Longitudinal analysis of iridian anterior segment OCT biomarkers in Fuchs uveitis syndrome and Posner-Schlossman syndrome.

PURPOSE: To analyze longitudinal iridial changes using swept-source anterior segment optical coherence tomography (SS-AS-OCT) in patients with Posner-Schlossman syndrome (PSS) and Fuchs' uveitis syndrome (FUS). METHODS: This prospective, comparative, longitudinal, single-center study included FUS and PSS patients who underwent both aqueous humor viral analysis and bilateral SS-AS-OCT iris imaging, performed at least twice and spaced a minimum of 9 months apart: initial OCT (i-OCT) vs final OCT (f-OCT). Stromal thickness (ST), smooth index (SI), and optical density (OD) were quantified and analyzed. Longitudinal and inter-group comparisons were analyzed, considering clinical and demographic factors. RESULTS: A total of 119 eyes from 60 patients were included: 31 PSS eyes, 32 FUS eyes, and 56 healthy contralateral eyes. The average time between i-OCT and f-OCT was 3.2 ± 1.5 years. In PSS eyes, ST decreased in superior and temporal quadrants, while SI increased in nasal and temporal quadrants. In FUS, ST declined in all quadrants except nasal one, with SI rising in both nasal and temporal quadrants. Viral etiology -Cytomegalovirus (CMV) in PSS, Rubella Virus (RV) in FUS- was linked to greater iris alterations. In healthy eyes, ST remained stable, but SI increased in both temporal and nasal quadrants. No changes were detected in OD in FUS and PSS over time. CONCLUSIONS: Quantitative OCT biomarkers revealed progressive iris stromal thinning and flattening in FUS and PSS. RV in FUS was associated with greater biomarker progression, while CMV in PSS correlated with increased stromal thinning. In healthy eyes, iris thickness remained stable, but gradual flattening was observed, possibly due to age-related changes.