Insights into Ocular Tuberculosis: Understanding Four Types of Eye Infections

Below we discuss four types of Tuberculosis of the eyes. Firstly Tuberculous episcleritis, then Tuberculous keratitis, followed by Tuberculous chorioretinitis, and lastly, Tuberculous iridocyclitis.

1. Tuberculous episcleritis

Tuberculous episcleritis (inflammation of tissue between sclera and conjunctiva) is a rare manifestation of extrapulmonary Tuberculosis (TB) resulting from reactivation of the bacilli lodged in the area from an original infection by Mycobacterium tuberculosis and rarely by Mycobacterium bovis or by direct introduction of the bacteria through an open wound.

1.1 Symptoms

A patient with tuberculous episcleritis can experience;

  • eye pain;
  • excessive tearing;
  • mild to moderate ocular discomfort;
  • nodular lesions;
  • blurred vision;
  • eye redness; and
  • sensitivity to light.

1.2 Diagnosis

Providers diagnose the condition based on blood tests, tuberculin skin tests, and previous Tuberculosis or active disease history.

Ocular imaging studies (such as fluorescein or indocyanine green angiography, ocular coherence tomography [OCT]) and chest X–rays may be helpful.

Definitive diagnosis is difficult, if not impossible, but polymerase chain reaction of intraocular fluid and Mantoux intradermal tuberculin test, which is more specific and sensitive than a simple tuberculin skin test, have been helpful.

1.3 Treatment

Treatment includes antituberculous chemotherapy with isoniazid, rifampin, rifabutin, pyrazinamide, and ethambutol; topical, periocular, intraocular, and systemic steroids may relieve inflammation. 

2. Tuberculous keratitis

Tuberculous keratitis (inflammation of the cornea) is a rare manifestation of extrapulmonary Tuberculosis (TB) that affects the cornea (the clear transparent covering in the front of the eye) resulting from reactivation of the bacilli lodged in the area from an original infection by Mycobacterium tuberculosis and rarely by Mycobacterium bovis or by direct introduction of the bacteria through an open wound.

Tuberculous keratitis is also known as:

  • Tuberculous interstitial keratitis
  • Tuberculous keratoconjunctivitis (interstitial) (phlyctenular)

2.1 Symptoms

A patient with tuberculous keratitis can experience;

  • eye pain;
  • excessive tearing;
  • mild to moderate ocular discomfort;
  • nodular lesions;
  • blurred vision;
  • eye redness;
  • thickening or clouding of the cornea; and
  • sensitivity to light.

2.2 Diagnosis

Providers diagnose the condition based on blood tests, tuberculin skin tests, and previous Tuberculosis or active disease history.

Biomicroscopy (combined slit lamp and microscopic examination) and histopathological examination of biopsy specimens can help confirm the diagnosis. A definitive diagnosis is made by culturing intraocular fluids.

2.3 Treatment

Treatment includes antituberculous chemotherapy with isoniazid, rifampin, rifabutin, pyrazinamide, and ethambutol; other drugs may be tried if these drugs are ineffective. 

3. Tuberculous chorioretinitis

Tuberculous chorioretinitis (inflammation of the uveal tract) is a rare manifestation of extrapulmonary Tuberculosis (TB) that affects the uvea of the eye resulting from reactivation of the bacilli lodged in the area from an original infection by Mycobacterium tuberculosis and rarely by Mycobacterium bovis or by direct introduction of the bacteria through an open wound.

3.1 Symptoms

A patient with tuberculous chorioretinitis, also called retinochoroiditis, can experience;

  • eye pain;
  • excessive tearing;
  • mild to moderate ocular discomfort;
  • blurred vision;
  • eye redness; and
  • sensitivity to light.

3.2 Diagnosis

Providers diagnose the condition based on cultures and polymerase chain reaction studies of the blood and intraocular fluid, a tuberculin skin test, and previous history of Tuberculosis or active disease.

Biomicroscopy (combined slit lamp and microscopic examination) and intraocular imaging studies may show typical intraocular manifestations of TB.

3.3 Treatment

Treatment includes antituberculous chemotherapy with isoniazid, rifampin, rifabutin, pyrazinamide, and ethambutol; other drugs may be tried if these drugs are ineffective. 

4. Tuberculous iridocyclitis

Tuberculous iridocyclitis (inflammation of the iris and ciliary body) is a rare manifestation of extrapulmonary Tuberculosis (TB) that affects the anterior chamber and iris (the colored part of the eye), resulting from reactivation of the bacilli lodged in the area from an original infection by Mycobacterium tuberculosis and rarely by Mycobacterium bovis or by direct introduction of the bacteria through an open wound.

4.1 Symptoms

A patient with tuberculous iridocyclitis can experience;

  • eye pain;
  • excessive tearing;
  • mild to moderate ocular discomfort;
  • blurred vision;
  • eye redness;
  • sensitivity to light; and
  • an irregular pupil.

4.2 Diagnosis

Providers diagnose the condition based on cultures and polymerase chain reaction studies of the blood and intraocular fluid, a tuberculin skin test, and previous history of Tuberculosis or active disease.

Biomicroscopy (combined slit lamp and microscopic examination) and intraocular imaging studies may show typical intraocular manifestations of TB, such as “mutton fat” precipitates (large, yellowish deposits in the cornea) and “cotton wool” spots and proliferation of new blood vessels (neovascularization) on the retina.

4.3 Treatment

Treatment includes antituberculous chemotherapy with isoniazid, rifampin, rifabutin, pyrazinamide, and ethambutol; other drugs may be tried if these drugs are ineffective. 

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