Lens epithelial inhibition by PMMA optic: Implications for lens design

Abstract

It has been a clinical impression that posterior chamber lens implants in some way inhibit opacification of the posterior lens capsule after extracapsular cataract extraction. The mechanism of this inhibition is unclear; it may be related to mechanical contact or blockage of migration of lens epithelial cells, or possibly to the leeching of toxic factors from the lens itself. A better understanding of the exact mechanism of opacification inhibition may have important clinical implications for intraocular lens design. For example, some lens designs that facilitate Nd:YAG capsulotomy by physically separating the posterior chamber lens and the posterior capsule may result in less inhibition and in fact more opacification of posterior capsules. We performed in vitro tissue culture studies of the effect of the polymethylmethacrylate (PMMA) optic of a planoconvex intraocular lens on cultured rabbit lens epithelium. These studies demonstrated both inhibition of lens epithelial migration beneath the PMMA optic (plano side down) as well as metaplasia and necrosis of lens cells growing directly beneath the optic. The clinical implications of these studies for intraocular lens design are discussed.

Posterior Capsule Opacification in Mice

“…These models have been used to study the pathogenic mechanisms that lead to PCO and to search for new therapies to prevent or treat this common complication of cataract surgery. In vitro models have included the use of cultures of lens epithelial cells (LECs) 3,4 and intact capsular bags. 5,6 Although cell cultures are adequate to evaluate LEC growth, the matrix and the culture medium used to grow these cells would be expected to affect the growth rate and the molecular characteristics of these cells.…”

Lens Epithelial Cell Migration between Posterior Capsule and Intraocular Lens with Variously Finished Posterior Optic Edge and Two Haptic Angulations

“…If For the purpose of a safe and easy prevention of PCO, we could consider the advancement of surgical techniques [3], topical medication [4] and design of IOLs. Santos et al [5] first described a barrier effect of IOLs against PCO in 1984, and other investigators confirmed it [6,7]. Nagata and Watanabe [8] and Nishi et al [9] proposed 'the sharp-edge effect' of the IOL for the reduction of PCO in clinical series, and many authors reported that IOLs with a sharp edge were beneficial for the reduction of PCO [10][11][12][13].…”

Aziridine in polymers: a strategy to functionalize polymers by ring-opening reaction of aziridine

“…Because of its high transparency, lightweight, and shatter-resistant characteristic, PMMA has attracted significant interest as an alternative to glass for applications in optoelectronic and medical devices. [20][21][22][23][24] With regard to post-modification, PMMA has inherently limited functionalizable ester side chains on its backbone. A strategy to modify PMMA is to exploit the possible reactions that can be performed with its methyl ester units.…”