Surgical waste and greenhouse gas emissions in cataract surgery: a multicenter interventional study at ten Japanese hospitals

Abstract Purpose To quantify waste and greenhouse gas (GHG) emissions from disposable materials used in cataract surgery in Japan and to assess pragmatic, site-selected waste-reduction interventions. Study design Prospective multicenter observational and interventional (before and after) clinical study. Methods Ten Japanese sites audited 10 consecutive standard phacoemulsification cases at baseline and after implementing low-risk intervention selected by each site and integrated into routine workflow. Disposable items were collected and weighed. GHG emissions were estimated as a partial footprint attributable to disposable materials, expressed as carbon dioxide equivalents (CO 2 eq), using published material emission factors and material-specific end-of-life assumptions. Primary outcomes were waste weight and GHG emissions per case. Results A total of 201 surgical procedures were analyzed (100 baseline, 101 post-intervention). Baseline mean waste was 2.28 ± 0.40 kg and mean GHG emissions were 9.80 ± 2.14 kg CO 2 eq per case; plastics were the largest contributor. Site-level medians decreased from 2.28 to 2.06 kg (P = .020) and from 9.09 to 8.35 kg CO 2 eq (P = .004). In mixed-effects models, reductions did not reach statistical significance (waste ratio 0.86, 95% CI 0.73–1.02, P = .092; GHG ratio 0.84, 95% CI 0.71–1.00, P = .051). Conclusions Cataract surgery in Japanese sites generates substantial disposable-material waste and associated CO 2 eq. Pragmatic site-selected interventions were associated with significant reductions in site-summary analyses, while case-level modeling showed similar trends without statistical significance, suggesting heterogeneity and/or limited power.