AVASCULAR OVERHANGING BLEB REDUCTION WITH MODIFIED SUTURELESS TECHNIQUE

SUMMARY

A late postoperative trabeculectomy complication could be the overhanging bleb, especially when antimetabolites are used. It can be associated with hypotony, foreign body sensation, dellen, and visual compromise. We report a case of an avascular overhanging bleb successfully reduced with a modified sutureless technique. Nine years before, our patient had trabeculectomy using mitomycin C. After the surgery, the intraocular pressure was correct, without progression in the visual field, but on slit-lamp examination, a large avascular overhanging bleb was noted. Partial excision was performed with dissection from the cornea, overhanging conjunctival trimming, leakage checking and Bandage Contact lens placement. Topical antibiotic and steroid treatment was administered for three weeks. The excised conjunctival histopathology showed avascular metaplastic epithelium. Six months after the surgery, the patient’s visual acuity improved, with intraocular pressure of 12 mm Hg and a Seidel negative asymptomatic bleb. In conclusion, this less invasive technique preserves better bleb function without ripping the surrounding ischemic tissue. The procedure is safe and easy to perform, with less surgical time and fast recovery.

Introduction

The main goal of glaucoma surgery is to relieve intraocular pressure for a long term. Trabeculectomy is the most common filtering procedure, the success of which lies not only on the surgical technique but also on the intraoperative and postoperative measures to modulate wound healing. Even though the surgery works, over years the bleb can change, and complications appear. A late and rare postoperative complication is the overhanging bleb, especially when antimetabolites are used (1). It can be associated with hypotony due to overfiltration or external leakage, foreign body sensation due to an extremely large bleb, dysesthesia due to interference with lid function, and closure leading to corneal drying with dellen formation, unacceptable cosmesis, and visual compromise due to astigmatism (2). We report a case of an avascular overhanging bleb successfully reduced with a modified sutureless technique.

Case Report

A 74-year-old woman was referred to our clinic with persistent discomfort and visual acuity loss on her right eye over a period of 3 months. The subject’s medical history presented hypertension and diabetes mellitus type 2 with pharmacological treatment. Her ocular history revealed cataract surgery and trabeculectomy using mitomycin C (2 mg/mL for 2 minutes) in both eyes 9 years before. After the surgery, the intraocular pressure (IOP) was correct, without progression in the visual field. She also underwent ptosis surgery on her right eye 4 years before. The right eye examination showed the best corrected visual acuity (BCVA) 20/50, while slit-lamp examination revealed a large avascular overhanging bleb (Fig. 1A-B). Her IOP was 10 mm Hg with stable cupping and visual field.

Fig. 1.

Bleb biomicroscopic appearance: overhanging avascular bleb at the time of presentation: (A) external appearance; (B) with the patient looking down; (C) three weeks postoperatively still with the Bandage Contact lens; (D) six months after the surgery.

Due to the decreased vision and symptomatology but IOP well controlled, the patient underwent bleb reduction. Partial excision was performed as follows (Fig. 2): 1) blunt dissection from the cornea using an iris spatula until reaching the limbus with minimal tissue resistance; 2) corneal overhanging conjunctival trimming using Vannas scissors; 3) leakage checking showing slow flow; and 4) placement of a 22-mm diameter Bandage Contact lens (BCL). The BCL was left for three weeks and treatment with topical moxifloxacin and steroids was administered and then tapered (Fig. 1C). The excised conjunctival histopathology showed an avascular metaplastic epithelium with an increased number of fibroblasts (Fig. 3). Six months after the surgery, the patient’s BCVA was 20/25 with IOP of 12 mm Hg and a Seidel negative asymptomatic bleb (Fig. 1D).

Fig. 2.

Surgical technique: (A) and (B) blunt dissection with an iris spatula until reaching the limbus; (C) and (D) corneal overhanging conjunctival trimming with scissors; (E) final result; (F) placement of a 22-mm Bandage Contact Lens.

Fig. 3.

Histopathology of the excised conjunctiva confirming the avascular clinical appearance: metaplastic epithelium with increased fibroblasts and absence of vessels.

Discussion

The pathogenesis of overhanging bleb is not well understood, but the most common relationship is the use of antimetabolites during surgery; these blebs are often extremely thin and cystic, with friable conjunctiva. It has been suggested to be related to unguarded ‘full-thickness’ filtration procedures and may be produced by the effect of continuous lid movement. Symptomatic large overhanging blebs frequently need surgical correction. When the remaining tissues are healthy, partial reduction techniques show very good results (3, 4). However, in cases of coexisting very thin ischemic tissues in which there is the risk of leaking with manipulation or suturing, surgical approach can be more difficult (5). Avascular blebs are often treated with complete bleb excision although this can compromise their function leading to hypertension (6).

In our patient, a symptomatic both avascular and overhanging bleb was noted. Since the IOP was correct without any previous leaking or blebitis episodes, we decided for a more conservative approach performing a sutureless partial excision technique. Blunt dissection of the corneal portion of the bleb with an iris spatula was performed as described by Lanzl et al. (3) but including large-diameter BCL placement at the end of the procedure as recommended by Anis et al. (4).

In conclusion, this less invasive technique is a good alternative for these patients because it is able to better preserve bleb function without ripping the surrounding ischemic tissue. The procedure is easy to perform, safe, with less surgical time and recovery. However, avascular tissue persists with potential complications.