Objective Pupillometry and Dexterity Assessment in Surgical Trainees: A Pilot Study

Acquisition of technical skills in surgery requires both precise motor coordination and efficient cognitive control. While simulation platforms and benchtop dexterity tests have demonstrated utility in differentiating performance levels, their predictive validity remains variable. Concurrently, physiologic metrics of cognitive load have emerged as promising tools for quantifying mental effort during surgical tasks. Pupillometry, in particular, offers high temporal resolution, noninvasiveness, and task-synchronized measurement capabilities. However, few studies have integrated objective dexterity metrics with real-time physiologic workload assessment in a unified, scalable framework. To address this gap, we developed a benchtop testing protocol combining standardized fine-motor tasks with pupillometry to evaluate technical performance and cognitive load at different levels of surgical training.

In a pilot cross-sectional observational study, 79 participants, including 49 medical students, 17 nonmedical controls, and 13 experts, completed 2 standardized dexterity tasks: the O'Connor Finger Dexterity and O'Connor Tweezer Dexterity Tests, followed by a knot-tying task. Performance metrics included completion time for each task. Cognitive load was indexed by baseline-corrected pupil diameter (Δ-BCPD), continuously captured and rescaled to normalized task time. Cognitive-load dynamics were compared across groups and performance tiers.

Finger dexterity scores differed significantly by role (p = 0.048) and correlated with knot-tying time (R² = 0.472), supporting their construct-specific validity. Tweezer-task scores showed no significant relationship with procedural performance (R² = 0.004). Pupillometry showed directionally consistent group-level gradients in Δ-BCPD, with experts exhibiting lower mean task-evoked dilation. High-performing participants demonstrated reduced cognitive load, particularly during the finger task, indicative of greater automation. Trends in Δ-BCPD were directionally consistent across groups but did not reach statistical significance.

Brief dexterity tasks paired with time-normalized pupillometry may provide complementary information about motor performance and cognitive workload. This exploratory, rater-independent framework showed promise for distinguishing performance differences and characterizing task demands, supporting further validation in larger cohorts.