Tubercular Retinitis: Clinical Spectrum and Multimodal Imaging Features of an Insufficiently Characterized Entity.

Abstract

Purpose: Ocular tuberculosis (OTB) affecting the posterior segment commonly presents with choroiditis lesions. However, tubercular retinitis (TBR) is a rare and poorly characterized phenotype. This study aims to define the clinical spectrum, multimodal imaging characteristics, natural course of TBR lesions, and differentiate it from similar appearing chorioretinal lesions in OTB.

Design: Single-center, retrospective case series.

Methods: The study included patients presenting with lesions clinically suggestive of retinitis. Clinical data, fundus findings, and multimodal imaging (ultra-widefield fundus photography, fluorescein and indocyanine green angiography (FFA and ICGA), and optical coherence tomography (OCT)) were analyzed. The diagnosis of OTB was established based on the Collaborative Ocular Tuberculosis Study (COTS) criteria, that includes supportive immunological and radiological evidence (positive Mantoux test or interferon-gamma release assay, and chest imaging). All patients received standard four-drug antitubercular therapy (ATT) with adjunctive corticosteroids and were followed for anatomical and functional outcomes.

Results: Eight patients (six males; age range: 21-54 years) were included. A total of 37 lesions were identified in 12 eyes (median: 2 lesions per eye). Twenty-five lesions (67.6%) were purely retinal with no choroidal involvement, and were classified as tubercular retinitis (TBR). Twelve lesions (32.4%) showed involvement of the choroid, retinal pigment epithelium(RPE), and outer retina, and were classified as tubercular retinochoroiditis(TBRC). All the eyes demonstrated occlusive retinal vasculitis. FFA of TBR lesions demonstrated early central hypofluorescence with circumferential perilesional hyperfluorescence ('moat sign'). On OCT, TBR lesions were intraretinal and characterized by full-thickness hyper-reflectivity and disruption of inner retinal architecture with no choroidal/RPE changes. TBRC lesions showed outer retinal disruption, RPE irregularity with focal defects, and choroidal shadowing. ICGA showed focal hypofluorescence in TBRC lesions, but was unremarkable in TBR. Following ATT, TBR lesions healed without pigmentation or scarring, whereas TBRC lesions resolved with discrete pigmented scars with retinal thinning and RPE disruption on OCT (32.4%) (p=0.028).

Conclusion: The spectrum of posterior segment involvement in OTB includes intraretinal inflammation that can present as TBR and TBRC. These lesions are typically present in eyes with occlusive retinal vasculitis. Features on clinical examination and multimodal imaging help identify the tubercular etiology and differentiate between TBR and TBRC lesions.