Factors related to filtration-bleb morphology after Ex-PRESS(®) surgery

PURPOSE: We investigated the factors influencing the morphology of filtration blebs after Ex-PRESS(®) surgery. We analyzed the thickness of the bleb wall and the height and the volume of blebs. METHODS: This was a retrospective non-randomized study. After excluding patients who had undergone an additional glaucoma surgery, we analyzed the cases of 145 consecutive patients (180 eyes) who underwent trabeculectomy with Ex-PRESS® for the first time at Toyama University Hospital and were followed for >1 year. We used anterior segment optical coherence tomography to analyze the morphology of the blebs after Ex-PRESS surgery. We also examined potential influencing factors including age, central corneal thickness, type of glaucoma (primary open-angle glaucoma [POAG] or pseudo-exfoliation glaucoma [PEXG]), preoperative intraocular pressure (IOP), postoperative IOP, history of trabeculotomy, and operation method: Ex-PRESS surgery only, or simultaneous cataract surgery. RESULTS: Ex-PRESS surgeries significantly decreased the IOP from 24.5 ± 8.8 mmHg to 11.1 ± 3.4 mmHg after 1 year (P < 0.001). The cases with higher blebs, larger volume of blebs, and thinner bleb wall had better surgical outcomes. CONCLUSION: Advanced age, higher postoperative IOP, PEXG, and simultaneous cataract surgeries were found to decrease the volume and height of blebs. Younger age, higher postoperative IOP, POAG, and simultaneous cataract surgeries were found to thicken the wall of blebs. Among the younger patients, there were many cases in which surgery was unsuccessful in spite the large volume of blebs. The reason for this may be that the wall of the bleb is thick.