Researchers have identified a significant association between increased macular thickness in the right eye and risk of developing postoperative delirium in older adults who undergo elective surgery. They suggested that optical coherence tomography measurements could serve as a noninvasive biomarker for identifying patients who may be vulnerable to this common postoperative complication.

Conducted at Shanghai 10th People’s Hospital, the study involved 169 participants aged 65 years or older who were scheduled for orthopedic or urologic surgery under general anesthesia. In the study, published in General Psychiatry, lead study author Zhongyong Shi, of the Shanghai Jiao Tong University School of Medicine, and colleagues measured preoperative macular and peripapillary retinal nerve fiber layer (RNFL) thicknesses using optical coherence tomography (OCT) and assessed postoperative delirium using the Confusion Assessment Method (CAM) as well as its severity via the CAM-Severity scale on postoperative days 1 through 3.

Incidence of postoperative delirium was 24% (n = 40). No statistically significant associations were found between postoperative delirium and left-eye macular thickness, peripapillary RNFL thickness, or macular ganglion cell–inner plexiform layer thickness, but right-eye macular thickness presented differently. It was significantly greater in patients who developed delirium (mean = 283.35 µm) vs those who didn't (mean = 273.84 µm; P = .013). Right-eye macular thickness was also associated with a higher risk of delirium after adjustment for age, sex, and Mini-Mental State Examination (MMSE) score (adjusted odds ratio [OR] = 1.593, 95% confidence interval [CI] = 1.093–2.322, P = .015) as well as greater delirium severity (adjusted beta = 0.256, 95% CI = 0.037–0.476, P = .022).

Participants who developed postoperative delirium had lower preoperative MMSE scores compared with those who didn't (median = 25 vs 27). The findings aligned with prior research that linked delirium with an increased risk of long-term cognitive decline, suggesting possible overlap in pathophysiology with early Alzheimer’s disease.

Previous studies have also shown that interocular asymmetry in retinal structure is common and may be influenced by hemispheric differences in neurodegeneration or anatomical variability.

The researchers proposed that macular thickening could result from early neuroinflammatory processes, extracellular protein deposition (eg, beta amyloid), and reactive gliosis, all of which paralleled early Alzheimer’s-related changes. These changes may increase neuronal vulnerability under surgical stress and precipitate delirium.

“The mechanisms behind the interocular differences in macular thickness in patients with postoperative delirium are not currently well understood,” the study authors wrote. “Pending further validation in larger samples, our findings suggest that macular thickness measured by OCT may serve as a noninvasive marker and identify [patients who are] vulnerable to developing postoperative delirium after anaesthesia and surgery among geriatric patients.” The researchers also suggested larger prospective cohort studies to further explore gender-specific effects on retinal thickness and postoperative delirium in this age demographic.

Competing interests can be found in the published research.