Optic nerve sheath diameter for predicting neurological outcomes after cardiac arrest: a systematic review and meta-analysis

Background Accurate prediction of neurological outcomes after cardiac arrest (CA) remains clinically challenging. Although optic nerve sheath diameter (ONSD) has emerged as a promising prognostic tool, its predictive performance varies substantially across patient populations and methodological approaches. Methods We systematically searched PubMed, Embase, the Cochrane Library, Web of Science, ScienceDirect, and three Chinese databases from inception through March 2026 for studies evaluating ONSD as a predictor of neurological outcomes after CA. The prognostic performance of ONSD was assessed using the area under the curve (AUC), pooled sensitivity and specificity, subgroup analyses, sensitivity analysis, and publication-bias assessment. Results A total of 17 studies involving 1,157 patients with CA were included. Higher ONSD was associated with poor neurological outcomes in the random-effects model (odds ratio [OR] = 8.97, 95% confidence interval [CI]: 5.51–14.61, P < 0.001; I2 = 48.7%, P = 0.013). The AUC was 0.82 (95% CI = 0.79–0.86), with a pooled sensitivity of 72% (95% CI = 63%–79%) and specificity of 81% (95% CI = 71%–89%). The association remained statistical significance across all predefined subgroups (all P < 0.01). Subgroup patterns suggested that sample size and study design may have contributed to heterogeneity. Leave-one-out sensitivity analysis supported the robustness of the pooled estimate. Deeks’ funnel plot asymmetry test suggested publication bias (P = 0.01); however, the trim-and-fill analysis indicated that the pooled estimate remained stable. Conclusion ONSD may be a useful adjunctive predictor of neurological outcomes after CA. Trial registration PROSPERO (CRD420261293166). Clinical trial number Not applicable.