Surgical technique for excisional bleb revision using a rotational conjunctival flap for a large conjunctival defect.

Bleb dysesthesia is a common but under recognized late complication of trabeculectomy, sometimes requiring surgical revision if conservative measures fail. We describe in detail a surgical technique for closure of a large conjunctival defect following bleb excision for refractory dysesthesia. Two subconjunctival 5-fluorouracil injections were given to improve bleb function. Eight months post-operatively, the intraocular pressure is well controlled on two agents, and the patient has had resolution of dysesthesia.

INTRODUCTION

Initial management of bleb dysesthesia involves the use of lubrication.1 If medical management fails, sutureless excision of overhanging blebs,2 neodymium:YAG laser to the bleb surface,3 and external compression sutures have been used.4 Various methods for conjunctival closure have been used should bleb excision be required, including direct closure and free graft.15 A large conjunctival defect or glaucoma surgery in the fellow eye precludes the use of these methods, as does the need to preserve conjunctiva for future glaucoma surgery. We describe the use of a rotational conjunctival flap in the closure of a large defect following bleb excision.

CASE REPORT

A 68-year-old white male who had undergone a limbus-based trabeculectomy with an anti-fibrotic 12 years prior in the left eye presented to our institution complaining of persistent, disabling bleb dysesthesia despite frequent lubrication. He had also previously experienced intermittent bleb leaks. Examination revealed an avascular bleb superonasally [Figure 1a], with a well-controlled intraocular pressure (IOP) in the mid-to upper single digits. He elected to undergo bleb revision to alleviate pain.

Figure 1

(a) This pre-operative photograph demonstrates a large avascular bleb superonasally in the patient’s left eye, (b) This photograph taken 8 months post-operatively demonstrates a thick-walled diffuse bleb superonasally

Anesthesia was achieved via retrobulbar block. The Vannas scissors were used to make a conjunctival incision demarcating the bleb. Subconjunctival preservative-free lidocaine was infused on a cannula to aid tissue dissection. The Vannas scissors were then used to excise the bleb, which measured 3 mm in its largest anteroposterior dimension. Hemostasis was achieved with wet-field eraser-tip cautery. Minimal leakage of the aqueous through the old scleral flap with well-maintained anterior chamber was noted, obviating the need to add tectonic support. A decision was made to close the conjunctival defect alone.

Due to the previous conjunctival incision for a limbus-based trabeculectomy, the remaining conjunctiva retracted, leaving a large conjunctival defect measuring 8 mm by 8 mm [Figure 2a]. Blunt dissection of the surrounding conjunctiva was performed using a Westcott scissors but still did not allow for direct wound closure. An alternative surgical technique, a rotational conjunctival flap, was then employed. In brief, the limbal side of the large conjunctival defect was measured by a caliper distance between points A and B, Figure 3a). An equal-sized limbal peritomy was created (distance between points B and C = distance between points A and B, Figure 3a). Figure 2b demonstrates intraoperative conjunctival peritomy and dissection. A relaxing incision (distance between points C and D) was created to facilitate the extension of the conjunctival flap for the closure. The prepared conjunctival flap was then rotated to cover the large defect [Figure 3b]. Figure 3c demonstrates the resultant closure. The proximal edge of the flap (point A) was sutured to the nasal aspect of the conjunctiva remaining after excision of the bleb (point B) and the resulting linear tangential defect closed in a running fashion using 9-0 polyglactin. The flap was secured at the 12 o’clock limbus using 9-0 polyglactin, and the temporal linear defect was also sutured in a running fashion. Two horizontal mattress sutures of 9-0 polyglactin were placed through the conjunctiva at the limbus to prevent corneal migration of the conjunctival edge. The wounds were watertight at the end of the case.

Figure 2

(a) This intraoperative photograph demonstrates an 8 mm by 8 mm conjunctival defect superonasally following excision of the avascular bleb, (b) This intraoperative photograph demonstrates subconjunctival and subtenon’s dissection in preparation for creation of a rotational flap

Figure 3

Diagrammatic representation of rotational conjunctival flap creation. (a) An equal size of peritomy (distance B to C = A to B) and a relaxing incision (point C to D) were made, (b) The conjunctiva at point (B) has been rotated to cover the conjunctival defect (A). The prepared conjunctival flap can be then rotated to cover to defect (from points D → C → B→ A), (c) The incisions can be closed with running polyglactin sutures

On post-operative day 1, the patient demonstrated a small thick-walled bleb with IOP of 12 mm Hg. He reported improvement in dysesthesia. He was treated with topical prednisolone acetate and gatifloxacin. One week post-operatively, the patient had a formed bleb with IOP of 10 mm Hg, with a small slow leak along the nasal running closure. A bandage contact lens was placed. By 2 weeks post-operatively, the leak had resolved. IOP measured 17 mm Hg. During the 3rd post-operative week, a large bleb was observed. IOP measured 24 mm Hg and decreased to 16 mm Hg with massage. Brimonidine was added, and the patient was instructed to perform digital massage. One month post-operatively, IOP measured 22 mm Hg, decreasing to 15 mm Hg with massage. A subconjunctival injection of 5-fluorouracil (50 mg/ml) was given. Approximately 2 weeks later, a large bleb was observed, and IOP measured 15 mm Hg and 10 mm Hg after massage. A second subconjunctival 5-fluorouracil injection was given. At 2 months post-operatively, a large bleb was present, with IOP measuring 16 mm Hg and 9 mm Hg after massage. Timolol 0.5% once daily was added. Seven months post-operatively, the patient demonstrates a large thick-walled bleb, and IOP measures 10 mmHg [Figure 1b]. He has had resolution of dysesthesia.

DISCUSSION

Varied methods of bleb revision for dysesthesia have been described. Palmberg and Zacchei4 reported an 80% success rate in reduction of bleb dysesthesia with placement of external compression sutures through the bleb using 9-0 or 10-0 nylon. Anis et al.2 describe a technique for sutureless trimming of overhanging blebs in six patients, whereby the overhanging portion is dissected from the cornea and trimmed at the junction of the cornea and limbus with a Vannas scissors. One patient continued to experience dysesthesia, while one patient required suturing of a persistent leak. Tabet et al.6 describe a “bleb window”-pexy technique in which a conjunctival window is created in the bleb and the cut edges of conjunctiva and Tenon capsule are glued to the underlying bare sclera with fibrin glue. All six eyes of six patients had rapid resolution of dysesthesia and adequate filtration.

Regarding surgical bleb reduction, La Borwit et al.5 describe bleb reduction in 11 patients for large, symptomatic blebs. Ten of 11 of these eyes underwent excision of excess bleb tissue with primary closure of the remaining tissue, while one eye required a conjunctival allograft. All patients achieved their target IOP at last follow-up; further bleb revision was required in five patients. In their retrospective study of surgical revision of dysfunctional blebs that included one case of dysesthesia, Lee and Holcombe7 report the use of a sliding conjunctival flap and fibrin glue. The patient had resolution of symptoms and adequate IOP control without medication. Lloyd et al.8 describe the use of modified conjunctivoplasty and subconjunctival scar tissue excision within the palpebral fissure to treat bleb dysesthesia. All 13 eyes had improvement in their symptoms and adequate IOP control, with three eyes requiring adjunctive topical glaucoma treatment.

Other authors have reported in general the use of conjunctival flaps for bleb revision; however, preparation of the conjunctival flap has not been well described. We illustrate in detail a specific technique for the closure of a large conjunctival defect using a rotational conjunctival flap following excision of a dysesthetic bleb. Specific advantages include preservation of the limbal border and the grafting of viable, vascularized tissue to avoid retraction and scarring that may be seen with forced direct closure or devitalized free conjunctival autografts. By measuring exact flap length [Figure 3a, distance B to C = A to B], the rotational autograft can be closed with minimal tension as long as sufficient subconjunctival dissection [Figure 3a, points B to C to D] has been performed. Adjunctive subconjunctival 5-fluorouracil was used to improve bleb function. The patient has had resolution of dysesthesia and is maintaining good IOP on two topical agents. This technique could be useful in eyes where excision of the bleb creates a defect too large for primary closure and in patients with glaucoma drainage procedures in both eyes or in patients who may require future glaucoma surgery in the fellow eye, limiting the use of a free conjunctival autograft.