Sandwich theory: bioactivity-based explanation for posterior capsule opacification

Abstract

Purpose: To present a bioactivity-based explanation for posterior capsule opacification (PCO) formation after cataract surgery.

Setting: Central Hospital, Vaasa, Finland.

Methods: The sandwich theory was based on findings in a keratoprosthesis study in which bioactivity of the prosthesis seemed to prevent epithelial downgrowth and clinical findings of the behavior of the AcrySof intraocular lens (IOL). The theory was formulated to explain PCO formation after cataract surgery with posterior chamber IOL implantation.

Results: If the IOL were of a bioactive material, it would allow a single lens epithelial cell to bond both to the IOL and the posterior capsule. This would produce a sandwich pattern including the IOL, the cell monolayer, and the posterior capsule. The sealed sandwich structure might prevent further epithelial ingrowth and PCO.

Conclusion: The degree of IOL bioactivity could explain the difference in PCO and the neodymium:YAG rates with different IOL materials. In theory, a bioactive IOL would prevent PCO better than poly(methyl methacrylate) and silicone IOLs, which have good biocompatibility but are bioinert.