Ophthalmology uveitis and glaucoma Flashcards
What are the two parts of the ciliary body
Pars plicata which produces aqueous and is the origin of the zonules
Pars plana which merges with the retina
What is the choroid
A layer of pigmented, vascular and lymphoid tissue behind the retina
Where is the reflective tapetum found
Within the inner choroid
Function of the choroicapillaris
To supply nutrients to the inner retina via retinal pigment epithelium
What is anridia and which domestic species does it affect
Lack of iris
Due to mutation in pax-6 homeobox genes; out of domestic species just horses seem to be affected
What does correctopia mean
Abnormal pupil position
Where is an iris coloboma usually seen
Ventrally
What does dyscoria mean
Abnormal pupil shap
What is the most common congenital defect of the uveal tract
Persistent puppilary membranes = vascular remnants from development; can cause cataract
What sections of uveal tract could uveitis affect
Anterior = iris
Intermediate = ciliary
Posterior = choroid
If all inflamed = panuveitis
What is rubeosis iridis
Red tinge to iris due to formation of new blood vessels in uveitis
WHy might we get a reduction in intraocular pressure in uveitis
Due to loss of function of the ciliary body
What is the classic triad of signs in uveitis
Miosis
Photophobia
Inflammatory cellular involvement
What are the main infectious causes of uveitis in the cat
TIP, FIV, FeLV, Toxoplasma
What infection in the cat causes pyogranulomatous inflammation and vasculitis with prominent rubeosis iridis
Feline infectious peritonitis (FIP)
How do common causes of uveitis differ in the dog and cat
In the dog it is mostly idiopathic and non-infectious; commonly see trauma and lens induced uveitis
In cats usually infectious
What causes lens induced uveitis
Gradual leakage of lens proteins (soluble) through lens capsule; triggers immune response since these antigens are ‘foreign’
Seen in diabetes as lens expands but capsule doesn’t
Get very dark brown iris
What type of uveitis is associated with dark brown iris
Lens induced
What is reflex uveitis
Specific traumatic uveitis condition; corneal injury leads to trigeminal nerve response to cause miosis; whole eye muscle ends up in spasm
Need atropine to stop this
What is Vogt-Koyanagi-Harada like syndrome
Autoimmune reaction against melanin-associated antigen in pigmented uvea and skin
–> Causes autoimmune uveitis and skin depigmentation
–> Seen in Japanese Akitas and Samoyeds
What common eye neoplasm in cats cause lead to uveitis
Leukaemia lymphocarcoma complex
What tumour can cause intraocular inflammation in the eye and what does this mean for tumour prognosis
Lymphoma
= automatically stage 5
What infectious agents can cause uveitis in the dog
Canine adenovirus
Agents from abroad e.g leishmania, borrelia, ehrlichia