Tuberculosis (TB)

Tuberculosis is a very rare cause of iritis. Most people are already known to have TB.

TB is rare in the Western world (although numbers are rising because of AIDS which makes people susceptible to TB). TB is common in the unindustrialized world.

Symptoms of TB

Loss of weight
Cough, breathing difficulties

Symptoms of TB in the eye

TB affects the eye in only 2% of sufferers of TB -- so these symptoms are rare! The infection is a secondary infection (see below)

Iritis (a specific form, called granulomatous iritis)
Decreased vision due to posterior uveitis (multifocal choroiditis, retinitis, vasculitis, optic nerve inflammation)
Nodules on eyelids
Infections of the tissue around the eye, including the tear glands and ducts
Decreased vision due to corneal opacity (interstitial keratitis)
Redness of the sclera (episcleritis, nodular scleritis)

Cause of TB

Infection by the bacterium Mycobacterium tuberculosis. In the immunosuppressed, other types of bacterium (M. bovis, M. avium, M. fortuitum) may cause infection.

Spread of TB

Respiratory droplet spread from infected patient when the disease is active

Course of infection

Primary infection - Usually causes a focus of infection in the lung
Secondary infection - May affect other parts of the lung, lymph nodes, abdomen (peritonitis), skin, meninges of brain, eye.


Chest X-ray - may show Ghon focus (shadow at the top of the lung)
Culture of sputum, urine for "acid fast bacilli" - this means that the bacteria stain in a certain way with certain dyes
Mantoux skin test


Oral antibiotics -- Isoniazid, Ethambutol, Rifampcin, Pyridoxine -- for at least six months. Other antibiotics are used in resistant cases, which are common outside the industrialised world (probably due to over-use of antibiotics).

Steroids are sometimes used, somewhat controversially, in iritis caused by TB


Public health measures, eg less crowding and proper sanitation
BCG vaccine

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