Comparison of surgically induced astigmatism following PreserFlo MicroShunt implantation versus trabeculectomy in Japanese patients with glaucoma

PURPOSE: We compared the magnitude of surgically induced astigmatism (SIA) following PreserFlo MicroShunt (PMS) implantation versus conventional trabeculectomy (Trab), with both procedures being performed with mitomycin C (MMC). STUDY DESIGN: Retrospective cohort study METHODS: We included 113 eyes of 113 patients who underwent standalone PMS surgery and 78 eyes of 78 patients who underwent standalone Trab, all with no previous history of glaucoma surgery. Corneal astigmatism was measured preoperatively and at 3 months postoperatively by use of an automated keratometer. The mean SIA (M-SIA) and centroid SIA (C-SIA) were calculated by use of a dedicated vector analysis tool. Preoperative and postoperative intraocular pressure (IOP) and visual acuity (VA) were compared by use of paired t tests. The Mann-Whitney U test was used to compare the M-SIA between the groups. RESULTS: Postoperatively, the IOP decreased from 20.9 to 11.5 mm Hg in the PMS group and from 20.6 to 9.3 mm Hg in the Trab group (P <0.001 for both). The C-SIA demonstrated an astigmatic shift toward the site of tube insertion in the PMS group and toward the scleral flap location in the Trab group. The M-SIA was significantly lower in the eyes treated with PMS than in those treated with Trab in the superonasal quadrant, but not in the superotemporal site. The VA remained stable in the PMS group, whereas a significant decline was observed in the Trab group. CONCLUSIONS: The PMS is an effective surgical option for reducing IOP while minimizing SIA at 3 months postoperatively. By better preserving visual function, the PMS may contribute to improved vision and overall patient satisfaction with the surgical outcomes.