Author
Year
Place
Percentage of ocular TB in pulmonary TB patients
Bouza et al. [2]
1997
Spain
18
Lara et al. [3]
2013
Philippines
6.8
Beare et al. [4]
2002
Africa
2.8
Donahue [5]
1967
United States
1.46
Biswas and Badrinath [6]
1995
South India
1.39
Ocular TB was first diagnosed by Maitre-Jan in 1711. The current prevalence of ocular TB varies from 0.5% to 1.4% [8]. Ocular TB is defined as an infection by M. tuberculosis which can involve any part of the eye, superficial, intraocular, or the structures around the eye with or without systemic involvement [9]. In primary ocular TB which is rare, the eye is the portal of entry which may be the conjunctiva, cornea, or sclera. In secondary ocular TB, the ocular involvement occurs by hematogenous spread of the organism, of which tuberculous uveitis is an example [10]. Due to the rich blood supply of the uveal tract, the choroid is the most common site of ocular TB manifestation [11, 12].
Ocular TB often presents without clinical evidence of active pulmonary TB and may be the first and only manifestation of the infection [13]. Among the various forms of ocular TB, posterior uveitis is the most common [9].
Epidemiology of Ocular TB in Patients with Pulmonary TB
Epidemiological data for ocular TB are rare due to the lack of standardized diagnostic criteria. Table 1.1 shows the rates of ocular TB among pulmonary TB patients.
In 1960, Woods reported that 20% of patients with pulmonary TB due to M. tuberculosis had uveitis [14]. In contrast in 1967, Danahue found that only 1.46% of pulmonary TB patients had concomitant ocular TB in the United States [5]. Surprisingly in 1997, a prospective study from Spain randomly examined 100 patients with pulmonary TB and diagnosed 18 patients (18%) with ocular TB [2].
Among the developing countries, Biswas and Badrinath in 1995 examined 1005 eyes of pulmonary TB patients in south India and found that 1.39% of patients concomitantly had ocular TB [6]. However, in another publication by Biswas et al. in 1997, they found that culture-positive ocular TB accounted for only 0.60% of the 1273 uveitis patients seen in his uveitis referral clinic [15]. In the Philippines, screening of 103 cases of pulmonary TB found seven patients (6.8% prevalence) with ocular TB in 2013 [3].
Thus, reports of the prevalence of ocular TB have been variable across time, patient populations, and geographical locations [16].
Ocular TB in Developed Countries
Currently, there is a lower prevalence of ocular TB cases in developed countries compared to developing countries (see Table 1.2). In Chile, Israel, the Netherlands, Portugal, and Turkey, the prevalence is very low, ranging from 0.7% to 2.7% [17–22]. In the United States, the percentage of ocular TB was 0.2% in 1987, reaching 0.6% in 1996 and then declining to 0.38% in 2014 [23–25]. Studies in the United Kingdom show a notable rise in prevalence from 0.28% in 1996 to 3.3% in 2015 [26, 27]. Japan is another country in which the prevalence increased from 0.2% in 1997 to 6.9% in 2003 and then settled at 1.4% in 2016 [28–30].
Table 1.2
Prevalence of ocular tuberculosis in reported series from different countries by percentage
Author | Year | Country | Percentage of ocular TB patients |
|---|---|---|---|
Abrahams and Jians [31] | 1986 | China | 4 |
Henderly et al. [23] | 1987 | United States | 0.2 |
Palmares et al. [21] | 1990 | Portugal | 2.2 |
Weiner and Ben Ezra [18] | 1991 | Israel | 0.7 |
Rothova et al. [19] | 1992 | Netherlands | 1.4 |
Couto and Merlo [32] | 1993 | Argentina | 6.8 |
Smit et al. [20] | 1993 | Netherlands | 2.7 |
Rodriguez et al. [24] | 1996 | United States | 0.6 |
Thean et al. [26] | 1996 | United Kingdom | 0.28 |
Kotake et al. [28] | 1997 | Japan | 0.2 |
Kaimbo et al. [33] | 1998 | Congo | 6 |
Rathinam and Namperumalsamy [34] | 2000 | India | 5.6 |
Mercanti et al. [35] | 2001 | Italy | 7.02 |
Bodaghi et al. [36] | 2001 | France | 6.2 |
Islam and Tabbara [37] | 2002 | Saudi Arabia | 10.5 |
Wakabayashi et al. [29] | 2003 | Japan | 6.9 |
Singh et al. [38] | 2004 | India | 10.13 |
Soheilian et al. [39] | 2004 | Iran | 1.5 |
Yang et al. [40] | 2005 | China | 0.7 |
Sengun et al. [22] | 2005 | Turkey | 1.3 |
Pathanapitoon et al. [41] | 2008 | Thailand | 2.2 |
Hanmade et al. [42] | 2009 | Saudi Arabia | 7 |
Hong et al. [25] | 2014 | United States | 0.38 |
Al-Shakarchi [43] | 2014 | Iraq | 11.4 |
Abdulaal et al. [44] | 2014 | Lebanon | 5.7 |
Liberman et al. [17] | 2014 | Chile | 2.3 |
Jones [27] | 2015 | United Kingdom | 3.3 |
Weiner and Ben Ezra [18] | 2016 | Israel | 0.7 |
Nakahara [30] | 2016 | Japan | 1.4 |
Manandhar [45] | 2016 | Nepal | 4 |
Win et al. [46] | 2016 | Myanmar | 32.4 |
A study from Denmark suggested that ocular TB is an important cause of ocular morbidity where cases presented as chronic iridocyclitis, peripheral phlebitis, and disseminated choroiditis [47]. In Russia, ocular TB was on the increase especially with cases presenting as posterior uveitis [48]. Studies in Argentina, France, Italy, and Saudi Arabia reported high prevalence than other developed countries with prevalence ranging from 6.2% in France to 10.5% in Saudi Arabia [32, 35–37, 42].
Ocular TB in Developing Countries
Infectious uveitis accounts for a significant proportion of uveitis cases seen in the developing countries. Studies in Congo, Iraq, Lebanon, and Nepal found a high prevalence ranging from 4% to 11.4% [33, 43–45]. Myanmar has an alarmingly high prevalence of 32.4% in a study conducted in 2016 [46]. There is also a rising trend in India increasing from 5.6% in 2000 to 10.13% in 2004 [34, 38]. Surprisingly in China there is an apparent decrease from 4% in 1986 to 0.7% in 2005 [31, 40]. Studies from Tunisia, Iran, and Thailand reported almost similar percentage of ocular TB with 1.1%, 1.5%, and 2.2%, respectively [39, 41, 49].
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