PRESERFLO MicroShunt implantation versus trabeculectomy for primary open-angle glaucoma: a two-year follow-up study

Background: To compare the intermediate-term efficacy of PRESERFLO (PF) MicroShunt implantation with trabeculectomy (TE) in patients with primary open-angle glaucoma, focusing on longitudinal changes of functional and structural parameters.Methods: This retrospective comparative study included 104 eyes of 104 patients who underwent TE and 83 eyes of 83 patients that underwent PF implantation between January 2019 and December 2020, with a minimum follow-up of two years. Baseline and postoperative intraocular pressure (IOP), number of IOP-lowering medications, visual field mean defect (MD) and peripapillary retinal nerve fibre layer (RNFL) thickness measured using optical coherence tomography were assessed and compared between groups.Results: Baseline characteristics (age, sex, IOP, number of IOP-lowering medications, MD, RNFL thickness) were comparable between the two groups (all P > 0.05). During the two-year of follow-up, mean IOP decreased from 24.09 +/- 1.15 mmHg and 21.67 +/- 0.77 mmHg to 11.37 +/- 1.13 mmHg (P < 0.001) and 15.50 +/- 1.54 mmHg (P = 0.028), and the mean number of IOP-lowering medications decreased from 3.25 +/- 0.14 and 3.51 +/- 0.14 to 0.53 +/- 0.14 (P < 0.001) and 1.06 +/- 0.43 (P < 0.001) in the TE and PF groups, respectively. MD remained stable [- 11.54 +/- 0.93 dB and - 11.17 +/- 1.66 to - 10.67 +/- 0.91 dB (P = 0.226) and - 10.40 +/- 4.75 dB (P = 0.628) in the TE and PF groups, respectively] but RNFL thickness decreased continuously during follow-up [62.79 +/- 1.94 <mu>m and 62.62 +/- 2.05 mu m to 57.41 +/- 1.81 mu m (P < 0.001) and 60.22 +/- 1.98 <mu>m (P = 0.182) in the TE and PF groups, respectively].Conclusion: PF implantation is comparably effective in the intermediate term in lowering IOP and reducing the use of IOP-lowering medications over a two-year follow-up period. Although visual field defects were stable, RNFL continued to decrease during postoperative follow-up.