Term
| Why are superficial corneal ulcers more painful than deep ones? |
|
Definition
| the superficial corneal stroma is more richly innervated |
|
|
Term
| Why are the collagen fibrils of the corneal stroma so precisely arranged? |
|
Definition
| uniform spacing allows the cornea to maintain optical transparency for light transmission |
|
|
Term
| How does the cornea exist in a relatively dehydrated state despite being bathed in tears and aqueous humor (3 mechanisms)? |
|
Definition
1. evaporation of tears (hypertonic tear film draws fluid away from the corneal stroma)
2. corneal epithelium is hydrophobic (mechanical barrier to fluid imbibition)
3. Corneal endothelium contains Na/K- pumps that actively remove fluid from the cornea and into the anterior chamber |
|
|
Term
| T/F: corneal endothelium consists of post-mitotic cells |
|
Definition
|
|
Term
| How long following an insult to the cornea does it take for the initiation of a neovascular response? |
|
Definition
|
|
Term
| what is the rate of corneal vessel in growth following the initial neovascular response to corneal damage (24-48 hrs post)? |
|
Definition
|
|
Term
| If you see sparkly white material in the cornea what is it? |
|
Definition
| corneal deposits of lipid or mineral, crystaline with discrete boarders that intersect with the first purkinje image (ie. in the cornea) |
|
|
Term
| If you see whispy white material in the cornea what is it? |
|
Definition
| stromal fibrosis/scar, has indistinct boarders (vs. lipid/mineral deposits that are sparkly and have sharp boarders) |
|
|
Term
| Superficial blood vessels that cross the limbus and encroach onto the cornea are indicative of what kind of disease process? |
|
Definition
|
|
Term
| What color and texture is associated with corneal edema? |
|
Definition
| blue color, "chicken wire" texture |
|
|
Term
| What does creamy or yellow corneal infiltrate signify? |
|
Definition
| inflammatory or neoplastic cellular inflitrate, diagnose with cytology! |
|
|
Term
| What color and pattern is associated with keratic precipitates? What is the etiology of these structures? |
|
Definition
| greasy tan splotches splattered on corneal endothelial surface. Keratic precipitates are inflammatory cells from the aqueous humor, indicative of anterior uveitis |
|
|
Term
| Brown pigment in the cornea could be from what two potential sites? |
|
Definition
melanocytes from conjunctiva (seen in chronic inflammatory conditions of the cornea)
uveal tract prolapsing out following corneal perforation |
|
|
Term
| What is a condition that cats get that is associated with tan-black regions on the cornea? |
|
Definition
corneal sequestrum, necrotic corneal stroma imbibes porphyrin pigments from the tears -->stained dark
eventually the necrotic plaque sloughs off |
|
|
Term
| What might cause black discoloration of the cornea in dogs (ie. don't get corneal sequestrums)? |
|
Definition
|
|
Term
| What is a corneal dermoid and where are they typically located? |
|
Definition
dermoid = haired skin on the corneal surface aka. choristoma (normal tissue, abnormal location)
usually located at temporal limbus
tx w/ keratectomy of superficial cornea |
|
|
Term
| How long should it take for an uncomplicated corneal ulcer to heal? |
|
Definition
|
|
Term
| T/F: corneal ulcers cause reflex anterior uveitis |
|
Definition
TRUE
*secondary to neuronal reflex from corneal nerves to anterior uveal tract with breakdown of blood-aqueous-barrier (ie. corneal endothelium)
severity of uveitis generally corresponds with severity of ulceration |
|
|
Term
| What are some clinical signs associated with anterior uveitis? |
|
Definition
| blepharospasm, episcleral injection, miosis (small pupil), aqueous humor flare (secondary to protein in AH), hypopyon |
|
|
Term
| How should you treat a superficial ulcer? |
|
Definition
identify underlying cause
broad spectrum topical antibiotic to prevent secondary bacterial infection
atropine +/- oral NSAID to tx reflex anterior uveitis (dilate pupil and stabilize blood-aqueous-barrier) |
|
|
Term
| What is another name for an indolent ulcer? How can you distinguish indolent ulcers from superficial ulcers? |
|
Definition
| aka. spontaneous chornic corneal epithelial defect (SCCED) non-adherent lip of epithelium at the edge of the ulcer results in peripheral rim of hazy flourescein stain uptake (while uncomplicated superficial ulcers have very distinct boarders) |
|
|
Term
| T/F: indolent ulcers form because abnormal corneal epithelium doesn't adhere to the corneal stroma |
|
Definition
FALSE
abnormal corneal STROMA prevents adherence of migrating epithelium
*boxers and corgis |
|
|
Term
| What is the treatment for an indolent ulcer? |
|
Definition
debride non-adherent epithelium with q-tip
grid keratotomy (penetrate abnormal corneal stroma w/ 25/27g needle to facilitate epithelial adhesion)
topical antibiotics (prevent secondary bacterial infection)
atropine/oral NSAID (tx reflex anterior uveitis)
85% heal w/in 2 weeks of starting tx |
|
|
Term
| In what species should you never perform a grid keratotomy? |
|
Definition
| Cats (causes corneal sequestrum) |
|
|
Term
| What clinical signs are associated with melting corneal ulcers? |
|
Definition
| soft thickened corneal stroma that shifts as the eyelids blink, severe corneal edema (blue), cellular stromal infiltrates (yellow), severe anterior uveitis (miosis, hypopyon, aqueous flare) |
|
|
Term
|
Definition
|
|
Term
| How do melting corneal ulcers form? |
|
Definition
| endogenous proteinases (from WBC, corneal epithelium, stromal fibroblasts) and bacterial collagenases (pseudomonas and beta hemolytic strep) as well as topical corticosteroids break down collagen fibers |
|
|
Term
| What is a descemetocoele? |
|
Definition
| deep stromal ulcer extending all the way down to descement's membrane, globe rupture is imminent! |
|
|
Term
| If the cornea is perforated what two structures/materials can plug the defect? |
|
Definition
iris prolapse (aka. anterior synechia)
fibrin plug |
|
|
Term
| What formulation of drugs should you avoid in eyes with present or impending perforation? |
|
Definition
| don't use OINTMENT b/c the petrolium vehicle can incite sever intraocular inflammation |
|
|
Term
| What treatment is used to inhibit corneal stromal melting (aka keratomalacia)? |
|
Definition
| patient's own serum (contains proteinase inhibitors) |
|
|
Term
| How does atropine help resolve uveitis? |
|
Definition
dilates the pupil by inhibiting ciliary muscle spasm associated with reflex uveitis (mydriasis can last days to weeks following treatment)
stabilized blood-eye-barrier
start with frequent doeses, taper over days |
|
|
Term
| T/F: you should use SYSTEMIC NSAIDs to treat uveitis occuring reflexively secondary to corneal ulcer |
|
Definition
TRUE
NEVER use topical NSAIDs or steroids if the patient has a corneal ulcer, this will delay corneal healing, predispose to infection and keratomalacia |
|
|
Term
| When should you consider surgical treatment (conjunctival graft) for corneal ulcers? |
|
Definition
if the ulcer is progressed greater than 50% of stromal depth
if the ulcer is rapidly progressive or melting
if there is no neovascular response
if the cornea is perforated or actively leaking |
|
|
Term
|
Definition
bilateral inferior-temporally located, immune-mediated chronic superficial keratitis, associated with UV exposure
affects german shep and greyhounds |
|
|
Term
| what corneal cytologic findings are consistent with pannus? |
|
Definition
| lymphocytes and plasma cells |
|
|
Term
| What is the treatment of choice for pannus? |
|
Definition
| long-term topical cyclosporine, steroids during flare ups |
|
|
Term
| presence of only a single eosinophil on corneal cytology from a cat is diagnostic for what disease? |
|
Definition
| Feline eosinophilic keratitis |
|
|
Term
| What is the treatment for feline eosinophilic keratitis? |
|
Definition
long term topical steroids +/- oral steroids
**if ulcerated tx plaque with oral steroids and ulcer with topical antibiotics, after ulcer heals you can use topical steroids for the plaque |
|
|
Term
| What is corneal dystrophy? |
|
Definition
| inherited condition in dogs, crystalline lipid deposits in corneal stroma, bilarteral and non-painful, no tx |
|
|
Term
| T/F: squamous cell carcinoma is the most common corneal neoplasia in dogs and cats |
|
Definition
FALSE - primary corneal surface epithelium neoplasia is most common in cats and dogs
**SCC is most common in horses and cows |
|
|
Term
| The sutures of the banana shaped lens fibers looks like a "Y" from which side of the len? |
|
Definition
anterior
(Y is upside down on the posterior aspect of the lens) |
|
|
Term
| T/F: the lens is avascular at birth |
|
Definition
TRUE
receives ALL nutrition from the aqueous and vitreous humor |
|
|
Term
| What is the etiology of nuclear sclerosis? |
|
Definition
| dehydration and loss of elasticity of the lens as the animal ages |
|
|
Term
| how can you differentiate nuclear sclerosis from a cataract? |
|
Definition
| retroillumination, can see tapetal reflection through nuclear sclerosis but cataracts show up as a dark shadow |
|
|
Term
|
Definition
| focal or diffuse lens opacity |
|
|
Term
| What is the number one cause of cataracts in dogs? in cats? in horses? |
|
Definition
K9: inherited
cat and horse: uveitis |
|
|
Term
| How much of the lens is affected in patients with incipient/punctate cataracts? |
|
Definition
|
|
Term
| How much of the lens is affected in patients with incomplete/immature cataracts? |
|
Definition
| >10% but <100% of the lens |
|
|
Term
| What is a defining characteristic of resorbing/hypermature cataracts? |
|
Definition
| the lens proteins start to leak out of the capsule --> wrinkled lens capsule and located deeper within the anterior chamber, also might have a sparkly appearance due to mineral/cholesterol deposits |
|
|
Term
| What is a morgangnian cataract? |
|
Definition
| complete liquification of the lens cortex with the lens nucleus settling to the inferior portion of the capsular bag |
|
|
Term
| What is one of the few cataracts that will NOT progress? |
|
Definition
fibrillar nuclear cataract (diffuse speckling of cataracts across the entire lens)
*german shepherds |
|
|
Term
| T/F: diabetic cataracts are intumescent and rapidly progressive |
|
Definition
| TRUE *intumescent = swollen b/c the lens absorbs fluid, anterior chamber becomes shallow as the lens swells |
|
|
Term
| what is the rate limiting enzyme in anaerobic glucose metabolism in the lens? |
|
Definition
|
|
Term
| When the hexokinase pathway becomes saturated by high serum glucose levels what alternative glucose metabolism pathway picks up the slack? |
|
Definition
| aldose reductase --> converts glucose to sorbitol |
|
|
Term
| Why does sorbitol contribute to the formation of diabetic cataracts? |
|
Definition
| sorbitol accumulates in the lens (poor diffusion across the lens capsule) and imbibes fluid from the aqueous humor resulting in a structural changes to the lens fiber --> cataract |
|
|
Term
| What are two negative sequelae to cataracts? |
|
Definition
| blindness and lens-induced uveitis (secondary to leakage of lens proteins) |
|
|
Term
| What are the two forms of lens induced uveitis? |
|
Definition
Phacolytic (slow leakage of lens proteins through an intact lens capsule secondary to hypermature/resorbing cataract --> mild chronic inflammation)
Phacoclastic (massive exposure of lens proteins secondary to penetrating trauma or intumescent cataract (ie. diabetic cataract)--> severe inflammation) |
|
|
Term
| When should you offer your client cataract surgery referal? |
|
Definition
when you first diagnose cataracts (post-op success goes down as cataract matures)
***determine extent of visual deficits before surgery via electroretinogram (ie. if the retina isn't functional removing the cataract won't restore vision) |
|
|
Term
| What are the top three complications associated with cataract surgery (ie. phacoemulsification)? |
|
Definition
| uveitis, glaucoma, retinal detachement |
|
|
Term
| What are the anatomical components of the anterior uveal tract? |
|
Definition
|
|
Term
| What are the anatomic components of the posterior uveal tract? |
|
Definition
|
|
Term
| What is the function of the uveal tract? |
|
Definition
light regulation (via pupil size)
blood aqueous barrier (tight junctions between endothelial cells keep most solutes out of the eye)
accomodation (zona fibers of cilliary body help adjust the lens depending on near or far focus)
formation of the aqueous humor (non-pigmented epithelium of ciliary body) |
|
|
Term
| What are the histological characteristics of the anterior boarder of the iris? |
|
Definition
no epithelial covering
contains melanocytes and fibroblasts (ie. this is what you're seeing when you look at the iris face on) |
|
|
Term
| Which iris muscle is strongest? What are the clinical implications of this? |
|
Definition
| Iris sphincter muscle is stronger than the iris dilator muscle, so spasm of the iris results in miosis (small pupil) |
|
|
Term
| What is the functional importance of the iridocorneal angle? |
|
Definition
| Where aqueous humor drains into systemic circulation |
|
|
Term
| What is heterochromia iridis? |
|
Definition
one iris with multiple colors OR one eye's iris is one color, the other eye's iris is a different color
this congenital anomaly is generally incidental and often concurrent with coat color dilution |
|
|
Term
| Where do persistent pupillary membranes arise from? |
|
Definition
iris collarette
if iris to iris usually incidental, no tx |
|
|
Term
| What type of persistent pupillary membranes are associated with pathology? |
|
Definition
iris to lens (cataract)
iris to cornea (corneal opacity)
no TX |
|
|
Term
| What ocular abnormalities are associated with merle ocular dysgenesis? |
|
Definition
iris hypoplasia
iris coloboma
corectopia (abnormally positioned pupil)
individuals homozygous for merle gene are affected, NO TX |
|
|
Term
| Where do uveal cysts arise from? What other condition should they be differentied from? |
|
Definition
arise from pigmented epithelium of iris and/or ciliary body
must be distinguished from melanoma (solid on transillumination) by characteristic light transmission during transillumination (or occular ultrasound)
**more commonly form spontaneously (sometimes secondary to chronic inflammation) |
|
|
Term
| When might you want to treat uveal cysts? |
|
Definition
| if they are associated with adverse behavior issues like fly biting and head shaking ---> REFER |
|
|
Term
| What are some exam findings characteristic of iris atrophy? |
|
Definition
| older animal (age related change) with dyscoria (moth-eaten, scalloped pupillary margin) and diminished PLR response (atrophied iris sphincter/dilator muscle) NO TX |
|
|
Term
| What are the two most common uveal neoplasms in dogs and cats? |
|
Definition
#1= melanoma
#2= ciliary body adeno(carino)ma |
|
|
Term
| What is the main rule out for iris melanoma? |
|
Definition
| nevus (ie. freckle) aka benign melanosis |
|
|
Term
| What are some clinical exam findings that increase suspicion of iris melanoma over nevus? |
|
Definition
| raised iris surface, rapid spread of pigmentation, interference with pupil shape or function, extension of pigment into sclera (negative prognostic indicator) |
|
|
Term
| What is a technique of visualizing the iridocorneal angle to assess for hyperpigmentation secondary to iris melanoma? |
|
Definition
|
|
Term
| What are three treatment options for iris melanoma/suspected iris melanoma? |
|
Definition
monitor with photography every few months
laser photocoagulation for small lesions (risk of dispersal of neoplastic cells)
enucleation and histopathology (esp. if eye is blind and/or painful) |
|
|
Term
| What is the primary organ affected by metastasis of iris melanoma? |
|
Definition
|
|
Term
| What is the number one metastatic neoplasm that affects the eye? What is a good treatment option? |
|
Definition
lymphosarcoma
*often chemotherapy will significantly resolve eye pathology |
|
|
Term
| What structures contribute to the blood-aqueous barrier? |
|
Definition
| non-pigmented epithelium of ciliary body and endothelium of iris vessels |
|
|
Term
| What structures contribute to the blood-retinal barrier? |
|
Definition
| retinal pigmented epithelium and the endothelium of retinal capillaries |
|
|
Term
|
Definition
| inflammation of the anterior (ciliary body and iris) and posterior (choroid) uvea |
|
|
Term
|
Definition
| all tunics of the eye inflammed |
|
|
Term
| What seven clinical signs are commonly associated with anterior uveitis? |
|
Definition
episcleral injection
deep corneal vascularization
corneal edema (blue)
miosis
aqueous flare (if you see this it's definitive for uveitis, but mild inflammation may not result in appreciable flare so can't r/o uveitis if flare is not seen)
hypopyon (creamy white cellular infiltrates tend to settle to inferior region of anterior chamber, localize btwn purkinje 1 and 2)
Keratic precipitates (greasy-tan color, inflammatory debris adhered to corneal endothelium, localize on purkinje 1)
**also hyphema(blood in AC) and fibrin |
|
|
Term
| What type of inflammation is associated with large keratic precipitates? With fine keratic precipitates? |
|
Definition
Large = granulometous
Fine = lymphoplasmacytic |
|
|
Term
| What iris color changes can be associated with anterior uveitis? |
|
Definition
rubosis iridis (redness secondary to iris congestion/hyperemia)
diffuse fibrin deposits and iris depigmentation can also occur with chronic inflammation |
|
|
Term
| What are 4 clinical signs associated with posterior uveitis? |
|
Definition
vitreous opacities (inflammatory debris and/or blood that localize behind purkinje 3)
tapetal hyporeflectivity
retinal hemmorhage
retinal detachement |
|
|
Term
| What is a good quantitative way to diagnose uveitis? |
|
Definition
| intraoccular pressure (<10 mmhg is associated with uveitis, occurs b/c cilliary body produces less aqueous humor) |
|
|
Term
| What is the most common cause of uveitis in dogs and cats? |
|
Definition
|
|
Term
| T/F: if a patient presents with the clinical signs of uveitis you need to do a diagnostic work up including CBC/Chem +(FIV/FeLV titers if a cat) |
|
Definition
TRUE
**idiopathic uveitis is a diagnosis of exclusion, you must rule out infectious and neoplastic etiologies |
|
|
Term
| T/F: vitreous or aqueous aspirates are a first line diagnostic test for uveitis |
|
Definition
FALSE
**high risk procedures, should only be considered in a blind eye |
|
|
Term
| Which uveitis etiology more commonly affects both eyes? |
|
Definition
| infectious (but not always bilateral) also tends to affect younger animals than idiopathic or neoplastic uveitis |
|
|
Term
| How is phacolytic uveitis different from phacoclastic uveitis? |
|
Definition
Phacolytic uveitis is mild and chronic, in response to slow leakage of lens proteins from hypermature/resorbing cataracts
Phacoclastic uveitis is acute and severe, associated with traumatic rupture of the lens (often cat claw) or rupture of intumescent cataract (ex. diabetic) |
|
|
Term
| What physical exam findings are consistent with uveodermatologic syndrome (aka. Vogt-Koyanagi-Herada)? |
|
Definition
Skin depigmentation, panuveitis and retinal detachement
(esp. nordic breeds- huskies/akitas)
heritable immune-mediated response against melanin, treat with immunosuppressive therapy |
|
|
Term
| What disease of golden retrievers is progressive to glaucoma and eventual blindness, and has no effective treatment? |
|
Definition
pigmentary uveitis of golden retrievers
uveal cysts form --> deposit melanin on the lens capsule --> glaucoma |
|
|
Term
| What 3 sequelae of FeLV infection can result in the development of uveitis? |
|
Definition
itraocular lymphoma
anemia --> endothelial hypoxia and vascular leakage
spastic pupil syndrome (neuritis of cranial nerve III *oculomotor* results in spasm of dialator and sphincter muscles) |
|
|
Term
| What are two sequelae of FIV infection that result in the development of uveitis? |
|
Definition
direct tissue damage secondary to viral replication
superinfection (ex. toxoplasma gondi) secondary to immune suppression |
|
|
Term
| How can FIP infection in cats manifest as uveitis? |
|
Definition
| "dry form" = granuloma formation with large "mutton fat" keratic precipitates (greasy-tan deposits of inflammatory debris on the corneal endothelium) |
|
|
Term
| How can canine distemper virus manifest as uveitis? |
|
Definition
| choroiretinitis +/- "bystander-effect" optic neuritis characterized by tapetal hyporeflectivity due to accumulation of cells or fluid overlaying the tapetum |
|
|
Term
| What systemic mycoses are dogs more likely to develop than cats? |
|
Definition
Blastomycosis (B. dermatidis)
**anterior lesions are ALWAYS extentions of posterior lesions, need to tx systemically |
|
|
Term
| What is the most common occular fungal disease in cats? What non-ocular clinical signs are often present? |
|
Definition
Cryptococcus (c. neoformans)
causes posterior uveitis and optic neuritis often with concurrent CNS and nasal pathology, need to tx systemically |
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