Differentiation of anterior chamber pigment and inflammatory cells using swept-source optical coherence tomography: a cross-sectional study

Background/Objectives: We aimed to investigate the potential of anterior segment OCT (AS-OCT) in differentiating anterior chamber (AC) pigment and inflammatory cells. Subject/Methods: Cross-sectional study of adults with uveitis. The exclusion criterion was corneal opacity sufficient to obscure slit lamp examination of the anterior chamber. Reference testing comprised slit lamp-based detection of pigment and Standardization of Uveitis Nomenclature (SUN) grading of intraocular inflammation. Index testing comprised CASIA2 swept-source AS-OCT acquisition, with semi-automated analysis to detect and measure hyper-reflective particles within the AC. Correlations between AS-OCT-derived counts of different-sized particles and clinical grades were explored using multilevel multivariable regression analyses. Results: 62 eyes (31 patients) were included. There was a positive correlation between AS-OCT particle counts of >4 pixels (equivalent to >24microns), and SUN grading (adjusted coefficient, adjCoef 24.3, 95% confidence interval 6.3 to 42.3, p = 0.03), strengthened in eyes clinically absent of pigment (adjCoef 20.6, 14.8 to 26.4, p < 0.001). A positive correlation was also noted between particle counts <= 2 pixels and the presence of AC pigment clinically. Conclusions: Swept-source (SS) AS-OCT holds potential utility in differentiating between pigment and cells within the AC, leading to improved management of individuals with or at risk of intraocular inflammation. SS AS-OCT-derived biomarkers may also provide information on uveitis aetiology, supporting the diagnosis of underlying conditions. Further work on a larger cohort, replication by other investigators and clinical teams, and clinical correlation with anterior chamber sampling will enable future clinical validation.