Ophthalmology Flashcards
Why doesn’t a deep corneal ulcer take up stain?
Descemet’s membrane is lipophilic and stain is hydrophilic so if you get all the way to Descemet’s membrane then ulcer will be stain negative, also epithelium will not take up stain
In a normal, more superficial eye ulcer, the stroma will be exposed bc the epithelial layer is eroded which is hydrophilic and does take up stain
What filter do we use to check for Fluorescein stain uptake?
Cobalt blue filter- stain uptake will be where there is exposed stroma (which is hydrophilic)
Superficial corneal ulcers
only the epithelium is affected with the anterior stroma being exposed, if not resolved in 7 days, it is considered non healing
Tx for non-healing corneal ulcers
e collar, atropine 1-2 times a day, NSAIDs-systemic, topical abx, recheck in 1 week
what are some anti-protease (enzyme breaking down protein and peptides) medications for ulcer tx?
Doxycycline, EDTA, homologous serum
What are the STT levels for KCS (early, mild, severe KCS)
> 15 mm/min= normal production
11-14 mm/min= early or subclinical KCS
6-10 mm/min= mild to moderate
< 5 mm/min= severe KCS
KCS tx
cyclosporine, tacrolimus for tear stimulation (an immunosuppressant) and refresh eye drops and avoid atropine
Exposure keratitis
lack of eyelids, poorly reconstructed eyelid injury or wedge resection can cause
What are macropalpebral fissures?
common in pugs, shih tzu’s, pekingese
Shallow orbit and prominent globe causing increased sclera to show and leads to corneal exposure and patient may have poor corneal sensitivity so less blinking or incomplete blinking
TX is canthoplasty where a small amount of the medial lid margin is removed and closes the eyelid down more so there is more complete blinking
basically, excessively wide eyelids
What is SCEEDS?
Spontaneous chronic corneal epithelial defect and is an epithelial defect that has not healed for the past 7 days and has fuzzy borders of the stain uptake, loose epith. edges, and epith. may be thickened around the ulcer
Tx is diamond burr, debridement with cotton tip applicator, or grid or multiple punctate keratotomy (DOGS ONLY!), or superficial keratectomy
why do we not do grid keratotomies on cats?
May predispose them to sequestrum formation
feline herpesvirus changes to the eye that can sometimes occur-
dendritic ulcers branching, corneal sequestrum (stromal collagen degradation- has other causes, too!!)
what is the primary purpose of the lens?
focus light to the retina
Degree of opacity with different types of cataracts
asses in a dark room with dilated examination using Tropicamide 1%
Incipient is less than 15%
Immature is 15-99%
mature is 100%
Hypermature is with breakdown/resorption occurring
What is the only proven way to resolve cataracts?
Surgery (Phacoemulsification, extracapsular lengs extraction, intracapsular extraction) and do Lanosterol drops to reduce the lens opacity
What is lens-induced uveitis??
How do you tx it?
Breakdown of the blood-ocular barrier, can occur at any stage of cataract development, usually has decreased IOP, aqueous flare, keratic precipitates
TX with topical prednisone acetate or use Neopoly Dex
What are the tx choices for phacolytic (meaning the lens boarder are in tact but fluid is leaking around it) lens-induced uveitis?
Topical and oral NSAIDs, atropine unless secondary glaucoma is present
Anterior vs posterior lens luxation
Anterior is displacement of the lens in front of the iris in the anterior chamber
Posterior is displacement of the lens into the vitreous chamber
what is gold standard sx procedure of lens luxation???
Intracapsular lens extraction– removal of the lens within its capsule but beware of retinal detachment or glaucoma post-op
Feline calicivirus overview notes-
a single stranded RNA virus, infection is most common in young shelter cats, chronic or intermittent shredders are common, incubation period is 2-14 days before symptoms occur
CS of feline calicivirus
URI, oral mucosal ulcerations, mild to severe conjunctivitis
Diagnosis of feline calicivirus and TX
virus isolation, PCR, samples should include oropharynx and eye; TX is Tobramycin (abx) and anti-viral drugs
what feline virus can live undetected in ocular tissue (the cornea)??
Feline herpes virus type 1
Feline herpesvirus CS
URI, nasal/ocular discharge, chemosis/hyperemia, conjunctivitis, keratitis, classic ocular lesion being dendritic ulcers
conjunctival cytology shows inclusion bodies and cellular infiltrates (neutrophils)
What is eosinophilic keratitis?
Suspected to be immune mediated, it is white/pink raised tissue extending across the cornea, may cause vision loss and some discomfort
ddx- will see eosinophils on cytology
Tx of eosinophilic keratitis
topical steroid, optimmune, megesterol acetate which is a synthetic progestin, systemic NSAIDs
Feline corneal sequestrum
predisposing factors include steroids, chronic irritation, ulcers, etc. and can be painful and can increased in depth and size.
what are some antivirals to use with feline herpesvirus?
Cidofovir, famciclovir, l-lysine, and reduce stressors
FIV review
lentivirus, transmission via saliva/bites, can also have in-utero and post-partum infections via milk, predisposed are older males outdoor with hx of fighting and has FeLV infection
CS of FIV–
chronic anterior uveitis, conjunctivitis, secondary glaucoma, ocular LSA can also occur
What are the 3 subgroups of FeLV?
FeLV A: only subgroup that is infectious
FeLV B: assoc. with lymphoma and neuropathy
FeLV C: assoc. with non-regenerative anemia
CS of FeLV
LSA, can affect uveal tract, conjunctiva, and/or the orbit and retinal hemorrhages associated with severe anemia
Tx of p with FeLV
topical steroids, enucleation if blind and painful eye/uncontrolled glaucoma, and systemic chemo/radiation for ocular LSA
What are the tx options in cats with glaucoma???
Dorzolamide or Timolol
Avoid using a prostaglandin analog like Latanoprost, bc that is for primary glaucoma and cats do not usually get primary glaucoma unlike in dogs where it is hereditary; cats usually get glaucoma secondary to uveitis or another form of trauma
FIP CS of the eye
anterior uveitis, other non specific findings of the eye, usually assoc. with the DRY form of FIP
What is gold standard diagnosis of FIP
Biopsy with immunohistochemistry staining of Feline coronavirus in macrophages of affected tissues.
Tx of uveitis assoc. with FIP in cats
Atropine, oral NSAIDs (pred or onsior but NOT TOGETHER!!!)
What is the most common virus in cats that is assoc. with ocular manifestations?
Feline herpes virus
Cats with ____ should be tested for viral agents that can cause inflammation to the eye
uveitis
Visual pathway review notes
light hits the retina and photoreceptors convert to electrical impulse, then goes to ganglion layers to the optic nerve. The tapetum also gives photoreceptors more light inflow
What are the tests to run for a neuro-ophthalmic examination?
Menace response and maze test, pupillary light reflex (PLR), dazzle reflex, oculocephalic reflex
PLR or dazzle reflexes tests do not test for ___
vision
Menace response notes:
Afferent nerve, efferent nerve, CN to open or close eyes
Stimulus is motion toward the eye
receptor is the retina
afferent is optic nerve (CN II) TOO SEE
efferent is facial nerve (CN VII) TO BLINK
response positive is p blinking
CN 3 oculomotor nerve to open eyes, CN 7 facial nerve to close the eyes
how to do the Menace response test
cover opposite eye while doing the test, do not cause wind or touch hair, it is not present in p less than 4 months old since it is a learned response
PLR pathway notes
Stimuli, afferent, efferent, effector, response notes
Stimulus is light
receptor is retina
afferent is optic nerve (CN II)
efferent is oculomotor nerve (CN III)
effeCTOR is the iris sphincter muscle
Response is pupillary constriction
what is direct vs indirect PLR
direct is observe eye being illuminated and indirect PLR is occurring when the opposite eye is illuminated
direct PLR should be slightly stronger than indirect PLR
does PLR mean there is vision?
Not necessarily, PLR can be present in p that have no vision from a cortical disease
andddd eyes with NEG PLR can have vision
Dazzle reflex notes
Stimulus is bright light
receptor is the retina
afferent is optic nerve (CN II)
interneuron is CNS/subcortical
efferent is orbicularis ocular muscle
response is a blink
Oculocephalic reflex notes
Afferent, efferent notes
stimulus is head motion,”doll eye motion”
receptor is semicircular canal
afferent is vestibulocochlear nerve (CN VIII)
efferent oculomotor/trochlear/abducens nerves (CN III/IV/VI)
emmetropia definition
normally focused vision, light accurately focused on the retina
myopia
nearsidedness
light focused in front of the retina
Hyperopia
farsidedness
rays of light focused behind the retina
What is an astigmatism?
Optical irregularities, imperfections in the refractive media where light is not focused in a uniform manner (like in p with corneal disease, cataracts, corneal tears, etc. etc)
Progressive retinal atrophy (PRA) in dogs
inherited retinal photoreceptor degeneration, progressive loss of night vision followed by day vision later on and rods are affected first and then the cones
may have reduced to absent PLRs, tapetal hyper-reflectivity, retinal vessels attenuation and optic nerve atrophy
Diagnosis and TX of PRA in dogs
Hx, eye exam, electroretinography, testing for genetic mutation through UC Davis
Tx - none available at this time
PRA in cats
rare in cats but has two forms:
Rod-cone dysplasia- in kittens
Rod-cone degeneration- older cats and slower loss of vision
Optic neuritis
inflammation of the optic n. and is a clinical symptoms from another disease process, usually is bilateral
will be blind with pupils dilated, causes are basically anything, and diagnosis is CS, ERG, and MRI. Tx depends on underlying cause and prognosis for vision is guarded to poor
Optic nerve atrophy
optic nerve loses myelin and appears grey to white in color, usually from secondary eye disease
Sudden acquired retinal degeneration syndrome (SARDS)
sudden vision loss, variable degree of PLR, initial absence of eye lesions, usually middle aged female obese dogs
Tx for SARDS
none at this time, unknown cause.
Chorioretinitis causes
Distemper, fungus, autoimmune in dogs
Cats- FIP, FeLV, toxoplasmosis, fugus
Horses- ERU
What are the two types of retinal detachement
non-rhegmatogenous- bullous retinal detachment, no retinal tear, commonly seen w infectious diseases
Rhegmatogenous- a hole or tear in the retina, shih tzu’s can commonly get this
What is this disease of the eye:
Acute blindness of a cat (can also occur in dogs but more common in cats) with dilated pupils, retinal hemorrhages (maybe even detachment)?
Hypertensive retinopathy
TX is correct underlying cause and systemic and topical steroids bc uveitis and calcium channel blockers!!!
What happens to cats if you baytril (enrofloxacin) to cats
dose related retinal drug toxicity, DO NOT give more than 5mg/kg/day!!!!!
causes retinal toxicity in cats
how do use of mouth gags in cats affect the eye?
may lead to retinal ischemia in cats due to impairment of bf through the maxillary artery
In cats, taurine def. can cause what in cats???
severe retinal degeneration and irreversible blindness in cats
What do we give dry eye P?
Tacrolimus, artificial tears (Dr. Betbeze’s favorite is hyaluronic acid for the eyes like Ocunovis), and/or cyclosporin
is tacrolimus the same as cyclosporin aka optimmune?
Nope
Something that looks like cataract in a dog with cloudy aqueous and is not a cataract bc you cannot even see the iris so you know it is in the anterior portion of the eye. What is the Tx?
Lipid within the cornea and blood vessels are inflamed and can be very sudden onset, usually patient presents blind, usually concurrent with endocrine disease (hypothyroidism, Cushings, diabetes, Schnauzers), may or may not be bilateral, and usually fed a high fat diet
Tx- tx underlying cause and improve the diet
Use lipid lowering medications with help of internist clinicians, once Tx these cases can improve a lot fast. Also tx the eye because lipids are leaking out due to inflammation in the eye, can use steroid to decrease inflammation
even a really mild looking ulcer in a _____ can progress very fast because they have the right environment for progression
Diabetic patient
