Background: Current after-cataract prevention relies on optimizing the natural barrier effect of the optic rim against lens epithelial cell (LEC) migration. However, deficiencies in circumferential capsular bag closure caused by the intraocular lens (IOL) haptic or delayed secondary re-division of the fused capsules by Soemmering s ring formation lead to primary or secondary barrier failure. Consequently, surprisingly high posterior laser capsulotomy rates have been reported long-term, even with optimal capsular surgery and the most widespread hydrophobic acrylic IOLs, considered to be the most advanced. Intraoperative removal of the central posterior capsule has been shown to be effective in further reducing LEC immigration. However, efficacy has turned out to be limited because of the propensity of LECs to use the posterior optic surface as an alternative scaffold.
Technique: in pediatric cataract surgery, buttoning-in of the optic into an adequately-centered posterior capsulorhexis opening has been described previously. This technique was further elaborated and applied as the standard technique in a large series of adult eyes. In general, the diameter aimed at was 5-6 mm for the anterior, and 4-5 mm for the posterior capsulorhexis. Between September 2004 and June 2007, 1000 consecutive cases have thus been performed and systematically evaluated. One hundred and fifty eyes additionally underwent extensive anterior LEC abrasion. Another sub-series investigated the option of further reducing capsular fibrosis by creating an anterior capsulorhexis larger than the optic.
Evaluation: special scrutiny was applied to detect postoperative vitreous entrapment. Regeneratory and fibrotic after-cataract formation were both meticulously followed-up. Postoperative pressure course, anterior segment inflammation, macular thickness and morphology, as well as axial optic stability and optic centration, were evaluated in intraindividual comparison studies.
Results: A low rate of vitreous complications was found, which can be avoided by appropriate surgery. Vitreous entanglement occurred in six eyes, and vitreous herniation after PPCCC over-sizing in two. In three, anterior vitrectomy was performed. There was only one single case of retinal detachment-supposedly unrelated to the technique itself-and no case of cystoid macular edema. Retro-optical regenerate formation was completely abolished, while fibrosis was drastically reduced by the posterior capsule sandwiched in between the anterior LEC layer on the backside of the anterior capsule and the anterior optic surface, thereby blocking contact-mediated myofibroblastic LEC transdifferentiation. Additional capsular polishing further reduced residual fibrosis emerging from the anterior capsule contacting the optic adjacent to the haptic junction, as well as regeneratory LEC re-proliferation on the posterior capsule overlying the optic. Postoperative pressure course was almost identical to that found after standard in-the-bag implantation of the IOL, as was flare, and macular thickness and morphology. As opposed to bag-fixated IOLs, no axial movement of the optic was detected. IOL optics always perfectly centered even when the capsular opening was not optimally centered. Due to the exquisite stretchability and elasticity of the posterior capsule, the 6-mm IOL optic could safely be buttoned-in in a posterior capsulorhexis of 4 mm and smaller.
Conclusions: Posterior optic buttonholing (POBH) is a safe and effective technique which not only excludes retro-optical opacification, but also withholds capsular fibrosis by obviating direct contact between the anterior capsular leaf and the optic surface. Anterior LEC abrasion significantly reduced both the residual fibrosis and regeneratory LEC proliferation. Apart from pediatric cataract, POBH is currently recommended for eyes with pseudoexfoliation syndrome, high axial myopia, peripheral retinal disease, and multifocal IOL implantation. Toric IOLs and magnet-driven accommodative IOL systems are other potential applications. Generally, POBH holds promise for becoming a routine alternative to standard in-the-bag IOL implantation in the future.