Isopropyl Alcohol in Bleb Revision: A Novel Approach for Aesthetic and Functional Success

Introduction

Trabeculectomy remains a cornerstone in the surgical management of glaucoma, effectively lowering intraocular pressure (IOP) through the formation of a subconjunctival filtering bleb to facilitate aqueous humor through an alternative pathway. However, postoperative complications, including overhanging filtering blebs (OFB), can arise, particularly in cases where antimetabolites such as mitomycin C (MMC) are used. OFB can extend toward the cornea, leading to cosmetic dissatisfaction, astigmatism, and an increased risk of bleb leaks or infection [1].

Multiple approaches have been employed in the treatment of OFB. Currently, the mainstay approach in managing OFB in the literature includes partial excision and careful dissection [2]. Sutureless techniques have also shown promise, with 83.3% of patients reporting symptomatic relief, yet some still had complications, including bleb leaks [3]. However, recurrence rates remain significant. For instance, a case report highlighted a patient who experienced recurrence of a large OFB just 7 months after excision, despite employing techniques like amniotic membrane application and cryotherapy [4]. Another study demonstrated that while excision improved corneal higher-order aberrations and alleviated symptoms, it did not significantly alter the IOP or prevent recurrence [5]. These challenges prompt a need for improved surgical strategies to ensure a functional and cosmetically appealing bleb to reduce the burden of repeated bleb revision. In this report, we describe a modified bleb revision technique incorporating isopropyl alcohol as an adjunct to excision and conjunctival reapproximation in an 18-year-old woman with an OFB.

Case Report

An 18-year-old woman presented to our glaucoma clinic with concerns regarding a large, cystic, and translucent OFB in her left eye. She had undergone a primary trabeculectomy with 0.2 mg/mL of MMC 2 years earlier, followed by a previous bleb revision 1 year after the trabeculectomy. Her BCVA was 20/20 in the right eye and 20/100 in the left eye, with a well-controlled IOP of 8 mmHg without the use of any IOP-lowering agents. Slit-lamp examination was significant for a superior OFB extending 2 mm inferiorly toward the cornea, with no leakage on Seidel test. Her remaining anterior segment examination was unremarkable, and fundus examination showed a healthy optic disc with no significant cupping. The decision to proceed with surgical revision was made to address her cosmetic concerns and ensure a functional filtering bleb.

The surgery was performed under general anesthesia. A clear corneal traction suture was placed to provide good exposure of the bleb, followed by a sub-tenon injection of 0.2 mg/mL MMC at the superior temporal quadrant. The overhanging bleb was then dissected from the superior corneal border using a Tooke corneal knife, followed by conjunctival trimming with Westcott scissors. The excised tissue was then sent for histopathological examination, which displayed epithelial ingrowth and fibrosis in the substantia propria (Figure 1).

To enhance wound healing and reduce recurrence risk, 70% isopropyl alcohol was prepared by diluting 99% isopropyl alcohol with balanced saline solution (BSS). Weck-Cel sponges soaked in the solution were applied to the de-epithelialized corneal tissue for 60 seconds, followed by irrigation with 30 mL of BSS. The conjunctiva was reapproximated and secured with a 9-0 continuous Vicryl suture, ensuring a smooth surface. A bandage contact lens was then applied at the end of the procedure, along with postoperative administration of Maxitrol™ ointment (dexamethasone 0.1%/neomycin sulfate 3.5 mg/polymyxin B sulfate 10 000 units).

On the first postoperative day, the anterior chamber was deep and quiet, IOP was 2 mmHg, and Seidel testing was negative for any leakage. The patient was placed on a tapering regimen of prednisolone acetate 1% over 4 weeks and moxifloxacin ophthalmic drops 4 times daily for 14 days. At the 1-year follow-up, her BCVA had improved to 20/30 in the left eye, and IOP remained stable at 10 mmHg without the need for additional medications. The bleb appeared well formed and functionally stable, with significant cosmetic improvement (Figure 2).

Discussion

The primary objective in our case was to achieve a well-functioning bleb while addressing the patient’s main concern for a cosmetically appealing bleb. This was particularly important given the risk of recurrence. The adjunctive use of isopropyl alcohol in this case served an important role in ensuring a stable functional bleb. While previous studies have explored the use of absolute alcohol in bleb revision, its direct application has been associated with significant corneal toxicity leading to corneal decompensation [6]. To mitigate this risk, we opted for a diluted isopropyl alcohol solution, allowing for effective fibroblast modulation while minimizing potential ocular surface damage. This adjustment aimed to balance therapeutic efficacy with safety, ultimately enhancing the likelihood of maintaining a functional and cosmetically acceptable bleb.

In recent advances, novel bleb revision techniques involving the use of a Tenon’s patch graft were effective in treating large, ischemic, leaking blebs with severe conjunctival scarring following trabeculectomy. This technique is particularly beneficial when traditional conjunctival mobilization is impractical. The procedure involves dissecting a small piece of Tenon’s tissue, which is then inserted under the ischemic bleb’s conjunctiva to seal the leakage. This method has shown success in sealing bleb leakages immediately after surgery, with sustained results in most cases during follow-up periods [7]. Other methods such as autologous Tenon’s grafts and transposition flaps have also demonstrated efficacy in similar scenarios. These alternative techniques can offer additional benefits such as cost-effectiveness and ease of application, depending on the specific clinical context [8].

The formation of OFB after trabeculectomy is a rare occurrence, but its development is still debated. Histopathological findings suggest that these blebs are consistent with the filtering cicatrix hypothesis, with tight connections to the corneal tissue or corneoscleral limbus [9]. The formation of OFB is occasionally linked to the surgical wound’s microleakage following phacoemulsification, which starts the healing and scarring process [10]. Important conditions for the formation of functional filtering blebs after non-penetrating deep sclerectomy (NPDS) include the structural organization of temporary extracellular matrix (ECM) in the early postoperative period and the timely degradation of ECM components, with a predominant concentration of matrix metalloproteinase 9 (MMP-9) over transforming growth factor β (TGF-β) [11]. OFB formation can also be influenced by myofibroblasts, which are identified by vimentin-positive stromal cells and the presence of alpha-smooth muscle actin (ASMA) [12].

When treating glaucoma patients, revision rates and failure rates are crucial factors to consider. Studies indicate that surgical bleb correction has varied success rates, ranging from 83% to 96% [13]. Factors such as bleb morphology and the use of antimetabolites like 5-fluorouracil have been found to influence the outcome of needle revision in failing filtering blebs [14].

Isopropyl alcohol has also been employed previously in other ophthalmic procedures due to its antiseptic and epithelial-modulating properties. It has been used in laser-assisted in situ keratomileusis (LASIK) for epithelial debridement [15]. In this case, isopropyl alcohol was applied to the de-epithelialized corneal surface to promote tissue remodeling and minimize fibroblast proliferation. The result was a well-formed and stable bleb without recurrence at the 1-year follow-up.

Conclusions

This case illustrates the successful application of isopropyl alcohol as an adjunct in bleb revision surgery, leading to improved cosmetic and functional outcomes. The adjunctive technique of incorporating diluted isopropyl alcohol was associated with stable IOP control and a favorable postoperative course, suggesting a potential role in managing challenging OFB cases. While this case adds to the growing body of literature exploring innovative techniques in glaucoma surgery, further studies are warranted to determine its long-term efficacy and safety.