Conjunctival microvascular alterations in dry eye disease: A comparative study of Sjögren's and non-Sjögren's subtypes.

PURPOSE: Conjunctival microvasculature is associated with ocular and systemic diseases. Previous studies have reported increased blood flow velocity (BFV), blood flow rate (BFR), vessel density, and diameter in dry eye disease (DED). This study aimed to compare bulbar conjunctival microvascular morphology and hemodynamics between patients with DED with and without Sjögren's dry eye (SSDE and NSDE) who had comparable symptoms, and to assess their correlations with Meibomian gland dysfunction (MGD) parameters. MATERIALS AND METHODS: In this prospective study, conjunctival imaging for the left eyes of patients with DED was performed using a previously developed optical system incorporating Attention-UNet-based vessel segmentation and a validated two-step motion-correction pipeline. Tear film lipid layer thickness measurement and meibography were performed using the LipiView® II Ocular Surface Inferometer. Microvascular parameters, including BFV, BFR, and diameter, were quantified. RESULTS: The mean microvessel diameter for the SSDE group (12.985 ± 2.478 μm) was significantly higher than that for NSDE (9.431 ± 3.982 μm) (P < 0.050). In the NSDE group, diameter correlated positively with BFR (P < 0.050), and BFR correlated with both upper and lower meiboscores (P < 0.050). CONCLUSION: These findings reveal distinct conjunctival microvascular signatures in patients with SSDE, and support vessel diameter as a discriminator. The association between hemodynamic changes and MGD parameters in the NSDE group underscores the interplay between MGD and conjunctival microcirculation in NSDE. The differences in microvasculature identified in this study may serve as valuable biomarkers for DED subtype classification and the development of personalized treatment.