|Year : 2017 | Volume
| Issue : 4 | Page : 392-393
Ocular tuberculosis: Challenge to ophthalmologists
Ocular Pathology Department, Sankara Nethralaya, Chennai, Tamil Nadu, India
|Date of Web Publication||4-Sep-2017|
Department of Ocular Pathology, Sankara Nethralaya, New No. 41 (Old No: 18), College Road, Nungambakkam, Chennai - 600 006, Tamil Nadu
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Biswas J. Ocular tuberculosis: Challenge to ophthalmologists. Med J DY Patil Univ 2017;10:392-3
Tuberculosis (TB) is one of the leading causes of morbidity and mortality worldwide. The causative agent of TB is Mycobacterium tuberculosis (MTB), discovered by Robert Koch in the year 1882. The World Health Organization (WHO) declared TB as a global health emergency in the year 1993. India is the country with highest burden of TB. The WHO statistics for 2015 gave an estimated incidence of 2.2 million cases of TB for India out of a global incidence of 9.6 million. The estimated TB prevalence in India for the year 2015 is about 2.5 million cases.
Ocular TB is a form of extrapulmonary TB. It can affect any part of the eye. It can occur in isolation or in conjunction with pulmonary TB. TB bacilli get disseminated from lung or any primary focus of tuberculous infection in the body, through hematogenous or lymphatic route to distant sites including the eye, where it remains dormant.
Ocular TB can be either intraocular TB (IOTB) or involves the ocular adnexa. IOTB is an important cause of uveitis and accounts for about 10.5% of uveitis cases., IOTB is now classified as “confirmed IOTB,” “probable IOTB,” and “possible IOTB.” Extrapulmonary disease is more common in immunocompromised patients.
Ocular TB can be caused either by an active infection or secondary to Type IV hypersensitivity reaction. Active infection results from reactivation of the dormant bacilli, leading to hematogenous spread and direct invasion into local ocular tissues, and Type IV hypersensitivity is due to an immune-mediated reaction to the latent MTB infection elsewhere in the body.,
Polymerase chain reaction analysis of ocular fluid has a vital role in establishing the diagnosis of ocular TB.
Antitubercualar treatment (ATT) drugs are being used around the world under various national TB control programs and have helped to decrease the prevalence of disease, but still TB remains the greatest killer of human beings. ATT leads to rapid killing of the tubercle bacilli, leading to cure of the disease. One of the first drugs used for the treatment of TB was streptomycin in 1950s. Development of isoniazid and rifampicin and their use led to considerable decrease in the number of TB cases.
An inability to isolate the bacilli from ocular samples leads to poor result from cultures of aspirates. Lack of associated systemic features in case of IOTB can create problems in management as chest physicians may be reluctant to start ATT in these patients. There is no consensus among ophthalmologists all over the world regarding diagnostic criteria and treatment guidelines in endemic and nonendemic countries leading to confusion. A wide spectrum of clinical features with varied presentation can further complicate the management. Delay in diagnosis and commencing anti-TB therapy (ATT) and management of ocular inflammation only with immunosuppressive and oral steroids may result in sight- and life-threatening consequences. Even the short-course chemotherapy under the directly observed treatment strategy, as advised by the WHO, is not applicable for the treatment of ocular TB as patients show variable response to treatment. The United States Food and Drug Administration has currently approved ten drugs and recommended a course of 9 months of ATT for the treatment of extrapulmonary disease including ocular TB.
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