Is chronic intraocular inflammation after lens implantation of bacterial origin?

In an effort to better understand the cause of chronic intraocular inflammation after intraocular lens (IOL) implantation, both scanning and transmission electron microscopy were used to compare 1 anterior chamber, 1 iris-fixated, and 3 posterior chamber IOLs removed for this condition between 2 and 16 months after implantation with 8 IOLs explanted for other reasons (decentration in 4 cases, bullous keratopathy in 4 cases). Colonization with non-slime-producing, as well as slime-producing bacteria (1 case) in the presence of a thin membranous structure of cellular origin (multinucleated giant cells and macrophage-like cells) was demonstrated on all of the 5 IOLs explanted from inflamed eyes. Neither bacteria nor membranous structures could be identified on the IOLs removed because of dislocation or from eyes with bullous keratopathy. These observations indicate that bacterial colonization and the consequent host response may be characteristic features of many otherwise unexplained cases of intraocular inflammation after IOL implantation.