Perspective

1

Ocular tuberculosis (TB) is an extra-pulmonary manifestation of TB within the eye and/or external eye. It has a multitude of potential mechanisms due to its broad tissue affinity, which has long contributed to diagnostic and management uncertainty. Despite the long history of TB infections, the first epidemiological reports on TB uveitis were only published in the mid-late 1900s. Other forms of systemic TB infections have been described in physician records from ancient Egyptian, Chinese and Indian civilisations, and were also recognised by Hippocrates for their contagious nature.¹ Prior to Robert Koch’s postulate including M. tuberculosis 1882, reports of tubercles in ocular tissue were already described.

Maitre-Jan was credited with the earliest description of ocular TB in 1711.² He observed an iris lesion which led to corneal perforation. This was followed by other reports of choroidal tubercles that were similar to extraocular tubercles seen in TB.³ Eventually, theories about ocular TB emerged for primary focal infection that is considered rare, ocular dissemination of a systemic focal infection that was attributed to most confirmed cases with positive cultures, and ocular inflammation arising from a immune adjuvant response to systemic focal and latent infections. These theories remain broadly accepted. However, since the 1900s, many epidemiological reports have emerged over the decades with one thing in common – tremendous phenotypic variations with no clear pattern.

It was unclear what factors contributed to clinically significant outcomes such as blindness, recurrence, and treatment resistant infection. Up until very recently in 2010, few studies were able to draw comparisons across the spectrum of clinical manifestations of ocular TB being reported globally. This prompted colleagues in the field of Uveitis to co-ordinate more closely to gain better understanding of ocular TB. The group of collaborators gathered momentum through increasing dialogue at meetings and officially established the collaborative ocular tuberculosis study (COTS) group in 2015. COTS is a multinational collaboration with the aim to improve understanding of phenotypic variations in ocular TB, and develop guidelines for the management and pertinently to direct in timely investigations, and the appropriate deployment of steroids and/or anti-tubercular therapy (ATT).

Enabled by cloud-based databases, COTS-1 established a multinational disease registry for ocular TB. Through voluntary contribution of retrospective structured, free-text, and image data, the group has been able to draw inferences about global variations in disease presentation and the management through data analytics. It is timely and forward thinking of Ocular Immunology and Inflammation to share these findings with the broader community of Uveitis colleagues. This will heighten, I am sure, the interest in forwarding this area and develop future opportunities to collaborate to prospectively collect data and refine existing guidelines for diagnosis, treatment, and management.