Contributing factors for intraocular pressure control in patients with mostly normal-tension glaucoma after initial Ex-PRESS drainage device implantation

Purpose To investigate the postoperative intraocular pressure (IOP) control and identify the factors associated with failure of initial Ex-PRESS surgery in patients with open-angle glaucoma for 3 years. Methods A total of 79 patients with medically uncontrolled open-angle glaucoma (55 normal-tension glaucoma and 24 primary open-angle glaucoma) were enrolled. All patients underwent Ex-PRESS implantation (including combined cataract surgery). The outcome measure was the survival rate using life table analysis, the failure was defined as IOP of > 18 mmHg (criterion A), > 15 mmHg (criterion B) or > 12 mmHg (criterion C) and/or IOP reduction of < 20% from baseline (each criterion) without any glaucoma medications. The Cox proportional hazards model was used to identify risk factors for IOP management defined as the above criterion. Results The mean preoperative IOP was 19.3 ± 5.8 mmHg. At 36 months, the mean IOP was 11.8 ± 3.6 mmHg with a mean IOP change of 7.5 mmHg (reduction rate 39.0%). The cumulative probability of success was 58% (95%CI: 42–64%) (criterion A), 48% (95%CI: 37–59%) (criterion B) and 30% (95%CI: 20–40%) (criterion C). In multivariate analyses, factors that predicted poor IOP control included the intervention of bleb needling after 6 months after the surgery (HR: 2.43; 95%CI: 1.35–4.37; P = 0.032). Transient hypotony was observed in 4 patients. Conclusion The implementation of bleb needling after Ex-PRESS surgery in the late postoperative period was suggested to be the main risk factor for achieving lower IOP.