Association between retinal layer thickness and postoperative delirium in older patients

Postoperative delirium is one of the most common complications in the older surgical population, but its pathogenesis and biomarkers are largely undetermined. Retinal layer thickness has been demonstrated to be associated with cognitive function in mild cognitive impairment and patients with Alzheimer's disease. However, relatively little is known about possible retinal layer thickness among patients with postoperative delirium.

We aimed to investigate the relationship between retinal layer thickness and postoperative delirium in this cross-sectional study.

The participants (≥65 years old) having elective surgery under general anaesthesia were screened via medical records from Shanghai 10th People's Hospital. Preoperative macular thickness and peripapillary retinal nerve fibre layer (RNFL) thickness were measured using optical coherence tomography (OCT). The Confusion Assessment Method (CAM) algorithm and CAM-Severity (CAM-S) were used to assess the incidence and severity of postoperative delirium on the first, second and third days after surgery.

Among 169 participants (mean (standard deviation (SD) 71.15 (4.36) years), 40 (24%) developed postoperative delirium. Notably, individuals who developed postoperative delirium exhibited thicker preoperative macular thickness in the right eye compared with those who did not (mean (SD) 283.35 (27.97) µm vs 273.84 (20.14) µm, p=0.013). Furthermore, the thicker preoperative macular thickness of the right eye was associated with a higher incidence of postoperative delirium (adjusted odds ratio 1.593, 95% confidence interval (CI) 1.093 to 2.322, p=0.015) and greater severity (adjusted mean difference (β)=0.256, 95% CI 0.037 to 0.476, p=0.022) after adjustment for age, sex and Mini-Mental State Examination (MMSE) scores. However, such a difference or association did not appear in the left macular or bilateral peripapillary RNFL thicknesses.

Current findings demonstrated that preoperative macular thickness might serve as a potential non-invasive marker for the vulnerability of developing postoperative delirium in older surgical patients. Further large-scale validation studies should be performed to confirm these results.