Materials for intraocular lenses (IOLs): Review of developments to achieve biocompatibility

Abstract

It is true that the developments in material sciences along with the improvements in various aspects of technology involved in transforming materials into products, over the years, have been responsible for making many of the impossible-looking devices possible. It is also a fact that the demand for a new, improved and better material has never ended; in fact it has been increasing to a greater degree and with bigger dimensions than ever before, especially in recent times. As a matter of fact, for certain advanced applications, the need for efforts to have new materials can never be over emphasized; for example, in the area of biomedical devices such as intraocular lens (IOL). The advances in the field of bio-medical applications require the materials of high quality meeting stringent norms of performance. For implants such as the ones like IOL used for correction of vision of the eyes, besides the quality and performance of materials, biocompatibility is an issue of major concern. The material scientists have been working on the development of materials for IOLs targeting the needs arising out of the developing countries. The challenges include not only to bring down the cost of the materials used for IOLs but also to increase the biocompatibility of IOLs. For making the development process easy and bringing the state-of-the- art of knowledge to those looking for new materials, it is thought necessary to review various facets of IOLs in the present paper. Not only the aspects related to the recent developments in biomedical devices of eye care but also related to the properties of available materials vis a vis the deficiencies in properties of existing materials have been covered in this review. The aim has been to bring out the gap areas at various levels of process of product chain starting from the monomer to polymer, blank to IOL, insertion of IOL into eyes to life cycle of IOLs, mainly to provide certain possible and feasible leads to meet the challenges of making new and more biocompatible materials.

Drug-Eluting Intraocular Lenses

“…They have a low refractive index and are not recommended in patients in which silicone oil is used as vitreous substitute [9]. …”

“Cell adhesion resistant, UV curable, polymer zinc oxide nanocomposite materials for intraocular lens application”

“…Due to advances in lens materials and surgical procedures, cataract surgery has been simplified, and phacoemulsification method has emerged as the most popular surgical procedure for replacement of affected lens with synthetic lens . Foldable lenses suitable for this surgery are mainly available in 2 different polymer material classes, acrylic (hydrophobic and hydrophilic) and silicone . Common complication that follows surgical implantation is opacification at the posterior side of the implanted synthetic lens.…”

“…1 Foldable lenses suitable for this surgery are mainly available in 2 different polymer material classes, acrylic (hydrophobic and hydrophilic) and silicone. 2,3 Common complication that follows surgical implantation is opacification at the posterior side of the implanted synthetic lens. This is commonly referred to as posterior capsular opacification (PCO).…”

Interpenetrating photopolymers for intraocular lens application

“…Polymethyl methacrylate (PMMA) was the original material that was used in fabrication of IOLs in the early days, but, innovation in materials and design of IOLs since then has revolutionized surgical replacement of affected lens with synthetic lens. Acrylates and silicones are the main classes of polymers that are used in manufacture of IOLs . Controlling thermomechanical and optical properties of these polymers by manipulating the chemical structure of monomers used in their manufacture has provided a wide range of materials that differ in their surface properties (hydrophobic, hydrophilic, tack), optical properties (refractive index, optical transmittance), mechanical properties (dimensional stability, flexibility), etc.…”

“…Thus phacoemulsification procedure has become the most favored method for replacing lens in a cataract patient. IOLs are typically manufactured either by lathe cutting from a preformed block of optical grade material or by cast moulding . Former method has a disadvantage that it is associated with loss of precious optical grade material.…”