Intraocular Pressure Fluctuation as Assessed by Water Drinking Test Following iStent inject Implantation in Open Angle Glaucoma Patients.

Introduction This study investigated the intraocular pressure (IOP) fluctuation as assessed by the water drinking test (WDT) in open-angle glaucoma (OAG) patients after combined cataract surgery with iStent implantation. Methods This was a prospective non-randomized comparative study. Eyes with OAG and cataracts that were planned for either combined phacoemulsification and iStent implantation (iStent+CS) or phacoemulsification alone (CS) were recruited. The iStent inject (Model G2-M-IS) or iStent injectW (Model G2-W) trabecular micro-bypass stent (Glaukos Corporation, San Clemente, CA, USA) was implanted in the iStent+CS group. Water drinking test (WDT) was performed before and 3 months after surgery. WDT-IOP parameters including peak IOP, IOP fluctuation, and area under curve (AUC) were compared between the two groups. Results There were 20 eyes in the iStent+CS group and 16 eyes in the CS group. Both groups had similar pre-operative baseline IOP (15.6 ± 3.7 mmHg vs 15.8 ± 1.8 mmHg in the iStent+CS and CS group, respectively, p = 0.883). The iStent+CS group experienced greater numerical reduction in peak IOP (2.6 ± 1.9 mmHg vs 1.9 ± 2.4 mmHg; p = 0.355), IOP fluctuation (1.7 ± 2.2 mmHg vs 0.8 ± 2.5 mmHg; p = 0.289), and AUC (54.8 ± 103.6 mmHg x minute vs 25.3 ± 79.0 mmHg x minute; p = 0.355) than the CS group. There was more reduction in the number of anti-glaucoma medications in the iStent+CS group (1.4 ± 1.2) than the CS group (0.3 ± 0.9; p = 0.005). Conclusion Both combined phacoemulsification with iStent inject implantation and phacoemulsification alone reduced peak IOP, IOP fluctuation, and AUC, and none of these parameters showed statistically significant difference. Greater reduction in anti-glaucoma medications was seen in the combined group.