Tissue reaction after silicone and poly(methyl methacrylate) intraocular lens implantation: a light and electron microscopy study in a rabbit model.

We describe the histopathologic results of extracapsular lens extraction and silicone and poly(methyl methacrylate) (PMMA) intraocular lens (IOL) implantation in 36 rabbit eyes. Phase-contrast microscopy was used to examine precipitates on IOL surfaces and posterior capsules. Semithin and ultrathin sections were taken from the central cornea, anterior uvea, capsular bag, and retina near the posterior pole. The follow-up was one to 16 weeks. Silicone IOLs did not cause significantly less precipitation than PMMA IOLs. Precipitates consisted of spindle-shaped fibroblast-like cells, various forms of inflammatory cells and multinucleated giant cells, single melanophages, and irregularly arranged birefringent collagen fibers. Corneal endothelial edema was slightly more prominent in PMMA IOL implanted eyes. Significant retinal edema in the posterior pole area was not observed with either of the two lens types. Severe precipitation in the form of large clusters of pigment cells and inflammatory reactions seemed to depend on mechanical trauma (iris capture and lens dislocation) and individual animal reactions, but not on the lens type used.