Ex-PRESS® surgery versus trabeculectomy for primary open-angle glaucoma with low preoperative intraocular pressure

To compare surgical outcomes between Ex-PRESS® surgery (EXP) and trabeculectomy (Trab) for primary open-angle glaucoma (POAG) with low preoperative intraocular pressure (IOP).This was a retrospective non-randomized study. We included POAG patients with preoperative IOP ≤ 16 mmHg who were taking tolerance glaucoma medications. We compared the surgical outcomes, postoperative IOP, number of glaucoma medications, reduction rate of corneal endothelial cell density (ECD), visual acuity, and postoperative complications between POAG patients who underwent EXP (34 eyes) or Trab (38 eyes) and could be followed up for 2 years.Both surgeries significantly decreased the IOP (p 0.001): At 2 years, EXP provided decreases from 13.4 ± 2.3 to 10.2 ± 3.1 mmHg, and Trab provided decreases from 13.5 ± 2.0 to 8.9 ± 3.2 mmHg. No significant differences were observed in the postoperative IOP (p = 0.076), number of postoperative medications (p = 0.263), success rate (p = 0.900), reduction rate of ECD (p = 0.410), or difference in visual acuity (p = 0.174). The reduction rate of IOP was significantly high in the Trab group (p = 0.047).Both surgeries significantly decreased IOP and were useful surgical methods for low-IOP glaucoma. Our results suggest that trabeculectomy can decrease IOP more than Ex-PRESS surgery but might have more complications.