Corneal epithelial thickness profiles in dry eye patients with or without primary Sjögren’s syndrome

To describe corneal thickness (CT) and corneal epithelial thickness (CET) in dry eye patients with/without primary Sjögren’s syndrome (pSS-DED/nSS-DED) and evaluate potential associations with dry eye symptoms and signs. 181 pSS-DED patients and 133 nSS-DED patients were recruited from dry eye outpatient of Peking University Third Hospital from December 2020 to December 2024. The pSS-DED patients were further diagnosed by rheumatologists. All participants received symptom assessment, slit lamp examination, Schirmer I test and optical coherence tomography (OCT) examination. pSS-DED patients had a higher ocular surface disease index questionnaire (OSDI) (20.31 vs. 16.89, P = 0.006), lower Schirmer I test value (P = 0.003), and lower fluorescein tear break-up time (FBUT) (P < 0.001) than nSS-DED patients. Among corneal thickness profiles, pSS-DED patients had thinner total corneal thickness (CT), including CT average (CTAV, P = 0.021), CT minimum (CTmin, P < 0.001), CT maximum (CTmax, P < 0.001), and so on. Critically, pSS-DED patients also exhibited significant alterations in epithelial profiles, including thinner superior corneal epithelium (SCET, P = 0.013), thinner minimum epithelium (CETmin, P = 0.040), and significantly greater epithelial thickness variability (CETSD, P = 0.005). Correlation analysis further revealed that epithelial variability (CETSD) was significantly associated with worse OSDI symptoms (r = 0.25) and thinner superior epithelium (r=-0.33). Multivariate logistic regression identified FBUT (OR = 0.697), CTmin (OR = 0.958), CTmax (OR = 0.986), central corneal stromal thickness (CCST, OR = 1.039), epithelial variability (CETSD, OR = 1.398), and superior-inferior stromal difference (SCST-ICST, OR = 1.017) as significant independent predictors for differentiating the groups. Receiver-operating characteristic (ROC) curve analysis revealed that a combined model integrating these parameters demonstrated high diagnostic efficacy. Patients with pSS-DED exhibited lower CT profiles and thinner, more variable CET profiles. These structural alterations likely reflect the chronic inflammatory and neurosensory pathology of pSS. The integration of OCT-derived corneal parameters with traditional clinical signs may serve as objective biomarkers to support the differentiation of pSS-DED from nSS-DED.