Learning Curve For Hydrus Microstent Implantation: A Retrospective Observational Study Using Segmented Regression Analysis

To evaluate the learning curve and identify the procedural proficiency threshold for Hydrus Microstent (HMS) implantation using segmented regression analysis.

Single-center retrospective cohort study at Saitama Red Cross Hospital, Japan.

This study included consecutive HMS implantations performed during the introduction phase between April 2025 and December 2025. Insertion time was recorded for each case. Segmented linear regression was applied with case sequence as the independent variable and insertion time as the dependent variable, adjusting for patient age. The breakpoint indicating procedural proficiency and its 95% confidence interval (CI) were estimated using bootstrap-based inference.

Segmented regression identified a proficiency breakpoint at the 11th case (95% CI, 4.4–17.6). Before the breakpoint, the insertion time significantly decreased by approximately 30 seconds per subsequent case (β = −30.17, p = 0.024). After the breakpoint, insertion time plateaued, indicating stabilization of procedural performance. Age was not significantly associated with insertion time.

Using segmented regression analysis, this study provides an objective benchmark for the learning curve of HMS implantation, indicating that procedural proficiency is typically achieved after approximately 11 cases. These findings may assist in structuring surgical training, optimizing supervision during early adoption, and enhancing patient safety through improved perioperative planning.