Long-term Visual Field Outcomes after Glaucoma Drainage Device Implantation

Abstract

Purpose : To measure visual field (VF) rates of change after Glaucoma Drainage Device (GDD) implantation and to investigate risk factors for postoperative perimetric progression

Methods : Retrospective, longitudinal cohort study. Patients who underwent GDD implantation with ≥ 4 eligible postoperative VFs and 2 years of follow-up were included. Baseline, intraoperative and postoperative data were collected. VF progression was explored with three methods: Mean Deviation (MD) rate, Glaucoma Rate Index (GRI) and Pointwise Linear Regression (PLR). For a subset of eyes with sufficient preoperative and postoperative VFs, rates were compared between each period. A multivariate analysis was conducted to explore risk factors for postoperative VF progression

Results : 183 eyes were included. The intraocular pressure (IOP) and number of glaucoma medications were significantly reduced from (median, IQR) 23.0(12.0) mmHg at baseline to 12.7(4.1) mmHg at final follow-up and from (mean ± SD) 3.3±1.2 to 2.2±1.4, respectively. Thirty-eight eyes (21%) showed VF progression and 109 eyes (60%) were stable by all three methods, which accounted for 80% of all eyes. The rate of VF decline (median, IQR) by MD and GRI was -0.29(0.6) dB/year and -2.21(10.5) (on a scale of 0 to -100), respectively. Fifty-four eyes (29%) showed progression by PLR. When comparing progression before and after surgery, the reduction was not statistically significant with any of the methods. The peak IOP (after three postoperative months) was associated with VF deterioration, with a 7% increase in risk per each additional mmHg

Conclusions : To our knowledge, this is the largest published series reporting long-term VF outcomes after GDD implantation. There is a continued, significant rate of VF decline after GDD surgery

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

Visual field progression after GDD implantation by different methods (N = 183).
*MD progression: MD slope ≤ -0.5, dB/y
† GRI progression: GRI < -6.0 (out of 100)
§ PLR progression: at least three locations had significant slope (p < 0.01) of ≤ -1 dB/y

 

Summary of univariate and multivariate analysis of postoperative IOP variables for VF progression and mean (± SD) for each variable in eyes judged as progressing and not progressing by all three methods (N = 147 eyes).
*HP = presenting at least one IOP > 21 mmHg within the first 3 months of follow-up
† Median (IQR)
‡ Variables with P values ≥ 0.2 in the univariate regression
§ Variables not selected for the multivariate model