Purpose: To determine the change in global and regional Humphrey visual fields (VF) after glaucoma drainage device (GDD) implantation over a 3-year follow-up period. Design: Retrospective interventional case series. Methods: Patients undergoing GDD placement from between 2010 and 2015 with reliable preoperative and yearly postoperative VF measurements were included. Clinical parameters were compared between preoperative and follow-up visits, including visual acuity, intraocular pressure (IOP), number of glaucoma medications, global VF metrics (mean deviation [MD]), pattern standard deviation (PSD), CIGTS (Collaborative Initial Glaucoma Treatment Study) score of total deviation probability (CIGTS_TDP) and pattern deviation probability (CIGTS_PDP), and regional metrics (regional total deviation (TD), regional pattern deviation (PD), and regional CIGTS_TDP and CIGTS_PDP). Multivariate regression analyses were performed to determine risk factors for VF worsening after GDD surgery. Results: A total of 106 eyes from 95 patients were included. Mean IOP ± SD was reduced from 23.1 ± 8.5 mm Hg to 12.7 ± 3.1 mm Hg at 3-year follow-up (P < .001). MD, PSD, and global CIGTS_PDP showed no significant changes in follow-up, whereas global CIGTS_TDP showed mild progression from 10.7 to 12.8 at 3-year follow-up (P = .01). No regional metrics showed worsening at follow-up examinations. Defects in the superior hemifield were more common than in the inferior hemifield at baseline and follow-up examinations for all regional metrics. Pre-operative number of glaucoma medications was associated with worsening on CIGTS_TDP. Conclusions: Overall, GDD surgery is effective at stabilizing VF function over 3 years of follow-up. The superior hemifield is affected more than other regions. The number of pre-operative glaucoma medications is associated with mild VF progression, measured by CIGTS_TDP. © 2020