Sevoflurane, Propofol and Desflurane on POD/POCD

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.