Gas–Lesion Contact and Postural Compliance After Vitrectomy With Tamponade: A Continuous Monitoring and 3D Quantitative Analysis

Purpose: To assess postoperative head positioning behavior and estimate gas-retinal lesion contact after vitrectomy using a wearable accelerometer-based monitoring system and geometric modeling. Methods: This study enrolled 56 patients who underwent pars plana vitrectomy between November 2024 and June 2025. Of these, 28 were prescribed prone positioning for 1 week and 28 received no postural instruction. A custom-designed eyeshield equipped with a triaxial accelerometer continuously recorded three-dimensional (3D) head orientation at 5-second intervals for 7 days. A geometric model integrating gas volume dynamics, lesion location, and head orientation was used to estimate time-resolved gas-lesion contact. Results: Prone compliance averaged 49.8% ± 4.3% and declined over the week; gas-lesion contact averaged 90.5% ± 2.1% and likewise decreased, being lower at night. Gas-lesion contact averaged 92.9% ± 2.5% in single-tear rhegmatogenous retinal detachment (RRD) cases and 88.1% ± 3.2% in non-RRD cases including macular hole. Gas-lesion contact increased with prone compliance and with octafluoropropane (C3F8) compared with sulfur hexafluoride (SF6). Patient self-report questionnaires indicated greater perceived burden in the prone group, affecting sleep quality. Conclusions: We established a quantitative framework to assess postural behavior and estimate lesion-specific gas contact in the early postoperative period. SF6 tamponade required strict adherence to maintain adequate gas-lesion contact, whereas C3F8 provided more consistent coverage despite variable compliance. These findings may inform postoperative patient counseling and tamponade selection. Translational Relevance: By integrating week-long vector-based monitoring and 3D visualization of real-world head posture with a generalized model that estimates gas-lesion contact at any retinal location, this study provides quantitative metrics that directly inform postoperative positioning and tamponade choice.