Anterior Uvea and Uveitis Flashcards
describe uveal anatomy
the vascular tunic of the eye; location of the blood eye barrier
-normally prevents entry of pathogens, drugs, and inflammatory cells from blood stream, as intraocular structures cannot tolerate inflammation
anterior uvea: blood aqueous barrier
1. iris
2. ciliary body:
posterior uvea: blood retinal barrier
choroid
describe the iris
- stroma
- vessels
- epithelium, posterior only
4 functions:
1. protection
2. nutrition
3. controls light entry (constrict and dilate)
4. removes waste and aqueous humor
-at the base of the iris is the iridocorneal angle/drainage angle where aqueous humor exits
describe the functions of the ciliary body
- produce aqueous humor
- lens accomodation: via the ciliary muscle for near and far sight
describe uveal persistent pupillary membranes
persistent pupillary membranes
-originate at the iris collarette and can be
-iris to iris: generally benign, common in horses, strand like, and may span the pupil
-iris to cornea: posterior corneal adhesions or corneal opacities that may cause chronic corneal edema and interfere with vision
-or iris to lens
-breed disposition
describe iris cysts and iris atrophy, two acquired uveal diseases
iris cysts:
1. some breeds predisposed
2. may rupture and cause pigment dispersion (pigment balloons that float to the front of the eye)
3. usually not clinically significant and trans-illuminate
iris atrophy:
1. common in older dogs as pupil loses ability to constrict
2. usually not clinically significant
describe uveitis, generally
- inflammation of the vascular tunic (uvea) due to a breakdown in the blood-ocular barrier
- can be devastating so IMMEDIATE treatment is required
- usually a manifestation of systemic disease with many many causes
what are 6 clinical signs of uveitis?
- change in pupil size (miosis, small pupil)
- change in iris color: red or dark and may have petechiae
- low IOP with greater than 5mm difference between eyes
- scleral injection +/- conjunctival hyperemia
- pain: blepharospasm, epiphora, rubbing
- FLARE (hallmark!!)
-increased protein and cellular content of AH due to increased vascular permeability
describe the flare seen as hallmark of uveitis
- increased cells and protein in AH
- hypopyon: pus in AC
-tan, yellow, or white opacities in AC
-having an eye full of pus doesn’t necessarily mean infection IN the eye; white cells are nonspecific; just means inflammation and breakdown of BAB - hyphema: blood in AC
-may be clots or diffuse - fibrin
- tyndall effect:
-dispersions of light in colloidal solutions of liquid
-extra protein acts like a fog machine so you can track light as it passes through AH - can also cause a hazy appearance on tapetal reflection or iris detail obscured
describe normal versus flare purkinje images
normal: beam of light concentrated on cornea produces 2 separate purkinje images:
-beam on cornea
-beam on iris or lens (next structure deep)
-NO light seen in anterior chamber (space of darkness)
flare: light seen in anterior chamber
what are 7 consequences of uveitis?
- glaucoma
- synechia: posterior or anterior (iris/pupil sticks to lens and can’t move)
- cataract
- retinal detachments: when inflammation in back of eye
- loss of vision
- complete blindness
- enculeation
what is the first thing you have to do with uveitis?
rule out primary intraocular causes!
- lens-induced uveitis
- blunt injury
- reflex uveitis from corneal ulceration
-rule out first! all corneal ulcers cause some degree of reflex uveitis - intraocular tumors
if it is not due to a primary intraocular cause, what are 5 systemic categories of uveitis?
- infectious: basically anything
-bacterial: often will be septic if affecting the eye unless a spicy bacteria
-fungal
-algal
-viral: more common in cats
-protozoa
-tick borne
-parasitic: will often see the worm in the eye - immune-mediated: uveodermatologic syndrome
- lens: cataract
- metabolic:
-diabetes
-hyperlipidemia - neoplasia:
-primary or metastatic
describe the 3 phases of uveitis diagnostics
- history (travel), physical exam, ophthalmic exam
-to rule out primary intraocular causes
-at this stage, if flueorescein negative, immediately start treatment with topical steroids while you investigate further!! - additional diagnostics based on suspicion:
-CBC, chem, UA
-thoracic rads to check for neoplasia
-various infectious disease tests
–viruses higher up in suspicion for cats!
-abdominal or ocular ultrasound - aqueous or vitreous aspirates for cytology and culture, diagnostic enucleation, advanced imaging (MRI/CSF tap)
describe uveitis due to neoplasia (4)
- tumors sometimes visible
- may be in ciliary body
- visible with dilation or may require ocular ultrasound
- lymphoma is very common in cats; if seeing in eye, implies later stages
describe the relationship between cataracts and uveitis
- cataracts cause lens proteins to leak through the capsule, causing inflammation
- if the cataract causes uveitis, it will be complete with rapid onset (more common in dogs)
- if uveitis causes cataracts, most patients can still see (more common in horses and cats)
