Uveal tract Flashcards
Embryology of uvea
Derived from mesenchyme (neural crest + mesoderm)
Iris musculature and epithelial layers are from neuroectoderm.
Stoma is from mesoderm.
Choroid layers
SUPRACHOROIDEA - pigmented, links to lamina fusca
LARGE VESSELS (vains)
MEDIUM VESSLES
TAPETUM
CHORIOCAPILLARIS
BRUCHβS MEMBRANE - joins with basement membrane of RPE
Difference of colour between two irides
Heterochromia iridis
Difference of the colour within the same iris
Heterochromia iridum
Merle ocular defects
Heterochromia irides, iris hypoplasia, correctional, dyscoria, ppm, colobomas.
Homozygous animals- retinal dysplasia, microphthalmos, ON hypoplasia, cataracts. Deafness.
Notch coloboma
At pupillary margin
Pseudopolycoria
Multiple colobomatous defects in iris
Anterior segment dysgenesis
ASD. Faulty differetiation of mesenchyme of the anterior segment Goniodysgenesis PPMs Peter's anomaly Uveal cyst
Iris atrophy
Senile or following trauma, chronic uveitis, glaucoma
Sings of uveitis
Pain-> lacrimation, photophobia, blepharospam Visual impairment Miosis, decreased iop, flare Swollen iris, loss of detail Hyperaemia or ciliary injection Vitreous opacities Chorioretinitis
Sequelae of uveitis
Chronic pain Glaucoma>blindness Corneal oedema/vasc Synechiae Iris bombe Iris rest Iris cyst Ectropion uvea Iris neovasc, colour change, atrophy Dyscoria/ immobile pupil Cataract / lens lux Vitreous opacities/liquefaction/haemorrhage Retinal detachment Chorioretinal degeneration/pigment proliferation Optic neuritis /atrophy Endophthalmitis/panophthalmitis Hydrophthalmos/phthisis bulbi
CAV uveitis
1Mild/transient uveitis during acute phase of illness
2 severe keratouveitis 1-3 weeks after inj
Red iop, hypopyon, KPs common
ARThus reaction -> corneal odedemaβ> keratoglobus or conus or bullous keratopathy
Clears from limbus to the centre
Usually unilateral
Canine herpesvirus uveitis
Kerato-uveitis, chirioretinitis and panuveitis in puppies. Neonatal death
Rickestial uveitis
Ehrlichia canis (UK - monocytic ehrlichiosis /tropical canine pancytopaenia )
E. platys ( infectious cyclic thrombocytopaenia)
Rickettsia rickettsii (Rocky Mountain β°οΈ spotted π€)
VASCULITIS AND THROMBOCUTOPAENIA
Leptospirosis uveitis
Number of serovars of diphasic protozoan causing asculitis or endothelitis
Ophth signs : conj, scleratitis, keratitis, kerato-uveitis +u.
Decreases T cell , incr B- cell
Brucellosis
May present as low grade uveitis
Zoonotic . Not in UK.
Borreliosis
Lime disease
Possibly implicated in uveitis
Lymphadenopathy
Lameness
Fungal uveitis
Imported animals Granulomatous or pyogranulomatous Blastomycosis Coccidio idomycosis Cryprococcosis Histoplasmosis Aspergillosis Geotrichosis
Toxoplasma uveitis
Rare in dogs( concurrent disease present, sometimes chronic or subclinical infection)
Ant / post uveitis, eom, scleritis, ONitis.
Neosorosis
Mild uveitis
Ascending paralysis
V young dogs
Migrating heminth larvae
Toxocariasis (border collie)
Angiostrongylosis (mild-granul)
Filariasis( D immitis common in N America)
Endophthalmitis
Severe introcular inflammation which does not extend beyond the sclera.
Panophthalmitis
Severe intraocular inflammation which involves all ocular coats
Breeds predisposed to USD (6)
Chow chow Sobering husky Samoyed Golden retriever Shetland π dog Japanese Akita
USD
Autoimmune reaction against melanocytes Signs: bilateral panuveotis Vitiligo (skin depigmentation) Poliosos (hair whitening) Mucocutaneous involvement
Additionally glaucoma., cataract , retinal detachment