CASE REPORT

Explantation of the Novel Ahmed Glaucoma Valve M4 Implant Wanda D. Hu, MD, Michael J. Pro, MD, Scott J. Fudemberg, MD, and Marlene R. Moster, MD

Purpose: To report a series of cases involving Ahmed Glaucoma Valve M4 (AGV) explantation and to discuss the surgical technique to remove the drainage device. Methods: Four cases were identified that presented with AGV M4 postoperative complications necessitating tube shunt removal. Three patients presented with conjunctival erosion and 1 patient with persistent diplopia. AGV M4 implants were removed successfully between 1.5 and 9 months after implantation. Results: Successful explantation of the AGV M4 novel implant was achieved in all cases without intraoperative or postoperative complications. Conclusions: If necessary, AGV M4 explantation can be successfully performed in the early postoperative period. Key Words: glaucoma, drainage device, tube shunt, polyethylene, Ahmed Glaucoma Valve, explantation

(J Glaucoma 2015;24:e1–e4)

T

he Ahmed Glaucoma Valve (AGV; New World Medical Inc., Rancho Cucamonga, CA) contains a flow-resistive valve to prevent postoperative hypotony before plate encapsulation.1,2 In prior studies, success rates for the AGV have ranged from 57% to 84% at 1 year follow-up.1–4 It is thought that a significant amount of the AGV failures are due to the properties of the fibrovascular capsule that forms around the plate.5 The new AGV M4 consists of a plate made of porous high-density polyethylene (Medpor; Porex, Atlanta, GA; subsequently Stryker Corp., Kalamazoo, MI), which allows for rapid tissue integration and vascular ingrowth, which may reduce encapsulation of the plate and allow for better intraocular pressure (IOP) control with a mitigated “hypertensive phase.”5,6 Recent studies have shown similar success rates in the new AGV M4 compared with the older AGV FP7 and S2 models.5,7 No complications requiring device explantation occurred in these studies. We report a series of cases involving explantation of AGV M4 implants and discuss the surgical technique to remove the drainage device. The AGV M4 was the AGV Received for publication June 5, 2014; accepted October 7, 2014. From the Wills Eye Hospital, Philadelphia, PA. Disclosure: The authors declare no conflict of interest. Reprints: Wanda D. Hu, MD, Wills Eye Hospital, 840 Walnut Street, Suite 1130, Philadelphia, PA 19107 (e-mail: [email protected]). Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Website, www.glaucomajournal.com. Copyright r 2014 Wolters Kluwer Health, Inc. All rights reserved. DOI: 10.1097/IJG.0000000000000192

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implant of choice at the time of implantation for each surgeon. Table 1 describes the clinical characteristics of these cases. To date, this is the first report describing complications necessitating AGV M4 explantation and the successful removal of this new device.

CASE SERIES Case 1 A 79-year-old woman with uveitic glaucoma presented with an uncontrolled IOP of 46 mm Hg on 500 mg oral acetazolamide twice a day (Diamox Sequels; Teva Pharmaceuticals USA Inc., North Wales, PA), prednisolone acetate 3 times a day, and travoprost 1 time at night (Travatan Z; Alcon, Fort Worth, TX). Visual acuity was measured at 20/50 preoperatively. Surgery was planned to insert an AGV M4 with VisionGraft (Tissue Banks International Inc., Baltimore, MD) superotemporally. Three months after AGV implantation, the patient developed a tube shunt exposure at the limbus with mucoid discharge and an elevated IOP of 40 mm Hg. The tube portion of the AGV was removed from the anterior chamber and amputated at the level of the plate and the conjunctival defect was closed with 8-0 vicryl sutures. Simultaneous endocyclophotocoagulation was performed for IOP control. The AGV plate was not removed at this time as the plate appeared adherent to the sclera and no infection appeared to be surrounding the plate. Two months later, plate exposure was noted along the anterior plate edge corner (Fig. 1A) with an IOP of 22 mm Hg. The AGV plate was explanted with simultaneous diode cyclophotocoagulation (CPC). Four months postoperatively, her vision is at baseline with good IOP control on Travatan Z and fixed combination brinzolamide/brimonidine (Simbrinza; Alcon).

Case 2 A 60-year-old woman presented with primary open-angle glaucoma. The patient also had a history of uncontrolled non– insulin-dependent diabetes mellitus with proliferative diabetic retinopathy in both eyes requiring panretinal photocoagulation. The patient also had cardiovascular medical problems. On presentation, her IOP was 49 mm Hg with hand motion visual acuity on brinzolamide (Azopt; Alcon), brimonidine tartrate/timolol maleate fixed combination (Combigan; Allergan, Irvine, CA), and acetazolamide. An AGV M4 implant was placed in the superotemporal quadrant with VisionGraft corneal patch graft. On postoperative day 7, the eye developed a massive suprachoroidal hemorrhage. On the postoperative month 3 visit, the eye was noted to be phthisical with an exposed anterior AGV plate edge (Fig. 1B). Anterior migration of the AGV plate was observed due to the phthisical nature of the eye. The implant was then removed in its entirety with improved pain postoperatively. The vision was bare light perception.

Case 3 A 70-year-old woman presented with an elevated IOP of 26 mm Hg after a prior supraciliary Gold Shunt implantation (SOLX, Waltham, MA) and failed trabeculectomy for primary open-angle glaucoma. An AGV M4 implant was placed superotemporally with Tutoplast pericardial patch graft (RTI Biologics,

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1.5 mo 55 W F 80 4

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AGV indicates Ahmed Glaucoma Valve; B, black; CPC, diode cyclophotocoagulation; Dx, diagnosis; Sx, surgeries; F, female; H, Hispanic; IOP, intraocular pressure (mm Hg); M, male; MAC, monitored anesthesia care; PCIOL, posterior chamber intraocular lens; VA, visual acuity; W, white.

General

CPC None New AGV M4 implantation CPC Retrobulbar Retrobulbar Local; MAC

plate exposure plate exposure intractable diplopia posterior tube exposure 6 mo 9 mo 2 mo 40 49 26

OD Uveitic Pseudophakic/PCIOL 20/50 OS POAG Pseudophakic/PCIOL HM OD POAG Trab/MMC; Gold Shunt; 20/20 Peudophakic/PCIOL OD NVG AGV M4; AGV Tube revision CF 4 ft W H B F F F 79 60 70 1 2 3

Combined Sx With AGV M4 Explant Preop Time Reason for M4 Anesthesia Used for IOP With M4 Explant M4 Explant Preop VA Prior Sx Dx Case Age Sex Race Eye

TABLE 1. Case Series

20/50 15 Bare LP 0 20/40 22-18 with flushing 20/600 14

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Postop VA Postop IOP

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Alachua, FL). At the postoperative week 1 visit, the patient was noted to have binocular diplopia. Forty-two days after surgery, the patient still had intractable binocular diplopia and the IOP elevated to 23 mm Hg. The decision was made at this time to explant the current AGV M4. Intraoperatively, the initial AGV M4 was found to be over the superior rectus. The entire device was removed and a new AGV M4 implant with VisionGraft was placed more temporally, avoiding the recti muscles. Ten months postoperatively, the patient was doing well with moderate IOP control on bimatoprost 0.01% (Lumigan, Irvine, CA), Combigan, and Azopt.

Case 4 An 80-year-old woman presented with an elevated IOP of 55 mm Hg with a preoperative visual acuity of counting fingers from neovascular glaucoma (NVG) after a central retinal vein occlusion. The patient also had a history of multiple bevacizumab (Avastin; Genentech Inc., San Francisco, CA) injections in that eye. The patient had an AGV model M4 implant with Tutoplast patch graft placed in the superotemporal quadrant. Three months postoperatively, the patient developed a tube exposure near the limbus, which was revised. Eleven months after initial AGV implantation, the IOP was elevated again to 41 mm Hg. A second AGV M4 with Tutoplast was then placed inferonasally. Six weeks postoperatively, the inferonasal tube shunt was noted to have a posterior tube exposure near the plate edge that was seidel positive (Fig. 1C) with an IOP of 6 mm Hg. The patient underwent removal of the inferonasal AGV M4 implant with simultaneous diode laser cyclophotocoagulation. At the postoperative week 2 visit, the patient is doing well with a visual acuity of 20/600 and an IOP of 14 mm Hg on Combigan.

Technique for AGV M4 Explantation This is the first report to document device explantation with the novel AGV M4 implant. The following describes the authors’ suggestion for successful explantation of this device should this become necessary. Because of the extensive dissection that must be performed to explant an AGV M4 in comparison with an AGV FP7 or S2, a retrobulbar block or even general anesthesia may be necessary. The conjunctiva is often friable and inflamed from tube/plate exposure and multiple prior surgeries; therefore, subconjunctival lidocaine may not be sufficient. After anterior conjunctival dissection and removal of the tube from the eye, closure of the old sclerostomy track is performed. Because of the porous material, which allows rapid soft tissue integration into the plate, extensive sharp dissection must be performed both above and below the AGV M4 plate (Video, Supplemental Digital Content 1, http://links.lww.com/IJG/A51, demonstrates extensive dissection necessary to explant AGV M4). Care needs to be taken when dissecting below the AGV M4 plate to avoid scleral rupture by direct visualization and by pulling the AGV tautly away from the globe. This is in contrast to the AGV FP7 and S2 plates, which are made of silicone and polypropylene, respectively, which require minimal blunt dissection to explant after the capsule is opened. However, unlike the model FP7 there are no fixation holes in the plate of the model M4 through which dense fibrous tissue stalks form and must be transected to remove the implant. After the AGV M4 is removed, the conjunctiva should be approximated to the limbus and closed in the usual manner.

DISCUSSION This case series is the first to report of postoperative complications necessitating AGV M4 explantation and the successful removal of the implant. AGV plate exposures requiring explantation are not common. A recently published study documenting the postoperative complications after AGV M4 implantations found no cases of diplopia, plate, or tube exposure in the AGV M4 group.5 Tube exposure rates have been reported to range from 1.8% to 25%.8–10 In the Tube Versus Trabeculectomy study, despite Copyright

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Novel Ahmed Glaucoma Valve M4 Implant

FIGURE 1. A, Superotemporal Ahmed Glaucoma Valve (AGV) M4 plate exposure (black arrow) 6 months after implantation. B, Superotemporal AGV M4 plate exposure (black arrow) 9 months after implantation in a phthisical eye. C, Inferonasal AGV M4 posterior tube exposure adjacent to plate (black arrow) 1.5 months after implantation.

5 eyes of 107 with tube exposure, only 1 eye required the whole device to be explanted due to repeated exposures. Recently, in a retrospective paper comparing the 3 AGV models, only 2 of 154 eyes were complicated by plate exposure.5 Most cases of tube exposure, which occur at the limbus, can be effectively managed by conjunctival repair with or without a patch graft. Plate exposure, plate extrusion, or persistent diplopia, however, may necessitate device explantation, as conjunctival advancement or mucous membrane grafts have limited success.9,11 The 3 patients in this case series who had AGV M4 explantations due to plate or tube exposures had predisposing conditions: uveitis with prolonged use of topical steroids, a phthisical eye in a Hispanic patient with uncontrolled diabetes and multiple cardiovascular problems, and NVG requiring multiple intraocular surgeries with inferior positioning of the implant. In prior studies, risk factors for tube exposure included Hispanic ethnicity, NVG, prior trabeculectomy, multiple prior intraocular surgeries, and inferiorly placed implants.12–14 In both plate exposures in this study, the exposures occurred at the anterior corner of the plate, which is rigid with a moderately sharp edge (Fig. 2). All 4 cases in this series had the AGV M4 explanted within 9 months of implantation. Histologically, collagen and blood vessels course through the porous polyethylene implant unlike the prior AGV implants made of silicone and polypropylene.15 Because of this tissue integration into the implant, it has been thought that the removal of this implant would be extremely difficult with significant

FIGURE 2. The anterior edge of the AGV M4 where both plate exposures occurred (cases 1 and 2).

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amounts of fibrosis to the plate and bleeding. All cases did demonstrate more intraoperative bleeding than a typical case, which may have been due to either the vascular ingrowth into the plate or the inflamed nature of the conjunctiva. With careful dissection and removal of adhesions around the plate, the plate was successfully removed in all 4 cases. All 4 cases demonstrated clinical improvement postoperatively. As this is a new AGV model and all of the complications reported in this case series occurred during intermediate follow-up, it is not known whether AGV M4 explantation after a longer follow-up will be possible or safe. Although this case series identifies a group of patients who experienced complications requiring AGV M4 explantation, additional long-term studies need to be performed to determine the incidence and risk factors for complications with this new device in comparison with prior models of AGV. Although uncommon, AGV M4 explantation is sometimes necessary and is feasible during intermediate follow-up. REFERENCES 1. Huang MC, Netland PA, Coleman AL, et al. Intermediateterm clinical experience with the Ahmed Glaucoma Valve implant. Am J Ophthalmol. 1999;127:27–33. 2. Coleman AL, Hill R, Wilson MR, et al. Initial clinical experience with the Ahmed Glaucoma Valve implant. Am J Ophthalmol. 1995;120:23–31. 3. Christakis PG, Kalenak JW, Zurakowski D, et al. The Ahmed versus Baerveldt Study: one-year treatment outcomes. Ophthalmology. 2011;118:2180–2189. 4. Budenz DL, Barton K, Feuer WJ, et al. Treatment outcomes in the Ahmed Baerveldt comparison study after 1 year of followup. Ophthalmology. 2011;118:443–452. 5. Kim J, Allingham RR, Hall J, et al. Clinical experience with a novel glaucoma drainage implant. J Glaucoma. 2014;23: e91–e97. 6. Netland PA. Ahmed Glaucoma Valve Model M4. In: Samples JR, Ahmed II, eds. Surgical Innovations in Glaucoma. New York, NY: Springer Science + Business Media; 2014:223–225. 7. Cvintal V, Moster MR, Hu WD, et al. Clinical Experience of Ahmed M4 Tube Shunt in Various Types of Glaucoma: a Pilot Study. Washington DC: American Glaucoma Society Annual Meeting 2014; 2014. 8. Lotufo DG. Postoperative complications and visual loss following molteno implantation. Ophthalmic Surg. 1991;22: 650–656. 9. Smith M, Buys YM, Trope GE. Replacement of Ahmed aqueous drainage devices in eyes with device-related complications. J Glaucoma. 2009;18:484–487.

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10. Trubnik V, Zangalli C, Moster MR, et al. Evaluation of risk factors for glaucoma drainage device-related erosions: a retrospective casecontrol study. J Glaucoma. 2013. [Epub ahead of print]. 11. Low SA, Rootman DB, Rootman DS, et al. Repair of eroded glaucoma drainage devices: mid-term outcomes. J Glaucoma. 2012;21:619–622. 12. Koval MS, El Sayyad FF, Bell NP, et al. Risk factors for tube shunt exposure: a matched case-control study. J Ophthalmol. 2013;2013:196215.

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13. Pakravan M, Yazdani S, Shahabi C, et al. Superior versus inferior Ahmed Glaucoma Valve implantation. Ophthalmology. 2009;116:208–213. 14. Byun YS, Lee NY, Park CK. Risk factors of implant exposure outside the conjunctiva after ahmed glaucoma valve implantation. Jpn J Ophthalmol. 2009;53:114–119. 15. Wellisz T. Clinical experience with the Medpor porous polyethylene implant. Aesthetic Plast Surg. 1993;17: 339–344.

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Explantation of the novel Ahmed glaucoma valve M4 implant.

To report a series of cases involving Ahmed Glaucoma Valve M4 (AGV) explantation and to discuss the surgical technique to remove the drainage device...
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