Mycobacterial uveitis

Tuberculosis

• Facultative intracellular bacterium
• Widespread chronic inflammation based on caseating granulomata
• Protean manifestations within the eye

Ocular features

• Scleritis
• Lid abscess
• Interstitial keratitis
• Granulomatous anterior uveitis
• Posterior uveitis: vitritis, vasculitis, macular oedema, choroidal granulomata, serpiginous-like choroidopathy, optic neuropathy, Eales disease (vasculitis with neovascularisation and risk of vitreous haemorrhage)

Tests:

• Microbiology: acid-fast bacilli stain with Ziehl-Neelsen stain
• Chest x-ray
• Tuberculin skin test (aka Mantoux): injecting tuberculin and measuring induration after 72h (false positive with BCG vaccine)
• Interferon gamma release assay (IGRA): measures release of IFN after stimulation by M. tuberculosis antigens.
  • Not affected by BCG vaccine
  • Does not cross react with other mycobacteria
  • Patient does not need to return 72h later
  • Overall better sensitivity/specificity profile than Mantoux

Management

• Rifampicin
• Isoniazid
• Pyrazinamide
• Ethambutol
• Management of ocular disease as for other forms of uveitis while on anti-Tb treatment
• U&Es and LFTs require monitoring while on the above

Leprosy (Hansen’s disease)

• Endemic in Asia
• Obligate intracellular bacterium: Mycobacterium leprae
• Cell-mediated immune response

Ocular disease is common

• Madarosis
• Trichiasis
• Lagophthalmos (VIIn palsy)
• Conjunctivitis
• epi/scleritis
• Keratitis
• Anterior uveitis: iris pearls at the pupil margin, iris atrophy, miosis

Tests

• Skin and mucosal smears for acid-fast bacilli