Achieving Best Visual Outcomes with a Monofocal Intraocular Lens
and complete optic edge overlap by the anterior capsule after capsulorhexis is critical to the prevention of PCO. However, they have been somewhat controversial in regard to the relative importance of almost every IOL design feature including the uveal and capsular biocompatibility of optic materials, optic surface treatments and optic edge design.4
Over the ensuing years, patients have benefited from continuous improvement in the AcrySof® IOL with the introductions of single-piece technology in 2000, light spectrum normalizing chemistry in 2003, bifocal performance in 2004, the incorporation of an aspheric profile in 2005 (see Figure 3) and the introduction of three toric models in 2006. At the end of 2010, 20% of the patients in my practice elected to have the toric or bifocal versions implanted while the remainder received the monofocal version.
Most monofocal patients prefer to have both eyes implanted with a residual refractive status of plano and just wear reading glasses after surgery. Some patients have experienced successful monovision or mini-monovision using contact lenses pre-operatively, usually with varying amounts of residual refractive status of the non-dominant eye between -0.50 and -2.00 D. If they wish, this pattern can be successfully duplicated in their pseudophakic state. Some lifelong myopes prefer to continue their pre-operative refractive status or have it adjusted to between -0.75 and -3.00 D.
The AcrySof® IOL single-piece monofocal platform is distinguished by the unique chemical and optic surface properties of its acrylic plastic and the square optic edge and haptic architecture, all of which combine to provide correspondingly unique biocompatibility characteristics and extraordinary vision performance for our patients.
Chemistry of the AcrySof® Intraocular Lens The proprietary chemistry of the AcrySof® IOL provides the major ingredients for its overall physical behavior, optical performance, and surface interactions within its biologic environment.
Physical Behavior
In surgery, the plastic is slow to fold and unfold, making controlled insertion into the current MONARCH® D-cartridge (see Figure 4) and exit from the cartridge into the capsular bag safe and uncomplicated (see Figure 5). By definition of their commercial availability, all of the models in the AcrySof® family have met US Food and Drug Administration (FDA) requirements for structural and chemical stability. There is enough rigidity and bulk to the high refractive index optic that physical deformities, such as z-syndrome, have never been observed. The haptics and optic–haptic junction are extremely tough and rarely become disturbed.
However, because of the size of the haptics, the single-piece lens should not be placed within the ciliary sulcus.16
The 3D bulk and square
These characteristics are especially important in situations where anterior radial capsular tears may exist (see Figure 7).
US OPHTHALMIC REVIEW
haptic edges of the 0.4mm-tall haptics, the persistent memory of the material and very low resistance to compression provide predictable immediate and long-term optic positioning within the capsular bag (see Figure 6).17
Courtesy of Alcon Surgical. Optical Performance
By definition, all of the various AcrySof® IOL versions have met all FDA requirements for optical performance. The acrylic plastic is hydrophobic with less than 1% water content, which allows it to have a thin profile and
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An ovoid intraocular lens (IOL) is seen within the capsular bag. A diamond-shaped neodymium-doped yttrium aluminium garnet (Nd:YAG) laser posterior capsulotomy has been created. The truncated optic of these lenses was more prone to create dysphotopsia. Courtesy of JA Davison.
Figure 2: Retroillumination Photograph of Posterior Capsule Opacification Behind Polymethyl Methacrylate Intraocular Lens at Two Years after Implantation
Figure 1: An Ovoid Intraocular Lens Within the Capsular Bag
A: Retroillumination photograph of posterior capsule opacification (PCO) behind polymethyl methacrylate (PMMA) intraocular lens (IOL) at two years after implantation; B: Retroillumination photograph of PCO behind silicone IOL at two years after implantation. C: Retroillumination photograph of PCO behind acrylic IOL at two years after implantation. Courtesy of Ursell et al., 1998.11
Figure 3: Alcon AcrySof® Intraocular Lens Three-piece, Single-piece, and Single-piece Light-normalizing Designs
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