Unit 2 - The Uvea Flashcards
The uvea is the ______ layer of the eye.
Vascular
What are the two components of the uvea?
Anterior uvea and posterior uvea
What are the components of the anterior uvea?
Iris and ciliary body
What are the components of the posterior uvea?
Choroid
What is the iris made out of?
Smooth muscles - the constrictor is stronger than the dilator
What does the iris do?
It regulates the amount of light that reaches the retina
What are the zones in this photo?
A - Ciliary
B - Collarette
C - Pupillary
Where do PPMs arise from?
The collarette of the iris
What is mydriasis?
Dilation of the iris
What drugs can cause mydriasis?
Tropicamide
Atropine
Phenylephrine
What is miosis?
Constriction of the iris
What drugs can cause miosis?
Pilocarpine and demecarium bromide
What is the ciliary body made up of?
Smooth muscles
What are the functions of the ciliary body?
Production of aqueous humor
Suspension of the lens zonules
Accommodation
What is the function of aqueous humor?
To nourish the cornea and lens
What accomodation does the ciliary body provide?
It accomidates focus by changing lens shape
Relaxed ciliary muscle results in what (to the zonules and lens)?
Taught zonules and thin lens
Contracted ciliary muscle results in what (to the zonules and lens)?
Loose zonules and rounder lens
Where is the choroid locateD?
Between the sclera and retina
T/F: A choroid can be atapetal but if there is a tapetum it will be located in the ventral region of the choroid.
False - it will be in the dorsal region of the choroid
What does the tapetum look like?
It is a highly reflective, yellow-green-orange ‘shine
What does the atapetal choroid look like?
It is variably pigmented and usually a dark, uniform color
What is the blood ocular barrier? What is its purpose?
It is a blood aqueous barrier that prevents the leakage of protein and cells into the eye from systemic circulation
It maintains the clarity of aqueous humor
What happens if the blood ocular barrier is broken down?
It results in clinical signs of uveitis
What is uveitis?
Inflammation of the uveal tissue
What is anterior uveitis?
Inflammation of the iris and ciliary body
What is posterior uveitis?
Inflammation of the choroid
What is chorioretinitis?
Inflammation of the choroid and retina
What is panuveitis?
Inflammation of all of the ocular layers
What is endophthalmitis?
Inflammation of the intraocular contents, excluding the fibrous tunic
What is panophthalmitis?
Inflammation involving all structures of the eye, including the neural, uveal, and fibrous tunics
What general clinical signs and findings are associated with uveitis?
Blepharospasm
3rd eyelid elevation d/t enophthalmos
Rubbing at the eye
Photophobia
Epiphora
Decreased vision or blindness
What are the ocular surface clinical signs and findings associated with uveitis?
‘Red eye’ due to episcleral and conjunctival BV injection
Corneal edema - localized or diffuse
Dense peripheral corneal neovascularization
What clinical signs and findings are associated with uveitis of the intraocular anterior segment?
Keratic precipitates
Aqueous flare, hypopyon, hyphema
Fibrin clots or strands
Iris hyperemia or ‘rubeosis irides’
Iris swelling or color change
Irideal hemorrhage
Peripheral anterior or posterior senechia
Dyscoria
Miosis or resistance to pharmacologic dilation
Lens subluxation
What clinical signs and findings are consistent with intraocular posterior segment uveitis?
Vitreal cells
Vitreal hemorrhage
Vitreal degeneration
Subretinal exudates causing hyporeflectivity in tapetal fundus or white-yellow discoloration in nontapetal fundus
Retinal hemorrhage
Retinal detachment
Optic neuritis
What is aqueous flare caused by?
Suspended protein/cells in the anterior chamber
How do you assess aqueus flare?
Deliberate 90 degree exam in a dark room with intense, focal light source close to the corneal surface
What is the normal intraocular pressure in a dog/cat?
10-20 mmHg
What intraocular pressure is consistent with uveitis?
<10 mm Hg or low normal range
What intraocular pressure is consistent with glaucoma?
> 20 mmHg
What clinical signs are consistent with active posterior uveitis?
Poorly defined lesions - +/- raised
Hyporeflective lesions in the tapetum
White/grey areas in non-tapetum
Retinal detachment
What clinical signs are associated with historic posterior uveitis?
Well defined lesions
Hyperreflective lesions in tapetum - +/- pigmented center
White grey areas in non-tapetum
What are the causes of uveitis?
Traumatic, neoplastic, lens-induced, infectious, immune-mediated, idiopathic
What are the primary ocular causes of uveitis?
Trauma - blunt or penetrating
Corneal ulceration
Intraocular neoplasia
Cataract
T/F: Any widespread infection or metastatic neoplasia can be a systemic cause of uveitis.
True
What immune mediated etiologies can result in uveitis?
Uveodermatologic syndrome (immune-mediated melanin attack)
Immune-mediated thrombocytopenia
Immune mediated vasculitis
Golden Retriever pigmentary uveitis - associated with ciliary cysts
T/F: Idiopathic uveitis may be up to 75% of non-ocular causes of uveitis.
False - it is 50%
What does a uveitis workup consist of?
Complete ocular exam
Complete physical exam
Additional diagnostic testing such as CBC, chemistry, urinalysis, LN aspirat, thoracic/abdominal imaging, ocular ultrasound +/- aspirate
What are the keys to uveitis treatment?
Start treatment immediately +/- submit labwork
Topical and systemic anti-inflammatory drugs
Topical mydriatic
Address underlying cause
What is the treatment protocol for uveitis?
Treat the eye aggressively at first and tehn taper medications as signs resolve
Treat 2-4 weeks
Address underlying cause
What is the preffered topical anti-inflammatory for the treatment of uveitis?
What other options are there?
Preferred - 1% prednisolone acetate (steroid) QID+
Others: 0.1% dexamethasone (Neo-Poly-Dex - steriod) QID+, Diclofenac, Flurbiprofen, ketorolac, suprofen, bromfenac TID-QID
When are topical NSAIDs preferred over steroids in uveitis treatment?
When there is concurrent corneal ulceration present
What topical steroids should not be used for the treatment of uveitis? Why?
Hydrocortisone, betamethasone, or sodium phosphate forms because they have poor penetration
What form of uveitis are topical NSAIDs great for?
They are great to prevent or treat mild lens-indued uveitis
What systemic drugs can be used for the treatment of uveitis (general)?
Systemic NSAIDs or systemic corticosteriods
What specific systemic NSAIDs can be used to treat uveitis? When are they contraindicated?
Drugs: Carprofen, meloxicam, firocoxib
Contraindication: Avoid if hyphema/hemorrhage
What systemic corticosteroids are indicated for treatment of uveitis? When are they contraindicated/should take caution?
Drug: 0.5-1 mg/kg prednisone BID then taper
Use caution with systemic infectious disease
What is the preferred topical mydriatic for treatment of uveitis?
Atropine SID-BID
Why would you want to use a mydriatic for treatment of uveitis?
To reduce ciliary spasm pain
Dilation of the pupil/prevents synechia
Stabilizes blood-aqueous barrier
In what uveitis cases is atropine contraindicated?
If the intraocular pressure is elevated
What side effects are associated with atropine use?
GI stasis, reduced STT, cat hypersalivation
If you don’t have atropine, what other mydriatic drug can you use in the treatment of uveitis?
Tropicamide TID-QID
What systemic anti-microbial drugs can be used to treat uveitis?
Doxycycline 10 mg/kg PO SID x 21 days
Broad spectrum abx if bacterial disease suspected
Oral antifungals if indicated
What are the possible sequelae to uveitis?
Cataract formation
Synechiation - usually posterior, iris bombe is bad
Lens luxation/subluxation
Phthisis bulbi
Secondary glaucoma
What are the keys to uveitis management?
Must recognize clinical signs
Perform a thorough evaluation
Get accurate diagnosis/diagnoses
Plan appropriate treatment and start ASAP
Timely rechecks
What are persistent pupillary membranes?
Embryologic membranes that usually regress by birth but have remained
What are the types of persistent pupillary membranes?
Iris to Iris
Iris to lens
Iris to cornea
How are PPM treated?
No treatment is needed
What is the difference between PPMs and Synechia?
PPMs arise from the iris collarette to the lens, cornea, or other areas of the iris
Synechia extend from the pupillary margin of the iris to the lens to the cornea
T/F: Uveal cysts are tumors, but they are typically benign.
False - they are not tumors, but they are typically benign
How are non-problematic uveal cysts treated?
No treatment is usually needed but you can aspirate them or deflate them with a laser if the vision is impacted
What type of uveal cyst is problematic? What is it associated with?
Ciliary-based cysts
Associated with autoimmune uveitis
What is iris hypoplasia?
Thin iris tissue
What is iris coloboma?
Focal absence of tissue manifesting as a hole that can occur anywhere in the iris
In what age group is iris atrophy common in?
Middle-aged and older animals
What is iris atrophy?
A thin iris or irregularity of the pupillary margin
It may limit pupil constriction resulting in a poor PLR and/or anisocoria in an otherwise normal eye
What primary uveal neoplasias occur in dogs and cats? What species are they more prevalent in?
Ciliary body adenoma/adenocarcinoma - dog > cat
Melanocytoma/melanoma - dog > cat
Diffuse iris melanoma - cat > dog
What should you do if you have a patient with primary uveal neoplasia?
Monitor the eye and intraocular pressure - they are usually benign but locally destructive
With what primary uveal neoplasia is metastasis more common with?
Diffuse iris melanoma
What is the most common metastatic uveal neoplasia?
Lymphoma - ‘hot’ eye but not painful
Note: A lot of neoplasia types can metastasize to the lungs, but lymphoma is the big one
