To assess the influence of body position on intraocular pressure (IOP) in patients who underwent vitrectomy and intraocular gas tamponade.

Patients who did not undergo any surgery were defined as Group 1. The remaining patients were divided into 3 groups according to the surgery performed (Group 2; cataract surgery, Group 3; vitrectomy and cataract surgery, Group 4; vitrectomy with intraocular gas tamponade and cataract surgery). IOP was measured by a non-contact tonometer, Goldmann applanation tonometer, and Tono-Pen in the sitting, supine, and prone positions.

The difference of IOP measured in the sitting position among the 4 groups was not significant. IOP was significantly elevated by 2.04 mm Hg on average when the posture was changed from sitting to supine or prone in all 4 groups. The IOP discrepancy between supine and sitting positions was significantly greater in group 4 by 3.61 mm Hg than the other groups ( p = 0.003, ANOVA test). The IOP difference between the prone and sitting position was also significantly higher in group 4 by 3.82 mm Hg than the other groups ( p = 0.001, ANOVA test).

The patients with vitrectomized gas tamponade eyes had a mean IOP increase of 3.82 mm Hg when the position was changed from sitting to prone. When performing vitrectomy and intraocular gas tamponade on patients in the prone position, an IOP elevation should be monitored thoroughly.