Eye Pathology III - Uvea Flashcards
What are the three layers of the eye? (3)
- Fibrous (outer) layer – composed of the cornea and sclera
- Vascular (middle) layer – the uvea (pigmented layer)
- Neuroectodermal (inner) layer – composed of the retina and optic nerve
Cross-sectional anatomy of eye + what is the uvea divided into? (3)
Anterior uvea:
- Iris – the colourful part of the eye that controls the amount of light entering the eye by changing the size of the pupil
- Ciliary body - produces aqueous humour
Posterior uvea:
- Choroid - noruishes the retina
Normal aqueous humour movement within the eye
What is persistent pupillary membrane (PPM)?
Failure of anterior chamber - goes from fibrovascular mesenchyme to atrophy; persistence of membranous tissues (connective tissues + blood vessels not regressed completely) (congenital disease)
Persistent pupillary membrane (PPM) - embryology, what does it affect? (9)
Congenital disease
Uveal cyst
What are uveal cysts? (5)
Purulent - resolved uveitis, doesn’t have active inflammation, no congestion, hyperaemia, neovascularization, blepharitis or inc blink rate. Hypopyon present = pus cells (purulent material - inflammatory cells)
What is uveitis and what does it result from?
What are the clinical signs of uveitis? (16)
How is uveitis classified? (3)
- Serous
- Suppurative
- Granulomatous or lymphoplasmacytic
What is serous uveitis? (3)
- Acute serous uveitis has - protein-rich fluid exudation, sometimes with fibrin.
- Immigration of neutrophils in the iris.
- Protein-rich fluid readily percolates (filters) through the loose stroma to enter the anterior chamber -> aqueous flare.
What is suppurative uveitis? (3)
- Reflects a bacterial pathogenesis.
- Usually bilateral when it is a reflection of haematogenous localisation.
- Can see clumps of material adhering to the corneal endothelium as keratic precipitates or settling eventually as hypopyon (inflammatory cells within anterior chamber), so you can see clumps of neutrophils in there.
What is granulomatous uveitis? (2)
- Characterised by granulomatous inflammation and lymphoplasmacytic uveitis
- Most common type of uveitis encountered in enucleated globes
Uveitis
What is hyphaema? (4)
- Collection of blood inside front of eye between cornea and iris
- Can see glaucoma because the blood cells can plug up the drainage angle of the eye, leading to increased intraocular pressure of the eye, leading to glaucoma
- Can also see cataracts or changes in the lens
- Shrinkage of the whole globe due to chronic change, when it comes to diagnosing hyphaema
What are the causes of hyphaema? (3)
- Ocular disease e.g. severe uveitis
- Congenital anomalies
- Systemic disease which causes bleeding into the eye
How is hyphaema diagnosed? (7)
Pupil miosis
What are the causes of uveitis? - infectious agents (6)
- Bacterial e.g. Brucella canis - causes chronic lymphocytic endopthalmitis (inflammation of internal eye tissues), may enter haematogenously via penetrating wounds
- Mycotic e.g. Blastomyces dermatitidis
- Protozoal e.g. Leishmania spp., Toxoplasma gondii, Encephalitozoon cuniculi
- Parasitic e.g. Ocular encephalitzoonosis in rabbits
- Viral e.g. canine adenovirus (infectious canine hepatitis), Feline Infectious Peritonitis-associated uveitis, bovine Malignant Catarrhal Fever (MCF), Feline Immunodeficiency Virus (FIV)
- Protothecosis = algae, protheca histologically similar to mycotic endopthalmitis
What are the causes of uveitis? - Immune-mediated (3)
- Canine uveodermatologic syndrome (Vogt-Koyanagi-Harada–like syndrome) - Akitas, Siberian Huskies and Samoyeds
- Histological lesion = destructive granulomatous endophthalmitis with abundant dispersal of melanin
Induced by endogenous antigens:
- Equine recurrent ophthalmitis (periodic ophthalmia)
- Lens-induced uveitis
- Characterised by lymphoplasmacytic uveal inflammation - suggestive of chronic inflammation, lymphocytes have time to form lymphoid aggregates and perivascular cuffs
