Effectiveness of Single-Digit IOP Targets on Decreasing Global and Localized Visual Field Progression After Filtration Surgery in Eyes With Progressive Normal-Tension Glaucoma

Purpose: To examine the effectiveness of achieving single-digit intraocular pressure (IOP) targets with filtration surgery on decreasing global and localized visual field (VF) progression in eyes with progressive normal-tension glaucoma (NTG). Methods: A retrospective chart review was conducted to identify NTG patients who underwent trabeculectomy with mitomycin C between 2006 and 2010 for progressive VF loss with preoperative IOP <= 15mm Hg during the 12 months before surgery. All eyes had glaucomatous optic neuropathy and progressive VF loss, uncontrolled IOP on maximum therapy, and a minimum of 2 baseline preoperative and 4 postoperative VF examinations. VF progression was assessed using Guided Progression Analysis (GPA) and Progressor software. Results: Fifteen eyes of 14 patients (mean age 71.8 +/- 7.5 y) were enrolled with mean follow-up of 71 +/- 26 months. Mean postoperative IOP (8.5 +/- 3.5 mm Hg) was significantly (P < 0.001) reduced compared with preoperatively (13.1 +/- 1.5 mm Hg). The probability of achieving an IOP goal <= 10 mm Hg was 66% at 4 years' follow-up. The overall rate of postoperative VF progression using any method was 13.3% (1 eye using Progressor; 1 eye using GPA and Progressor). Average postoperative slope of MD (-0.25 +/- 0.86 dB/y) and pattern SD (0.49 +/- 0.83 dB/y) were improved (P = 0.05 and 0.07) compared with the preoperative slopes (-1.05 +/- 0.66 and 1.21 +/- 0.71 dB/y). Conclusions: Achieving single-digit IOP targets with filtration surgery has a beneficial effect on reducing global and localized rates of VF progression in NTG eyes with progression at low IOP.