Efficacy of low-concentration nitrous oxide gas anesthesia in routine cataract microsurgeries.

[KEY MESSAGES] WHAT IS KNOWN : • Low-concentration nitrous oxide (LCNO) has been used in dentistry and some ophthalmic procedures and is believed to reduce anxiety and discomfort. • Evidence for its sedative effect in cataract microsurgery has largely relied on subjective patient reports rather than objective monitoring.

[WHAT IS NEW] • This study provides objective evidence, using bispectral index (BIS) monitoring, that LCNO induces mild sedation during routine cataract microsurgery. • LCNO significantly reduced the BIS values during surgery without causing clinically relevant changes in the vital signs or adverse events, supporting its safety and practicality for outpatient cataract surgery.