Changes in intraocular pressure after intraocular eye surgery——the influence of measuring technique

AIM: To investigate the changes in intraocular pressure(IOP) before and after intraocular surgery measured with Goldmann applanation tonometry(GAT) and pascal dynamic contour tonometry(PDCT), and assessed their agreement.METHODS: Patients who underwent trans pars plana vitrectomy(TPPV) with or without cataract extraction(CE) were included. The IOP was measured in both eyes with GAT and PDCT pre-and postoperatively, where the nonoperated eyes functioned as control.RESULTS: Preoperatively, mean IOP measurements were 16.3±6.0 mm Hg for GAT and 12.0±2.8 mm Hg for PDCT for the operated eyes. Postoperatively, the mean IOP dropped to 14.3±5.6 mm Hg for GAT(P=0.011) and rose up to 12.7±2.6 mm Hg for PDCT(P=0.257). Bland-Altman analysis showed a poor agreement between GAT and PDCT with a mean difference of 2.9 mm Hg preoperatively and 95% limits of agreement ranging from -3.2 to 9.0 mm Hg. Postoperatively, the mean difference was 1.2 mm Hg with 95% limits of agreement ranging from-8.3 to 10.7 mm Hg. There were no significant differences between the TPPV and TPPV+CE group, except when measured with PDCT postoperatively(P=0.012).CONCLUSION: The IOP is reduced after surgery when measured with GAT and remained stable when measured with PDCT. However, the agreement between GAT and PDCT is poor. Although PDCT may be a more accurate predictor of the true IOP, it seems less suitable for daily use in the clinical practice.