Lane ea, lmaging of Hydrogel Episcleral Buckle Fragmentation as a Late Complication after Retina) Reattachment Surgery, AJNR Am J Neuroradio/ 2001;22:1199-1202  

In juni 2001 is de MIRAgel problematiek kernachtig beschreven in het artikel van Lane e.a.:

One of the objectives of retinal reattachment surgery is to relieve significant vitreous traction on the detached retina by indenting the sclera (buckling) to mechanically support the areas under traction. Silicone rubber bands are commonly placed circumferentially around the episcleral surface of the globe with grooved pieces of silicone rubber or sponge placed beneath the band, if necessary, to achieve a buckle of greater height.
Episcleral bands composed of MAl, a hydrophilic polymer (copoly[methyl acrylate-2-hydroxyethyl acrylate]) cross-linked with ethylene diacrylate, were introduced in the early 1980s as a superior product to bands composed of solid silicone rubber or silicone sponges for producing sc1eral buckles (1, 2). The softness and elasticity of this hydrogel substance were thought to guard against the scleral erosions occasionally seen with solid silicone rubber. As with silicone sponge, this gelatinlike polymer had the ability to absorb antibiotics; however, unlike sponge, its inherent lack of dead space theoretically made it less prone to infection. Enthusiasm over its use began to wane in the early 1990s owing to the unanticipated instability of the product in vivo (3, 4). An increasing number of reports of swelling and fragmentation of this buckling material, producing orbital discomfort and diplopia 7 to 10 years after implantation, led to its discontinuation in 1995. We report the imaging features of this late complication in five patients treated for retinal detachment with sc1eral buckle procedures using MIRAgel (Mira, Waltham, MA) encircling bands.

Zoals blijkt uit dit citaat is de MIRAgel plombe in 1995 vanwege zijn defecten van zwelling en defragmentatie uit de markt genomen. Ook uit onderstaand citaat blijkt dit (persoonlijk bij MIRA Inc. ingewonnen informatie).

MIRAgel and its precursor, MAl, are hydrophilic polymers that are permeable to water and other low molecular weight hydrophilic substances. The polymer is copoly(methyl acrylate-2-hydroxyethyl acrylate) cross-linked with ethylene diacrylate. It is softer than silicone rubber and therefore presumably less likely to produce scleral erosion or extrusion. It was initially thought th at its ability to absorb and slowly release water-soluble antibiotics would lead to a reduction in infectious complications, offering an advantage over silicone sponges. Early reports supported these assumptions (1, 2). However, longterm follow-up studies (7-11 years) began to reveal complications ranging from buIging to intraocular erosion and migration of the buckle (3,4, 8). At surgery, the fragmented bands were described as translucent, gellike, and friable. Surgical removal was complicated by a thick, fibrous capsule, which often fixed the swollen implant to Tenon's capsule, limiting the mobility of the globe. Removal of the fragmented implant in its entirety required meticulous technique but provided substantial relief of ocular discomfort and improved mobility, with a low risk of recurrent retinal detachment (12). Infrared spectroscopic analysis of recovered buckle fragments showed chemical alteration of the polymer, with hydrolytic degradation and swelling (3). The chemical alteration in vivo allowed the hydrogel to absorb more water. The implant changed from soft, spongy, opaque, and compact to friable, gellike, and translucent. The MIRAgel product was taken off the market in 1995 subsequent to these reports (personal communication, MIRA, Waltham, MA).

Lane ea besluiten hun artikel met:

Although the hydrogel product was pulled off the market in 1995, presentations of this late complication may occur for several years to come.