The investigators will perform clinical studies to test the hypothesis that participants who have total hip/knee replacement under sevoflurane, propofol or desflurane anesthesia will have different effects on the incidence and severity of POD/POCD, and POD/POCD is associated with retinal nerve fiber layer (RNFL) thickness, as well as Serum level of vitamin B12, folic acid, homocysteine and human myeloid differentiation protein-2 (MD-2s). The investigators plan to perform the studies in 300 participants at Shanghai 10th People's Hospital.

Postoperative delirium (POD) and postoperative cognitive disorder (POCD) are the most common complications of geriatric surgical patients, which could cause long-term social dysfunction, high mortality and increased medical cost. Currently, there is no efficient biomarker for POD/POCD, and it also remains largely unknown whether different anesthesia might lead to different incidence and severity of POD/POCD. The investigator's previous studies showed that thickness of retinal nerve fiber layer thickness (RNFL-T) measured by optical coherence tomography (OCT) was associated with POD/POCD; change of RNFL thickness (RNFL-C) in certain period correlated with cognitive deterioration. Thus, the investigators consider that RNFL might be a potential biomarker of POD/POCD. In the proposed large-scale longitudinal studies, the investigators will clinically validate RNF-LT as pre-operative POD/POCD biomarker, and RNFL-C as post-operative biomarker of POD/POCD. Finally, the investigators will compare the effects of surgery (total hip/knee replacement) under general anesthesia with sevoflurane, propofol and desflurane on the incidence and severity of POD/POCD in patients. Results from the proposed studies will likely establish RNFL as a potential POD/POCD biomarker, promote the clinical utilization of OCT-RNFL in early screening and outcome prediction of POD/POCD, and finally optimize anesthesia care of geriatric surgical patients to avoid or reduce POD/POCD incidence. These findings will lead to better postoperative outcomes of geriatric patients.

Inclusion Criteria:

• 60 years old or older
• Chinese Mandarin as the native language
• scheduled to undergo hip/knee surgery under general anesthesia
• American Society of Anesthesiologists (ASA) class I-Ⅲ

Exclusion Criteria:

• Prior diagnoses of neurological diseases according to ICD-10
• History of severe psychiatric disorders according to DSM-IV
• Visual or auditory defects
• Participating in the investigation of another study

Patients, aged 60 years old or older, who admitted to the Department of Orthopedics at Shanghai 10th People's Hospital and had been scheduled to undergo knee or hip fractures were screened and asked to participate in the study.