Tear inflammatory cytokine profiles in orbital inflammatory disease

Tear inflammatory cytokines are a novel biomarker studied in a range of ocular surface diseases, periorbital and orbital conditions. This single-centre prospective study between 2022 and 2024 aims to characterise tear cytokine profiles (Interleukin-1β [IL-1β], IL-2, IL-6, Interferon-γ [IFN-γ] and Tumour Necrosis Factor-α [TNF- α]) in orbital inflammatory disease (OID). OID patients had pre-treatment tear collection via micropipette, and cytokine analysis via multiplex bead array analysis. Thirteen healthy controls with no prior ophthalmic history were enrolled for comparison. Eighteen tear specimens from seventeen OID patients (6 males; mean age: 52.1 ± 17.1-years-old), with one repeat tear sample taken for recurrent contralateral orbital inflammation. Diagnoses included non-specific orbital inflammation (47.1%), IgG4-related orbital disease (17.6%), orbital granulomatosis with polyangiitis (5.9%), giant cell arteritis (5.9%), herpes zoster ophthalmicus with orbital apex inflammation (5.9%), viral dacryoadenitis (5.9%), bacterial dacryoadenitis (5.9%) and orbital inflammation of uncertain cause (5.9%). Overall, OID patients, and specifically those with dacryoadenitis, had greater IL-6 levels compared to controls (P = 0.038 and 0.002, respectively). OID with dacryoadenitis had higher IL-1β levels compared to those without (P = 0.029). Higher IL-6 levels were observed in idiopathic dacryoadenitis compared to healthy controls (P = 0.008, respectively). There is significant variability in tear inflammatory cytokines profiles observed in OID. IL-1β and IL-6 levels may be non-specific markers of dacryoadenitis and may be particularly elevated in idiopathic dacryoadenitis. Tear cytokines may be affected by severity, localisation and pattern of inflammation. The utility of tear cytokines in the monitoring and prognostication of OID remains to be elucidated.