Effect of different surgical positions on intraocular pressure: a cross-sectional study

Abstract

Background: Intraoperative intraocular pressure (IOP) elevation is a risk factor for postoperative blindness. Surgical position is associated with intraoperative IOP elevation. In China, there are few studies on the effect of various surgical positions on intraoperative IOP. This study was conducted to explore IOP change and its related factors in four common surgical positions in China.

Methods: This was a cross-sectional observational study. A total of 325 surgical patients who had non-ocular surgery from January 2019 to December 2019 in the hospital, were enrolled in this study. During their surgeries for general anesthesia, these participants were placed in lithotomy position/lateral position/prone position/supine position according to their surgery requirement. IOP was measured by icareTA03 handheld portable tonometer at 9 different time points from admission to exiting the operation room. And general information, postural position, and surgery information were collected through a uniform questionnaire. Multivariate analysis was performed to explore the related factors of IOP change.

Results: IOP of both eyes on lithotomy position, lateral position, and supine position showed statistical differences by ANOVA test at each time point (p < 0.05). IOP of both eyes in the prone position before exit from the operating room was significantly higher than IOP 10-min after anesthesia (p < 0.01). IOP under different postural angles showed statistical differences (F value = 4.85, P < 0.05), and the larger the head-down angle, the higher the IOP. IOP on the compressed side in the lateral position was higher than that on the non-compressed side (p < 0.01). In the multivariate linear regression analysis adjusted by other factors, postural position and baseline IOP were associated with IOP difference between before and after surgery (p < 0.01).

Conclusion: IOP in the four surgical positions showed different change patterns with the surgical process and position change. Nurses should assist the surgeon to reduce the head-down angle without interfering with the surgical operation and strengthen the inspection of IOP on patients with long-time surgery, to avoid intraoperative rapid IOP changes.

Keywords: Head-down position; Influencing factors; Intraocular pressure; Lateral position; Lithotomy; Prone position; Supine position.