- Tuberculosis (TB) can infect the eyes and is one of the leading causes of uveitis. It can spread to the eyes directly, via a hypersensitivity reaction, or hematogenously. Diagnosis is challenging as lab tests lack sensitivity and culture is not always possible. Treatment involves a combination of anti-TB drugs for 4-6 months along with corticosteroids for ocular inflammation. Drug-resistant strains pose a serious challenge to effective treatment.

1. ocular TB

2. • TB – one of the leading cause of death
• 1/3 world’s population infected

3. • Three classic forms
• Direct ocular infection
• hypersensitivity reaction
• hematogenous spread

4. pathogenesis
• Direct consequence of infection
• Nonresolving inflammation
• ESAT-6
• CFP-10 vigorous helper T-cell responses
• Stimulate the trafficking of infected macrophages into the granulomas
• Host genetic factors - genes encoding the IFN-gamma and IL-2
• RPE

5. • unilateral or asymmetrically bilateral
• chronic and insidious course
• anterior, intermediate, posterior, or pan uveitis
• often a granulomatous than nongranulomatous uveitis

6. Ant. uveitis
• mutton-fat keratic precipitates
• broad based posterior synechiae
• granulomas in the angle
• Inadequate treatment may be complicated by band shaped
keratopathy and iris neovascularisation

8. INTERMEDIATE UVEITIS
• moderate to severe vitritis with or without snowballs and pars snow
bank
• vascular sheathing and cme are usually present
• Tuberculomas may form in the ciliary body

9. POSTERIOR UVEITIS
• most common
• choroidal tubercle
• Nearly 30% of the patients suffering from disseminated tuberculosis
or tubercular meningitis may show tubercular granulomas

11. SERPIGINOUSLIKE CHOROIDITIS

12. RETINAL VASCULITIS
• usually accompanied by moderate vitritis
• frequently develop neovascularization
• associated with focal choroiditis
• Neuroretinitis

14. • Diagnosis as definitive TB only when the bacilli are isolated from eye
• presumed tuberculous uveitis -
• Signs suggesting TB + positive tuberculin skin test (TST) or
QuantiFERONTB Gold or chest radiograph and computed tomography
• Good response to antitubercular treatment and absence of
recurrence

15. DD
• Granulomatous uveitis
• herpes simplex or varicella zoster infection
• Phacoantigenic uveitis
• Sarcoidosis
• Syphilis
• Leprosy
• Vogt–Koyanagi–Harada disease and sympathetic ophthalmia.
• Fungal granuloma.

16. NTM
• saprophytic and are ubiquitous in the environment
• Causes endophthalmitis after various surgical procedures or
injections
• Often misdiagnosed as Propionibacterium acnes, nocardial or fungal
endophthalmitis
• Cultures took variable periods to demonstrate growth or failed
entirely to show the causative organism

17. Lab. tests
• history and examination are fundamental
• suboptimal specificity and sensitivity - delay the diagnosis and treatment
• Clear understanding of principles and proper test selection
• Mantoux - cellular immune response, can cross-react with BCG and NTM
• 5 mm or more to be positive in very high-risk individuals (e.g., abnormal
chest radiograph, HIV patients
• 10 mm or more in high-risk patients (e.g., patients from endemic areas
• 15 mm or more in patients with no identified risk factors
• negative test does not rule out TB (40%)

18. • IGRA
• QuantiFERON (QFT) and TSPOT.TB
• T cells, collected from the patient, are exposed to these specific
tubercular antigens - measures the IFN-γ released by sensitized T cells
• guidelines suggest IGRAs sh’d be used only to confirm a positive TST
• sensitivities and specificity of both IGRAs are higher than that of TSTs

19. • Chest x-ray may reveal infiltrations, cavitation, hilar
lymphadenopathy, pleural effusion, fibrotic, or calcific lesion
• proven ocular TB patients, 57% of patients had negative chest
radiograph

20. • culture remains the cornerstone for diagnosis
• isolation is not always possible – specimen is often too small for all
the procedures, such as Ziehl– Neelsen staining, inoculation in liquid
and solid media, species identification, and drug susceptibility testing
• PCR -the method of choice because of rapid test in a very small
sample

21. Treatment
• pulmonary TB and extrapulmonary TB to be treated with a four-drug
regimen
• isoniazid 5 mg/kg daily
• Rifampicin 10 mg/kg daily
• ethambutol 15 mg/kg daily, and
• Pyrazinamide 20–25 mg/kg daily
• Ethambutol and pyrazinamide are stopped after 2 months and
isoniazid and rifampicin are continued for 4–6 months

22. • Corticosteroids seem to have a potential benefit in patients with
tubercular pericarditis and meningitis.
• Similarly, steroids are used in ocular TB as well.

23. Drug-Resistant Tuberculosis
• MDR - isoniazid and rifampicin
• XDR - isoniazid and rifampicin and to any one of the fluoroquinolones
and at least one of the injectable second-line drugs