Background: Mycobacterium tuberculosis is rarely cultured from ocular tissue, contributing to the diagnostic and therapeutic conundrum of OTB. Typical phenotypes of OTB include peripheral occlusive vasculitis, serpiginous-like chorioretinitis or choroidal granulomas. Intermediate uveitis, non-occlusive vasculitis and most anterior uveitis are atypical.

Aim: To compare our patients with typical and atypical OTB phenotypes; in particular microbiology and the role of CT-PET imaging.

Methods: Retrospective study of patients referred with suspected OTB to our specialist London TB unit between 2010-2022. Using electronic patient records, demographic, phenotypic and microbiological data was collected.

Results: 109 patients referred; 57 typical and 52 atypical phenotypes.

In the typical group 33/57 had normal CXR on initial assessment. 26/57 had CT-PET with 19/26 demonstrating avidity (14/19 at extra-pulmonary sites). 12 had culture-confirmed disease, with an additional 4 being TB-PCR positive.

In the atypical group 37/52 had normal CXR on initial assessment. 30/52 had CT-PET with 20/30 demonstrating avidity (10/20 at extra-pulmonary sites). 3 patients had culture confirmed TB and 1 was TB-PCR positive.

The mean age in the typical group was 40, 43 in the atypical group. An equal number of patients had EBUS-TBNA across both groups. >80% were non-UK born.

Conclusion: We demonstrated positive microbiology or PCR in 18% (20/109) of patients. CT-PET identified additional sites for microbiological sampling in both phenotypes. Normal CXR at time of referral is seen more in patients with atypical phenotypes. Patients with OTB should be managed within experienced multi-disciplinary teams.