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Case 3 : A Case of Ocular Toxoplasmosis. Dr Johnson Tan Medical Officer Tan Tock Seng Hospital. 17/Chinese/male c/o: RE floaters x 5 days No trauma. O/E : VA 6/7.5 OU No RAPD Colour 15/15 OU Decreased red desaturation RE Confrontational fields full Anterior segment NAD

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case 3 a case of ocular toxoplasmosis

Case 3 : A Case of Ocular Toxoplasmosis

Dr Johnson Tan

Medical Officer

Tan Tock Seng Hospital

mr scha
17/Chinese/male

c/o:

RE floaters x 5 days

No trauma

O/E :

VA 6/7.5 OU

No RAPD

Colour 15/15 OU

Decreased red desaturation RE

Confrontational fields full

Anterior segment NAD

RTL cells 1 +

Mr SCHA
slide4
What were the findings?
  • Rt superior optic disc swelling superiorly
  • Superior-temporal peripapillary white lesion with indistinct edges
  • Adjacent vasculitis
  • What would be the next step?
  • Take a full history
further questioning
Further questioning…
  • No headache / neck stiffness / tinnitus
  • No joint pains
  • No mouth ulcers
  • No dysuria
  • No travel history
  • No chronic cough / fever / constitutional symptoms
  • No contact history with TB
investigations
Investigations
  • ESR / CRP
  • ANA, dsDNA
  • ANCA
  • CXR / Mantoux
  • VDRL/TPHA
  • Toxoplasma IgG : 18.7 IU/ml (positive)
  • Aqueous tap for CMV/HSV/VZV/Toxoplasma /TB PCR: not detected

NORMAL

ocular toxoplasmosis
Ocular Toxoplasmosis
  • Obligate, intracellular parasite
  • Commonest cause of retinochoroiditis and posterior uveitis
  • Manifest between the 2nd & 4th decades of life
  • Risk factors
    • Immunodeficiency states
    • Exposure to cats
    • Eating raw or partially cooked meat
  • Symptoms
    • Blurred vision
    • Floaters
    • Pain
    • Red eye
    • Metamorphopsia
    • Photophobia
ocular presentations
Ocular Presentations
  • Iridocyclitis
  • Unifocal superficial necrotizing retinochoroiditis
    • Classical presentation involving inner retina
    • Surrounded by oedema with contiguous inflammation of choroid and sclera
    • May be a/w dense vitritis "headlight in the fog"
    • May be a/w adjacent focal vasculitis kyrieleis arteriolitis
  • Jensen’s papillitis
    • Involvement of optic nerve from adjacent juxtapapillary retinitis
    • Optic nerve sheath may serve as a conduit for the direct spread of Toxoplasma into the optic nerve from an adjacent cerebral infection  optic neuritis/papillitis
  • Punctate outer retinitis -rare
  • Deep retinitis - rare
uncommon ocular findings
Uncommon Ocular findings
  • Ocular inflammation without necrotizing retinochoroiditis
  • Retinal and optic nerve neovascularization, usually regresses with resolution of inflammation.
    • Exact aetiology not well understood
    • Retinal ischemia associated with severe retinal vasculitis
    • Inflammatory reaction
ocular toxoplasmosis11
Ocular Toxoplasmosis

Immunocompetent adults:

  • Unilateral, painless. unifocal
  • Vision good if macula not involved

Neonates:

  • Congenital toxoplasmosis
  • Bilateral, severe
  • 70% retinochorioditis
  • ⅔ macula involved a/w severe visual loss
  • Micorophthalmia, vitritis, glaucoma, ocular palsies

Immunocompromised:

  • Bilateral, multifocal, severe
  • May be a/w SOL of CNS  Ocular palsies, nystagmus, VF defects
follow up
Follow-up
  • Bactrim 11/11 bid x 1/12
  • Prednisolone 1mg/kg (50mg od) tapered over 2 weeks
serological diagnosis
Serological diagnosis

IgG:

  • IgG seroconversion 2-4 weeks after systemic infection, peak titres 4-6 weeks after infection
  • Titres maintained at high levels for many months or years.
  • Recent infection : 4x rise in antibody titres over a 2-4 week period
  • Clinical signs may develop before seroconversion occurs, or after peak titres have developed.
  • A single antibody titre is difficult to interpret and is rarely of any value

Negative IgG excludes ocular toxoplasmosis

serological diagnosis15
Serological diagnosis

IgM

  • Less value than IgG
    • A negative IgM test excludes recent infection
    • A positive IgM test is difficult to interpret because Toxoplasma-specific IgM antibodies may be detected up to 18 months after acute acquired infection

Goldmann-Witmer coefficient

Ratio of Toxoplasma IgG [eye] : [serum] > 3 is generally accepted as being consistent with active ocular infection

    • But invasive procedure!

Aqueous humor and serum immunoblotting for immunoglobulin types G, A, M, and E in cases of human ocular toxoplasmosis. J Clin Microbiol. 2004 Oct;42(10):4593-8.

slide16
PCR
  • Presence of T. gondii in ocular fluids is detected on PCR considered to be confirmation of active eye disease
  • A negative finding does not exclude ocular toxoplasmosis
  • Real-time PCR (Light-cycler, LC-PCR) more sensitive than nested PCR (n-PCR).

Evaluation of a Real-time PCR-based assay using the lightcycler system for detection of Toxoplasma gondii bradyzoite genes in blood specimens from patients with toxoplasmic retinochoroiditis. Int J Parasitol. 2005 Mar;35(3):275-83. Epub 2005 Jan

treatment updates
Treatment: Updates
  • Triple drug therapy :pyrimethamine, sulfadiazine, prednisolone
  • Quadruple therapy : pyrimethamine, sulfadiazine, clindamycin, prednisolone.
  • Bactrim (2 tabs bid) is as effective as pyrimethamine/sulfadiazine for lesions outside fovea.
    • 61% in classic triple therapy grp vs 59% in Bactrim grp

Soheilian et al. Prospective randomised trial of Trimethoprim/sulfamethoxazole vs pyrimethamine & sulfadiazine in the treatment of ocular toxoplasmosis. Ophthalmology. 2005 Nov;112(11):1876-82

  • At least 6 weeks treatment
  • Others: Azithromycin + pyrimethamine (AJO 2002;134:34-40)

Spiramycin (Klin Montasbl Augenheildk 1998;212:84-7)

Atovaquone (hydroxynaphthoquinone) (Ophthalmology 1999;106:148-53)

Allopurinol (Adam et al. Berlin 2000)

  • Corticosteroids
    • Topical : depending on AC reaction.
    • Depot absolutely contraindicated
      • Risk of rampant necrosis and blind, phthisical globe
    • Systemic adjunct to minimize collateral damage from the inflammatory response
      • Usually from Day 3 @ 1mg/kg, tapered over 2 weeks
thank you
Thank you

A presentation by

The Eye Institute @

Tan Tock Seng Hospital