Francesco Baino, The Use of Polymers in the Treatment of Retina) Detachment: Current Trends and Future Perspectives, Polymers 2010, 2, 286-322  

Baino vermeldt - evenals eerder Länsman – dat destijds drie types hydrogel uitgebreid zijn onderzocht: PGM, PHEA en MAI, dat onder de naam Miragel verkocht werd. MAI werd door vele chirurgen als de ideale oplossing beschouwd voor netvliesoperaties, maar na 10 jaar bleken excessieve zwelling en fragementatie op te treden met risico op ernstige complicaties en de noodzaak van operatieve verwijdering. Om die redenen zijn MAI implants geleidelijk in onbruik geraakt.

p. 294-296
6.1. Permanent Buckles
6.1.1. Implants Fallen in Disuse: Historical Overview
(…)
A particular mention should be made to hydrogel implants, as they were considered superior to silicone implants for almost 20 years (from their introduction in the mid 1970s to their progressive abandonment in the 1990s), especially as they were softer and seemed to carry a lower risk of infection (less than 1 % vs. 2-5%) [51,52]. Specifically, three types of hydrogels, i.e., poly(glyceryl methacrylate) (PGMA), poly(2-hydroxyethyl acrylate) (PHEA), and poly[methyl acrylate-co-(2-hydroxyethyl acrylate)] (MAI), have been widely investigated [53]. Major advantages of hydrogels are softness, defined swelling under hydration and the potential to act as devices for the controlled release of hydrophilic drugs [54], which is an advantage over solid silicone implants in controlling infection. PGMA was found to suffer from lack of tensile strength when swollen, whereas PHEA exhibits a dramatic tendency to fragment after swelling [55]. MAI, which is commercially sold as Miragel, offers better bulk features and can promote the formation of a strong surrounding capsule [53,54]. Although Miragel has been considered by many surgeons as the ideal solution for scleral buckling, fragmentation of such implants can occur after 10-year follow-up [55-58], as well as buckle overexpansion [56,59], with an associated risk of severe longterrn complications (persistent pain, foreign body sensation) and the need of re-operation for implant removal.
 

Baino F. (2010). Scleral buckling biomaterials and implants for retinal detachment surgery. In: MEDICAL ENGINEERING & PHYSICS, vol. 32, pp. 945-956. - ISSN 1350-4533  

p. 15-16
5.5. Hydrogels
Since the early 1970s, three type of hydrogels, i.e. poly(glyceryl methacrylate) (PGMA), poly(2-hydroxyethyl acrylate) (PHEA) and poly[methyl methacrylate-co-(2-hydroxyethyl methacrylate)] (MAI), have been widely tested in scleral buckling procedures [10,85-91] and MAI has been commercially available under the name of Miragel for several years. Hydrogels, thanks to their softness, ease of shaping and defined swelling under hydration, have been considered for many years as the revolutionary materials in scleral buckling surgery. Some authors also emphasized the potential of hydrogels to act as devices for the in situ release of hydrophilic drugs, which could be an additional advantage over solid silicone implants in controlling infections [92]. After the initial enthusiasm, however, many surgeons realized progressively that hydrogel buckles could induce severe mid-term and long-term complications [93-99]. Specifically, PGMA was found to suffer from a lack of tensile strength when swollen and PHEA exhibited a dramatic tendency to fragment after swelling [95]. MAI implants, which could be placed both intrasclerally and episclerally, seemed to offer better bulk features and were found to promote the formation of a strong surrounding capsule of connective tissue [45,47,100,101]; although after 3 weeks from implantation a mild inflammatory response was generally detected, after 3 months almost no inflammatory cells were found [88]. In spite of their excellent biocompatibility, however, in many cases MAI buckles need to be removed due to foreign body sensation, ocular motility limitations, subconjunctival bulge or pain complained by patients [96,97,99]. These drawbacks were essentially ascribable to hydrogel overexpansion: Oshitari et al. quantified this problem and reported that the cross-sectional area of MAI implant could increase up to 185% due to excessive swelling [97]. In addition, experimental studies carried out in both rabbits and humans demonstrated that MAI implant became surrounded by a capsule of connective tissue, but the inner surface of this capsule was irregular due to the presence of hydrogel debris and foreign body giant cells, which indicated material fragmentation [45,47,100,101]. Therefore, also MAI implants have been progressively fallen in disuse, particularly due to buckle degradation and friability occurring after about 10 years, as reported by several researchers [93,94,98].