The Effect of a Laryngeal Mask Airway on Optic Nerve Sheath Diameter

This study examines whether using a laryngeal mask airway (LMA — a breathing device placed over the airway during anesthesia, rather than a tube inserted into the windpipe) affects pressure inside the skull by measuring the optic nerve sheath diameter (a non-invasive way to detect elevated brain pressure) during surgery. **You may be eligible if...** - You are 18 or older, in good to fair health (ASA classification I or II) - You are scheduled for a routine procedure lasting more than 30 minutes under general anesthesia - Your surgery can be safely done with an LMA (not requiring deep breathing tube insertion) **You may NOT be eligible if...** - You are having head, neck, brain, laparoscopic, or thoracic surgery - Your surgery requires a tilted position (Trendelenburg or reverse Trendelenburg) - You have neurological disorders, glaucoma, or a history of eye trauma in both eyes - You have an intellectual disability Talk to your doctor to see if this trial is right for you.