Increased Macular Thickness Linked to Higher Risk of Postoperative Delirium in Seniors

Research published in General Psychiatry has established a connection between thickening of the macular layer of the retina and an elevated risk of postoperative delirium in older patients undergoing surgeries with general anesthesia. This finding is particularly significant as postoperative delirium is a common complication among elderly individuals, often leading to extended hospital stays and increased dependence on care for daily activities.

Postoperative delirium can have serious implications, including a higher likelihood of cognitive decline and dementia. Identifying patients at risk for this condition is challenging, as there are no straightforward tests currently available. Given that visual impairment is known to be a risk factor, researchers aimed to explore whether the thickness of the macular layer could serve as a potential biomarker for susceptibility to postoperative delirium.

The study analyzed 169 patients aged 65 and older scheduled for surgeries, including hip and knee replacements as well as kidney and prostate procedures, at Shanghai 10th People's Hospital. As part of their preoperative assessment, patients underwent an eye imaging test known as optical coherence tomography (OCT) to measure the thickness of the retinal macular layer.

Post-surgery, the patients were monitored for signs of delirium using the Confusion Assessment Method (CAM) for the first three days. The severity of any delirium was assessed using the CAM-Severity (CAM-S) rating, which considers ten features of delirium, such as inattention and disorganized thinking.

Results indicated that 24% of the participants developed postoperative delirium, and those affected demonstrated a significantly greater mean macular thickness in the right eye (283.35 µm) compared to those who did not experience delirium (273.84 µm). After accounting for variables such as age, sex, and mental state, researchers found that increased preoperative macular thickness in the right eye correlated with a 1.593 times higher likelihood of developing postoperative delirium, as well as greater severity of the condition.

Interestingly, the relationship observed was specific to the right eye, with no similar association found for the left eye. The reasons behind this asymmetry remain unclear, although previous studies have noted that the mean macular thickness tends to be greater in the right eye among healthy individuals. Additionally, research into neurodegeneration has indicated asymmetrical degeneration patterns in both the retina and the brain.

As an observational study, the authors caution that definitive conclusions regarding cause and effect cannot be drawn. They also acknowledge limitations such as the small sample size and the lack of examination of confounding factors like pre-existing eye dominance.

The researchers propose that macular thickness measurements taken via OCT could potentially serve as a non-invasive indicator of individuals at risk for developing postoperative delirium following anesthesia and surgery in geriatric patients. They emphasize the necessity for larger validation studies to confirm these findings.