A SIMPLE WAY TO REMOVE MIRAGEL EXPLANTS AFTER LONG-TERM INFLAMMATION AND EXTRUSION Konstantinos Chalioulias, MRCSED, MRCOPHTH, Acharya Nachiketa, FRCSED, Rob Scott, MD, FRCSED, FRCOPHTH
Purpose: To report three cases of exposure of Miragel (Medical Instruments Research Associates, Waltham, MA) implants many years after buckling surgery and a new surgical technique to avoid significant fragmentation and achieve safe and effective removal of the exposed implants. Methods: Retrospective interventional series of three cases. Results: Many years after the initial retinal detachment surgery, Miragel explants can be exposed, causing inflammation. Their removal can be difficult due to increased fragility. Conclusion: We have developed a simple and safe technique to remove extruded Miragel explants, reducing the risk of fragmentation. RETINAL CASES & BRIEF REPORTS 3:74 –76, 2009
From the Vitreoretinal Unit, Birmingham and Midland Eye Centre, Birmingham, United Kingdom.
the lids. If required, a limbal stay suture is placed to expose the surgical field. The conjunctiva is reflected back using Wescott scissors (Duckworth and Kent, London, UK) and Moorfield forceps (Duckworth and Kent, London, UK) to expose the Miragel explant. The capsule around the explant is divided along its entire length. Care must be taken if the capsule extends under a rectus muscle. The sclera is carefully checked at this stage to confirm that the explant has not eroded into the uvea. A sub–Tenon space cannula with 10 mL of balanced salt solution is placed at the base of the explant, and gentle irrigation around the area allows the entire explant to be floated anteriorly out of the orbit when it is removed. Close inspection of the capsule remnant is made to confirm that no fragments of explant are inadvertently retained and that the sclera remains intact. The conjunctiva is repositioned with 7-0 polyglactin 910, and a topical antibiotic drop is administered.
ethylacrylate-2-hydroxyethylacrylate was first used in the 1980s in different forms (Miragel, Medical Instruments Research Associates, Waltham, MA) to achieve scleral indentation for retinal detachment surgery. It was then considered to be less prone to extrusion and infection and easier to manipulate1; however, long-term follow-up revealed that these implants had the tendency to erode late and cause inflammation. In addition, their removal proved to be a difficult task due to their fragility, and some surgical techniques have been introduced to deal with this problem, requiring special equipment or chemicals.2,3 We report our simple and safe technique to remove extruded Miragel explants, reducing the risk of fragmentation. Technique
A suitable local periocular anesthetic block is administered, and the eye is prepared with 1% povidone– iodine, a sterile drape, and a wire speculum to separate
A 67-year-old man presented with severe right sectorial scleritis associated with exposure of a scleral explant (Fig. 1). He had a history of bilateral cryopexy and buckling procedures for maculaon retinal detachments 12 years previously; 515 Miragel circumferential sponges were used in the procedures. The surgery on the right eye was initially unsuccessful, and the patient required two further procedures: one to readjust the explant, and one procedure including vitrectomy, cryopexy, and encirclement.
None of the authors has any proprietary interest in the development or marketing of any product mentioned in this report. Reprint requests: Dr. Rob Scott, Birmingham and Midland Eye Centre, Dudley Road, Birmingham, B18 7QH, United Kingdom.
MIRAGEL EXPLANT REMOVAL
cryopexy and Miragel scleral explant procedure 11 years earlier for a macular-on retinal detachment. She had developed a stage IV macular hole 12 months earlier and had declined treatment, although visual acuity was 20/80. There was a sectorial area of scleritis associated with an extruding Miragel scleral explant. The capsule was laid open, and the Miragel explant floated out (Fig. 2B) using a Stevens sub–Tenon space cannula; a careful check was made to ensure that it had not eroded through the sclera into the globe. No attempt was made to grasp the explant with forceps. The scleritis was treated with oral flurbiprofen (50 mg three times a day) and topical dexamethasone and resolved after 6 months.
Discussion Fig. 1. Case 1. Exposure of explant with localized scleritis.
The explant was surgically removed but fragmented when an attempt was made to grasp it with forceps (Fig. 2A). The capsule around the explant was divided along its full length, and the fragments floated out using balanced salt solution. The retina remained attached 6 months later with no loss of visual function; the scleritis resolved after 4 weeks of topical treatment with dexamethasone (0.1%).
Case 2 A 69-year-old man presented with a painful blind right eye with rubeosis iridis, sectorial scleritis, and an exposed scleral explant 14 years after bilateral surgery for macula-on retinal detachments. He underwent a right cryopexy and encirclement (silicone 240 band and 277 tire) procedure and a left cryopexy and silicone sponge explant procedure. The right eye required four further procedures, including insertion of a 515 Miragel explant followed by pars plana vitrectomy and silicone oil tamponade 2 years later for an inferior retinal detachment with proliferative vitreoretinopathy. The explant fragmented when an attempt was made to grasp it with forceps; it was removed by dividing the capsule around the explant, and the fragments were floated out using balanced salt solution. The scleritis resolved after 4 weeks of topical treatment with dexamethasone.
Case 3 A 90-year-old woman presented with a 3-month history of a severely painful red right eye. She had a history of a right
Fig. 2. A, Multiple fragments of explant after forceps removal in Case 1. B, Significantly less fragmentation after flotation of the explant from the sub-Tenon space in Case 3.
Methylacrylate-2-hydroxyethylacrylate was first used as an intrascleral implant in 1980. Its main advantages were the ability not to attract dust and less susceptibility to infection due to its small pores. Postoperatively, a capsule formed around the implant, which was thought to reduce the risk of exposure. The buckles were considered easy to remove or reposition.1 Methylacrylate-2-hydroxyethylacrylate was superseded by Miragel, which had a similar chemical composition but was inserted as a scleral explant. Miragel explants were used in all our cases. It was shown that methylacrylate-2-hydroxyethylacrylate had a tendency to erode externally through conjunctiva or into the vitreous cavity many years postoperatively. At removal, it was observed that the material was friable and the procedure was technically difficult.4 A similar experience of late extrusion and difficult removal was found with Miragel explants, although there was less chance of extrusion than with silicone explants. Microbial invasion of extruded Miragel explants was less than with extruded silicone explants. Swelling of the Miragel explant material with surrounding granulomatous inflammation and consequent chemical degradation were thought to cause its friability.5 From these studies, it was suggested that patients with Miragel buckles should be kept under review to detect swelling or exposure early, making removal of the explant easier. Various
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surgical techniques have been suggested to aid removal of Miragel explants, including the use of a cryoprobe or boric acid to dehydrate the buckle and reduce its friability.2,3 Our cases represent some of the longest recorded retention of this material before extrusion: 11 years to 14 years after surgery. In all our cases, the extruding explant was associated with localized scleritis, which was persistent in one case. This finding highlights the necessity to keep patients with Miragel explants under long-term follow-up. We believe that our technique of dissection of the capsule around the buckle with flotation of the explant using balanced salt solution is an excellent method of removing an extruding Miragel explant. It does not require complex chemical solutions or equipment, and it ensures complete removal of the material, reducing the degree of fragmentation. Care must be taken to
avoid rupturing the thinned, eroded sclera under the explant by not using excessive force. Key words: exposure, hydrogel implants, scleral buckling. References 1. 2.
Schepens CL, Acosta F. Scleral implants: an historical perspective. Surv Ophthalmol 1991;35:447–453. Le Rouic JF, Bejjani RA, Azan F, et al. Cryoextraction of episcleral Miragel buckle elements: a new technique to reduce fragmentation. Ophthalmic Surg Lasers 2002;33:237–239. Roldan-Pallares M, Avila MI, Refojo MF. The use of boric acid solution to help in the removal of biodegraded Miragel episcleral buckles. Retina 2005;25:90–93. Marin JF, Tolentino FI, Refojo MF, Schepens CL. Long-term complications of the MAI hydrogel intrascleral buckling implant. Arch Ophthalmol 1992;110:86–88. Le Rouic JF, Bettembourg O, D’Hermies F, et al. Late swelling and removal of Miragel buckles: a comparison with silicone indentations. Retina 2003;23:641–646.