Eighteen eyes containing an intraocular lens (IOL) removed post mortem from 16 patients after an uncomplicated postoperative course of up to 50 months, and 2 IOLs removed intraoperatively were studied macroscopically, histologically and ultrastructurally to detect changes in the lenses themselves and in the surrounding ocular tissues. Various types of lens-loop degradation, erosion of the iris pigment epithelium with formation of posterior synechiae and pressure atrophy of the iris stroma were found, but there was little evidence of iritis. A mixed cell population containing many foreign-body giant cells had settled on most lenses, some of which were encased in membranes. The loops of one Sinskey PCL had penetrated the ciliary body and iris root to reach the trabecular meshwork. The significance of these findings is discussed.