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Scott Schultz, Shawn Iverson, Wei Shi, Joyce Schiffman, David Greenfield; Long Term Outcomes of Filtration Surgery for Normal-Tension Glaucoma with Visual Field Progression at Low Intraocular Pressure. Invest. Ophthalmol. Vis. Sci. 2013;54(15):4762. doi: https://doi.org/.
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The purpose of this study was to examine the long-term outcome of glaucoma filtration surgery for progressive normal-tension glaucoma (NTG) at low intraocular pressure (IOP).
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 visual field (VF) loss with preoperative intraocular pressure ≤ 15 mmHg during the 12-month period prior to surgery. All eyes had evidence of glaucomatous optic neuropathy and progressive VF loss, uncontrolled IOP on maximum medical therapy, and minimum postoperative follow-up of 12 months. Exclusion criteria consisted of age ≤ 18, recorded IOP > 22 mmHg, ocular disease other than glaucoma, or prior incisional surgery except uncomplicated cataract extraction. Failure was defined as IOP reduction < 20% below baseline (criteria 1), <30% (criteria 2), or <40% (criteria 3) on two consecutive follow-up visits after 3 months, reoperation for glaucoma, or loss of light perception, and was assessed using Kaplan-Meier survival analyses.
Thirty eyes of 28 patients (mean age 73 ± 8.7 years) were enrolled with a mean follow-up period of 50 ± 31 mos. Mean postoperative IOP (8.3 ± 3.2 mmHg) and number of medications (0.6 ± 1.00) at final follow-up was significantly (p<0.001) reduced compared to prior to surgery (13.2 ± 1.4 mmHg and 2.5 ± 1.2, respectively). The cumulative probability of failure during 5 years of follow-up was 35% (criteria 1), 46%, (criteria 2), and 65% (criteria 3). Hypotony (IOP ≤ 5 mmHg on two consecutive follow-up visits after 3 months) was observed in 10 eyes. One eye developed clinical evidence of chorioretinal folds in the macula. Mean change in logMAR visual acuity in eyes (n=10) with hypotony (-0.14±0.18), was not significantly different (p=0.37) than eyes (n=20) without hypotony (-0.04±0.28). Other complications included CME (3), bleb leakage (2), endophthalmitis (1), blebitis (1), corneal edema (1), and choroidal effusion (1).
Trabeculectomy with MMC is an effective method for achieving long-term IOP reduction of 20-40% in NTG eyes with progression at low IOP. Hypotony is a common postoperative occurrence but did not result in a significantly greater degree of vision loss compared to the patients without hypotony in this series.
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