Predictors of intraocular pressure change after phacoemulsification in patients with pseudoexfoliation syndrome.

Abstract

To evaluate anterior chamber biometric factors and intraoperative metrics associated with the intraocular pressure (IOP) reduction after phacoemulsification in non-glaucomatous pseudoexfoliative syndrome (PXS) eyes. Thirty-three patients were enrolled in this prospective interventional study. Images were excluded if they had poor quality, poor perpendicularity or inability to locate sclera spurs. Anterior chamber depth (ACD), anterior chamber area (ACA), iris thickness, iris area, iris curvature, lens vault, angle opening distance (AOD500, AOD750) and trabecular iris space area (TISA500, TISA750) were measured in qualified images using the Zhongshan Angle Assessment Program and compared preoperatively and 3 months postoperatively. Cumulative dissipated energy (CDE), aspiration time and infusion fluid usage during cataract surgery were obtained from the phacoemulsification machine's metrics record. Postoperative IOP change was compared with these anatomical and intraoperative metric parameters. Mean IOP was 18.1±3.4 mm Hg preoperatively and decreased by 3.3 mm Hg (18%) to 14.8±3.6 mm Hg at 3 months postoperatively (p<0.001). All angle parameters, ACD and ACA increased significantly postoperatively (p<0.001 for all) and iris curvature decreased (p<0.001). In univariate analysis, preoperative IOP (B=-0.668, p=0.002), infusion fluid usage (B=-0.040, p=0.04) and aspiration time (B=-0.045, p=0.003) were negatively associated with IOP decrease after phacoemulsification. Changes in IOP did not demonstrate significant associations with CDE measurements or anterior segment optical coherence tomography measurements, including preoperative angle, iris or anterior segment parameters. In the final multivariate regression model, preoperative IOP (B=-0.668, p=0.002) and infusion fluid usage (B=-0.041, p=0.04) were significantly associated with IOP drop and together can predict 45.1% (p=0.002) of the variability in IOP change. Non-glaucomatous patients with PXS experience moderate IOP reduction following phacoemulsification, and this effect is correlated with preoperative IOP, aspiration time and infusion fluid used intraoperatively.