DIS - Posterior Uveitis I - Week 4 Flashcards
Define posterior uveitis (4).
Inflammation posterior to the vitreous base
- choroid
- choroid and retina
- vitreous
- possible accompanying anterior uveitis
What are the two classifications of posterior uveitis? How does this change the relevancy of chronic vs acute? Explain.
Active vs resolved
Most posterior uveitis is chronic or slow moving
-acute vs chronic is less relevant
List the two main types of posterior uveitis by cause.
Infectious
Distinct inflammatory disorders of uncertain aetiology
List the four classifications of infectious posterior uveitis. Give at least three examples for each.
Viral -CMV, HSV, HZV, rubella Bacterial -syphilis, TB, strep/staph, lyme Fungal -candida, aspergilla, histoplasmosis, crptococcus Parasitic -toxoplsmosis, toxocara, onchocerciasis
Is diagnosis of posterior uveitis easy or difficult?
Often difficult
List three ocular causes of unifocal chorioretinitis.
Toxoplasmosis
Toxocara
Candida
List four ocular causses of diffuse chorioretinitis.
CMV
ARN
PORN
What are the four aims of assessing a patient with posterior uveitis?
Diagnose the ocular condition
Diagnose the systemic condition
Diagnose the cause of visual loss
Management - referral/treatment
What is the main role of optometry in posterior uveitis?
Mainly detection and appropriate referral
What is intermediate uveitis? Is it generally acute or chronic?
Pars planitis
-chronic
Does pars planitis have a common HLA error like other forms of uveitis?
No
In what four ways does pars planitis differ from other forms of uveitis (aside from HLA)?
Bilateral in 95%
Different inflammatory cells involved
Limited ciliary body inflammation
Few, if any, systemic associations
What are three possible systemic associations of pars planitis?
MS
Sarcoidosis
Syphilis
List three symptoms of pars planitis. Note the most dominant first.
Floaters
Blurred vision
Reduced VA
-if CMO is present
List three signs of pars planitis.
Exudation in to the vitreous
-cells in the vitreous
Small gelatinous snowballs/cottonballs
Grey/white plaque snow banking
Where are small gelatinous snowballs/cottonballs generally seen in pars planitis?
Inferior vitreous
Where is grey/white snow banking generally seen in pars planitis? What is it? What is needed to see it?
Overlying inferior pars plana
Is a fibroglial membrane
Only seen with scleral depression
-unless very extensive
What kind of diagnosis is pars planitis?
Diagnosis of exclusion
List at 7 differential diagnoses for pars planitis.
Sarcoidosis Lymphoma Infectious posterior uveitis Behcets disease VKH Exudative vitreoretinopathy Retinoblastoma
List four labs tests often used for exclusion in pars planitis.
ACE/chest Xray
CBC
FTA-ABS
Infection titres
What is the most common cause of infectious retinochoroiditis? What kind of organism is it?
Toxoplasmosis gondii
-protozoan
How does toxoplasmosis initially enter humans?
By crossing mucosal surfaces
-the gut
Which animal is the reservoir for toxoplasmosis and what is required for reproduction? How do they spread from this reservoir and in what form?
The cat
Feline intenstinal mucosa needed for reproduction
Resistant oocysts shed in faeces
List 5 common ways that toxoplasmosis is contracted.
Non-pasteurised milk Transfusion/transplant Poorly/partly cooked meat infected by cysts Unwashed fruit Cat faeces
describe congenital toxoplasmosis infections of the eye and the percentage risk of foetal infection. When is infection required for tis to occur? What type of foetal tissue is infected?
Occurs in non-immunised pregnant women
-is trans-placental
40% risk of foetal infection if the mother is infected just before conception or during pregnancy
Likes foetal neural tissue
List four foteal effects of congenital toxoplasmosis.
Stillbirth/spontaneous abortion
Multiorgan disability
Asymptomatic offspring but neurological/ocular sequelae later in life
Is post-natal acquired toxoplasmosis common or rare?
Rare allegedly
Note the two forms of toxoplasmosis gondii and whether or not they are infectious.
Trophozoites
-infectious
Cysts/oocysts
-non-infectious
Are trophozoites responsible for acute or chronic disease?
Acute
What are toxoplasmosis oocysts? Where do they concentrate (3) and what happens if they rupture?
Cysts containing many trophozoites
Concentrate in heart, muscle, neural tissue (including retinal)
If ruptured, leads to inflammation
Describe how txoplasmosis is able to persist in a reservoir animal host (4).
Survives stomach acids and invades gut wall
Cysts are impervious to host immune system/drugs
Bradyzoites live inside cells without killing or being killed by the host
Transmits to another host via faeces or when host is consumed by a predator
-cats eating rats, humans eating pork
When toxoplasmosis reaches the eye, what happens as the host immune system responds (3)? Is anything visible?
Organism converts to cyst form
Resistant to immune system
Chronic latent infection
Nothing visible
When toxoplasmosis reaches the eye and the host immune system response, what happens if for some reason the immune system declines (3)?
Cyst wall rupture, releasing organism
Fresh infection locus
Satellites with reactivation
How does toxoplasmosis infections look once healed?
A chorioretinal scar
Is acquired post-natal toxoplasmosis generally self-limiting or require urgent treatment (4)? Explain.
Generally is benign, self-limiting, subclinical, and asymptomatic
In individuals with symptoms, list 6 symptoms of acquired post-natal systemic toxoplasmosis.
Flu-like illness
- lymphadenopathy
- fever
- malaise
- myalgia
- sore throat
- papillo-macular rash
List three individuals who generally show symptoms of acquired post-natal systemic toxoplasmosis (6).
Adults without antibodies -with cats -farming -unwashed vegetables Pregnant women without antibodies Immunocompromised -HIV
What does positive toxoplasmosis serology show? Will patients with other forms of uveitis be positive or negative?
Shows only previous exposure
Patients with other forms of uveitis will be positive
What immunoglobin levels are elevated with acquired toxoplasmosis?
High IgM
What percentage of systemic toxoplasmosis infections cause ocular toxoplasmosis?
1-3%
Can the high incidence of toxoplasmosis infection in some countries (like Brazil) be explained by transplacental infection?
No
What was found to be a cause of an acquired toxoplasmosis epidemic in southern India?
Contaminated drinking water
What is the classical look of congenital ocular toxoplasmosis? What shape and colour does it have and where is it usually found?
An atrophic scar
Round/oval with pigmented edge
Often at/near the macula
List 8 features of active ocular toxoplasmosis.
Satellite lesions near the scar Cyst rupture Fresh focus of necrotising retinochoroiditis Vitreous -cells/exudates -damage Retinal thickening Cells in the anterior chamber -mild anterior uveitis Vasculitis with fresh infection -frosted branch angiitis
What is there a risk of with active ocular toxoplasmosis?
SRN
Is congenital toxoplasmosis generally uni-or bilateral?
Can be bilateral
Is acquired toxoplasmosis generally uni-or bilateral?
Usually unilateral
Where are lesions typically found in acuired toxoplasmosis?
Distant from the fovea
Is recurrence common or rare with toxoplasmosis?
Common
How long does active ocular toxoplasmosis last?
1-2 months
-self-limiting
List four indications for treatment/intervention of active ocular toxoplasmosis.
Significant reduction in VA Threat to macula Intense inflammation -marked vitritis Large lesion
What is the medical management of active ocular toxoplasmosis (3)? List in order and note drug names if applicable (2).
High dose antibiotics for 24h before any steroid
-clindamycin
-sulphonamide drugs + pyrimathamine
Oral steroids
Are oral steroids ever given alone for treating active toxoplasmosis?
Never - risk of ARN
What surgery is available for treating active toxoplasmosis (2) and when is it indicated? List two risks associated with these interventions.
Cryopexy/laser
-useful when drug therapy is contraindicated
Risk of vitreous contraction and epiretinal membranes
What causes toxocariasis? What kind of organism is it? What is a reservoir animal?
Infection by toxocara canis
-parasitic roundworm
Infects gut of dogs, especially puppies
How do children typically get toxocariasis?
Eating dirt
-geophagia
What two organs are involves with systemic toxocariasis?
Liver and spleen
List three systemic manifestations of toxocariasis.
Fever Pulmonary effects -coughing, athsma-like attacks Neurological symptoms -convulsions, meningitis
In what age are most cases of toxocariasis found (include percentage)?
80% in <16 years
What is the ocular manifestation of toxocariasis and where is it found (2)? What does it resemble and in what percentage of cases is it found?
A granuloma resembling a retinoblastoma near the posterior pole in about 50% of cases
Can also be found in the periphery (causes dragged disc)
List four features of a toxocariasis granuloma including colour, size, and elevation.
White elevated lesion
Variable size
Adacent exudate, haemorrhage, sensory RD
Well defined mass with healing
List three ocular manifestations of toxocariasis aside from a granuloma. Explain why they occur if applicalbe (1).
Vitritis - severe
-immune response to dead worms
Peripheral retinitis/perivasculitis
Endophthalmitis
Should you refer toxciariasis?
Yes
How is toxocariasis treated (2)?
Steroids
Anti-helminthics
-thiabendazole/diethylcarbamazine
What is sarcoidosis characterised by (4)?
Non-caseating granulomas
- little or no necrosis
- resolves completely or fibrosis
What percentage of sarcoidosis cases involve the eye?
40%
What often precedes systemic onset of sarcoidosis?
Uveitis
Is sarcoidosis granulomatous or non-granulomatous?
Granulomatous
Which is less common, posterior or anterior segment in sarcoidosis? Which is more visually disabling?
Posterior segment to both
List 7 posterior ocular manifestations of sarcoidosis
Vitritis -clump of cells/protein resembling snowballs Granuloma Cystoid macular oedema -chronic Periphlebitis -may resemble BVO Peripheral neovascularisation Candle wax exudates Disc swelling/atrophy
Describe candle wax exudates in posterior sarcoidosis.
Exudates dripping from sclerosed/white retinal vessels
List a treatment option for sarcoidosis. Is spintaneous improvement common or rare?
Spontaneous improvement common
Corticosteroids
-low dose, long term
What is the most common cause of VA loss in sarcoidosis?
Cystoid macular oedema
List 3 ocular manifestations of behcets disease when it affects the posterior uvea. Is the visual prognosis good or poor with posterior uvea changes?
Diffuse vascular leakage Retinal vasculitis -periphlebitis Retinitis Poor visual prognosis from posterior changes
What is ocular histoplasmosis caused by? What kind of organism is it, where is it found (environment) and what country is it endemic to?
Histoplasma capsulatum
-fungus
Found in rivers and valleys worldwide
Endemic to mid-west USA
In what age group is ocular histoplasmosis commonly found?
Middle aged people
What is histoplasmosis primarily? What does it resemble?
A lung disease
-resembles TB
Are there any visual symptoms of ocular histoplasmosis (2)?
No, unless the macula is involved
What are the four main features of ocular histoplasmosis?
Disseminated choroiditis -punctate atrophic lesions Macular lesions -simulates CSR Peripapillary atrophy -with SRN Complete absence of vitreous cells
What is treatment of ocular histoplasmosis limited to? List three treatment options.
Limited to macular lesions
- steroids
- laser/surgical removal if SRN is present
- antiVEGF
