Neuro-Mimic Indicators of Anesthesia Depth During General Anesthesia

Monitoring Eyelid Reflex, Eye Movements, and Pupil Responses in Patients Undergoing General Anesthesia: Neuro-Mimic Indicators of Anesthesia Depth

This prospective observational study will evaluate neuro-mimic indicators of anesthesia depth, including eyelid reflex, eyeball movements, and pupil responses, in patients undergoing elective surgery under general anesthesia. Sixty adult patients will be observed at three standardized time points: after induction, during skin incision, and mid-surgery. All parameters will be recorded alongside bispectral index (BIS) monitoring. The study aims to determine whether these observable signs correlate with anesthesia depth, contribute to early detection of intraoperative awareness, and provide a basis for developing non-invasive depth monitoring systems.

Accurate assessment of anesthesia depth is essential to ensure patient safety and reduce the risk of intraoperative awareness. Current technological monitoring tools such as BIS do not always provide sufficient reliability. Neuro-mimic indicators, including eyelid reflex, spontaneous and stimulus-related eye movements, and pupil responses, may offer additional insights into anesthesia depth. This observational, prospective, non-interventional study will enroll 60 adult patients (aged 18-65, ASA I-III) scheduled for elective abdominal surgeries lasting 1-3 hours under general anesthesia at Başakşehir Çam and Sakura City Hospital. Observations will be performed at three intraoperative stages: post-induction, skin incision, and mid-surgery. Parameters include palpebral reflex, eyeball position and movement, and pupil diameter, all systematically documented alongside BIS values. The primary endpoint is the change in pupil diameter across three time points. Secondary outcomes include the presence or absence of eyelid reflex, eye movements, and their correlations with BIS values. Data will be analyzed using repeated measures ANOVA, McNemar test, correlation analyses, and appropriate non-parametric tests where necessary. The study is entirely observational and involves no additional interventions or risks for patients. Results may provide evidence for the integration of observable physiological signs into anesthesia monitoring practice and contribute to the development of contactless depth monitoring systems.

Inclusion Criteria:

• The study will include patients aged 18-65 who will undergo elective abdominal surgery (e.g., cholecystectomy/gastrectomy/colorectal surgery/prostatectomy/hysterectomy, etc.) under general anesthesia, with a planned duration of 1-3 hours.
• Patients whose eye area is left uncovered and who are in a position suitable for observation
• Patients who have signed the informed consent form
• Patients with an ASA score of I-III

Exclusion Criteria:

• Patients undergoing surgical procedures in the head, neck, or face region (e.g., ENT, eye, jaw surgery, neurosurgery, thyroid/parathyroid)
• Patients whose eye area must be completely covered with a sterile drape
• Patients with an ASA score of IV or higher
• Individuals with neurological disorders and impaired pupil response, patients who have previously undergone eye trauma or surgery and cannot undergo pupil evaluation
• Patients who are unable to communicate and cannot provide informed consent
• Emergency surgeries (e.g., appendectomy/ileus/gastrointestinal perforation/cesarean section/gunshot wounds/stab wounds/multiple trauma/traffic accidents, etc.)
• Individuals who have previously been included in this study (to prevent repeated inclusion)