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Incision-Free Minimally Invasive Conjunctival Surgery (MICS) for Late-Onset Bleb Leaks After Trabeculectomy (An American Ophthalmological Society Thesis)

  • Neeru Gupta
    Correspondence
    Inquiries to Neeru Gupta, 30 Bond St., Cardinal Carter Wing, Suite 8-072, Toronto, M5B 1W8, Ontario, Canada
    Affiliations
    Departments of Ophthalmology and Vision Sciences and Laboratory Medicine and Pathobiology, University of Toronto, and Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada; and Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Unity Health Toronto, Canada
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Open AccessPublished:May 13, 2019DOI:https://doi.org/10.1016/j.ajo.2019.04.031

      Purpose

      This study describes an incision-free minimally invasive conjunctival surgical (MICS) technique to repair late-onset leaking blebs after trabeculectomy.

      Methods

      A surgical technique to repair leaking blebs without incision or excision of conjunctiva is described. This is followed by retrospective review of all patients treated at the Glaucoma Unit at St. Michael's Hospital for bleb leaks repaired with MICS from 2012 to 2017. With Research Ethics Board approval, clinical data obtained from the charts included demographic information, vision, intraocular pressure (IOP) data before and after surgery, need for additional medication, and complications. Resolution of the bleb leak without the need for additional therapy or intervention for glaucoma control was considered a success.

      Results

      The MICS approach was applied to 14 eyes of 13 consecutive patients with a leaking bleb. Mean age of presentation was 70.2 ± 14.8 years, and all patients had a history of mitomycin use at the time of glaucoma surgery. The onset of bleb leak following trabeculectomy ranged from 7 months to 16.3 years. Mean pre-operative IOP was 4.5 ± 2.8 mm Hg; IOP measured 12.3 ± 3.0 mm Hg immediately after the procedure. Complete resolution of the bleb leak was observed following surgery in all cases. The follow-up period ranged from 2 weeks to 61 months (10.2 ± 18.1). Recurrent bleb leak was reported in 1 patient 2 years following initial surgery. In all cases, the initially repaired filtering blebs remained functional at last follow-up, and no additional medications were required.

      Conclusions

      The MICS procedure is an effective option for treating late-onset leaking blebs without cutting or excising conjunctival tissue. The minimal requirements of this method make it additionally accessible to low-resource settings. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.
      The leaking filtering bleb is a sight-threatening complication of trabeculectomy surgery that requires immediate attention. Aqueous fluid escaping from the eye through an opening in the conjunctiva can lead to unacceptably low intraocular pressure (IOP) with related vision-threatening complications. A cycle of hypotony may lead to a shallow or flat anterior chamber, peripheral anterior synechiae, cataract, hypotony maculopathy, and choroidal effusion, or hemorrhage and surgical failure.
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      Use of isobutyl-2-cyanoacrylate tissue adhesive in the repair of conjunctival fistula in filtering procedures for glaucoma.
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      or closure of the bleb using an argon laser
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      or continuous wave neodymium: yttrium-aluminum-garnet treatment
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      may require multiple treatments. If a leak from a wound edge persists in the early postoperative period, as with a fornix-based flap, it may need to be re-sutured to obtain watertight closure.
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      Close patient follow-up to look for evidence of anatomical restoration, negative Seidel test, and normal IOP is essential. When conservative measures fail to resolve the bleb leak, surgical bleb revision is indicated.
      Antimetabolites (eg mitomycin) commonly used during filtration surgery have led to thinner avascular blebs, and a growing number of late-onset bleb leaks months to years after trabeculectomy surgery.
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      Late onset of sequential multifocal bleb leaks after glaucoma filtration surgery with 5-fluorouracil and mitomycin C.
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      Late-onset bleb leaks after glaucoma filtering surgery.
      The repair of these blebs is particularly challenging due to their thin, friable nature, which makes direct closure of the defect extremely difficult. Currently, the most commonly used approach is to remove the epithelial bleb tissue or the ischemic bleb entirely, and to mobilize healthy conjunctival tissue into the area by advancement and cutting techniques.
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      Revision of filtration surgery.
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      Surgical repair of leaking blebs.
      Filtering blebs may also be reconstructed using conjunctival rotational or pedicle flaps or free conjunctival autografts from the same or fellow eye.
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      • et al.
      Autologous conjunctival resurfacing of leaking filtering blebs.
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      Bleb reduction and bleb repair after trabeculectomy.
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      Although time consuming, success has been reported with the latter approaches to protect against late bleb-related infections.
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      • et al.
      Long-term bleb-related infections after trabeculectomy: incidence, risk factors, and influence of bleb revision.
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      • et al.
      Outcomes of bleb repair for delayed bleb leaks and sweating blebs.
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      Conjunctival advancement versus nonincisional treatment for late-onset glaucoma filtering bleb leaks.
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      • et al.
      Outcomes of surgical bleb revision for complications of trabeculectomy.
      When conjunctival tissue is scarce, a scleral patch graft,
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      amniotic membrane,
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      oral buccosal mucosa,
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      and fascia lata
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      Bleb revision with temporalis fascia autograft.
      have all been tried. Unfortunately, surgical bleb revisions for recalcitrant bleb leaks still fail, and previously well-controlled glaucoma may become unstable.
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      A Cochrane review exposed the need for more knowledge in this field,
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      and glaucoma colleagues acknowledged inconsistencies in the way that bleb leaks are managed.
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      • King A.J.
      Surveillance of late-onset bleb leak, blebitis and bleb-related endophthalmitis--a UK incidence study.
      The search for improved surgical success rates to treat the leaking bleb continues.
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      Combined conjunctival relieving incisions and advancement for the repair of late-onset leaking trabeculectomy blebs.
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      Revision of dysfunctional filtering blebs by conjunctival advancement with bleb preservation.
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      Surgical repair of leaking filtering blebs using two different techniques.
      An incision-free minimally invasive conjunctival surgical (MICS) procedure to repair the late-onset leaking bleb without tissue incision or excision is described. I hypothesized that this technique could be an alternative to more invasive surgical techniques and have found it to be most helpful in caring for patients with late-onset bleb leaks. I share my experience with this surgical technique as a relatively simple, effective, safe approach to consider, which requires minimal time and resources.

      Minimally Invasive Conjunctival Surgical Technique

      Patients with avascular defined blebs and late-onset bleb leak (Figure 1, Figure 2, Figure 3) were considered for the procedure. The method described can be performed in a minor procedure room or operating room theater using a sterile technique. Following topical anesthesia with proparacaine hydrochloride 0.5%, a lid speculum is inserted to bring the superior avascular leaking bleb into view. The eye is rotated downward to expose the superior bulbar conjunctiva behind the bleb (Figure 4A, Figure 5A ) and then injected with subconjunctival lidocaine 2% with epinephrine (1/100,000) (Figure 4B, Figure 5B). The superior bulbar conjunctiva behind the bleb is injected to balloon the conjunctival tissue, which creates a raised cuff of conjuntival tissue at the bleb perimeter (Figure 4C, Figure 5C). Behind the bleb demarcation line where it is anchored to sclera, mobile conjunctival tissue raised away from the sclera is gently grasped and advanced over the thin bleb toward the limbus (Figure 4D, Figure 5D). A10-0 nylon black monofilament suture with 5.5-mm tapered needle engages corneoscleral tissue and is pulled up through the full thickness of the leading edge of grasped conjunctival tissue (Figure 4E, Figure 5E). The suture is cut, and after the first throw of the tie, using only the tensile strength of the suture, the mobile conjunctiva is drawn up comfortably and without undue tension to cover the area of the leak and sutured only as far forward as it is willing to go (Figure 4F, Figure 5G). Typically 2 to 4 sutures are used; their knots are buried according to the amount of conjunctival tissue brought forward to cover the leaking bleb (Figure 4H, Figure 5H). Following the procedure, conjunctival integrity and IOP are re-assessed at the slit lamp to check for bleb leak. Prednisolone and antibiotics are administered for approximately 1 week.
      Figure thumbnail gr1
      Figure 1Leaking bleb 11.7 years following trabeculectomy. Clinical slit-lamp photo of the right eye of a 78-year-old woman shows (A) a large elevated avascular filtering bleb and (B) thin focal cystic area. (C) Conjunctival epithelium appears irregular at higher power, and (D) a bleb leak is confirmed by Seidel test showing fluorescein stream under cobalt blue light.
      Figure thumbnail gr2
      Figure 2Leaking bleb 13.5 years following trabeculectomy. Clinical slit-lamp photo of the right eye of a 63-year-old male shows (A) an avascular bleb and conjunctival defect with (B) evidence of bleb leak by Seidel test showing fluorescein stream over the cornea under cobalt blue light.
      Figure thumbnail gr3
      Figure 3Leaking bleb 12.8 years following trabeculectomy. Clinical slit-lamp photograph of a right hypotonous eye in an 87-year-old male shows (A) a focally elevated central and transparent thin walled bleb, with (B) a leaking Seidel positive bleb and (C) corneal striae.
      Figure thumbnail gr4
      Figure 4Minimally invasive conjunctival surgery (MICS) technique to repair a leaking bleb in a 64-year-old woman, 11.3 years following right eye combined trabeculectomy and cataract surgery. (A) The eye was rotated downward to expose the superior avascular bleb and posterior bulbar conjunctiva. (B and C) Subconjunctival anesthetic was injected behind the bleb and ballooned conjunctival tissue to the outer edge of the bleb. (D) Raised conjunctival tissue was gently grasped and stretched over the thin bleb toward the limbus. (E) A suture (10-nylon) was used to anchor the leading folded edge to limbal tissue with (F) a surgical knot. (G and H) Adjacent mobile conjunctiva was similarly brought anteriorly and sutured in place. (I) Conjunctival tissue brought over to cover the leaking bleb was held in place at the limbus with 4 surgical knots.
      Figure thumbnail gr5
      Figure 5Minimally invasive conjunctival surgery (MICS) technique to repair a leaking bleb in a 78-year-old woman, 11.7 years following right eye trabeculectomy. (A) The leaking avascular superior bleb was exposed. (B) Subconjunctival anesthetic injected behind the bleb raised conjunctival tissue away from sclera, and (C) surrounded the bleb perimeter. (D) Elevated conjunctival tissue was gently grasped and stretched over the bleb toward the limbus only as far as it would go freely and without undue tension. (D) A needle with 10-0 nylon suture engaged corneoscleral tissue and then (E) conjunctival tissue before (F) it was tied. (G and H) Adjacent mobile conjunctiva was similarly stretched anteriorly over the bleb and sutured in place at the limbus. (I) Four surgical knots anchored the conjunctiva over the leaking bleb area, and not necessarily all the way to the limbal edge.
      Figure thumbnail gr6
      Figure 6Post-minimally invasive conjunctival surgery (MICS) repair of bleb leak in 2 patients. Slit-lamp photos following MICS bleb repair show conjunctival tissue overlying an avascular conjunctival filtering bleb (A) 3 weeks later in a 63-year-old man and (B) almost 3 months later in a 78-year-old woman.
      Figure thumbnail gr7
      Figure 7Post-minimally invasive conjunctival surgery (MICS) repair of bleb leak in a patient with iridocorneal endothelial syndrome. (A) Slit-lamp photos following MICS bleb repair for bleb leak in a 64-year-old woman with iridocorneal endothelial sydrome show vascular conjunctival tissue extending over avascular tissue 1 week after surgery. (B) At 3 weeks following surgery, there is reduced conjunctival vascularity and marked healing with bleb preservation.
      Figure thumbnail gr8
      Figure 8Post-minimally invasive conjunctival surgery (MICS) repair of bleb leak at 15 months. Slit-lamp photos 15 months following left eye MICS bleb repair in a 78 year old woman shows blending of (A) anterior conjunctival tissue with underlying conjunctival tissue and (B) a translucent functioning bleb at high power.
      Institutional Research Ethics Board approval was obtained and the chart of every patient who underwent the MICS procedure for late-onset conjunctival bleb leak was identified by review of the surgical logs. The MICS procedure was performed by a single surgeon (N.G.) at St. Michael's Hospital, Unity Health Toronto, University of Toronto in either the minor procedure room or operating theater. Demographic and clinical information was collected and included history of trabeculectomy, adjuvant antifibrotic use, medications used before bleb leak, time from surgery to the onset of bleb leak, previous attempts to treat the bleb leak, IOP data before and after surgery, need for additional medications, final IOP, and any complications in the postoperative course. The main outcome measures were the status of the bleb leak following surgery, IOP, vision, and need for additional therapy.

      Results

      Table 1 shows the study group consisted of 8 women and 5 men, ranging in age from 30 to 89 years (mean 70.2 ± 14.8 years). Patient races included Caucasians (n = 6), Asians (n = 5), and Blacks (n = 2). All patients had primary open angle glaucoma, except for 1 patient with iridocorneal endothelial syndrome. The indication for surgery was a nonhealing bleb leak in all cases; a bandage contact lens was tried unsuccessfully in 11 of 14 cases (Table 1). A bandage contact lens was not used in 3 cases because the leak was too far posterior to the limbus.
      Table 1Patient Demographics
      PatientsAge (yrs)SexRaceDiagnosis
      130FAsianPOAG
      263MAsianPOAG
      364FCaucasianPOAG
      464FCaucasianICE
      567MCaucasianPOAG
      668MAsianPOAG
      770FBlackPOAG
      875MAsianPOAG
      976FCaucasianPOAG
      10
      Both eyes were treated.
      78FCaucasianPOAG
      1181FBlackPOAG
      1287MAsianPOAG
      1389FCaucasianPOAG
      ICE = iridocorneal endothelial; POAG = primary open angle glaucoma.
      a Both eyes were treated.
      Baseline characteristics are shown in Table 2. All cases followed either a trabeculectomy (5 of 14 eyes) or trabeculectomy combined with cataract surgery and lens implantation (9 of 14 eyes). Six patients had a history of 2 trabeculectomies. Thirteen cases had known previous treatment with mitomycin, and 10 had received supplemental postoperative 5-fluorouracil. Five treated eyes had a remote history of blebitis (Table 2). Onset to bleb leak ranged from 7 months to 196 months (mean 102.7 ± 64.8 months) after the last trabeculectomy surgery.
      Table 2Baseline Characteristics
      CasesPrimary SurgeryAntifibrotic AgentOnset to Bleb Leak (mos)No. of TrabsHistory of BlebitisPrevious Treatment
      MMC5-FUAntibioticsBCL
      1TRABUnknown1732NoYesYes
      2TRAB/IOLYesYes1621NoYesYes
      3TRAB/IOLYesYes1351YesYesNo
      4TRAB/IOLYesYes1661NoYesYes
      5TRAB/IOLYesYes782YesYesYes
      6TRAB/IOLYesYes382NoYesYes
      7TRAB/IOLYesNo421YesYesYes
      8TRABYesYes1961NoYesNo
      9TRABYesNo72NoYesYes
      10
      Right and left eyes of same patient, respectively.
      TRABYesYes1401YesYesNo
      11
      Right and left eyes of same patient, respectively.
      TRABYesYes472YesYesYes
      12TRAB/IOLYesNo181NoYesYes
      13TRAB/IOLYesYes1542NoYesYes
      14TRAB/IOLYesYes821NoYesYes
      5 FU= 5 fluorouracil; BCL = bandage contact lens; IOL = intraocular lens; MMC = mitomycin-C; TRAB = trabeculectomy.
      a Right and left eyes of same patient, respectively.
      Table 3 shows patient outcomes. Before repair of the leaking bleb, IOP ranged from 0 to 10 mm Hg, with mean IOP of 4.5 ± 2.8 mm Hg. Immediately after surgery, IOP ranged from 8 to 19 mm Hg, with mean IOP of 12.3 ± 3.0 mm Hg. All patients had a Seidel negative test and complete resolution of the bleb leak. Follow-up period ranged from 2 weeks to 61 months (10.2 ± 18.1 months). At the last follow-up, IOP ranged from 8 to 13 mm Hg, with mean IOP of 11.5 ± 1.7 mm Hg. No additional glaucoma medications were prescribed at any point during the follow-up period. All patients had similar to improved vision at the last visit, except for 1 patient who 2 years later had bleb leak, blebitis, vitrectomy, and underwent retinal detachment surgery. Additional bleb repair and medication were not required in this patient because the bleb survived. Loose sutures were removed at the slit lamp in 1 patient at 2 weeks and 2 patients at 3 months. Slit lamp examination after surgery in all cases showed resolution of the bleb leak with vascular conjunctival tissue extending over avascular underlying conjunctival tissue. Examples of post-operative bleb appearances ranging from 1 week to 15 months following MICS surgery are shown in Figure 6, Figure 7, Figure 8.
      Table 3Patient Outcomes
      CasesEyePre-op VisionFinal VisionPre-op IOPImmediate Post-op IOPFinal IOPMonths Post-opMedicationPost-op Complications
      1OD20/3020/2008100.5NoneNone
      2OS20/7020/50411132.3NoneNone
      3OD20/4020/3071781.7NoneNone
      4OS20/4020/20212133.0NoneNone
      5OS20/4020/40812123.1NoneNone
      6OS20/20020/200081060.8NoneNone
      7OD20/4020/2004141441.1NoneNone
      8OD20/4020/201012102.8NoneNone
      9OD20/20020/100510122.1NoneNone
      10
      Right and left eyes of same patient, respectively.
      OD20/6020/302111217.6NoneNone
      11
      Right and left eyes of same patient, respectively.
      OS20/4020/30614102.6NoneNone
      12OD20/5020/30614121.0NoneNone
      13OD20/20020/100319132.6NoneNone
      14OD20/7020/40610111.8NoneNone
      IOP = intraocular pressure in mm Hg.
      a Right and left eyes of same patient, respectively.

      Discussion

      Intra- and peri-operative use of mitomycin-C (MMC) and 5-fluorouracil have increased the long-term success of filtration surgery
      Five-year follow-up of the Fluorouracil Filtering Surgery Study. The Fluorouracil Filtering Surgery Study Group.
      ; however, the increase in late-onset bleb leaks is also related to their use.
      • Belyea D.A.
      • Dan J.A.
      • Stamper R.L.
      • Lieberman M.F.
      • Spencer W.H.
      Late onset of sequential multifocal bleb leaks after glaucoma filtration surgery with 5-fluorouracil and mitomycin C.
      • Matsuo H.
      • Tomidokoro A.
      • Suzuki Y.
      • Shirato S.
      • Araie M.
      Late-onset transconjunctival oozing and point leak of aqueous humor from filtering bleb after trabeculectomy.
      All patients in this study had excellent glaucoma control with no medication before their late-onset bleb leak, and 50% of them were stable for well over a decade. However, they had a documented history of MMC, and many of them were supplemented with 5-fluorouracil. Late-onset leaking blebs present a significant risk of infection,
      • Soltau J.B.
      • Rothman R.F.
      • Budenz D.L.
      • et al.
      Risk factors for glaucoma filtering bleb infections.
      and 5 patients who underwent MICS had a history of blebitis.
      Conservative management for late-onset leaking blebs may work in only 50% of patients, and many will need bleb revision surgery.
      • Burnstein A.L.
      • WuDunn D.
      • Knotts S.L.
      • Catoira Y.
      • Cantor L.B.
      Conjunctival advancement versus nonincisional treatment for late-onset glaucoma filtering bleb leaks.
      The patients in this study did not respond to conservative management for the leaking bleb.
      Other surgical approaches such as bleb excision and conjunctival autograft or advancement techniques report success rates as high as 75%, although additional medication or surgery are frequently needed to control glaucoma.
      • Tannenbaum D.P.
      • Hoffman D.
      • Greaney M.J.
      • Caprioli J.
      Outcomes of bleb excision and conjunctival advancement for leaking or hypotonous eyes after glaucoma filtering surgery.
      • Lin A.P.
      • Chung J.E.
      • Zhang K.S.
      • et al.
      Outcomes of surgical bleb revision for late-onset bleb leaks after trabeculectomy.
      Pedicle flaps, conjunctival advancement, or autologous graft with bleb excision techniques may be similarly successful; however, patients may need multiple surgical interventions.
      • Wadhwani R.A.
      • Bellows A.R.
      • Hutchinson B.T.
      Surgical repair of leaking filtering blebs.
      Bleb reconstruction involving resection of the bleb and rotational conjunctival flap has also been reported to stop the leak in approximately 80% of cases; however, medical therapy is needed in approximately one-half of patients.
      • Hamard P.
      • Tazartes M.
      • Ayed T.
      • Quesnot S.
      • Hamard H.
      [Prognostic outcome of leaking filtering blebs reconstruction with rotational conjunctival flaps] (in French).
      It is quite difficult to compare studies due to the array of non-standardized approaches, and most studies are retrospective.
      • Bochmann F.
      • Azuara-Blanco A.
      Interventions for late trabeculectomy bleb leak.
      Bleb revision surgery may be technically challenging and often involves difficult dissections, complex suturing, with varying surgeon preferences. Following conjunctival peritomy, relaxed conjunctiva alone or with its attached undissected Tenon's fascia superiorly may be used to reconstruct the filtering bleb.
      • Cohen J.S.
      • Shaffer R.N.
      • Hetherington Jr., J.
      • Hoskins D.
      Revision of filtration surgery.
      • Budenz D.L.
      • Chen P.P.
      • Weaver Y.K.
      Conjunctival advancement for late-onset filtering bleb leaks: indications and outcomes.
      In some cases, a forniceal relaxing incision is placed to avoid traction on the conjunctiva and tenons at the limbus.
      • O'Connor D.J.
      • Tressler C.S.
      • Caprioli J.
      A surgical method to repair leaking filtering blebs.
      The tissue is fastened at the limbus with winged or running sutures, depending on the surgeon. Methods to address the cystic leaking bleb during the procedure also vary a lot. Although some surgeons advocate cautery or debridement of the friable bleb tissue, or chemical de-epithelialization,
      • Gehring J.R.
      • Ciccarelli E.C.
      Trichloracetic acid treatment of filtering blebs following cataract extraction.
      others excise it completely, leaving only the exposed filtering flap.
      • Melo A.B.
      • Razeghinejad M.R.
      • Palejwala N.
      • et al.
      Surgical repair of leaking filtering blebs using two different techniques.
      Preservation of the bleb without excision during reconstruction has been reported with good success.
      • Catoira Y.
      • Wudunn D.
      • Cantor L.B.
      Revision of dysfunctional filtering blebs by conjunctival advancement with bleb preservation.
      Others advocate bleb excision with similar success.
      • Tannenbaum D.P.
      • Hoffman D.
      • Greaney M.J.
      • Caprioli J.
      Outcomes of bleb excision and conjunctival advancement for leaking or hypotonous eyes after glaucoma filtering surgery.
      Complications from conjunctival advancement and bleb excision studies include elevated IOP, recurrent bleb leaks, bleb failure and dysesthesia, hypertropia, and blepharoptosis.
      • Sugar H.S.
      Complications, repair and reoperation of antiglaucoma filtering blebs.
      Thin avascular leaking blebs treated with mitomycin lack the normal healing response due to inhibited cell proliferation.
      • Jampel H.D.
      Effect of brief exposure to mitomycin C on viability and proliferation of cultured human Tenon's capsule fibroblasts.
      Irregular surface epithelium and fibroblastic hypocellularity have been noted histologically.
      • Nuyts R.M.
      • Felten P.C.
      • Pels E.
      • et al.
      Histopathologic effects of mitomycin C after trabeculectomy in human glaucomatous eyes with persistent hypotony.
      Current approaches to bleb revision have the common goal of using fresh conjunctiva whenever possible, to cover the pre-existing filtration site, and to preserve the function of the original scleral flap. In conjunctival advancement surgery, healthy conjunctival tissue is derived mainly from the superior bulbar conjunctiva behind the cystic thin bleb. Conjunctival tissue must sometimes be harvested from a remote site if there is too much scarring, which is technically more demanding and more time consuming among surgical approaches.
      • Wilson M.R.
      • Kotas-Neumann R.
      Free conjunctival patch for repair of persistent late bleb leak.
      Although amniotic membrane transplantation has been tried, this seems less effective than conjunctival advancement.
      • Budenz D.L.
      • Barton K.
      • Tseng S.C.
      Amniotic membrane transplantation for repair of leaking glaucoma filtering blebs.
      Grabbing healthy intact conjunctiva next to the leak and suturing it to promote healing before it falls back has been suggested as a temporizing measure.
      • Ritch R.
      • Schuman J.S.
      • Belcher 3rd, C.D.
      Management of the leaking filtration bleb.
      Meticulous blunt conjunctival dissection is typically performed with Tenon's layer dissected for added laxity and additional support.
      Using the MICS approach in these patients, bulbar conjunctiva surrounding a focal avascular bleb was found to lift easily away from the sclera following subconjunctival injection. Abundant bulbar conjunctival surface tissue stretched loosely and easily without Tenon's dissection, and this capacity may be generally underestimated. Typical surgery includes Tenon's dissection from sclera to strengthen the reconstruction. The double conjunctival layer offered by the MICS approach seemed to adequately reinforce the area over the leaking blebs. It may be considered a biological patch while also allowing underlying bleb to bind to the conjunctiva, leaving the underside of the original bleb undisturbed to preserve the original filtration environment. This was particularly helpful in a patient with iridocorneal endothelial syndrome who underwent complex surgery, with a desire to protect the original filtration site. Conjunctival injection observed after surgery in the first week gradually settled over the ensuing weeks.
      The MICS method described here uses a double-sided flap of conjunctival epithelial tissue pulled down from behind the avascular filtering bleb, laid to rest directly over the area of bleb surface conjunctival breakdown. The prolonged apposition of healthy conjunctival epithelium to the exposed bleb area likely creates adhesion with time in addition to providing a protective covering. This approach stopped the leak and allowed continued conjunctival filtration below the thin bleb. Amniotic membrane transplants have been similarly folded to form a double layer with epithelial layers facing outward and mesenchymal surfaces apposed on the inside, serving as a scaffold and patch at the same time.
      • Li G.
      • O'Hearn T.
      • Yiu S.
      • Francis B.A.
      Amniotic membrane transplantation for intraoperative conjunctival repair during trabeculectomy with mitomycin C.
      Slow integration and blending of the overlying conjunctiva into the underlying bed of tissue was observed with a similar appearance over time. Longitudinal studies of healing blebs using ultrasound biomicroscopy or optical coherence tomography may shed insight into these tissue planes. The long-term integrity of the conjunctival epithelium will need to be watched; a future leak from the remaining avascular uncovered bleb remains a possibility.
      All patients had immediate resolution of the bleb leak following surgery and resumed activities of daily living without restriction other than postoperative steroid and antibiotic drops with instructions to wear a shield at night. One patient developed a new bleb leak 2 years later, with blebitis and underwent retinal surgery (Case 7, Table 3). Despite this, bleb function was maintained off of medication. During follow-up of up to 5 years, no patient required additional medication or bleb revision surgery, and all cases except the preceding complex case had stable to improved vision.
      Limitations of this study are its retrospective nature, small sample size, and lack of complete follow-up in all patients. Similar limitations are common to publications of new or variations on surgical approaches, as highlighted in a Cochrane review of interventions for late trabeculectomy bleb leak.
      • Bochmann F.
      • Azuara-Blanco A.
      Interventions for late trabeculectomy bleb leak.
      Despite these shortcomings, reporting early surgical results advances surgical methods, and facilitates replication and validation by others.
      The MICS procedure seems particularly well suited for the classic focal avascular bleb close to the limbus that requires little tissue coverage from the conjunctiva above. It is not an option for patients with severe conjunctival scarring or in whom conjunctival mobilization is impractical. The main desired outcome for the MICS procedure is prompt resolution of the bleb leak. The procedure was generally completed within 15 minutes, and the number of sutures required ranged from 2 to 4. Patients reported that the experience was pleasant, with return to usual activities without pain. The procedure did not disturb any of the underlying tissues close to the site of filtration, and this may explain why bleb function was saved in these cases. Surgical bleb revision with the MICS procedure for bleb leaks was effective and without complications in the postoperative period. Because tissue cutting and undermining is not performed, it may be performed in the minor procedure room.
      The MICS approach, without cutting or excision of conjunctiva as described here, is a relatively simple approach to repair late-onset bleb leaks. The minimal resource requirements of this procedure make it accessible to colleagues around the world for consideration when faced with a sight-threatening, late-onset leaking bleb.

      Acknowledgments

      The author has completed and submitted the ICMJE form for disclosure of potential conflicts of interest, and none were reported. The author alone is responsible for the content and preparation of this manuscript. There were no ghost authors or other writing assistance.

      Supplemental Data

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