Uvea Flashcards
what are the 3 components of the uvea
anterior uvea - iris, ciliary body
posterior uvea - choroid
muscles of the iris
sphincter muscle - parasympathetic (CN III)
dilator muscle - sympathetic
what is the purpose of the blood ocular barrier
allows for selective nutrition of avascular intraocular structures
prevents free passage of cells or proteins into the anterior chanber
allows clear media for vision
2 componenets of the blood ocular barrier
blood-aqueous barrier - iris blood vessels, ciliary body
blood-retinal barrier - retinal blood vessels, retinal pigmented epithelium
clinical signs of uveitis depend on ______ and _____ of barrier disruption
clinical signs of uveitis depend on location and severity of barrier disruption
inflammation in uveitis is driven by _______
prostaglandins
responsible for: miosis, decreased IOP, iris hyperpigmentation
ocular pain is mediated by ….
spasm of the ciliary body
clinical signs of ocular pain
blepharospasm
epiphora
photophobia
hidding or agressive behaviors
common rule outs for miosis
bright light
Horner’s syndrome
brain trauma
drugs (latanoprost)
uveitis (via prostaglandins)
aqueous flare
proteins (and cells) which leak into the anterior chamber
visualizing light scatter through turbid environment (tyndall effect)
dyscoria is often caused by _______
posterior synechia
is this anterior or posterior synechia
posterior synechia
is this anterior or posterior synechia
anterior synechia
often distorts the ocular surface
iris bombe is a risk factor for ….
secondary glaucoma via obstruction of aqueous from posterior chanber through the pupil
hypopyon
white blood cells settling in the anterior chamber
typically severe inflammation/break down of BOB
hyphema
RBCs settling in the anterior chamber
occurs primarily from uvetitis; also consider coagulopathies and hypertension
what is decreased IOP called
hypotony
- if you find a low reading, consider the effects of uveitis:*
- blood ocular barrier disruption = leaky*
- inflammation of ciliary body = decreased aqueous production*
what is the most clinically significant sequelae of chronic uveitis
secondary glaucoma
exogenous causes of canine uveitis
blunt or perforating trauma
corneal ulceration (reflex uveitis)
endogenous causes of canine uveitis
lens induced
infectious
neoplastic
metabolic
auto-immune
what causes “blue eye” in some dogs
canine adenovirus I
most common primary neoplasm in canine eye
melanocytoma
- DDx: uveal cyst*
- benign, enucleation is typically recommended*
characteristics of uveal cysts
spherical
transluminate
can be attached to pupil margin or free floating
only rarely need to be treated
common fungus casuing uveitis in cats
cryptococcosis
signs: “roman nose,” gramuloatous chorioretinitis
primary feline uveal tumor
feline diffuse melanoma - most common
only primary melonocytic tumor in companion animals that commonly displays malignant characteristics (check liver, spleen and lungs)
characteristics of feline diffuse iris melanoma that can assist in diagnosis
rapid progression (weeks to months)
texture is velvety
dyscoria due to invasion of iris musculature
pigmented cells floating in anterior chamber
freckle or melanoma?
can be hard to differentiate, need histopathology (enucleation) to confirm
metabolic causes of endogenous uvetitis in cats
hypertension - renal disease, hyperthyroidism
uveitis therapy
treat primary cause (if known)
all cases need anti-inflammatory therapy - systemic/topical coritcosteroids or NSAIDs, atropine, doxycycline
when should corticocosteroids not be used to treat uveitis
in the presence of corneal ulcers
what is wrong with this cat
given atropine as a mydriatic - has a bitter taste and may cause hyper-salivation
what are some pros to using atropine in the treatment of uveitis
induces cycloplegia (paralysis of the ciliary body - alleviates pain from spasm)
reduces risk of posterior synechia
stabilizes blood-ocular barrier
