Ischaemic Optic Neuropathy After Cardiac Surgery: A Systematic Review and Meta-Analysis of Incidence and Risk Factors.

BACKGROUND: Ischaemic optic neuropathy (ION) is the most common cause of perioperative visual loss, with the highest incidence reported after cardiac surgery involving cardiopulmonary bypass (CPB). Despite devastating complications, the overall incidence and risk factors for patients with ION in the setting of cardiac surgery remain contentious. We performed a systematic review and meta-analysis to evaluate the pooled incidence and risk factors for ION after cardiac surgery. METHODS: This review conformed to PRISMA guidelines. PubMed, MEDLINE, Web of Science and Cochrane were searched up to 24 March 2024 for multivariable-adjusted and propensity-matched observational studies assessing the incidence of ION exclusively in patients undergoing cardiac surgery. Odds ratios (ORs) with 95% confidence intervals (CIs) for each risk factor were pooled from the selected studies using a random-effects model. RESULTS: Eleven studies totalling 6 471 577 patients were included. The pooled incidence of ION was approximately 1.50 per 10 000 cardiac surgeries. Significant risk factors for developing ION included coronary artery disease (OR 1.81, 95% CI 1.17-2.79), peripheral vascular disease (OR 1.67, 95% CI 1.10-2.54) and anaemia (OR 1.06, 95% CI 1.00-1.13). Notably, the incidence varied widely between studies, reflecting differences in diagnostic criteria and reporting standards. Newcastle-Ottawa risk of bias assessment found the studies to be of overall moderate methodological quality, with a high risk of bias. CONCLUSION: This study demonstrates a relatively low overall pooled incidence of ION following cardiac surgery, with identifiable risk factors such as pre-existing coronary artery disease, peripheral vascular disease and perioperative anaemia.