Risk factors for Ex-Press^® surgery failure

Purpose: To investigate the risk factors for Ex-Press^® (EXP) surgery failure. Patients and methods: This was a retrospective non-randomized study of 98 patients who had undergone EXP and were followed up ≥ 5 years. We investigated the following nine risk factors: age, gender, hypertension, diabetes mellitus (DM), previous glaucoma surgery, type of glaucoma (primary open-angle glaucoma vs. pseudo-exfoliation glaucoma), surgical methods (EXP alone vs. EXP + cataract surgery simultaneously), central corneal thickness (CCT), and preoperative intraocular pressure (IOP). We defined a successful surgery as a postoperative reduction in the IOP ≥ 20% from the preoperative IOP and ≤ 18 mmHg. We determined the risk factors using multivariate cox regression models. Results: Performing EXP significantly decreased the IOP (preoperative: 25.2 ± 8.7, at 5 years: 11.1 ± 4.1). The success ratio of EXP was 67.4% at 5 years. We found no significant risk factors for EXP surgery failure. The p values of the factors were age (p = 0.936), gender (p = 0.0587), hypertension (p = 0.409), DM (p = 0.967), previous glaucoma surgery (p = 0.940), type of glaucoma (p = 0.435) surgical methods (p = 0.521), CCT (p = 0.091), and preoperative IOP (p = 0.082). Conclusions: No preoperative factors that could be used to predict the failure of EXP surgery were identified. EXP can be safely performed for primary open-angle glaucoma and pseudo-exfoliation glaucoma.