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Ocular Tuberculosis

URGENT — Systemic

Symptoms

  • insidious decreased vision, floaters, or redness (weeks to months)
  • often asymptomatic and found incidentally in high-prevalence populations
  • systemic: chronic cough, weight loss, night sweats, or fever (often absent)
  • risk: travel to endemic areas (india, se asia, africa), hiv, or homelessness

Clinical Findings

Anterior segment

  • granulomatous uveitis: large "mutton-fat" kps and iris nodules (busacca/koeppe)
  • extensive posterior synechiae ("sticky" uveitis)

Posterior segment

  • choroidal tubercles: pathognomonic yellowish, ill-defined lesions (miliary tb)
  • serpiginous-like choroiditis: placoid lesions progressing centrifugally
  • retinal vasculitis (eales-like): peripheral non-perfusion and neovascularization

Optic nerve & other

  • neuroretinitis, optic neuritis, or papilledema (if meningitis present)
  • phlyctenular keratoconjunctivitis (hypersensitivity response)

Etiology

Pathophysiology

  • mycobacterium tuberculosis infection via hematogenous spread
  • direct ocular infection or immune-mediated response to circulating antigens

Disease nature

  • can occur without active pulmonary disease (chest x-ray may be normal)
  • reactivation of latent tb (hiv, tnf-α inhibitor use, or steroid use)

Red Flags

  • initiating tnf-α inhibitors (e.g., adalimumab) without tb screening can reactivate latent disease
  • choroidal tubercles in a febrile patient suggests life-threatening miliary tb
  • hiv coinfection dramatically increases risk; always test hiv in suspected cases

Investigations

TB screening

  • interferongamma release assay (quantiferon-tb gold/t-spot) or ppd skin test
  • chest x-ray or chest ct to look for active or healed pulmonary involvement

Ocular & systemic

  • ivfa: characterize retinal vasculitis and capillary non-perfusion
  • ac/vitreous pcr for m. tuberculosis (specific but low sensitivity)
  • rule out mimics: syphilis (rpr/fta), sarcoid (ace/ct), lyme, and behçet

Treatment

Anti-TB therapy (ID directed)

  • 4-drug ripe regimen: rifampin, isoniazid, pyrazinamide, ethambutol (2 months)
  • maintenance: rifampin + isoniazid (4–7 months)

Anti-inflammatory

  • oral prednisone (1 mg/kg): used once anti-tb therapy is established to prevent scarring

Ocular complications

  • anti-vegf or prp for retinal neovascularization
  • monitor ethambutol toxicity: dose-dependent optic neuropathy risk

Clinical Pearl

choroidal tubercles — creamy-yellow, ill-defined lesions scattered across the fundus — are pathognomonic for miliary tb. in any immunocompromised patient or patient from a high-prevalence area with granulomatous uveitis, always exclude tb before starting tnf-α inhibitors for presumed idiopathic disease.

Differential Diagnosis

  • • sarcoidosis (primary granulomatous mimic)
  • • syphilitic uveitis
  • • idiopathic serpiginous choroiditis
  • • vogt-koyanagi-harada (vkh) disease
  • • sympathetic ophthalmia

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