Abstract
Purpose:
To examine the effectiveness of achieving single digit intraocular pressure (IOP) targets with glaucoma 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 that underwent trabeculectomy with mitomycin C (MMC) between February 2006 and October 2010 for progressive VF loss with preoperative IOP ≤ 15 mmHg during the 12-months prior to surgery. All eyes had evidence of glaucomatous optic neuropathy and progressive VF loss, uncontrolled IOP on maximum medical therapy, and a minimum of 2 baseline preoperative and 4 postoperative VF examinations. Exclusion criteria consisted of age ≤ 18, recorded IOP > 22 mmHg, ocular disease other than glaucoma, prior incisional surgery except uncomplicated cataract extraction, and unreliable (>15% fixation loss or > 33% false positives or false negatives) VFs. VF progression was assessed using Guided Progression Analysis™ (GPA) and Progressor™ software (defined as ≥ 2 adjacent test locations losing ≥ 1.0 dB/year at p ≤ 0.01 for inner locations or ≥ 2.0 dB/year at p ≤ 0.01 for edge locations).
Results:
Fifteen eyes of 14 patients (mean age 71.8 ± 7.5 years) were enrolled with mean follow-up of 71 ± 26 months. Mean postoperative IOP (8.5 ± 3.5 mmHg) and number of medications (0.80 ± 1.32) were significantly (p<0.001) reduced compared to prior to surgery (13.1 ± 1.5 mmHg, 2.5 ± 1.3 respectively). The mean number of VF examinations was 8.21 ± 5.11 preoperatively and 6.73 ± 3.49 postoperatively. The overall number of eyes judged to have postoperative VF progression using any method was 2 of 15 (13.3%) eyes (1 eye using Progressor™ analysis; 1 eye using both GPA™ and Progressor™). Average postoperative slope of mean deviation (-0.20 ± 0.68 dB/year) and pattern standard deviation (0.13 ± 0.29dB/year) were improved (P=0.07 and 0.08) compared to the preoperative slopes (-0.76 ± 0.76 and 0.59 ± 0.56 dB/year).
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.
Keywords: 568 intraocular pressure •
758 visual fields •
462 clinical (human) or epidemiologic studies: outcomes/complications