To test the hypothesis that retinal nerve fiber layer (RNFL) thickness is correlated with Aβ and Tau concentration of cerebrospinal fluid (CSF) in an older population.

retinal nerve fiber layer (RNFL) thickness changing has been reported in Alzheimer's Disease (AD) patients at an early stage, and has been demonstrated as a potential biomarker able to predict cognitive deterioration (Hinton DR et al., N Engl J Med 1986; London A et al. Nat Rev Neurol 2013; Chang LY et al., Alzheimers Dement 2014). However, whether RNFL thickness is correlated with cerebrospinal fluid (CSF) features of AD pathogenesis (e.g., Aβ and Tau) remains unclear. The investigators thus conducted this observational cohort study to test the correlation between RNFL thickness changing and CSF, to further validate RNFL as a potential AD biomarker.

Inclusion Criteria:

1. 50 years old or older;
2. five years or more of education and scores of MMSE ≥ 24 points;
3. Chinese as their first language;
4. Having spinal anesthesia.

Exclusion Criteria:

1. prior diagnoses of neurologic diseases, e.g., dementia, Parkinson's diseases, multiple sclerosis or stroke according to DSM-IV;
2. history of mental disorders (e.g., major depressive disorder and schizophrenia) diagnosed according to DSM-IV;
3. known diseases contributing to the retina pathologies, e.g., diabetes, glaucoma or increased intraocular pressure (more than 22 mmHg), cataract, and macular degeneration and hypermyopia;
4. unwillingness to comply with the cognitive assessments;
5. ungradable images of OCT.

A total of 300 old adults who were scheduled to have elective total hip or knee replacement surgery, ureteroscopic lithotripsy and transurethral resection of the prostate at the Shanghai 10th People's Hospital were asked to participate in this study. A total of 104 participants were enrolled from August 2013 to December 2014, and the data from 86 participants were finally included in the study.