The effect of spinal versus general anesthesia on intraocular pressure in lumbar disc surgery in the prone position: A randomized, controlled clinical trial

Objective: To compare IOP changes between spinal anesthesia (SA) and general anesthesia (GA) in patients who underwent lumbar disc surgery in the prone position. Design: Prospective, randomized, controlled trial. Setting: Operating room. Patients: Forty ASA I-II patients scheduled for lumbar disc surgery in prone position. Intervention: Patients were randomly allocated to the SA or GA groups. Measurements: IOP was measured before anesthesia (IOP1), 10 min after spinal or general anesthesia in supine position (IOP2), 10 min after being placed in the prone position (IOP3), and at the end of the operation in the prone position (IOP4). Main results: There was no significant difference between baseline IOP1 (group GA = 19.4 +/- 3.2 mmHg; group SA = 18.6 +/- 2.4 mmHg) and IOP2 values (group GA = 19.7 +/- 4.1 mmHg; group SA = 18.4 +/- 1.9 mmHg) between and within the groups. IOP values after prone positioning and group GA measurements (IOP3 = 21.6 +/- 3.1 mmHg; IOP4 = 33.9 +/- 3.1 mmHg) were significantly higher when compared with the SA group (IOP3 = 19.3 +/- 2.7 mmHg, IOP4 = 26.9 +/- 2.4 mmHg) (p = 0.018 and p < 0.001, respectively). Furthermore, IOP3 was significantly increased when compared with IOP2 in the GA group but not in the SA group (p = 0.019 and p = 0.525, respectively). In both groups, IOP4 values were significantly higher than the other three measurements (p < 0.001). Conclusion: The results indicated that IOP increase is significantly less in patients who undergo lumbar disc surgery in the prone position under SA compared with GA.