Intraoperative flash visual evoked potentials (FVEPs) can be used to monitor the integrity of the visual pathway in real-time during surgeries, and is to prevent the damage and deterioration of visual function caused by visual pathway damage, which is the key method of intraoperative monitoring of visual function.

Spinal surgery in the prone position may compress the eyeball and reduce the blood supply of the ophthalmic artery, which is still one of the main causes of postoperative visual impairment. Intraoperative FVEPs monitoring is easily affected by inhale anesthetics, and there is little studies on the effect of intravenous-inhalation balanced anesthesia on FVEPs monitoring. Desflurane wakes up quickly, which is conducive to the recovery of early respiratory function and orientation, and early neurological evaluation. This study aims to compare the effects of desflurane-propofol balanced anesthesia and desflurane pure inhalation anesthesia on the amplitude and latency of FVEPs during spinal surgery under the same sedation depth monitored by bispectral index (BIS) monitoring.

Inclusion Criteria:

1. Patients undergoing spinal cord surgery under elective general anesthesia;
2. At the same time, other electrophysiological monitoring is required;
3. 18-65 years old;
4. ASA I-III;
5. Sign the informed consent form.

Exclusion Criteria:

1. Patients with visual impairment;
2. Patients with severe liver and kidney function diseases;
3. History of asthma; Uncontrolled hypertension, diabetes, severe arrhythmia or unstable angina pectoris;
4. Have mental illness or unable to communicate;
5. BMI≥30kg/m2；
6. Abuse of analgesics and drug abuse history;
7. Silicone allergy;
8. Visual evoked potential monitoring was rejected.