Lecture 3 Flashcards
what is this
iris atrophy. not a persistent pupillary membrane because it does not originate from the collarette
also a mature cataract in the lens
explain what iris atrophy is
a senile old age loss of iris tissue where the pupillary margin starts to look moth eaten, creating dyscoria (abnormal pupil shape). if it’s severe it can cause PLR deficit
what is this?
iris atrophy, can see the pupil on the right side of the picture and then a bunch of holes and moth eaten appearance. this dog is likely old.
what is this? what treatment is required?
uveal cyst (in the anterior chamber in front of the iris). these are benign and not painful at all
no treatment is required as long as it doesnt affect vision, but you can do a laser ablation or aspirate with a 27G needle if you want
what breeds like to get uveal cysts?
goldens, labs, boston terriers
what is this
hyphema: blood in the anterior chamber
usually just from disease in the eye but can be from systemic disease too
what is this? treatment and prognosis?
hyphema: complete filling of anterior chamber with blood secondary to a globe rupture. this eye has zero prognosis for vision and the eye needs to come out
what are the causes of hyphema?
trauma: intraocular tumors, retinal detachment, anterior uveitis
systemic: leukemia or polycythemia, clotting abnormalities, circulatory disorders (hypertension)
what is this
iris melanoma: multifocal areas of iris hyperpigmentation
the most common primary intraocular tumor in cats is
iris melanoma
does iris melanoma in cats like to spread/metastasize?
no they usually dont spread
if iris melanoma in a cat progresses enough, it can cause…
anterior uveitis, glaucoma, ocular discomfrt and vision loss
how will you treat this cat
iris melanoma
can watch/monitor for changes and measure IOP
can do a laser ablation of the pigmented lesions
take the eye out when glaucoma occurs or if there’s diffuse changes noted
what is this
iris melanoma
what is this? what is the prognosis?
iris melanoma, diffuse pigmentation everywhere on the iris.pigment is also now on the anterior lens capsule and it is “too late” and if the cat doesn’t already have glaucoma it will get it :(
what is buphthalmia?
enlargement of the eye associated with glaucoma
10 yo border collie acutely blind but owners said his eyes have been abormal for a while. he has no menace, dazzle, or PLRs. IOP OD 40 and OS 62. Diagnosis?
glaucoma: elevated IOP with damage to the optic nerve
the aqueous humor is produced by the _____
ciliary body by the non pigmented epithelium
normal IOP is
15 to 25
describe the normal flow of the aqueous humor
produced by the ciliary body then goes into the posterior chamber (between the iris and the lens) and thru the pupil into the anterior chamber. then it flows to the iridocorneal angle (ICA) which is where the base of the iris meets the cornea and sclera.
what are the 2 different ways in which the aqueous humor can flow out of the eye?
conventional outflow: this is how 85% of the aqueous humor exits, flows thru the corneoscleral trabecular meshwork and this is where the majority of the resistance happens. It’s sort of like a seive for the flud, slows it down. it then goes into collecting veins
nonconventional outflow: thru uveoscleral outflow and thru the sclera. this is INDEPENDENT of IOP and is driven by OSMOSIS, then goes into systemic circulation.
he most frequent cause of irreversible blindness in dogs is
glaucoma
true or false: glaucoma can be caused either from increased production of the aqueous humor or a laxck of outflow
FALSE it is only due to decreased outflow, NEVER from over production
what is goniodysgenesis?
a predisposition to glaucoma/primary cause of glaucoma; the normal pectinate ligaments and spaces between them for the aqueous humor to flow through fail to form and the ICA becomes smaller, making it difficult for the aqueous humor to outflow. usually affects both eyes at different times
true or false: the prescence of gondiodysgenesis indicates glacuoma will develop later in life
false! most of the time they do but it’s no ensured
list at least 3 breeds predisposed to gondiodygenesis
atika, shiba inu, chow chow, beagle, husky, dalmation, GSD, etc
true or false: congenital primary causes of glaucoma are rare
truel
list some secondary causes of glaucoma
anterior lens luxation (prevents normal outflow)
anterior uveitis (debris and cells plug everything up)
intraocular neoplasia
hyphema
retinal detachment
true or false: most cases of glacuoma occur chronically
false, most cases occur acutely
glaucoma destroys which cells?
ganglion cells and the optic nerve leading to loss of vision
how quickly can vision be lost in acute cases of glaucoma?
in less than 1 day, necrosis and apoptosis of the ganglion cells in the retina occurs, and by day 7 there will be end stage retinal atrophy
what are the 3 effects of an elevated IOP?
ischemic damage
compressive damage to axons (can be reversible if caught early)
later degeneration: lamina cribosa gets pushed and you get optic nerve cupping, this is irreversible blindness
why does increased IOP cause mydriasis?
axon compression in the retina and optic nerve, ischemic damage to the iris sphincter muscle initially, and chronic atrophy of the iris stroma
why does increased IOP cause corneal edema?
the aqueous humor is pushed into the cornea from pressure, and the endothelial cells alter in function; they are no longer able to pump water out and eventually die off with chronicity
list some chronic changes of elevated IOP
buphthalmia (globe gets stretched from pressure)
Haab’s striae: stretch marks in descemet’s membrane
lens subluxation: globe enlargement causes zonules to stretch, usually a posterior lens luxation when glaucoma is the primary cause
why is glaucoma painful?
the globe stretches and this hurts!! but signs can be subtle: irritability, decreased appetite, sleeping more, hiding.
how do you tell if glacuoma is primary or secodnary?
you need to use gonioscopy to assess the iridocorneal angle
when presented with a glaucoma patient what are some questions you want to answer?
is vision present? do dazzle and menace
how long has the pressure been elevated?
are there signs of chronicity?
the goal of emergency glaucoma therapy is
to reduce the IOP quickly to reduce damage to the retina and optic nerve
with a glaucoma patient, we want to reduce the pressure to
<10mmHg ideally
describe medical management for glaucoma
carbonic anhydrase inhibitors: reduces aqueous production
prostaglandins: increase outflow
sometimes: beta blockers, parasympathomimetics
what are some side effects of using beta blockers to treat glaucoma?
can reduce ability to heal epithelial defects
contraindicated in patients with lower airway disease or heart failure
doeesnt work well by itself, better as add on tx
which drug can be used on an emergency basis (or for more chronic use) for glaucoma that can work as fast as 30 minutes?
prostaglandin analouges: Xalatan (lantanaprost)
which drug is good for long term glaucoma treatment but can be irritating?
carbonic anhydrase inhibitors like dorzolamide
why doesnt brian like using mannitol for glaucoma?
you have to give it IV and essentially dehydrate the patient and therefore dehydrate the vitrous. it requires hospitalization.
when should surgical therapy for glaucoma be considered?
patients that become refractory to medical treatment or not respond at all
if surgery for glaucoma is to be done, it needs to be done when?
before significant optic nerve damage has occured
what are the surgery options for glaucoma?
laser cyclophotocoagulation: damage the ciliary body to decrease fluid production, this is best for long term treatment
gonioimplant: a drainage procedure ith poor long term succes, tends to fail in 3-4 months
in a patient with glaucoma that is already blind, what treatment options are there then?
we just need to keep the patient comfortable, so use medical therapy to keep the IOP below 35. if you can’t do this, then you either need to do an enucleation or an evisceration
what is a nice option for older dogs with chronic glaucoma that are at risk for undergoing GA?
intravitreal gentamicin injection: damages ability to produce aqueous and can be done with just IV sedation/anesthetic.
if one eye has really bad glaucoma how can you prophylactically treat the other eye?
can use dorzolamide (carbonic anhydrase inhibitor)
a cataract is
an opacity of the lens
if a cataract is severe enough it will
prevent light from reaching the retina and can impair vision
briefly describe the classifications of cataracts
incipient: small dit dots
immature: more diffuse, tapetal reflex still present
mature: diffuse cloudiness and no more tapetal reflex, vision lost
hypermature: tapetal reflex comes back, lens is liquifying
what are these?
incipient cataracts
what dis
immature cataracts, can still see tapetal reflection!
true or false: even if you can see the back of the eye and do a complete fundic exam, surgery is still a good option for treating cataracts
false! only do surgery if you CANNOT visualize the fundus and the tapetal reflection is gone
what is this?
a late immature cataract, still tapetal relfection and its hard to see he fundus but still possible
what is a hypermature cataract?
where the lens material liquifies and leaks into the eye, usually associated with anteiror uveitis and wrinkling of the lens capsule
what dis
mature cataract (no tapetal reflection)
what dis
hypermature cataract, tapetal reflection is back
____% of dogs with diabetes will develop cataracts will develop within 5-6 months from the time of diagnosis
50
why does diabetes cause cataracts?
glucose overwhelms glycolysis pathways and is shunted into the sorbitol pathway and sorbitol struggles to leave the lens and draws in water and damages the lens fibers.
why dont cats with diabetes get cataracts?
they have low levels of the enzyme that converts glucose to sorbitol
what is this
a cataract with anterior lens capsule rupture. this can happen diabetic patients get cataracts really quickly
what causes cataracts?
genetic: really common in dogs, uncommin in cats
age
congenital: uncommon
uveitis: in horses and cats
nutritional: puppies on poor milk replacement
what medical treatment is available for cataracts?
SIKE nothing beech
how can you prevent cataracts from forming in diabetic patients?
aldose reductase inhibitors: kinostat or ocu-GLO
you MUST keep using it bc if you stop, cataracts can develop in 2 weeks of stopping
what is the most effective treatments for cataracts?
surgery: phacoemulsification and lens replacement
this dog is 13. what is this?
nuclear sclerosis: central hazy area
explain what nuclear sclerosis is
hardening and increased density of the nucleus of the lens, a normal age related change, the lens gets hazy but not opaque
wot dis
anterior lens luxation with a cataract in the lens
wot dis
lens subluxation: aphakic crescent present, zonules missing on one side
which lens luxation will you see the aphakic crescent?
posterior subluxation
what is iridodonesis and phacodenesis?
iridodonesis: when the iris wiggles with eye movement
phacodonesis: when the lens wiggles with eye movement
list causes of lens luxation
primary: genetic, terriers and heelers, a specific gene
secondary: glaucoma, chronic uveitis (cats), trauma, age, anything causing zonules to breakdown
primary lens luxation and secondary glaucoma will present…
primary glaucoma and secondary lens luxaion will present…
no buphthalmia and aterior luxation
buphthalmia and posterior luxation
how do you treat lens luxation (each type)?
subluxation: meds to induce miosis (xalatan or latanoprost
posterior lux: induce miosis
anterior: remove the lens asap especially if increased IOP
wot dis
asteroid hyalosis: opacities behind the lens from either cholesterol or calcium. causes no problems and no treatment is needed
what is syneresis?
liquifaction of the vitreous seen as swirling cotton candy. no treatment needed
what is seen here?
areas of increased reflectivity on the right side=progressive retinal atrophy
what causes progressive retinal atrophy?
a group of inherited, acquired photoreceptor diseases
will be night blind first (nyctalopia) since rods lost first, and then eventual blindness when cones are gone
will see mydriasis and cataracts
clinical signs of sudden acquired retinal degeneration and what causes it?
poor PLRs, the retina looks normal
we dont know the cause and theres no treatment
wot dis
chorioretinitis: inflammatory granules from blasto underneath the retina, can cause eventual retinal detachment
wot dis
chorioretinal scar (flat and no raised like chorioretinitis)
hyperreflective area with focal hyperpigmentation
wot dis
chorioretinal scars
wot dis
a cat with underlying kidney disease and their retina detaches
difference between buphthalmia and exopthalmia?
buphthalmia: enlargement of the eyeball
exophthalmia: abnormal protrusion of the eyeball
buphthalmia: globe size is enlarged, IOP will be elevated, retropulsion is normal, and vision absent
exopthalmia: globe size normal, IOP normal, retropulsion is reduced, and vision is present
