Postoperative visual function injury occurs after spinal cord, neurosurgery, ophthalmology and other operations, which directly affects the postoperative quality of life of patients. Flash visual evoked potential (FVEP) is important for evaluating visual function under general anesthesia during operation. The changes of visual function can be observed and recognized in time through the amplitude changes of FVEP, which can avoid or reduce the visual function damage during operation. Anesthesia method determines the success and variability of electrophysiological monitoring to a certain extent. The purpose of this study is to investigate the effect of total intravenous anesthesia based on cyclopol on FVEP compared with propofol.

Inclusion Criteria:

1. Patients undergoing elective spinal surgery under general anesthesia;
2. Intraoperative electrophysiological monitoring is required;
3. 18-65 years old;
4. ASA I-III;
5. Sign the informed consent.

Exclusion Criteria:

1. Patients with visual impairment;
2. Patients with severe liver or kidney disease;
3. Uncontrolled hypertension, diabetes, severe arrhythmia or unstable angina pectoris;
4. Have mental illness or unable to communicate;
5. BMI≥30kg/㎡;
6. Abuse of analgesics and drug abuse history;
7. Muscle weakness, motor dysfunction or neuromuscular junction disease before operation;
8. Preoperative somatosensory dysfunction;
9. Retain trachea catheter after operation;
10. Narcotic drugs and silicone allergy;
11. Visual evoked potential monitoring was rejected.