DIS - Posterior Uveitis I - Week 4 Flashcards by B H

Define posterior uveitis (4).

Inflammation posterior to the vitreous base
-choroid
-choroid and retina
-vitreous
-possible accompanying anterior uveitis

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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

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List the two main types of posterior uveitis by cause.

Infectious
Distinct inflammatory disorders of uncertain aetiology

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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

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Is diagnosis of posterior uveitis easy or difficult?

Often difficult

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List three ocular causes of unifocal chorioretinitis.

Toxoplasmosis
Toxocara
Candida

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List four ocular causses of diffuse chorioretinitis.

CMV
ARN
PORN

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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

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What is the main role of optometry in posterior uveitis?

Mainly detection and appropriate referral

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What is intermediate uveitis? Is it generally acute or chronic?

Pars planitis
-chronic

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Does pars planitis have a common HLA error like other forms of uveitis?

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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

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What are three possible systemic associations of pars planitis?

MS
Sarcoidosis
Syphilis

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List three symptoms of pars planitis. Note the most dominant first.

Floaters
Blurred vision
Reduced VA
-if CMO is present

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List three signs of pars planitis.

Exudation in to the vitreous
-cells in the vitreous
Small gelatinous snowballs/cottonballs
Grey/white plaque snow banking

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Where are small gelatinous snowballs/cottonballs generally seen in pars planitis?

Inferior vitreous

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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

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What kind of diagnosis is pars planitis?

Diagnosis of exclusion

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List at 7 differential diagnoses for pars planitis.

Sarcoidosis
Lymphoma
Infectious posterior uveitis
Behcets disease
VKH
Exudative vitreoretinopathy
Retinoblastoma

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List four labs tests often used for exclusion in pars planitis.

ACE/chest Xray
CBC
FTA-ABS
Infection titres

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What is the most common cause of infectious retinochoroiditis? What kind of organism is it?

Toxoplasmosis gondii
-protozoan

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How does toxoplasmosis initially enter humans?

By crossing mucosal surfaces
-the gut

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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

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List 5 common ways that toxoplasmosis is contracted.

Non-pasteurised milk
Transfusion/transplant
Poorly/partly cooked meat infected by cysts
Unwashed fruit
Cat faeces

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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?

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