The efficacy and safety of reducing intraocular pressure to single‐digit levels in Normal‐tension glaucoma: A systematic review and meta‐analysis

Purpose This systematic review and meta‐analysis aim to evaluate the efficacy and safety of further lowering intraocular pressure (IOP) to single‐digit levels in treated patients with progressive normal‐tension glaucoma (NTG). Methods A literature search was conducted in MEDLINE (via PubMed), Scopus and Web of Science. We selected studies that reported quantitative visual field (VF) data on the efficacy of the interventions. Study outcomes include VF progression rates, changes in IOP and IOP‐lowering medication use. Meta‐analysis was conducted for VF mean deviation (MD) slope (db/year) using R, with paired mean differences and 95% confidence intervals (CI) calculated. Results Nine observational studies, including 270 eyes, were analysed. Trabeculectomy was performed across all studies. One study compared trabeculectomy with prostaglandin analogues. On average, IOP decreased from 14.77 ± 0.95 mmHg preoperatively to 9.82 ± 1.55 mmHg postoperatively, reflecting a mean reduction of 33.65 ± 10.37%. This reduction slowed glaucoma progression, as indicated by a change in the mean VF MD slope from −0.91 ± 0.27 dB/year preoperatively to −0.25 ± 0.16 dB/year postoperatively. Meta‐analysis showed a significant change in VF MD slope following trabeculectomy, with a pooled mean difference of 0.59 dB/year (95% CI: 0.38 to 0.80; p < 0.0001). Single‐digit IOP levels were shown to be both achievable and sustainable. The most common postoperative complications included hypotony‐related complications and hyphema. Conclusions Achieving single‐digit IOP levels is associated with a significant reduction in visual field progression rates. However, the balance between efficacy and safety must be considered, as aggressive IOP reduction is also associated with a higher risk of hypotony‐related complications. Postoperative hypotony was relatively frequent but generally transient and did not appear to have a significant impact on long‐term visual acuity.