Interferon-gamma release assays in tuberculous uveitis: a comprehensive review

Abstract

Tuberculous uveitis (TBU) comprises a broad clinical spectrum of ocular manifestations, making its diagnosis challenging. Ophthalmologists usually require evidence from investigations to confirm or support a clinical diagnosis of TBU. Since direct isolation of the causative organism from ocular specimens has limitations owing to the small volume of the ocular specimens, resultant test positivities are low in yield. Immunodiagnostic tests, including the tuberculin skin test and interferon-gamma release assays (IGRAs), can help support a clinical diagnosis of TBU. Unlike the tuberculin skin test, IGRAs are in vitro tests that require a single visit and are not affected by prior Bacillus Calmette-Guerin vaccination. Currently, available IGRAs consist of different techniques and interpretation methods. Moreover, newer generations have been developed to improve the sensitivity and ability to detect active tuberculosis. This narrative review collates salient practice points as a reference for general ophthalmologists, such as evidence for the utilization of IGRAs in patients with suspected TBU, and summarizes basic knowledge and details of clinical applications of these tests in a clinical setting.

Keywords: interferon-gamma release assays; ocular tuberculosis; review; tuberculous uveitis.

Figure 1. Clinical findings of tuberculous uveitis include keratic precipitates, anterior chamber cells, posterior synechia, iris nodules, ciliary body tuberculoma, snowballs/snow bank, retinal vasculitis, multifocal/serpiginoid choroiditis, choroidal tuberculoma (single or multifocal), optic disc granuloma.

Figure 2. Current interferon-gamma release assays approved by the Food and Drug Administration for commercial use.