CAUSES OF SEVERE DECENTRATION AND SUBLUXATION OF INTRAOCULAR LENSES

Background: Severe decentration and subluxation of intraocular lenses (IOLs) may lead to double vision, glare and deterioration of vision to the point of functional aphakia. The purpose of the present study was to analyse causes for severe IOL dislocation. Material and methods: B etween January 1989 and January 1996, 37 patients required IOL exchang e because of decentrated or subluxated posterior chamber lenses. Twent y-five of the exchanged lenses were implanted in our hospital, 12 lens es elsewhere. After explantation the lenses were examined by light and electron microscopy. Results: In 10 eyes, asymmetric implantation of the posterior chamber lens was responsible for decentration. Three of the lenser concerned were multifocal IOLs. Asymmetric implantation led to a significantly higher rate of explantations in eyes with multifoc al lenses (P<0.005). In five eyes decentration developed due to asymme tric capsular shrinkage, in four eyes due to posterior synechiae. A le ns subluxation developed in three eyes as a result of rupture of the p osterior capsule and in nine eyes because of zonular defects. In three cases decentrations were induced by an extensive secondary cataract. Macroscopically visible changed, geometry of the haptics was found in nine lenses; eight of these had polypropylene haptics. Seven lenses sh owed severely altered haptics on electron-microscopic examination. In four eyes subluxated lenses had to be explanted together with the caps ular bag because of severe defects of the zonula, which caused decentr ation in nine eyes, Conclusions: Asymmetric implantation of posterior chamber lenses should be strictly avoided. Multifocal lenses require s pecial attention concerning symmetric capsulorhexis and positioning of their haptics.