Current and future concepts of the design of the intraocular lens

Anterior chamber lenses are currently much less popular than posterior chamber lenses. They are mainly used in conjunction with intracapsular cataract extraction, as a secondary lens implant, and as a back up lens in case of intraoperative complications of extracapsular cataract extraction. A major disadvantage of anterior chamber lenses is improper sizing. Rigid lenses cause the greatest ocular tenderness and present serious problems with errors in sizing but they are the easiest to explant. Semiflexible and flexible lenses show a greater tendency to develop peripheral anterior synechiae. This makes explanation a very difficult procedure. Posterior chamber lenses are the most popular today. There is a trend toward all-PMMA lenses because of concern over the biocompatibility of polypropylene. The use of a laser ridge may inhibit posterior capsule opacification and facilitate YAG laser posterior capsulectomy. Ultraviolet blockers are being incorporated as a copolymer of a mechanical additive. There is a major trend towards capsular bag fixation of posterior chamber lenses as a result of complications associated with sulcus-fixated lenses. These include: disruption of the blood-aqueous barrier due to loop penetration of the ciliary body; chafing of the posterior surface of the iris leading to transillumination defects, microhyphaemas, and pigment dispersion glaucoma. It is predicted that the number of cataract extractions and the percentage of intraocular lens implantations will continue to increase due to demographic factors. Budgetary allocations for research and development will increase because of the involvement of some of the giants of medical industry. This will lead to new implant materials and new surgical techniques.