Chung ea, Diplopia and periorbital mass associated with Mirage! buckling explant, Korean J Ophthalmol. 2004 Jun; 18(1):47-51  

In een artikel van juni 2004 beschrijven Chung ea het eerste Koreaanse geval, een patiënte met een gezwollen en gefragmenteerde Miragel explant, 9 jaar na de netvliesoperatie. 

Abstract
A 28-year-old female presented with a palpable mass lesion on the superonasal aspect of her right globe and she had a progressive diplopia. She had a scleral encircling surgery with a Miragel explant (MIRA, Waltham, Mass, USA) for the tractional retinal detachment associated with pars planitis 9 years previously. On examination, she revealed restricted eye movements of her right eye. The magnetic resonance imaging documented a swelling of the Miragel explant that mimicked a periorbital mass lesion. The Miragel explant was removed and fragmentation of the explant was found intraoperatively. The removed Miragel explant was examined by a scanning electron microscopy, and this demonstrated a disintergrated and swollen structural eomposition of the Miragel explant. Postoperatively, her extraocular movement was almost restored and the retina remained weil attached. Alterations in the structural composition of the Miragel explant results in an excessive swelling that causes a restrietion of the extraoeular movement, and this can mimiek a periorbital mass lesion.

INTRODUCTION
Hydrogels that are used in retinal reattachment surgery are hydrophilic materials formed by a 3-dimensional polymer network. Miragel (MIRA, Waltham, Mass, USA) is a soft, elastic and smooth material, and it is one of the most widely used hydrogels. It consists of co-poly (methylacrylate-2-hydroxyethy acrylate) cross-Iinked with ethylene diacrylate and 15% water. It was first introduced in the late 1970s and initially, it was thought to offer several advantages over the silicone materials that were then used.1,2 It was soft, elastic and considered less likely erode through the conjunctiva. The material did not contain any dead space and it could absorb and slowly release antibiotics; this minimized the risk of infection. However, the explant was withdrawn from the market in the 1990s because of the late complications occurring 7 to 11 years after the surgery.3-6 These problems include erosion into the globe, extrusion of the explants, formation of a periorbital mass and a progressive diplopia. In this paper, we report a case of the development of a progressive diplopia associated with restricted extraocular movement and the presence of a pseudo tumor 9 years following the use of a Miragel explant. This case presents the first Miragel-associ ated, long-term complications reported in Korea.

Bij de operatieve verwijdering bleek het Miragel materiaal extreem bros en het neigde te desintregeren bij pogingen het met een tang vast te pakken. De plombe was gezwollen tot 2.06 maal de oospronkelijke grootte.

CASE REPORT
(…) At surgery, the Miragel material was found to be encapslilated with a thick fibrous capsule and it was extremely friable and tending to disintergrate when we tried to hold it with forceps. (Fig. 3) A tedious and complete removal of the encircling material was done, along with the dissection and removal of the fibrous capsule on the explant. 
The removed Miragel material demonstrated that the buckle had swollen up to 2.06 times its original size. Scanning electron microscopy revealed a deteriorated material with micropores; the explant was distorted in shape and irregular in size.(Fig. 4 A,S) (…)
 

De auteurs vermelden de historie van de hydrogel explant, de aanvankelijek voordelen boven conventionele siliconen materialen en de later gebleken lange termijn complicaties. 

DISCUSSION 
Scleral buckling material evolves from the autologous fascia Iata to attach to the non-absorbable synthetic agents, such as polyethylene, silicone, and hydrogels. The hydrogels, including Miragel, were initially thought to be ideal substitutes for the other synthetic material because their structural and chemical characteristics. The explant was as effective in buckling as solid silicone rubber and silicone sponge, Altering the state of hydration could vary the degree of swelling and this increased the buckling height in the immediate postoperative period. Hydrogels were soft, elastic and considered less likely to erode through the conjunctiva. In addition, the material was assumed to be less prone to infection because it did not contain any dead space and it could absorb and slowly release water-absorbable antibiotics. ^1,2 However, the long-term complications of the Miragel material began to emerge 7 to 11 years following the surgery.^3-6 The complications included erosion into the globe, extrusion of the explants and a progressive diplopia. The material has shown to be structurally unstable and this leads to excessive water absorption, swelling and disintergration. ^2-4 These complications necessitated the removal of buckling material. At surgery, the explants were seen as translucent and gel-like materials that were extremely friable, and this made it hard to remove them with a conventional method of using scissors and forceps. This resulted in a particle retention on removal of the scleral buckling element. According to the report by Marin, the alteration of the material is associated with a deterioration of its chemical composition. ² Micro-Fourier transform infrared spectroscopie analysis of recovered impJants demonstrated the hydrolytic degradation of the implant; this led to a swelling greater than the original polymer.³ In our present case, the Miragel explant that was removed from the patient had swollen to 2.06 times its original volume. This resulted in a restrietion in extraocular movement and the formation of a mass-like lesion. 

Zij roepen de oogartsen op om zich bewust te zijn van de problemen en hun patienten regelmatig te volgen:

Considering the historical data and the late complications observed in the present case, the hydrogel explants can no longer claim to provide advantages over other conventional scleraJ buckling materiais. The hydrogel explants have been withdrawn from the market since the 1990s. As these complications usually occur 7 to 11 years following the surgery, it is highly recommended for the ophthalmologists who have used hydrogel materials in retinal surgery to be aware of these problems and do regular follow ups for the patients with hydrogel explants.