This study investigated the effect of desflurane and propofol anesthesia on visual acuity in patients in prone position for spinal surgery. Many trials have investigated the effects of different anesthetic agents on intraocular pressure, propofol may reduce intraocular pressure more than other intravenous anesthetics.

Perioperative increase in intraocular pressure can be caused by prone positioning. In addition to surgical factors, patients with glaucoma, uncontrolled hypertension, arthrosclerosis, and morbid obesity are at risk for potentially damaging optic nerve and loss of optic nerve function. Some studies found that intraocular pressure values were significantly lower in patients undergoing propofol total intravenous anesthesia than in patients undergoing desflurane anesthesia during intraoperative positional changes. Pronounced vasodilatation caused by desflurane might produced hyperaemia with higher intraocular pressure. Hemodynamic response to prone position measured by near-infrared spectroscopy (NIRS) on the prefrontal cortex could determine changes caused by prone position.

Inclusion Criteria:

• Glasgow Coma scale 15
• American Society of Anesthesiologists (ASA) Physical Status Classification System I-III
• spinal surgery in duration less than 3 hours
• sinus rhythm

Exclusion Criteria:

• postoperative artificial ventilation
• serious neurological disease
• lung disease with hypercapnia
• propofol allergy