Comment on the Paper by Mondzelewski and Colleagues: “Intraocular Pressure During Robotic-assisted Laparoscopic Procedures Utilizing Steep Trendelenburg Positioning.” J Glaucoma. 2015;24(6):399–404
We previously described that intraocular pressure (IOP) as detected by Icare Pro Tonometer (Icare, Finland) may increase after pneumoperitoneum during colorectal surgery.2 We also demonstrated that patients in Trendelenburg position showed an IOP trend after pneumoperitoneum induction that was slightly different from that of patients without Trendelenburg positioning, with the former showing a greater increase. Noteworthy, in some patients the IOP elevation persisted after surgery.2 Various studies in the literature reported significant increases in IOP in patients placed in combined head-down position and prone position, posing a major risk for perioperative visual loss. 2,3
We would like discuss some issues with the authors.
A critical point that needs to be addressed is demonstration of whether the transient IOP increase that occurs during pneumoperitoneum for laparoscopic surgery leads to persistent visual defects or disturbances. More in general the results of our and Dr Mondzelewski’s studies shed light on the potential damage caused by transient IOP changes that may occur after intravitreal injections of drugs in the management of age-related macular degeneration. It really depends on how long the IOP is elevated. It may also be that people with limited outflow facility experience a greater increase in IOP. It is unlikely that a 5-mm Hg increase for a few hours will impact the optic nerve per se (it rises by that amount every night when we sleep), but if combined with a reduced blood pressure may lead to insufficient optic nerve head perfusion. This may be further exacerbated by the relative changes in blood pressure and IOP with posture, as shown in the paper by Dr Mondzelewski. Preliminary data from our current prospective clinical study show that the peripapillary retinal nerve fiber layer thickness values before and after surgery are not statistically significantly different, as evaluated by Spectralis Heidelberg Optical Coherence tomography.
A second point of discussion is trying to understand why IOP increases during pneumoperitoneum: we are currently analyzing the results from a prospective clinical study to evaluate the dynamics of anterior segment structures by Visante Optical Coherence Tomography.
We want to stress the importance of a multidisciplinary collaboration between surgeons and ophthalmologists, both aware of the potentially blinding consequences following increases in the IOP during pneumoperitoneum in laparoscopic surgery.
Patients need to be informed about the opportunity of an ophthalmological examination after surgery. Further, as shown in our protocol, a single IOP measurement might not adequately approximate the IOP fluctuations, and efforts are made by the ophthalmological community toward a continuous 24-hour monitoring of IOP.