Comparison of 3 different releasable suture techniques in trabeculectomy

Abstract

Purpose: The use of releasable sutures provides an effective and simple way of titrating intraocular pressure (IOP) postoperatively. The purpose of this study was to compare the surgical outcome of 3 releasable suture techniques for closing scleral flaps in patients undergoing primary trabeculectomy.

Methods: The Wills Eye Glaucoma Research Center retrospectively reviewed the charts of patients who underwent primary trabeculectomy by 3 surgeons using 3 different releasable suture techniques. Ninety eyes of 90 glaucoma patients were divided into 3 groups by releasable suture technique (n = 30 eyes for each group). Main outcome measures included best-corrected visual acuity (BCVA), intraocular pressure (IOP), rate of surgical success, use of supplemental medical therapy, need for additional glaucoma surgery, and complications during suture removal.

Results: The BCVA and IOP were similar among the groups for all follow-up visits. As a determinant of success rate of trabeculectomy, mean decrease of IOP after surgery was over 30% in all groups (p = 0.43). The number of postoperative antiglaucomatous medications, number of complications, and need for an additional glaucoma surgery were similar in all groups (p = 0.40, p = 0.87, and p = 0.47, respectively). The differences in suture-related complications, defined as suture break or need for laser suture lysis, were not significant among the groups (p = 0.09).

Conclusions: We found that the 3 most common surgical techniques had similar mechanisms of action. All techniques were safe and effective, yielding similar outcomes. All 3 techniques can be used for closing scleral flaps in patients undergoing primary trabeculectomy.

Introduction

Glaucoma is a chronic optic neuropathy resulting in visual field defects and progressive vision loss. Intraocular pressure (IOP) is a major risk factor for glaucoma, and lowering IOP remains the mainstay of glaucoma treatment. Trabeculectomy is an effective treatment tool safely achieving low IOP. However, a serious problem with trabeculectomy can be excessive overfiltration with subsequent anterior chamber shallowing, choroidal effusion, suprachoroidal hemorrhage, aqueous misdirection, and hypotony maculopathy. To prevent these complications, releasable suture techniques have been employed. The use of releasable scleral flap sutures provides an effective and simple way of titrating IOP postoperatively, allowing the surgeon to close the scleral flap relatively tightly and then adjust filtration at the slit lamp during early postoperative care.

Methods

Patient selection: The charts of patients who underwent primary trabeculectomy with releasable sutures by one of three surgeons at Wills Eye Hospital from January 2008 through May 2011 were retrospectively reviewed. Ninety eyes (30 per technique) were randomly selected. Patients with prior glaucoma surgery were excluded.

Data collection: Demographics, glaucoma type, preoperative IOP, BCVA, visual field mean deviation, number of medications, intra- and postoperative complications, timing and effects of suture removal, and need for additional procedures were recorded. Success was defined as an IOP reduction ≥30% from baseline at last visit, adjusted for glaucoma stage as clinically appropriate.

Surgical techniques (brief)

Technique 1 (L.J.K.) — Fornix-based conjunctival flap, mitomycin C (0.4 mg/mL) applied, partial-thickness rectangular scleral flap, Kelly punch trabeculectomy, 2 permanent corner sutures, and a single L-shaped corneal releasable suture externalized under the corneal epithelium and trimmed so its end lay below the corneal surface. Additional releasable sutures could be placed as needed.

Technique 2 (M.R.M.) — Fornix-based flap, mitomycin C applied via sponges or injected mixture, partial-thickness rectangular flap, iridectomy, interrupted sutures at flap corners. Releasable suture passed cornea → intact sclera → scleral flap → backhand to clear cornea and tied on corneal surface; one or more releasable sutures placed as needed.

Technique 3 (G.L.S.) — Limbus-based conjunctival flap, brief mitomycin C application, partial-thickness scleral flap, sclera-to-clear-cornea releasable suture with cornea-to-cornea passage and burying of the cut end on scleral side; conjunctiva closed in two layers.

Postoperative care: Topical antibiotics for 1 week and topical steroids (± NSAID) tapered over 4–8 weeks. After suture removal a topical antibiotic drop was given.

Statistics: Continuous variables described by means ± SD; comparisons by ANOVA or Kruskal–Wallis. Categorical variables by χ2 or exact tests. Mixed-effects models handled repeated measures for IOP and logMAR VA. Statistical significance at p < 0.05.

Results

Demographic and baseline clinical characteristics were similar across groups, with small differences: group 2 had somewhat lower mean age and more African American patients (see Table I in the original article). Mean follow-up was ~24 months. Preoperative diagnoses were predominantly primary open-angle glaucoma; mean baseline IOPs were similar between groups (≈25–28 mmHg).

Sutures and antimetabolite use: Technique 3 used more releasable and fewer nonreleasable sutures. Antimetabolites (mitomycin C) were used in all surgeries for techniques 1 and 2, and in 77% of technique 3 cases.

Timing and effect of suture removal: In technique 1, ~30% of releasable sutures were not removed; among removed sutures most were removed after the 3rd week. In technique 2, all releasable sutures were removed (90% within first 3 weeks). In technique 3, 37% were not removed and the remainder were removed mostly within 3 weeks. Pre- vs post-removal IOP decreased significantly after removal; the magnitude varied by technique (see Table II).

Outcomes: Mean IOP reduction exceeded 30% in all groups. Surgical success rates (IOP reduction ≥30%) were: technique 1 = 63.3%, technique 2 = 83.3%, technique 3 = 70.0% (p = 0.21). Numbers of postoperative antiglaucoma medications, complications, and need for additional glaucoma surgery were similar among groups (p-values 0.40, 0.87, 0.47 respectively).

Complications: Postoperative complications (shallow AC, choroidal effusion, hyphema, vitreous loss in one patient) were uncommon and similar across the three groups. Suture-related complications (suture break or need for laser suture lysis) were rare and not significantly different between groups (p = 0.09). No suture-related corneal abscesses or endophthalmitis were reported.

Visual acuity: BCVA did not differ significantly between groups across follow-up visits; BCVA at last visit correlated with preoperative BCVA. One patient underwent cataract surgery during follow-up.

Discussion

Releasable sutures in trabeculectomy enable titration of filtration postoperatively, aiming to reduce early hypotony while allowing staged increase of filtration as needed. Laser suture lysis is an alternative but can carry conjunctival or leakage complications; releasable sutures avoid these issues and do not require extra instrumentation.

In this comparative study, the three commonly used releasable suture techniques produced similar outcomes in terms of IOP lowering, BCVA, complication rates, and need for additional surgery. Timing of suture removal varied by technique and surgeon preference; most removals occurred within the first 3 postoperative weeks. No serious suture-related infectious complications were observed, suggesting that leaving some releasable sutures in place (with epithelialization) may be acceptable in selected cases.

Limitations include the retrospective design, modest sample size, and variations in antimetabolite application between surgeons that could confound results. Nonetheless, findings support that the choice among these releasable suture methods may be made on the basis of surgeon preference and experience.

Conclusions

All three releasable suture techniques studied are safe and effective for controlling postoperative IOP after primary trabeculectomy. Outcomes and complication rates were comparable, and releasable sutures remain a useful method for early postoperative IOP titration.