Bleb revision with Tenon's transposition flap: Case report

Abstract

Introduction

To describe the use and technique of a Tenon's transposition flap without overlying conjunctiva to cover bare sclera following bleb excision and tube shunt implantation.

Presentation of case

A 76-year-old man with severe stage primary open-angle glaucoma in both eyes presented with a nonfunctioning trabeculectomy with a thin-walled, cystic bleb overhanging the cornea. A Baerveldt-350 Glaucoma Implant in the ciliary sulcus was recommended for further lowering of intraocular pressure, along with concurrent excision of the bleb due to patient dissatisfaction with the cosmesis of the bleb and to prevent future bleb-associated complications. Conjunctiva could be closed without tension over the new tube entry site; however, a defect remained at the prior trabeculectomy site. A Tenon's transposition flap without overlying conjunctiva was created to cover this site. By postoperative week 6, new conjunctiva had grown over the Tenon's transposition graft, appearing as if there had never been a bleb.

Discussion

This case illustrates the use of a Tenon's transposition flap to cover bare sclera following bleb excision. This technique proves valuable when conjunctiva is limited, offering an alternative when adjacent conjunctiva cannot be mobilized.

Conclusion

In cases requiring non-water-tight coverage of bare sclera with limited available conjunctiva, a Tenon's transposition flap can be used, permitting new conjunctiva to safely grow over bare Tenon's. This technique is useful during a variety of scenarios, including tube shunt and trabeculectomy revisions, where conjunctival closure may be difficult.

Highlights

• •Trabeculectomy and tube shunt surgeries sometimes require revision.
• •Closing the conjunctiva can be difficult if there is insufficient tissue.
• •A full-thickness conjunctival/Tenon's rotational flap may leave defects elsewhere.
• •Tenon's can be isolated and transposed while leaving conjunctiva in place.
• •This technique is useful when there is insufficient conjunctiva to close.

1. Introduction

Trabeculectomy allows aqueous to drain to the subconjunctival space, creating a filtering bleb. Several well-described bleb-associated complications can occur, including bleb leaks, blebitis or endophthalmitis, and blebs overhanging the cornea which can affect vision or cause dysesthesia. Blebs may require revisions such as needling to increase outflow, compression to restrict outflow, or excision to address overhanging or leaking blebs [1]. If bleb excision is planned, conjunctival advancement is often performed to cover the defect. However, conjunctival closure can be challenging if there is insufficient tissue to perform a conjunctival advancement [2]. In these cases, a free conjunctival graft, amniotic membrane graft, or buccal mucous membrane graft may be used [3,4]. Furthermore, eyes with failed prior trabeculectomies often undergo subsequent aqueous shunt implantation to further lower intraocular pressure (IOP). Often, the original bleb is flat and does not require revision or excision; however, if needed, a bleb revision can be performed along with aqueous shunt implantation. Herein we describe an eye with a failed prior trabeculectomy and a cystic bleb overhanging the cornea that underwent bleb excision with Tenon's transposition flap without conjunctival advancement at the time of Baerveldt-350 Glaucoma Implant (BGI-350) surgery (Johnson & Johnson Vision, Santa Ana, California). The patient was evaluated and treated at a tertiary academic medical center.

This work has been reported in line with the SCARE 2023 guidelines for surgical case reports [5].

2. Case report

The patient is a 76-year-old African American man with severe stage primary open-angle glaucoma in both eyes. His left eye had a functioning trabeculectomy which failed after cataract surgery with goniotomy for visually significant cataract (Fig. 1). No hyphema was noted on postoperative day 1. A sliver of hyphema was visible on gonioscopy at postoperative week 1, but it had resolved by the postoperative month 1. Eight months after the cataract surgery with goniotomy, the trabeculectomy failed, and the patient elected to undergo a superotemporal BGI-350 in the sulcus with concurrent bleb excision rather than a bleb needling, because he was dissatisfied with the cosmesis of the overhanging bleb. In addition, the bleb was very thin walled and avascular, so revising it at the time of the tube shunt implantation would also eliminate any future risk of bleb associated complications [6,7].

Fig. 1.

Preoperative and postoperative photographs of combined Baerveldt-350 Glaucoma Implant surgery and bleb excision with Tenon's transposition flap. Preoperatively, a non-functioning, thin-walled cystic overhanging bleb can be seen. Photographs of the eye at postoperative week (POW) 1, 3, and 6 are shown, as well as postoperative month (POM) 9 and 14, which together depict the progressive growth and vascularization of healthy conjunctiva over the Tenon's transposition flap.

The video of the surgery is available online (Video 1). A superior conjunctival peritomy was made from 3 o'clock to 9 o'clock, and lidocaine was injected subconjunctivally to facilitate dissection. There was a “ring of steel” around the superonasal bleb, and the peritomy was carried out posterior to the bleb [8]. A paracentesis was made, and the anterior chamber was filled with Healon Pro, a cohesive viscoelastic containing 1 % sodium hyaluronate (Johnson & Johnson Surgical Vision, Santa Ana, California). The bleb was grasped with 0.12 forceps, separated from underlying sclera using blunt dissection, and discarded. The partial-thickness scleral flap from the prior trabeculectomy could not be identified. The thin-walled cyst at the sclerotomy site was filled with Healon Pro, as it was continuous with the anterior chamber. A BGI-350 was implanted in the superotemporal quadrant in usual fashion after being stented with a 3-0 Prolene (polypropylene) ripcord and ligated with a 7-0 Vicryl (polyglactin 910) suture (Ethicon, Raritan, New Jersey). The tube was trimmed with a posterior bevel and inserted into the sulcus. Three needle-puncture fenestrations were made with the TG140-8 needle attached to the ligature, and a scleral Tutoplast (Innovative Ophthalmic Products, Costa Mesa, California) patch graft was placed overlying the tube entry site. The 3-0 Prolene ripcord was buried subconjunctivally in the inferior fornix, with a segment exposed for easy removal. Attention was returned to the bleb revision. The portion overhanging the cornea was removed, resulting in an epithelial defect. The cyst was punctured, and the edges were debrided. The scleral defect was filled with a scleral Tutoplast inlay, which was trimmed to fill the defect and sutured with 8-0 Vicryl on a blood vessel (BV) needle. The conjunctiva and Tenon's were reapproximated to the limbus and could be closed without tension superotemporally at the new tube and patch graft site. However, it could not be closed without tension superonasally at the prior trabeculectomy site, since the bleb excision had left a full-thickness, semi-circular conjunctival and Tenon's defect. The superonasal conjunctiva and Tenon's were separated from each other to attempt a conjunctival advancement but was still under considerable tension. Priority was given to using conjunctiva to cover the new superotemporal tube entry rather than the prior trabeculectomy site. The superotemporal conjunctiva and Tenon's were separated from each other, and a Tenon's transposition flap was created by making a circumferential relaxing incision in Tenon's temporally. This Tenon's flap was transposed superonasally to cover the bare sclera and scleral patch graft inlay at the bleb excision site. The Tenon's was sutured to sclera with 8-0 Vicryl on a BV needle. The overlying conjunctival layer was neither advanced nor rotated, and it was affixed to sclera at its original position with 8-0 Vicryl on a BV needle, leaving an area of uncovered “bare Tenon's” superonasally at the bleb excision site. Since the prior trabeculectomy was not expected to function, it was deemed safe to leave this area uncovered by conjunctiva, since new conjunctiva would be expected to grow over the Tenon's transposition flap. The Tenon's was trimmed along the limbus to avoid overhanging the cornea, Healon Pro was rinsed out of the anterior chamber with balanced salt solution, and subconjunctival antibiotic and steroids were administered.

On postoperative day 1, the IOP was 45 mm Hg and an anterior chamber paracentesis was performed to lower the IOP. Postoperative prednisolone acetate and moxifloxacin were started four times daily, and the baseline three IOP-lowering medications were continued. At postoperative week 1, the conjunctiva had begun to grow over the Tenon's transposition graft that was covering the bleb excision site. The IOP was 27 mm Hg, so oral acetazolamide 250 mg twice daily was added to lower the IOP until the tube was expected to open at postoperative week 6 when the ligature would spontaneously dissolve; moxifloxacin was stopped and prednisolone was continued. By postoperative week 4, the conjunctiva had fully grown over the Tenon's transposition graft. The IOP was 37 mm Hg on 3 IOP-lowering medications because the patient had run out of acetazolamide 5 days prior. Acetazolamide was resumed and the patient was instructed to stop it leading up to the postoperative week 6 visit since the ligature was expected to dissolve. At postoperative week 6, the IOP was 12 mm Hg on 3 IOP-lowering medications, there was fluid over the plate indicating that the ligature had dissolved, and the anterior chamber was quiet. The ripcord was pulled to fully open the tube lumen, the prednisolone was tapered, and the patient was instructed to stop 2 out of 3 of the baseline IOP-lowering medications. One week later at postoperative week 7, the IOP was 19 mm Hg on 1 IOP-lowering med, there were no hypotony-associated complications, and the 2 IOP-lowering medications that had been stopped the previous week were resumed. By postoperative week 14, the prednisolone taper was finished, and the IOP was 16 mm Hg on baseline 3 IOP-lowering medications. By postoperative month 9, the IOP was 13 mm Hg on baseline 3 IOP-lowering medications. By postoperative month 14, the most recent visit, the IOP was 15 mm Hg on baseline 3 IOP-lowering medications. The conjunctiva and Tenon's overlying the bleb excision site was mobile and vascularized, appearing as if there had never been a bleb at this location.

3. Discussion/conclusion

This case demonstrates the technique of bleb excision at the time of aqueous shunt implantation, featuring the use of a Tenon's transposition flap from the new tube's location to cover bare sclera at the prior trabeculectomy's location. It highlights the utility of a Tenon's transposition flap in situations where conjunctiva is limited, which is particularly relevant in eyes requiring bleb excision for any reason.

In this patient's case, the bleb was non-functioning due to a “ring of steel” of scar tissue, and there was a focal, thin-walled tall cyst which was overhanging the cornea [8]. Rather than excising the entire bleb, as was done in this case, the portion overhanging the cornea could have been excised, and the remaining portion of the bleb overlying the sclera could have been left intact [9]. However, this patient had a melted scleral flap with brisk flow through the flap, and the trabeculectomy failed due to this posterior “ring of steel” rather than the lack of flow through the flap. Consequently, if the anterior edge of the bleb had been excised, this could have resulted in a bleb leak. For these reasons, it was decided to shut down and cover the entire trabeculectomy site at the time of the tube implantation. Another alternative would have been bleb needling to restore aqueous outflow through the bleb; however, this would not have addressed the poor cosmesis of the portion of the bleb that was overhanging the cornea [10].

Regardless, the primary purpose of this report is to showcase the surgical technique of using an isolated Tenon's transposition flap for areas that need coverage with otherwise insufficient Tenon's or conjunctiva. This technique is versatile and can be used in a variety of situations, notably trabeculectomy or tube revision surgeries. Importantly, this strategy is only viable when covering sclera and/or patch grafts that do not overlie a functioning filtering bleb, as functioning filtering blebs should still be covered water-tight with conjunctiva. We propose that this Tenon's transposition flap technique is a safe, effective, quick, and cost-effective alternative to free conjunctival graft, amniotic membrane graft, or buccal mucous membrane graft. This technique can be used in a variety of scenarios during trabeculectomy or tube shunt revision surgery where there is an area of sclera requiring non-water-tight coverage and insufficient tissue to close conjunctiva primarily.

The following is the supplementary data related to this article.

Supplementary Video 1

Baerveldt-350 Glaucoma Implant with concurrent bleb revision with Tenon’s transposition flap.

Ethical approval

This case report of a single individual without identifying information is exempt from ethical approval per institutional policies.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Author contribution

Jason Xiao – Data collection, interpretation, writing

Jessie Wang – Interpretation and writing

Mary Qiu – Study concept, data collection, interpretation, and writing

Guarantor

Mary Qiu

Informed consent

Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Declaration of competing interest

None.