title: Cytotoxic effects of residual chemicals from polymeric biomaterials for artificial soft intraocular lenses.
abstract: Development of improved hydrogels for soft intraocular lenses, based on 2-hydroxyethyl methacrylate monomer, requires the use of various other monomers and polymerization additives which have potential ocular toxicity. Three monomers, 2-hydroxyethyl methacrylate, methyl methacrylate, and 2-ethoxyethyl methacrylate, as well as two common inhibitors, hydroquinone and 4-methoxyphenol, were subjected to in vitro cytotoxicity assays as aqueous solutions at different concentrations. A new polymerization initiator, 2,2'-azo-bis-(2,4-dimethyl valeronitrile), was thermally decomposed in water at different concentrations and the products were also assayed for cytotoxicity. Assays were based on incubation with human choroidal fibroblasts. Cell death was evaluated by trypan blue dye exclusion, DNA synthesis inhibition, and lactate dehydrogenase tests. While methyl methacrylate and 2-ethoxyethyl methacrylate were found nontoxic, the other chemicals displayed high cytotoxicity. However, when extracts of synthesized poly(2-hydroxyethyl methacrylate) specimens, differentially treated after polymerization, were subjected to the same assays it was found that toxicity from residual 2-hydroxyethyl methacrylate monomer was lost during steam sterilization and storage in water because of the removal of the monomer through aqueous washing. The lack of toxicity in these specimens suggests that residual contents of inhibitor and initiator are too low to cause toxic effects on choroidal fibroblasts. It is concluded that hydrogels have low cytotoxic effects in vitro.
authors.affiliation: Lions Eye Institute, Perth, Western Australia.
authors.forename: T V
authors.initials: TV
authors.lastname: Chirila
authors.forename: L N
authors.initials: LN
authors.lastname: Walker
authors.forename: I J
authors.initials: IJ
authors.lastname: Constable
authors.forename: D E
authors.initials: DE
authors.lastname: Thompson
authors.forename: G D
authors.initials: GD
authors.lastname: Barrett
mesh_terms: D000840:Anisoles / Q000633:toxicity; D001391:Azo Compounds / Q000633:toxicity; D001672:Biocompatible Materials / Q000633:toxicity*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002829:Choroid / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology; D006801:Humans; D006873:Hydroquinones / Q000633:toxicity; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D007910:Lenses, Intraocular; D008689:Methacrylates / Q000633:toxicity; D008768:Methylmethacrylates / Q000633:toxicity; D009570:Nitriles / Q000633:toxicity
chemical_list: D000840:Anisoles; D001391:Azo Compounds; D001672:Biocompatible Materials; D006873:Hydroquinones; D008689:Methacrylates; D008768:Methylmethacrylates; D009570:Nitriles; C055792:2,2'-azobis(2,4-dimethylvaleronitrile); C029263:2-ethoxy ethyl methacrylate; C005044:hydroxyethyl methacrylate; C009760:mequinol; D007770:L-Lactate Dehydrogenase; C031927:hydroquinone