LENS CAPSULE OPACIFICATION IN APHAKIC AND PSEUDOPHAKIC EYES

Background: Posterior capsule opacification (PCO) is the most common c omplication of lens extraction. Although intraocular lenses (IOLs) are thought to inhibit capsule opacification, the mechanisms by which the y do this are poorly understood. This study was done to determine the effects of pseudophakia on secondary cataract and PCO in experimentall y lentectomized dogs. Methods: Twenty-four normal dogs were bilaterall y lentectomized by phacoemulsification and unilaterally implanted with a plano-convex polymethylmethacrylate IOL. Secondary cataracts and ca psule opacification were evaluated at weeks 1, 2, 4, 10, 14, and 20 af ter surgery by retrolillumination photography, light microscopy, and s canning and transmission electron miscroscopy. Results: The pattern of secondary cataract and PCO in dogs was found to be similar to that in other animal species. Production of new lens material was prominent i n the equatorial region, and PCO resulted from fibrous metaplasia of l ens epithelium and subsequent capsular fibrosis and wrinkling. The pre sence of an IOL did not prevent the posterior migration of epithelium, nor did it prevent fibrous metaplasia. The presence of an IOL did, ho wever, minimize the capsule-wrinkling effects of fibroplasia and limit the space available for lentoid formation. Conclusion: In pseudophaki c eyes, IOLs influence secondary cataract formation by limiting the sp ace available for lentoid formation and by maintaining a linear scaffo lding for lens epithelial fibrous metaplasia.