Uvea Flashcards
What are the parts of the uvea?
- Iris
- Choroid (with tapetum)
- ciliary body
Where is the choroid in relation to the retina?
- It is posterior to it
Where does the iris sit?
- In front of, and rests on the lens
What is the central opening of the iris?
- Pupil
What is the role of the iris?
- Controls amount of light entering the back of the eye with sphincter and dilator muscles
What does a blue iris mean?
- Lacks pigment
Pupil type and PLRs in the dog
- Round
- Strong consensual PLR
What is the main blood vessel in the iris?
- Greater arterial circle
What is the pupillary ruff?
- little projections from the center of the iris
Equine pupil and PLR
- Horizontal when constricted , round when dilated
- Moderate consensual PLR
- Corpora nigra seen in the superior (and inferior) pupil
Camelid pupil and PLR
- Moderate consensual PLR
- Elliptical pupil with large plicating corpora nigra on upper and lower pupillary margins
Cat pupil and PLR
- Strong consensual PLR
- Vertical pupil when constricted and round when dilated by sympathetic input
Which CN is involved in constricting the cat pupil?
- Parasympathetic CN III
Bird PLR and pupil
- Round pupil
- No consensual PLR
- Hard to assess
- Can’t menace
Heterochromia
- 2 colors in the iris or two colored eyes
What type of blood vessel in the iris is abnormal?
- Blood vessels reaching towards the pupil
- The greater arterial vessel is normal around the peripheral iris
Can you normally see the ciliary body?
- NO
Where is the ciliary body?
- At the posterior base of the iris
What part of the ciliary body epithelium secretes aqueous?
- Pars plicata
What is the flat area between the ciliary processes and the retina?
- Pars plana
What is the choroid?
- Vascular layer between the sclera (posterior) and the retina (interior)
- Contains the tapetum
When is the choroid visible?
– In non-pigmented eyes (blue eyed animals)
Persistent pupillary membrane
- Can be from the iris to the cornea
Significance of PPM
- Residual and often incidental
- In some breeds it can cause cataracts
What does a merle-merle cross mean for the eye?
- Usually bad things
- We had an example with a hole in the iris, medial strabismus, and smaller eyes
Iris cyst - how can you differentiate from a uveal melanoma?***
- It will transilluminate so that you can see the edge of the iris through it**
- Usually perfectly round and delineated
Who gets iris cysts?
- Goldens
- Danes
- American Bulldog
- Any breed
- Cats
- Horses
When should you refer iris cysts?
- If it’s a Golden Retriever, a Dane, or a Bulldog
Corpora nigra cyst management
- Should do treatment as it will impact vision
- Diode laser ablation or aspiration/ablation
- Needs an ophthalmologist
Iris cyst management
- Usually don’t need anything
- However, if it’s a Golden Retriever, a Dane, or an American Bulldog, you should refer it
Iris atrophy signs
- Holes or imperfect margin in the iris
- Non-responsive, mydriatic pupil in a visual eye
Iris freckle appearance
- Flat pigmented area
- Melanosis
Importance of iris freckles
- Does not interfere with iris function
- Does not alter iris architecture
Treatment for iris freckle in a cat
- don’t need to do anything
Diffuse iris melanoma in a cat appearance
- Loss of iris architecture
- Raised and velvety appearing
- Often quite smooth
Treatment for iris melanoma in cats
- It will metastasize through the iridocorneal angle
- Take the eye out ultimately
Possible consequences of iris melanoma in cats
- Obstructs drainage angle
- Results in glaucoma
- Also metastasis
Canine iris melanoma appearance
- Can change the shape and function of the pupil
- May be swollen and distinct line
% of benign/malignant iris melanomas in dogs
- > 80% are benign but destroy the eye
- Hemorrhage/glaucoma
Limbal melanoma - who gets?
- GSD
- Labradors
Age of limbal melanoma
- MAY present at a young age
Treatment for limbal melanoma
- Surgical excision
- Diode laser
Ciliary tumor - benign or malignant?
- Most often benign
- Usually adenoma; may be adenocarcinoma
- Will destroy the eye
- Want to find out if it’s gone anywhere else or came from somewhere else
What forms the blood-eye barrier?
- Uvea
- Retinal vessels
- Retinal pigmented epithelium
Function of blood-eye barrier
- Protects the eyes from systemic disease and circulating toxins and drugs
- Eye responds poorly to inflammation and lacks lymphatic drainage
WHat is uveitis?
- Intraocular inflammation
What is a consequence of uveitis?
- Breakdown of the blood-eye barrier and allows protein and inflammatory cells to enter the eye through the uvea
Anterior uveitis - what’s involved?
- Iris and ciliary body
Posterior uveitis - what’s involved?
- Choroid/choroiditis
Panuveitis
- All structures closely related and all are affected to some degre
Anterior uveitis appearance
- Pain, injection, edema, inflammatory cells in the anterior chamber
Chorioretinitis appearance
- +/- pain, red eye, vision loss
- Subretinal infiltrate
Clinical signs of anterior uveitis
- PAIN!**
- Blepharospasm
- Miosis**
- Photophobia
- Conjunctival hyperemia
- Episcleral injection
- Corneal edema
- Corneal vascularization
- Low IOP***
What is the IOP in uveitis vs glaucoma?
- LOW in uveitis
Main clinical features of anterior uveitis
- Low IOP
- Miosis
- Painful eye
- Flare!
What is the first thing that will happen after uveitis starts?
- Protein leaks from vessels into the aqueous
- Flare
Flare
- Protein in aqueous
- Seen with slit beam
How can you differentiate corneal edema vs flare?
- Flare is flecks that are seen best with a slit beam
- Corneal edema is blue and mottled
What’s the 2nd step after proteins leak into the aqueous?
- Inflammatory cells
- May appear as hypopyon or sparkles (KPs)
Where do neutrophils go after they accumulate and settle?
- Inferior anterior chamber
- This is hypopyon
Keratic precipitants
- Macrophages and lymphocytes adhered to the epithelium
Rubeosis iridis
- Vessels grow across the face of the iris perpendicular to the pupil
How can hyphema occur with uveitis?
- Fragile vessels in the iris can easily bleed and lead to hemorrhage
Posterior synechia
- Iris adhered to the lens
- Pupil might not be able to move
- Vessels grow over the iris and stick to the lens
Iris bombe
- Complete posterior synechia of pupillary margin to lens
- Aqueous trapped behind the iris and causes the iris to bulge forward
Treatment for iris bombe and urgency of treating?
- EMERGENCY SURGERY to create iris window allowing aqueous to enter anterior chamber
Signs of chronic uveitis
- Posterior synechia
- Cataract
- Pigment on anterior lens capsule
- Secondary glaucoma
Posterior synechia
- Iris adheres to lens
Anterior synechia
- Iris adheres to cornea
Causes of uveitis - two main categories
- Primary ocular and systemic disease
- If you cannot find a primary ocular cause, look for a systemic cause
General primary causes of uveitis?
- Trauma
- Corneal ulcer
- Lens induced (cataract, lens perforation, lux or subluxation)
- Intraocular tumor
- Equine ERU
Systemic disease causes of uveitis
- Immune mediated
- Infectious
- Neoplasia
- Coagulopathy
- Hypertension
When can the lens cause uveitis?
- If it’s unstable (subluxated or luxated)
- Cataract
- Perforated
Uveal melanoma
- Primary ocular tumor
- Mostly benign but can lead to uveitis, hemorrhage, and secondary glaucoma
Equine recurrent uveitis causes
- Can be primary ocular cause of result of systemic disease
- Will become a primary, self-perpetuating, recurring uveitis
What can cause hyphema in the anterior chamber?
- Can be the result of or cause uveitis
Dfdx for hyphema in the anterior chamber
- Trauma
- Coagulopathy or anticoagulant rodenticide
- Immune-mediated
- Neoplasia
- Hypertension
Diagnosing causes of hyphema
- Check blood pressure
- Clotting times
- Platelets
Treatment for hyphema secondary to uveitis?
- Dilate pupil with atropine to reduce spasming
- Prednisolone acetate
- Address primary cause
- Avoid NSAIDs
Why avoid NSAIDs with treatment of uveitis?
- May potentiate bleeding
Golden Retriever Pigmentary uveitis - early signs?
- Translucent ciliary cysts
- NOT SEEN UNLESS LOOKED FOR WITH A LIGHT AND MAGNIFICATION
Course of disease with golden retriever pigmentary uveitis
- Progressive
- Ultimately results in glaucoma and loss of the globe
Clinical signs: golden retriever pigmentary uveitis
- Minimal to no inflammation or pain (until you hit glaucoma)
- Entropion uvea
- Pigment dispersion on lens
- Posterior synechia
- Cataract development
- Ultimate glaucoma and globe loss
Treatment of golden retriever pigmentary uveitis
- REFER EARLY
- Medical management with SID Atropine and topical NSAID may delay progression of disease
- Secondary glaucoma temporarily managed with dorzolamide and timolol
End stage of golden retriever pigmentary uveitis
- Glaucoma
Immune mediated diseases that can cause uveitis
- Lens induced uveitis
- Idiopathic (steroid responsive)
- Uveodermatologic syndrome
- Feline lymphocytic-plasmacytic uveitis (most likely infectious)
- Vaccine reaction
- ERU
Uveodermatologic syndrome - who gets
- Akita, arctic breeds
- Miniature Aussies
Clinical signs of Uveodermatologic syndrome
- Often acutely affected and blind
- VERY high pressure and painful
- Disease of exclusion
Uveodermatologic syndrome - pathophysiology
- Immune system impacts melanocytes
- Results in ocular and cutaneous disease
Treatment for Uveodermatologic syndrome
- Often have to take the eye out
- Systemically will be immune suppressed
Infectious diseases that can cause uveitis
- Tick borne (RMSF, Ehrlichia, Borrelia)
- Systemic mycosis (any of the ones we’ve learned about)
- lepto
- Brucella
- Toxoplasma
- Prototheca
- CAV1
- Bartonella
- Herpes
- Septicemia
What is often the infectious etiology implicated with ERU?
- Leptospirosis
What are the most common bacterial infectious agents causing uveitis in rabbits?
- Pasteurella and Staph are common infectious agents in rabbits causing dacryocystitis, dacryoadenitis, conjunctivitis, and uveitis
- E. cuniculi needs to be ruled out too
How does E. cuniculi cause uveitis?
- Parasite within the lens –> rupture –> granuloma –> uveitis
Treatment for E. cuniculi
- Remove the eye
Neoplasias that can cause uveitis?
- Metastatic ones include:
- LSA
- Histiocytic sarcoma
- HSA
- MSA
- Multiple myeloma
- Adenocarcinomas
Typical appearance for lymphoma in the eye
- Nodular, cellular infiltrate in the iris
- Can cause hemorrhage in the retina
- Look at the lymph nodes first
Treating the eye in a case with neoplasia?
- Must do, especially in the case we talked about with lymphoma
Patient work up for uveitis in dogs
- PE
- CBC/Chem/UA
- Tick titers
- Fungal screen
- Lepto/Brucella/Toxo titers
- Rule out systemic disease with chest rads and abdominal ultrasound
Treatment for immune-mediated disease underlying uveitis
- Steroids - topical and systemic
iF ASLL TESTS ARE NEGATIVE ONLY
Uveodermatologic syndrome diagnosis and treatment for uveitis
- SKin biopsy
- Topical and systemic prednisolone
Infectious disease diagnosis and treatment for uveitis
- Identify agent and treat accordingly
Neoplasia treatment for uveitis
- Chemotherapy depending on the type of cancer I’m guessing
General treatment principles for uveitis
- Topical prednisolone acetate 1% OR NSAIDs if inappropriate (topical and systemically)
- Atropine
- Possible systemic antibiotic depending on underlying disease
- Possible topical antibiotics
How often to give pred acetate and what must you rule out before giving?
- 1 drop every 4-8 hours based on severity
- Inflammation MUST be controlled
- MUST RULE OUT CORNEAL ULCER
How does pred acetate help with uveitis?
- Penetrates cornea and enters anterior chamber
- Do not use with corneal ulcer
- Decreases inflammatory response
When to do systemic NSAIDs or prednisone in dogs with uveitis?
- If infectious disease is ruled out or being treated
- Might try topical treatment first
NSAIDs - when to use for anterior uveitis?
- When steroids aren’t indicated
- Diclofenac
Function of NSAIDs in treating uveitis
- Block prostaglandins (inflammatory mediators)
- Facilitate dilating resistant miotic pupil
- CAN use with corneal ulcers, but use caution
- Systemic NSAIDs could be used (Carprofen, Deracoxib, Zubrin; banamine or bute in horses)
Use of systemic NSAIDs in cats
- Avoid
- You can use topical NSAIDs
- Diclofenac is systemically absorbed, so caution in cats with kidney disease
Function if atropine
- Mydriatic and cycloplegic
- Prevent synechia
- Reduce ciliary spasm and pain
- Stabilizes blood vessels (Blood-eye barrier)
When to use caution with atropine?
- If pupil is dilated, caution (may lead to uveitis)
- Avoid if increased IOP
Tropicamide use
- Not cycloplegic
- Probably don’t use
Cycloplegia
- Paralysis of the ciliary muscle in the eye
Treatment for tick borne diseases and Bartonella
- Oral doxycycline (careful)
Treatment for toxoplasmosis or oral disease
- Clindamycin
- Doxy works well for oral disease
Treatment for uveitis related to oral disease
- Clavamox
- Clindamycin
- Doxycycline
When to use topical antibiotics for uveitis
- With corneal ulcers, penetrating wounds
- Other intraocular infections
Which topical abx would you give for uveitis due to something penetrating the cornea?
- Want to choose an antibiotic that will go through the cornea
- Fluoroquinolone (ofloxacin, ciprofloxacin)
- Chloramphenicol
Which antibiotics do NOT penetrate the cornea?
- BNP, erythromycin, gentocin, tobramycin, terramycin
What must you consider in uveitis with a normal or high IOP?
- DO NOT TREAT WITH ATROPINE
- MUST ASSESS FOR SECONDARY GLAUCOMA**
When is enucleation indicated in uveitis?
- Patients with destructive ocular tumors
- Blind painful eyes (secondary glaucoma)
What can cause chorioretinitis?
- Immune-mediated disease
- Infectious disease
- Trauma
- Neoplasia
- Toxin
How do animals with chorioretinitis present?
- Decreased vision
Treatment for chorioretinitis
- Systemic treatment specific for the disease, in addition to anti-inflammatory use
- Generally prednisone
Panophthalmitis appearance-
ALL OCULAR TISSUES ARE AFFECTED
- Sclera will be bulging
IOP of panophtlamitis
- High normal intraocular pressure
Treatment for panopthalmitis
- No effective treatment
- Enucleation is indicated
