Shields ea, Expanding MIRAgel Scleral Buckle Simulating an Orbital Tumor in Four Cases, Ophthal Plast Reconstructive Surg.;2005,Jan; 21(1),32-34  

Shields ea beschrijven in een artikel van januari 2005 vier patiënten met "uncomplicated retinal detachment surgery 12 to 20 years earlier", bij wie "orbital tumor" vermoed werd. Het bleek hier te gaan om "a swollen MIRAgeI implant". Zij concluderen dat patiënten zich vaak geen bijzonderheden van de oogoperatie herinneren. Zij waarschuwen dat de medisch specialist de MIRAgel implant herkent en anticipeert op ‘postoperative clinical challenges’ indien de implant gedeeltelijk is verwijderd of verstoord.

Abstract - Conclusions
MIRAgel scleral buckle material can greatly enlarge over a period of 10 years and simulate an orbital tumor or orbital cyst. Patients often do not recall details of the retinal surgery. Caution is advised regarding excision of this material because it is friable and can lead to extensive postoperative inflammation.
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 Several materials have been used as scleral buckling elements, including silicone sponge, silicone rubber, and hydrogel. The hydrogel implant (commercial name MIRAgel, Waltham, Massachusetts) was a popular scleral buckle in the 1980s and early 1990s, as it was marketed as a soft, flexiblc implant with physical properties allowing it to swell slowly over time, irnproving the buckling effect, lacking dead space, and minimizing infection. ^1-4 
Camplications of MIRAgeI have been reported. A study of 757 eyes with a scleral buckle followed for a mean of 6 years revealed that removal of the element was necessary in 9% of those with silicone sponge, 1% of silicone rubber, and 1% of MIRAgel.⁵ However, most authors have noted that extrusion or complications of MIRAgel happen after 10 years' follow-up, and, more importantly. that removal of MIRAgel is challenging because it typically undergoes fragmentation and can lead to serious periocular inflammation.^5-15 In 1997, Hwang and Lim ¹⁰ reported the first case of MIRAgel scleral buckle extrusion and emphasized the long-term friability of this material. leading to fragmentation at the time of removal. 
In this report we describe 4 patients who were referred to us with an enlarging orbital mass, presumed to be a malignancy. All 4 patients vaguely recalled retinal detachment surgery 12 to 20 years earlier without postoperative problems. None of the patients had any information regarding the surgical technique or scleral buckling element. We suspected MIRAgel implant in 3 patients and avoided surgery, but 1 patient underwent orbital exploration for presumed orbital cyst, and piecemeal removal ofthe "friable soft mass" was necessary, leading to extensive postoperative inflammation. We caution the orbital surgeon to recognize this implant and anticipate postoperative clinical challenges if this implant is partially removed or disturbed.

De auteurs vermelden dat hydrogels aanvankelijk superieur werden  geacht boven siliconen plombes en sponges, en dat de eerste 4 tot 5 jaar slechts minimale complicaties werden gerapporteerd. Maar na  7 tot 11 jaar kwamen complicaties aan het licht als gevolg van uitgebreide zwelling van de implant en zelfs erodering van de implant in het oog. Zij verwijzen ook naar de door Marin in 1992 gerapporteerde casus 4: “In one case, a fragment of hydrogel foated through the eroded sclera in the vitreous cavity” 7 en verder naar de bevindingen van LeRouic ea, Li ea en Braunstein. Hoewel Miragel als gevolg van de complicaties van de markt is gehaald, is deze implant bij vele patiënten toegepast en lopen de risico’s die de auteurs hebben beschreven.

Discussion (…)
MIRAgel is a hydrogel (copoly methylacrylate-2-hydroxyethyl acrylate), which is a hydrophilic material formed from 3-dimensional polymer networks. ¹ Hydrogels are low-molecular-weight substances that are permeable to water and can absorb and slowly release water-soluble substances such as antibiotics.³ This elastic buckling material was shown to be as effective as silicone rubber or sponge and believed to be possibly superior as the result of its low risk for infection. Early related complications in the first 4 to 5 years were reportedly minimal. ^3-4 However, long-term observations of hydrogel implants at approximately 7 to 11 years revealed some complications related to extensive swelling of the implant.⁷ These included conjunctiva] buIging, implant migration, and rarely implant erosion in the eye, occasionally with poor visual outcome. Removal of implant material was particularly difficult because fragmentation of the swollen, friable material with piecemeal removal was encountered. In one case, a fragment of hydrogel foated through the eroded sclera in the vitreous cavity.⁷ 
In 2003, Le Rouic et al. ⁶ compared complications from various buckling elements and found that MIRAgel complications occurred much later (mean, 92 months) than solid silicone (mean, 11 months) and silicone sponges (mean, 19 months). The progressive swelling of MIRAgel led to limitation of ocular motility, diplopia, ocular pain, ocular inflammation, and protrusion of the buckle beneath the eyelids, necessitating removal in 34 of 38 eyes (90%). The rate of buckle infection was much lower with MIRAgel than other buckling materials. In 2003, Li et al. ¹³ cautioned that complications of this material could be on the rise because it was used extensively in the past decade. and most complications occur approximately 10 years after placemcnt. Difficult removal should be anticipated.¹³
Swollen MIRAgel can resembIe an orbital tumor. In 2002, Braunstein ¹² described a patient who had diplopia and an orbital mass 13 years after MIRAgel buckle. On MRI, there was no indentation of thc eye and, in fact, the swollen buckJe had folded on itsclf. creating an orbital mass effect. The buckle had expanded 4-fold in volume, and tedious removal was encountered. Case I in our series showed similar folding of the buckle on itself secondary to swelling, leading to the appearance of a knuckle. To avoid buckle fragmentation at removal, Le Rouic et al.¹⁸ advised opening the conjunctiva generously and using cryoextraction rather than forceps extraction. 
The orbital surgeon should be aware of the orbital complications of retinal detachment surgery. Previous reports on orbital complications from scleral buckles have described clear or hematic orbital cysts.^19-21 From the results in this report, we add the complication of MIRAgel that includes marked late onset swelling of the implant, simulating a solid or cystic tumor. In each of our 4 cases, the patient was referred by an ophthalmologist with a newly diagnosed. enlarging orbital mass. In 3 cases, the mass was visible in the superotemporal orbital region near the lacrimal gland fossa, raising concern for a lacrimal gland tumor. In each case, the mass proved to be swollen MIRAgel implant.
MIRAgel has subsequently been rcmoved from the market. However, many patients have this implant and are at risk for development of the problems seen in our cases. It is not known if injection of corticosteroids might minimize the tissue swelling. The orbital surgeon should recognize this implant and be prepared for challenging surgical removal if necessary.