Satu Länsman, Evaluation ofbioabsorbable poly-1/d-lactide implant for scleral buckling, 2009, blz. 39-40  

Länsman vermeldt dat er destijds drie types hydrogel bestonden: PGMA, PHEA en MAI. Alleen MAI is gecommercialiseerd. Toepassing van de MAI hydrogel geschiedde zowel episcleraal als intrascleraal maar is gestaakt als gevolg van lange termijn complicaties, namelijk aanzienlijke zwelling.

Hydrogels are semisolid hydrophilic materials with the ability to absorb water. Three types of hydrogels have been tested, polyglyceryl methacrylate (PGMA), poly(2-hydroxyethyl acrylate) (PHEA), copoly(methylacrylate-2-hydroxyethyl acrylate) (MAi) but only MAI has been commercially available (Refojo et al. 1980, Tolentino et al. 1981, Schepens et al. 1991). An MAI implant bas been used both episclerally and intrasclerally (Tolentino et al. 1981 ). It was in clinical use for several years but was abandoned due to long-term complications (Schepens et al. 1991, Marin et al. 1992, Hwang & Lim 1997, Roldán-Pallarés et al. 1999).
The swelling of hydrogels has been reported to occur to a remarkable degree in a relative volume, i.e. one study reported that the cross-sectional area of hydrogel implants had increased on average by 185% in a group of 28 patients (Oshitari et al. 2003). The reasons for implant removal were sensation of foreign body, subconjunctival bulge, ocular motility problems and pain (Oshitari et al. 2003, Le Rouic et al. 2003). A histological follow-up from 3 weeks to 3 months in rabbits noted that the material was surrounded by a capsule of connective tissue. In three weeks there was a mild inflammatory reaction but in 3 months there were almost no inflammatory cells (Refojo et al. 1980). Later in experimental studies in rabbits with a longer follow-up it was found that the material became surrounded by a capsule of connective tissue, but the inner surface of the capsule contained deposits of material (indicating material fragmentation) surrounded by foreign body giant cells (D´Hermies et al. 1995, D´Hermies et al. 1999b). Findings of irregular inner surface of capsule and foreign body giant cell granulomas have also been found in human samples (D´Hermies et al. 1998, D´Hermies et al. 1999a).