Comparison of temporal versus nasal positioning of iStent Inject W®

PURPOSE: The goal of the present study was to compare the effect of nasal versus temporal placement of the iStent Inject W® during phacoemulsification on intraocular pressure (IOP). DESIGN AND PARTICIPANTS: Over 5 consecutive years, 389 eyes of 244 patients undergoing phacoemulsification with 2 iStent Inject W® injections in a tertiary referral center were included retrospectively. In 50.6% of eyes, 2 iStent Inject W® were injected in the inferior nasal region of right eyes, while 49.4% received injections in the inferior temporal region of left eyes. MAIN OUTCOME MEASURES: The main parameters were IOP and the number glaucoma medications. RESULTS: One month after surgery, there was no significant difference in the mean (SD) change in IOP between right eyes injected nasally [-1.2 (6.7) mmHg] and left eyes injected temporally [-1.2 (6.7) mmHg; P=0.71] and no significant difference in the mean (SD) change in the number of glaucoma medications for the right eyes injected nasally [-0.4 (1.3)] and left eyes injected temporally [-0.5 (1.3); P=0.67]. There was also no significant difference at 6 months or 12 months. Subgroup analysis in patients who underwent surgery in both eyes found no significant difference in IOP or change in glaucoma medications at 1, 6, or 12 months. The complication rate was low. CONCLUSION: The efficacy of the iStent Inject W® is not dependent on its area of implantation. From these results, we propose that iStent Inject W® can be injected either temporally or nasally based on the surgeon's preferences. This has significant implications for simplifying and speeding up the procedure and might result in improved surgical outcomes for the patient.