Purpose <p>This study aimed to evaluate the feasibility of real-time intraoperative pain assessment using a digital force gauge during vitreoretinal surgery under sub-Tenon’s anesthesia.</p> Methods <p>In this prospective observational study, 63 patients undergoing vitreoretinal surgery under sub-Tenon’s anesthesia were enrolled between April and August 2023. The participants were asked to constantly compress a digital force gauge during the operation. The magnitude of the compressive force was directly proportional to the severity of pain they experienced. A Pain Index (PI) was derived from peak compressive force measurements to evaluate the intraoperative pain intensity. Immediately after the surgery, patients reported their intraoperative pain score and anxiety score using the Numerical Rating Scale (NRS). Concordance between PI and pain scores was analyzed using the intraclass correlation coefficient (ICC) and Kendall’s tau-b analysis.</p> Results <p>The PI was slightly higher than the patient-reported pain scores (1.37 ± 1.27 vs. 1.05 ± 1.28, <i>P</i> = 0.01). Complete consistency in values was observed in 33 cases (52.38%). Strong concordance emerged between PI and pain score (ICC = 0.75, 95% CI: 0.62–0.84; <i>P</i> &lt; 0.01), along with a significant rank-order correlation (τ = 0.66, <i>P</i> &lt; 0.01). Moreover, the PI showed a weaker correlation with anxiety score (τ = 0.32, <i>P</i> = 0.02) compared to pain score (τ = 0.51, <i>P</i> &lt; 0.01).</p> Conclusion <p>The PI demonstrated favorable consistency and correlation with the conventional NRS for pain evaluation.</p>