An Introduction to Intraocular Lenses: Material, Optics, Haptics, Design and Aberration

Several intraocular lens (IOL) materials and types are currently available. Polymethyl methacrylate IOLs used to be the gold standard, but the inability of folding limits their use to selected countries and patients. Silicone IOLs were used more in the past because they are less suitable for microincisions. Foldable hydrophobic acrylic is the most popular material, which is also available in yellow (blue light absorbing) models and several IOL shapes. Although a very effective and safe material, water penetration producing glistenings and some dysphotopsia has been reported with some IOL types. Foldable hydrophilic material is widely employed in Europe, and especially for microincision cataract surgery lenses because of its plasticity, even if rare optics opacification and higher posterior capsular opacification rates have been reported in the past. Single-piece IOLs are the most employed in modern cataract surgery, but 3-piece IOLs are preferred for sulcus implantation and in infants. The aspheric design to correct or to control spherical aberration in implanted eyes is now the rule after the problems of centration we had before the capsulorhexis era were solved. However, the optical quality of pseudophakic eyes will depend not only on aberration control, but also on good media transparency and low light scattering. Copyright © 2013 S. Karger AG, Basel Definition and History An intraocular lens (IOL) is a lens implanted in the eye to treat large refractive errors. IOLs usually consist of small optics with side structures, called haptics, to hold the lens in place within the capsular bag inside the eye. The most common type of IOL is inserted into the capsular bag after cataract (lens) removal and is known as ‘aphakic IOL’. The second type of IOL, more commonly known as a phakic IOL, is placed inside the eye without removing the existing natural lens, to correct large refractive errors. The first IOL was implanted by Sir Harold Ridley on 29 November 1949, at St Thomas’ Hospital in London (fig. 1). That first IOL was manufactured from polymethyl methacrylate (PMMA, also known as Perspex or Plexiglas), that was chosen because Ridley noticed it was inert in the eyes of RAF pilots [1]. The IOL concept spread slowly until the 1970s, when new and lighter posterior chamber lenses were designed, introducing polypropylene haptics for ciliary sulcus fixation [2]. Currently, there are several types and models of IOLs designed for specific purposes. Güell JL (ed): Cataract. ESASO Course Series. Basel, Karger, 2013, vol 3, pp 38–55 DOI: 10.1159/000350902 An Introduction to Intraocular Lenses: Material, Optics, Haptics, Design and Aberration