Flashcards in 8: the uvea - pearce Deck (87):
which vascular tunic is the uveal tract?
middle vascular tunic
what are the components of the anterior uveal tract?
what are components of the ciliary body?
anterior: pars plicata
posterior: pars plana
what is the fxn of the pars plicata?
what makes up the posterior uveal tract?
where is the choroid loc?
behind the retina
what is the significance of the uveal tract being an "immuno sensitive" organ?
it tells us a story - manifestation of 1* ocular dz OR is an ocular manifestation / sentinal for systemic dz
what is the importance of the choroid in terms of pharmacokinetics of drugs in the eye?
topical medication cannot reach the back of the eye d/t the choroid
NEED systemic meds to reach the back of the eye
what is heterochromia iridis?
multiple colors occurring w/in one iris
what is heterochromic iridium?
multiple colors occurring btwn 2 eyes
in cases of heterochromia iridis, the posterior uveal tract, in addition to the anterior uveal tract, is affected
what part of the posterior uveal tract is impacted in cases of heterochromia iridis?
choroid has less or no pigment - so less or absent tapetum
why the red eye reflection occurs in blue eyes
what is the normal appearance of the reflection of the eye?
how is it different in humans, animals with blue eyes and in cases of heterochromia iridis?
normal: green/yellow reflection is the tapetum w/in the choriod
abnormal: red eye reflection b/c non pigmented choroid / lack of pigment / tapetum
what is an iris coloboma?
absence / defect of iris tissue
which location does an iris coloboma MC occur?
in the "6 o'clock" position
b/c there is an incomplete closure of the embryonic fissure in this location
what are persistent pupillary membranes (PPMs) ?
incomplete resorption of iridal embryonal vasculature and mesenchymal tissues
normal: the sheet of mesenchyme in the pupil atrophies in the embryo
what is the result of persistent pupillary membranes?
what is seen in the eye?
strands of tissue seen in the eye - originate at the iris collarette [in the middle of the iris]
in persistent pupillary membranes, what are 3 locations the strands can go to?
what is the manifestation of each?
iris to iris [more benign]
iris to cornea [corneal opacity]
iris to lens [cataract]
how does synechia differ from persistent pupillary membranes?
synechia is adherence of tissue
PPMs are strands
PPMs originate from iris collarette - synechia does not
what is pupil dyscoria?
abnormally shaped pupil
what is pupil corectopia?
abnormal location of pupil
what is anterior segment dysgenesis also referred to? [why?]
what conditions typically occur with this condition?
merle ocular dysgenesis - common with accidental Merle to Merle breeding
- iris colobomas
- others also
what is anterior segment dysgenesis?
lens does not sepaarate properly from corneal tissue
what is iris atrophy?
spontaneous progressive thinning of the stroma or pupillary portion of the iris (or both)
common finding in middle-aged and older dogs
why might iris atrophy lead to light sensitivity?
- thin area allows light through instead of through the pupil
- and/or dec constriction ability of the pupil
2 common degenerative uveal changes?
how to differentiate a cyst from a melanoma?
melanoma does NOT transilluminate - neoplasia will not let light though
cysts DO transilluminate
what are 2 forms of 1* uveal neoplasia?
- melanocytic iridal neoplasia [melanoma / melanocytoma]
- ciliary body adenoma / adenocarcinoma
what is MC 1* uveal neoplasia?
which species (dog or cat) has the worst prognosis?
melanocytic iridal neoplasia [melanoma / melanocytoma]
cat worse prognosis
overall - less than 10% malignant typically
what is the 2nd MC 1* uveal neoplasia?
ciliary body adenima / adenocarcionma
- pigmented or non pigmented
50/50 benign / malignant
what is MC 2* uveal neoplasia?
c/s of 2* uveal neoplasia d/t LSA?
what ocular structures are typically affected?
what % of dogs and cats show ocular signs?
- 40% of dogs show ocular signs
- 50% of cats show ocular signs
- iris and ciliary body usually affected
what are less common causes of 2* uveal neoplasia?
carcinomas (renal, panc, thyroid)
what are 3 ways uveal tumors are treated?
- locally - Sx excision, diode laser for focal lesions
- chemotherapy [systematic or metastatic dz]
in what cases would enucleation be considered to Tx uveal tumor?
- extensive 1* tumors
- inflamed or glaucomatous eyes
what are some benefits to using laser Tx for uveal tumors?
- less invasive Tx option
- does NOT damage the cornea => only affects damaged tissue
- good for focal lesions and/or in early stages
what is aqueous flare?
what condition is it pathogneumonic for?
tyndall effect of haziness in the posterior chamber d/t presence of particulates suspended in the fluid and illuminated by light
anterior uveitis => inflammation leading to inc permeability of ocular vessels [impaired blood/ocular barriers] -> protein leaks out, into the posterior chamber
c/s of anterior uveitis?
hypopyon / fibrin
iris color change
what is ciliary flush?
360* corneal vascularization ("hedge" appearance) that is present with deep intra ocular dz, uveitis, glaucoma, deep corneal dz
why is corneal edema seen with anterior uveitis?
hazy cobblestone appearance of cornea
b/c endothelial cells are not able to pump fluid out of the cornea like they should do, b/c of the inflammation
why does dec IOP occur w anterior uveitis?
toxic things floating around in the eye affects its ability to produce fluid - b/c the non pigmented epithelium of the ciliary body does not perform well
dec fluid production -> dec IOP
what is hypopyon?
pus in the eye
what color changes occur to the iris during anterior uveitis?
under what circumstances?
darker -> brown to dark brown / black OR blue to yellow
what is reubeosis iridis and what does it mean?
blood vessels grow on the iris surface
pathogneumonic for uveitis
what do keratic precipitates look like?
a greasy appearance => granulomatous inflammation
why does miosis occur with anterior uveitis?
inflammation with PGs - stimulates PG receptors of the iris - miosis occurs
also - spasm of iris sphincter M occurs
what are c/s of posterior uveitis?
- tapetal hyporeflectivity
- retina: edema, detachment, hemorrhage
- vitreous opacity
what part of the uveal tract does posterior uveitis occur in?
what is common sequelae of uveitis?
what is synechia?
adherence of iris to lens tissue
posterior: can stick to lens
anterior: can stick to cornea
what are common sequelae to uveitis?
lens luxation - d/t zonular break down
phthisis bulbi - d/t chronic lack of fluid produciton
iris bombe - 360* adherence of pupil martin -> fluid pushes iris fwd and pupil stays on loc of lens b/c it is stuck there
what is endophthalmitis?
inflammation of intra ocular contents
NOT cornea and sclera
what is panophthalmitis?
inflammation of all ocular structures ==> including orbital fissure
includes fibrous tuinc (cornea and sclera)
the first thing to do when approaching a uveitis patient is to make an etiologic diagnosis. over ____% of cases are idiopathic.
common infectious causes of canine uveitis?
viral - distemper, CAV-1
tick born - RMSF, ehrlichia
bacT - brucella, lyme
parasitic - dirofilaira
algal - protheca
protozoal - toxo, neospora
common causes of feline uveitis?
4 Fs and 1 T:
classifications of non infectious uveitis?
what are metabolic causes of uveitis?
hyper lipidemia -> aqueous fills up with lipid -> eye looks very milky
diabetic - cataract related / lens induced uveitis
common immune mediated cause of uveitis?
targets pigmented cells - many loc w/in uveal tract
2 types of lens associated uveitis?
phacolytic - protrusion across intact lens capsule
phacyclastic - lens capsule rupture
2 types of traumatic causes of uveitis?
blunt or piercing
Dx of uveitis?
blood work (cbc, chem)
chest x rays
abdominal x rays
infectious dz testing
after etiologic dx of uveitis is made, what next?
px undesirable sequelae
Tx of uveitis?
Tx 1* cause, if an etiologic cause is made
specific abx, chemotherapy, remove lens / foreign material, Tx of ulcerative keratitis
presumptive tx of uveitis in cats:
presumptive tx of uveitis in dogs:
doxycycline (anti rickettsial)
drugs to control inflammation in Tx of uveitis?
3 classes and some examples in each
corticosteroids - topical, systemic, sub conjunctival
NSAIDs - topical, systemic
immuno suppressive agents - cyclosporine, azathioprine
what 2 classes of drugs should NOT be used together in the Tx of uveitis?
systemic NSAIDs and steroids
contra indications to corticosteroid use?
ulcerative keratitis - NO topicals
deep mycotic dz - NO systemics
concerns with topical corticosteroid use?
inhibits wound healing
concerns with systemic corticosteroid use?
the best treatment for an ulcer is topical steroids
never give topical steroids if an ulcer
what is solubility of a corticosteroid?
solubility: acetate and alcohol forms more lipid soluble than phosphate forms; relates to penetration of the drug into a tissue
potency: the extend of the anti-inflammatory effect, irrespective of penetration
high lipid solubility of a steroid means better penetration into which tissue layer?
the addition of what to a molecule enhances the anti inflammatory activity?
i.e. improves potency
fluoride and methyl molecules
a more potent corticosteroid is just as good as a more soluble steroid, if given at higher doses
a more potent drug will do NO good if it cannot penetrate the target tissue
what corticosteroids are very lipid soluble, therefore penetrate tissues well?
this is effective in the Tx of what?
common NSAIDs used to treat uveitis?
for what type of uveitis are systemic NSAIDs necessary?
necessary for posterior uveitis
topical NSAIDs are often used along with topical steroids
what are two examples of commonly used topical NSAIDs?
what is the 1* indication for topical NDAID use in uveitis?
concerns of the use of NSAIDs in Tx of uveitis?
indications for systemic NDAIDs?
- adjunct to topical Tx of anterior uveitis
- ocular discomfort
concerns with systemic NSAIDs in tx of uveitis?
dry eye (KCS)
what drugs are used in the Tx of uveitis to Px undesirable sequelae?
- anti glaucoma drugs
- mydriatics / cycloplegics
2 classes of mydriatics / cycloplegics used in Tx of uveitis?
- anti cholinergics [atropine, tropicamide]
- adrenergics [phenylephrine hydrochloride]
- eliminates ciliary spasm / pain
- dilates pupil and Px synechia
- stabilizes blood aqueous barrier
- contraindicated in glaucoma or if tear deficiency