Comparison between Surgical Techniques Used for Revision of the Filter Bleb: A Randomized Controlled Clinical Trial

Abstract

Introduction/purpose: The aim of this study was to compare two surgical revision techniques in failed trabeculectomies after 6 months.

Methods: Patients diagnosed with open-angle glaucoma who underwent trabeculectomy in at least one eye with uncontrolled intraocular pressure (IOP) after trabeculectomy performed at least 6 months before were enrolled in this prospective trial. All participants underwent a complete ophthalmological examination at baseline. Randomization was performed to one eye per patient to double-masked trabeculectomy revision or needling. Patients were examined on the first day, 7 days, 14 days, and then monthly until completing 1 year after surgical intervention. All follow-up visits included the following: patients reported ocular and systemic events, best-corrected visual acuity, IOP, slit-lamp examination, and optic disc evaluation for cup-to-disc ratio. Gonioscopy and stereoscopic optic disc photographs were taken at baseline and 12 months. After 1-year, the IOP and number of medications were compared between the groups. Absolute success criteria in the study were IOP <16 mm Hg, for 2 consecutive measurements without using a hypotensive medication.

Results: Forty patients were included in this study. Among them, 38 completed 1-year follow-up (18 in revision group and 20 in needling group). The age ranged from 21 to 86 years, with a mean of 66.82 ± 13.44. At baseline, the average IOP was 21.64 ± 5.12 mm Hg (range from 14 to 38 mm Hg) in the entire group. All patients were using at least two classes of hypotensive eye drops, and 3 patients were using oral acetazolamide. The mean use of hypotensive eye drop medications was 3.11 ± 0.67 at the baseline for the entire group. In the present study, 58% of the patients presented complete success, 18% qualified success, and 24% failed in both groups. After 1-year treatment, both techniques were similar for IOP parameters and also for number of medications (p = 0.834 and p = 0.433, respectively). Regarding intra- or postoperative complications, one patient in each group needed a new surgical intervention, one in the needling group due to shallow anterior chamber and one in the revision group due to spontaneous Seidel sign, and one patient in the needling group underwent posterior revision due to fail.

Conclusions: Both techniques were safe and effective for IOP control after 1 year of follow-up in patients who underwent to trabeculectomy more than 6 months before.

Keywords: Filtering bleb; Glaucoma; Needling; Revision; Surgery; Trabeculectomy.