Ophtho Flashcards
causes of a hyperreflective tapetum
retina atrophy or degeneration
dogs, cats, ruminants, camelids and humans have what retina blood vessel pattern
holangiotic (304 major venules)
horses and guinea pigs have what retina blood vessel pattern
paurangiotic (small retinal vessels)
rabbits have what retina blood vessel pattern
merangiotic (vessels in focal region)
birds have what retina blood vessel pattern
anagiotic (no retinal vessels)
optic n is myelinated in which species
canine and ruminants
optic n is not myelinated in which species
cats, horses, camelids
what are the 3 parts of the dog optic n head
neurorim
physiologic cup
venous anastomosis
where does a dog optic disc lay
tapetal and non tapetal junction
where does a cats optic disc lay
tapeal fundus
where does a horses optic disc lay
non-tapetal fundus
progressive retinal atrophy
cause?
inherited autosomal recessive but also autosomal dominant and X linked
progressive retinal atrophy symptoms
loss of night vision then day
increase tapetal reflectivity
retinal vascular attenuation
optic n atrophy
how can you diagnose progressive retinal atrophy?
minimal retinal function on ERG or fundic exam
cats predisposed to progressive retinal atrophy? cause?
abyssinian and persian
autosomal recessive
signs of an active inflammatory retinal lesions
chorioretinitis or retinal detachment causes hyporeflective lesions due to accumulation of cells/fluid
signs of post-inflammatory retinal lesions
hyperreflective scar - retinal degeneration
what are the most common lesions associated with blindness
retinal disease
optic n disease
cortical disease
retinal disease resulting in blindness is usually due to what?
retinal detachment = decreased tapetal reflectivity and hazy appearance
PLR response due to retinal disease?
dilated pupil
sluggish PLR
PLR response due to optic n disease (optic neuritis)?
dilated pupil (mydriasis)
sluggish PLR
most common cause of optic neuritis? what must you rule out?
idiopathic
must rule out infectious (toxo, crypto, borreliosis)
how to diagnose optic neuritis?
fundic exam - swelling, hemorrhage, peripapillary edema
ERG normal
MRI or CT helpful
CSF analysis
what are two systemic causes of non-infectious blindness?
hypertensive retinopathy
uveodermatologic syndrome
what is termed hypertensive retinopathy?
> 160mmHg
what will you see in a cat with hypertensive retinopathy?
older cat, bilateral mydriasis, blindness
+/- renal disease, cardiomyopathy or hyperthyroidism
what is the prognosis for hypertensive retinopathy?
50% will regain vision w/ treatment of systemic hypertension and underlying systemic disease
what is uveodermatologic syndrome in dogs?
immune mediated disease - targets dermal and uveal melanocytes
usually arctic breeds, akitas
ocular signs first then derm signs
what’s the cause of sudden acquired retinal degeneration syndrome (SARDS)
unknown - thought to be immune mediated
signs of SARDS
blind in both eyes
normal fundus early in the disease course
abnormal PLR
signs similar to cushings (PUPD, polyphagia, weight gain)
diagnosis of SARDS
ERG flat line
treatment for SARDS
none, permanent blindness
neomycin, polymyxinB, bacitracin (neopolybac)
does it penetrate the corneal epithelium?
when is it used?
caution in?
NO penetration
used for simple corneal ulcer (no active infection)
cats - anaphylaxis
what is neomycin polymyxinB gramicidin?
a solution instead of ointment
what drug should be used for an actively infected corneal ulceration? why?
olfoxacin or ciprofloxacin
good penetration through intact epithelium
when should you use tobramycin? does it penetrate the intact epithelium?
simple ulcers in high risk patients (brachycephalics)
yes
what topical antibiotic is epithelial toxic?
gentamicin - don’t use unless culture says to
which two antibiotics are effective against Chlamydophilia and Mycoplasma?
erythromycin
terramycin
what antibiotic is useful for cats with conjunctivitis and uncomplicated corneal ulcerations?
erythromycin
what antibiotic is shown to reduce healing time in dogs with SCEED (indolent ulcers)
terramycin (oxytet + polymyxinB)
why is there a caution of terramycin use in cats?
polymyxin anaphylaxis
what antibiotic has the risk of aplastic anemia?
chloramphenicol
what are the 4 options for anti-collagenase medications?
acetylcysteine
EDTA
doxycycline PO BID
serum
what is the best choice for stabilizing the cornea with keratomalacia?
acetylcysteine
dendritic ulcerations are pathognomonic for what?
FHV
if a cat has unilateral hyperemia, top ddx?
FHV
if a cat has bilateral chemosis, ddx?
chlamydophilia
mainstay treatment for FHV
famciclovir
L-lysine
how does L-lysine help prevent FHV? how often must it be given?
L-lysine competes with arginine which is required by the virus to replicate = stops viral replication
must be given 2x a day bc the body will eliminate Lysine
what drug should be used for long term uveitis prevention (e.g. lens induced uveitis) or mature cataracts?
NSAIDs - flurbiprofen, diclofenac, ketorolac
which steroid is a good choice for uveitis and immune mediated keratitis? why?
Prednisolone Acetate
penetrates the cornea
which steroid is a good choice for superficial disease like conjunctivitis? why?
dexamethasone sodium phosphate
does not penetrate the cornea well
with what steroid should you watch out for fungal keratitis and stromal abscesses in horses?
dexamethasone sodium phosphate
NSAIDs
penetration of the cornea?
when do they become epithelial toxic?
yes
when used more than 4x/day
what is the most effective drug for allergic conjunctivitis (inflammatory) in the dog?
neopolydex
NeoPolyDex
caution in which species? why?
cats - they get infectious conjunctivitis not inflammatory
horses - stromal abscess and fungal keratitis
what are some options for topical glaucoma medications?
beta blockers - timolol
Carbonic anhydrase inhibitors - dorzolamide or methazolamide
prostaglandin analog - latanoprost
timolol MOA
decreases aqueous humor by blockage of beta receptors in ciliary body = mild decrease in IOP
dorzolamide
- MOA
- what can you combine it with?
- effective in who?
carbonic anhydrase inhibitor - decreases aqueous humor production in ciliary body epithelium
can combine with timolol = cosopt
dogs/cats
methazolamide is also a carbonic anhydrase inhibitor but has a higher risk of what?
systemic effects - metabolic acidosis (clients watch for panting)
what is Latanoprost used for?
emergency situation in dogs to decrease IOP
excellent if posterior lens luxation
Latanoprost MOA
increase aqueous outflow
why is latanoprost not used in cats? when do you not want to use it?
cats don’t have PGA receptors thus has minimal affect
NOT if there’s sig uveitis OR anterior lens luxation
what mydriatic agent has the longest onset and duration?
atropine
when is tropicamide useful?
fundic exams
when should you NOT dilate the eyes?
if IOP is elevated
when is phenylephrine used?
reduce conjunctival hemorrhage during ocular surgery = drain to mouth and blanch gums
what drugs do you use for dry eye (KCS)?
calcineurin inhibitors
- cyclosporine (mild)
- tacrolimus (if sensitive to cyclo or can be combined with cyclo if severe)
what are the two risks of using calcineurin inhibitors for dry eye?
- risk of SCC
- immunosuppression
orbital neoplasia
clinical signs:
ddx:
best diagnostic:
exophthalmos + third eyelid elevation
tumor vs abscess vs cellulitis vs salivary gland mucocele
CT/MRI
what is the most common primary eyelid tumors in dogs
meibomian gland adenoma
Meibomian Gland Adenoma
benign or malignant?
treatment?
benign, locally invasive
debulk w/ cryo or wedge resection
how is a fibropapilloma different than a meibomian gland adenoma
less friable
generally not on the eyelid margin
treatment same
Melanoma
location:
predispositions:
diagnostics:
treatment:
eyelid margin - dark/pigmented
vizlas, weimaraners
histopath
cryo +/- debulk or wedge resection
what is the most common primary eyelid tumor in cats
SCC
SCC
location:
diagnostics:
treatment:
lower lid or 3rd eyelid
biopsy w/ histopath
complete sx ecision +/- RT, chemo or immunotherapy
what 3 neoplasms can occur on the third eyelid
SCC
hemangioma/hemangiosarcoma
adenoma/adenocarcinoma
treatment for hemangioma/HSA on the 3rd eyelid?
excise (1mm margins) w/ adjunctive cryotherapy or radiofreq electocautery
treatment for adenoma/adenosarcoma on the gland of the 3rd eyelid
surgical excision of 3rd eyelid often curative
corneal SCC are more common in what species
equine (UV exposure)
dogs (brachycephalics)
what are the underlying causes of corneal SCC
KCS
immune mediated/chronic keratitis (increased risk w/ chronic use of cyclo or tacro)
treatment for corneal SCC
keratectomy
adjunct cryo, RT or chemo
how to differentiate a limbal melanoma/melanocytoma limbal origin from uveal origin
ultrasound
treatment for a limbal melanoma/melanocytoma
excision w/ cryo
cryo alone
+/- graft
what are the two types of primary anterior uveal neoplasias?
ciliary body adenoma/adenocarcinoma
uveal melanoma
ciliary body adenoma/adenocarcinoma
behavior?
diagnosis?
treatment?
benign, slow growing, locally aggressive
intraocular mass, elevated IOP, uveitis
enucleate once uveitis or glaucoma develop
uveal melanoma
location:
behavior in dogs vs cats:
on iris or ciliary body
dogs: slow growing, unilateral, middle age/older animals
cats: starts small, can grow fast and met, but majority are slow growing
treatment of uveal melanoma in dogs
laser
enucleation
treatment of uveal melanoma in cats; what are the criteria for enucleation
depends on age (4 vs 12)
monitor
enucleation
1. iris abnormal
2. uveitis and/or glaucoma
3. rapid progression
what neoplasia is the secondary anterior uveal neoplasia
lymphoma
lymphoma in the eye
behavior:
diagnostics:
treatment:
bilateral, stage V
LN asp, chest/abd imaging, aqueocentesis
systemic + treat uveitis and glaucoma
choroidal melanoma
diagnostics:
treatment:
fundic exam (dark raised lesion, retinal detachment)
enucleation
