole eye and seeing if there are other problems present
primary: ICA blocked/problematic
secondary: ICA normal/open
what is the goal of emergency therapy for glaucoma? what do you do in this situation?
reduce IOP quickly to reduce damage to the retina and optic nerve. goal is to reduce IOP <10 mmHg (lower is better)
institute medial therapy ASAP, if unresponsive, then emergency surgery
describe medical mgmt for glaucoma
- decrease aqueous humor production –> beta blocker, carbonic anhydrase inhibitor
- increase aqueous humor outflow –> parasympathomimetics, prostaglandins
tell me about beta blockers for glaucoma. what is the name? when is it contraindicated? what are the side effects?
Timolol (0.5% BID)
contraindicated in pt’s w lower airway dz or heart failure
side effects: reduces ability to heal epithelial defects
poor clinical efficacy if used alone
tell me about prostaglandin analogues for glaucoma. what is the name? what are the side effects? what are the contraindications?
Lantanaprost (1-2x/day)
side effects: miosis, conjunctival irritation, may worsen uveitis
effects can be seen within 30 mins!
contraindicated: anterior lens luxation (traps pupil in lens)
tell me about carbonic anhydrase inhibitors for glaucoma. what is the name? what are the side effects?
dorzolamide, brinzolamide
side effects: well tolerated but can be irritating topically
what do osmotics do for glaucoma? (ex. mannitol)
Brian doesn’t use this, this is a NAVLE question
reduces vitreous size via dehydration –> ICA opens in process
requires hospitalization and placement of IVC
what do parasympathomimetics (pilocarpine) do for glaucoma?
Brian doesn’t use this, this is a NALVE question
opens ICA
topical –> stings and not very effective
with glaucoma that needs surgery, the prognosis is always ____ for long term maintenance of vision
guarded
what are your options for acute glaucoma surgery?
- laser cyclophotocoagulation (best long term)
- gonioimplant (poor longterm success, inevitable failure)
for chronic glaucoma when vision isn’t restored, what are your treatment options?
1) keep pt comfortable: IOP <35 mmHg
2) enucleation
3) evisceration (take out inside part of eye and put in silicone ball)
4) intravitreal gentamicin injection
what is this
dog with eviscerated eyeball OD (healed)
what is glaucoma?
increase in intraocular pressure
what is a cataract?
opacity of the lens
if severe enough, will prevent light from reaching the retina and will impair vision
cataract classification is based on ____. tell me the classifications.
based on “stage of development”
incipient = small focal opacity
immature = more diffuse, but tapetal reflection present
mature = fundic reflection obliterated
hyper mature = lens material liquifies and leaks into eye (assoc w anterior uveitis), wrinkling of lens capsule
what is this showing
incipient cataracts
note small specks throughout lens (these are the cataracts)
note tapetal reflection
what is this showing
immature cataract (early)
multifocal coalescing opacities in lens, esp at equator
note tapetal reflection
what is this
immature cataract (early) as seen via indirect ophthalmoscopy
what is this showing
immature cataract (late)
diffuse opacification of the lens, but tapetal reflection present
what is is this showing
mature cataract
diffuse opacification of lens without tapetal reflextion
what is this
hyper mature cataract
diffuse opacitfication of lens and wrinkles in lens capsule, no tapetal reflection
what are the causes of cataracts?
- diabetes mellitus (dogs only)
- genetic (dogs > cats)
- age
- congenital (uncommon)
- uveitis (most common cause in horse + cat)
- nutritional (puppies fed poor milk replacement)
why does diabetes mellitus cause cataracts?
50% of dogs w DM will develop cataracts within 5-6 mo from time of dx.
80% of dogs will develop cataracts w/i 16 mo of dx
increase glucose overwhelms glycolysis, so it’s shunted to sorbitol pathway where it builds up and doesn’t leave lens, creates osmotic gradient that pulls H2O into lens and damages lens fibres
what is this showing
diabetic patient with anterior lens capsule rupture + cataract due to rapid onset cataract development and swelling
how do you treat cataracts?
phacoemulsification and lens replacement surgery
medical mgmt doesn’t make a clinical difference
how can you medically prevent cataracts in diabetic patients?
aldose reductase inhibitor (kinostate and Ocu-GLO)
don’t stop once started bc cataracts form within 2 weeks of stopping therapy
what is this
nuclear sclerosis
central hazy zone with tapetal reflectivity
can see ring in middle of eye and can see through it more. with immature cataract, the opacity is more diffuse
what is nuclear sclerosis? why does it occur?
hardening and increased density of nucleus of lens
occurs with age, beginning around 7yo in dogs
nucleus of lens becomes hazy but not opaque –> owners describe blue appearance
what dis
anterior lens luxation
note cataractous lens anterior to iris + iris is hyperaemic due to underlying anterior uveitis (feline)
what dos?
lens subluxation
aphakic (without a lens) crescent laterally
in order for aphakic crescent to be noted, zonules have to be missing
lens still in relatively normal position, hence SUBluxation
what is lens luxation? what are the two types?
dislocation of lens form its normal anatomic location. zonules need to be disrupted.
anterior lens luxation: lens located in anterior chamber (in front of iris)
posterior lens luxation: lens behind iris, may visualize aphakic crescent between iris and lens equator
what two things can you see with lens subluxation?
iridodonesis: trembling of iris with movement of eye
phacodonesis: trembling of lens with movement of eye
true or falsE: lens subluxation can be asymptomatic
true
what causes lens luxation?
primary:
- genetic (terriers)
secondary:
- glaucoma
- chronic uveitis (most common in cats)
- trauma
- age
what is the relationship between glaucoma and lens luxation?
lens luxation can cause glaucoma, and glaucoma can cause lens luxation.
a dog has glaucoma + lens luxation. how can you tell which came first?
primary lens luxation + secondary glaucoma: no buphthalmia, lens luxated anteriorly
primary glaucoma + secondary lens luxation: buphthalmia, posterior lens luxation
how do you treat lens subluxation?
medication to induce miosis (Lantanoprost) to trap lens behind iris
how do you treat posterior lens luxation?
induce miosis (lantanoprost)
how do you treat primary anterior lens luxation?
remove lens ASAP (esp if IOP elevated)
what is this
asteroid hyalosis
numerous circular opacities located behind lens
what is asteroid hyalosis?
calcium/cholesterol bodies in vitreous humor
multifocal white vitreal opacities
wot dis?
progressive retinal atrophy
tapetal hyper-reflectivity, vessel attenuation
what is progressive retinal atrophy?
group of photoreceptor diseases characterized by slowly progressive vision loss
what are the C/S of progressive retinal atrophy?
- nyctalopia (night blindness) - bc rods are affected first
- eventual blindness - as cones are lost
- mydriasis
- cataracts
what does progressive retinal atrophy look like ophthalmoscopicly?
- diffuse tapetal hyper-reflectivity
- vessel attenuation (narrowing of vessels at back of eye)
- optic nerve atrophy
what is sudden acquired retinal degeneration?
sudden onset blindness in which the retinas appear normal but are not functioning properly
blindness occurs over hours to days, sometimes PU/PD
what are the C/S of sudden retinal degeneration?
- poor PLRs
- retinas appear normal initially
- electroretinogram –> flat line
what is syneresis and what does it look like?
liquefaction of the vitreous humor
looks like cotton candy material
degenerative or aging change
what are the causes of sudden acquired retinal degeneration and what is the treatment?
causes: unknown!! (could be immune mediated or cancer assoc, but we dunno)
treatment: none :(
what is this?
chorioretinitis
tan/white lesions with hazy borders overlying tapetum and nontapetum
what is chorioretinitis? what is the difference between if it’s diffuse vs small/focal?
chorioretinitis can be associated with…?
inflammation of the choroid and retina
diffuse: can cause retinal detachment
small/focal: no notifiable signs may be appreciated.
can be assoc with anterior uveitis and is often a manifestation of systemic disease
what is this
chorioretinal scar
hyper-reflective area with focal hyperpigmentation lesion dorsally
Brian says this one requires more interpretation lol
what dis
chorioretinal scar
focal well demarcated white lesions in non-tapetum
what is the difference between ophthalmoscopic appearance of active vs inactive chorioretinitis?
active:
- focal/multifocal
- dull grey/tan colour
- poorly demarcated
- can have a “mass” appearance
- occasionally associated hemorrhage
inactive:
- focal/multifocal
- hyper-reflective if in tapetum
- depigmented if in non-tapetum
- flat
- well demarcated
what is this
bullous retinal detachment
translucent material (retina) with vessels located behind lens
what are these photos showing?
rhegmatogenous retinal detachment
translucent material (retina) overlying optic nerve head
what is retinal detachment? what are the types?
separation of the neurosensory retina from underlying retinal pigmented epithelium
Bullous/Serous: separation due to accumulation of inflammatory material, transudate, or hemorrhage
rhegmatogenous: separation begins as a tear (usually in periphery), then progresses as vitreous accumulates between layers
what are the causes of serous/bullous retinal detachment?
- assoc w chorioretinitis
- steroid responsive retinal detachment
- hypertension (most common cause in cats)
- hyper viscosity
what are the causes of rhegmatogenous retinal detachment?
- breed disposition (bichon frise, shih tzu)
- assoc w hyper mature cataract
- trauma
what dis
optic neuritis
optic nerve head hyperaemic and edge is indistinct with overlying hemorrhages
what is optic neuritis? what are the clinical signs?
inflammation of the optic nerve
acute to subacute onset of blindness
ophthalmoscopic appearance; swollen, edematous, hyperemic optic disc and edges indistinct
what are the causes of optic neuritis?
- idiopathic (immune-mediated 90% of cases)
- GME
- neoplastic (lymphoma)
- infectious (CDV, toxoplasmosis, fungal)
how do you diagnose and treat optic neuritis?
dx: ophthalmoscopy, ERG, MRI/CT, CSF tap
tx: depends on cause.
- immunosuppressive dose of corticosteroids –> rapid response, treat on tapering regimen for months, may recur
