Uvea Flashcards
Uvea
The uvea is the middle vascular area of the eye. Any inflammation in the eye is associated with these vessels and hence “uveitis” describes any intraocular inflammation.
anterior uvea
iris and ciliary body
posterior uvea
choroid (between the nervous retina and the sclera)
Iris
the vascular structure located in front of the lens and rests on it
pupil
central opening of the iris; controls how much light enters
Corpora nigra
lobulated structure at the superior pupillary margin and is the dilation and extension of the posterior iris epithelium through the pupil.
What controls the iris sphincter muscle
parasymp innervation + CN III
Iris Dilator muscle is under what control
sympathetic control and dilates the pupil.
greater arterial circle
only normal iris vessel seen as it meanders around the peripheral iris.
Ciliary Body
vascular structure located posterior to the base of the iris and is not normally seen when viewing through the pupil
PPMs – Persistent pupillary membranes
mbryologic remnants that fail to regress by 6 weeks of age. They may be incidental iris to iris PPMs, or pathologic iris to cornea or iris to lens PPMs causing focal cataracts on the lens or opacities on the corneal endothelium.
Iris atrophy
Atrophy of the iris sphincter prevents normal pupillary constriction and appears as scalloping of the pupillary margin.
Iris cysts
These are fluid filled, pigmented, transilluminating (light passes through) structures that form from the posterior iris epithelium and may enter the anterior chamber.
In American Bulldogs uveal cysts are associated with
inflammation (uveitis) and glaucoma.
In the Golden Retriever lightly pigmented uveal cysts
are considered early sign of pigmentary uveitis.
Synechia
Anterior synechia refers to the adhesion of the iris to the corneal endothelium and posterior synechia refers to the adhesion of the iris to the lens capsule. Synechia is usually the result of an inflammatory episode.
Iris freckles
focal areas of increased pigmentation without a change in the normal iris face architecture.
Iris freckles… in the cat
In cats they need to be monitored for change and progression to melanosis or melanoma.
Uveal (iris/ciliary) melanoma in the dog
usually benign but is catastrophic to the eye. Choroidal melanomas are reported to be benign, but the cases I have seen invaded the sclera or optic nerve. Melanomas that are focal and involve <25% of the iris may be surgically excised by a partial iridectomy.
treatment of uveal melanoma in the dog
Melanomas of the iris face may respond temporarily to diode laser treatment. Once glaucoma occurs enucleation is indicated. Histopathology should be performed to rule out more sinister disease such as histiocytic sarcoma. Met check should be performed pre-op.
Anterior uveitis
iris & ciliary body - painful
Posterior uveitis=
choroid
Anterior & posterior uveitis
panuveitis
Panophthalmitis
all layers of the eye
clinical signs of anterior uveitis
- *Blepharospasm
- *Photophobia
- *Miosis: constricted pupil
- *Hypotony: low intraocular pressure
Signs of chronic uveitis
Keratic Precipitates Posterior synechia Cataract – any opacity of the lens Lens luxation/subluxation Rubeosis iridis (vessels on face of iris) Iris hyperpigmentation Iris degeneration Secondary glaucoma
Keratic Precipitates
Inflammatory cells (lymphocytes, plasma cells & macrophages), fibrin, or pigment deposits on the corneal endothelium
Posterior synechia:
Pupillary margin adhered to anterior lens capsule. A complete obstruction to aqueous flow through the pupillary opening into the anterior chamber due to complete posterior synechia of pupil margin is ‘iris bombe’. This is an emergency referral.
Causes of Uveitis
primarily an ocular disease or the result of systemic disease
Primary ocular neoplasia:
Most commonly uveal melanoma, ciliary adenoma /adenocarcinoma occur in dogs as primary ocular tumors. They generally do not metastasize but are destructive to eye resulting in enucleation.
Pigmentary Uveitis what breed
goldens
Pigmentary Uveitis
In any age group, pigment dispersion occurs on the anterior lens capsule with subsequent development of posterior synechia, cataracts and glaucoma. This is not a painful disease and very little inflammation is present.
treatment of pigmentary uveitis
There is no specific treatment but daily topical prednisolone acetate and atropine are commonly used to delay the onset of glaucoma.
early sign of pigmentary uveitis
Transilluminating uveal cysts are early indication of PU in the Golden Retriever.
Uveitis is often present in Bassett Hounds with what
glaucoma
Retinal detachment
may be due to a primary ocular disorder leading to the detachment such as: vitreal dysplasia and retinal tears in the Shih Tzu; Collie Eye Anomaly or vitreal traction bands in the Labrador.
Uveodermatologic Syndrome
is an immune mediated disease with Akitas and Arctic breeds overrepresented, but it can occur in any breed.
Clinical signs of uveodermatologic syndrome
Clinical signs are anterior uveitis, often with hyphema, uveal depigmentation, retinal separation/detachment, blindness and secondary glaucoma. Dermatologic signs follow ocular signs and include vitiligo of eyelids, nasal planum, lips, perineum, and footpads. Diagnosis is by skin biopsy or breed and clinical signs.
Tick-borne diseases:
Ehrlichia, Rickettsia (RMSF), Lyme’s, Babesia
Bacterial:
Leptospirosis, Brucella, Bartonella, Septicemia any cause
Fungal
Histoplasma, Blastomycosis, Cryptococcus, Coccidiodes, Aspergillosis (GSD)
Viral:
CAV 1, canine herpes (puppies), canine distemper virus
Parasites
Toxoplasmosis, Neospora, ocular larval migrans, filariasis, opththalmomyiasis, Leishmania, E caniculi (rabbit & cat)
Algae
Prototheca
Treatment of uveitis (topicals)
Steroids: Topical steroids that penetrate the cornea are prednisolone acetate and dexamethasone.
NSAIDS: diclofenac or flurbiprofen
treatment of uveitis (systemic)
Prednisone should be used only if infectious disease has been ruled out or after antibiotics have been initiated.
Systemic NSAIDs can be used if infectious disease precludes use of systemic steroids (avoid in cats).
Cycloplegic Drugs
ATropine
Antibiotics - systemic
Doxycycline is indicated if tick borne disease, leptospirosis or bartonella are suspected.
Clindamycin if toxoplasmosis is suspected.
Clavamox should be used if the uveitis is associated with recent dental extractions
Topical antibiotics
ciprofloxacin, ofloxacin and chloramphenicol penetrate the intact cornea.
