Preoperative Brimonidine on IOP of Patients Undergoing RALP

Plain-language summary

Patients with prostate cancer undergoing robot assisted radical laparoscopic prostatectomy (RALP) in steep Trendelenburg position (sTBURG) are noted to have elevated intraocular pressures (IOP) intraoperatively. One study showed an increase in IOP of 13 millimeters of mercury (mmHg) from baseline IOP levels intraoperatively. Other studies have shown the IOP to more than double intraoperatively during RALP in sTBURG. IOP is found to be directly related to angle of inclination and increases time dependently with sTBURG. The IOP may remain significantly elevated until the first postoperative day after RALP. There are no previously published data concerning the safe threshold for IOP elevation and the effects of this increased IOP on vision and on generalized eye health are still not entirely known. One study showed postoperative visual field defects in 28% (7/25) of patients who underwent RALP in sTBURG. It has been theorized that sTBURG and subsequent increased IOP are risk factors for postoperative vision loss (PVL). It is believed that the increased IOP decreases optic nerve perfusion pressure causing ischemic optic neuropathy. Some previously recommended ways to reduce the intraoperative IOP spike during RALP include shorter operating times, decreased angle of inclination, modified Trendelenburg position, use of Propofol for maintenance anaesthesia and intraoperative topical hypotensive agents to reduce IOP. Given the challenges with some of the above options, this study aims to evaluate the effect of pre-operative treatment with topical Brimonidine Tartrate 0.2% on the IOP of patients undergoing RALP with sTBURG. The goal is to prevent the anticipated IOP spike thereby reducing risk of postoperative vision loss.

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