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May 28, 2006
Uveitis after IOL removal
Review of Ophthalmology May 2006
Foldable acrylic IOLs, despite excellent safety, sometimes require removal. Following two cases of unexpectedly protracted post lens-removal uveitis, researchers at the Texas Health Science Center, San Antonio, sought a physical or chemical basis for such chronic inflammation associated with a brief intraocular exposure to a transected acrylic lens.They tested four commercially available acrylate-methacrylate copolymer lenses. Lenses were cut with a surgical scissors to check for ejection of physical debris. Chemical analysis of the supernatant was carried out to determine if potentially irritating substances were liberated. Lens fragments were soaked in a variety of solvents and deionized water (DIW). Nuclear magnetic resonance spectroscopy confirmed the structures of liberated chemical compounds.Videomicroscopy demonstrated that no solid lens fragments were released during cutting. In both methylene chloride solvent and DIW, bis-2-ethylhexyl phthalate was identified with gas chromatography, and the structure confirmed with NMR. Phthalates are chemical compounds that are added to plastics to increase their flexibility. The concentration of phthalate eluted into ionized water (~35 µg/ml) was comparable to that liberated by methylene chloride (~50 µg/ml). They exposed cultured human lens epithelial cells to the identified phthalate to evaluate cell viability. The results indicated cell viability was reduced at phthalate concentrations as low as 20 µg/ml. As a result, the group recommends that if replacement of a defective lens becomes necessary, bisection of the lens in situ should be avoided, as a bisected IOL may release phthalates into the eye. Because bis-2-ethylhexyl phthalate was isolated in DIW, it could be released into the aqueous and affect intraocular tissues. The emerging awareness of the toxicity of low-level phthalates in a variety of biological settings warrants further studies of the interaction of plasticizers with intraocular tissue.608
Posted by mehdi khanlari at May 28, 2006 11:24 PM