Optimization of orbital retraction during endoscopic transorbital approach via quantitative measurement of the intraocular pressure - [SevEN 006]

Background Increased use of the transorbital approach (TOA) warrants greater understanding of the risk of increased intraocular pressure (IOP) and intraorbital pressure (IORP) due to orbital compression. We aimed to investigate the changes in IOP and IORP in response to orbital retraction in TOA and establish a method for the continuous measurement of intraoperative IORP. Methods We assessed nine patients who underwent TOA surgery from January 2017 to December 2019, in addition to five cadavers. IORP and IOP were measured using a cannula needle monitor, tonometer, cuff manometer, and micro strain gauge monitor. Results In all nine clinical cases and five cadavers, increased physical compression of the orbit increased the IOP and IORP in a curvilinear pattern. In clinical cases, when the orbit was compressed 1.5 cm from the lateral margin in the sagittal plane, the mean IOP and IORP were 25.4 +/- 5.2 mmHg and 14 +/- 9.2 mmH(2)O, respectively. The IORP satisfactorily reflected the IOP (Pearson correlation coefficient = 0.824, p < 0.001). Conclusion We measured IOP and IORP simultaneously during orbital compression to gain basic information on pressure changes. In clinical cases, the change in the IOP could be conveniently and noninvasively monitored using continuous IORP measurements.