title: Accelerated ultraviolet aging of intraocular lens optic materials: a 50 year simulation.
abstract: OBJECTIVE
  To introduce an updated accelerated photoaging model for application to intraocular lens (IOL) materials and to apply this model to determine the photostability of AMO PhacoFlex model SI-18NGB and PhacoFlex II model SI-20NGB silicone IOL materials over a simulated 50 years of exposure.
  
  
  METHODS
  Research laboratory, AMO Surgical Products, Irvine, California, USA.
  
  
  METHODS
  Previous photoaging models and aging parameters, including intraocular exposure intensity, daily exposure duration, and acceleration exponent were critically reviewed and analyzed, and an updated model was introduced. The test specimens were continuously irradiated with ultraviolet (UV) light in a Suntest UV chamber at an intensity of 8 mw/cm2 for 86 days to simulate 50 years of in vivo exposure. The silicone lenses were evaluated for focal length, resolution, and surface integrity, while regular slabs were tested for tensile strength, elongation, hardness, contact angle, and percentage light transmission. The UV-absorption capacity was monitored using ultrathin slabs (0.127 mm). Six replicate samples were used for each determination, and a two-sided t-test with significance set at P < .05 was used to evaluate the difference before and after aging.
  
  
  RESULTS
  No significant difference in optical, physical, and surface properties of the lenses and lens materials was found. No change in UV-absorption capacity was observed after a simulated 50 years of accelerated photoaging.
  
  
  CONCLUSIONS
  The AMO PhacoFlex SI-18NGB and PhacoFlex II SI-30NGB silicone lens materials resisted UV light degradation over 50 years of simulated exposure.
authors.affiliation: Allergan, AMO Surgical Products, Research and Development Department, Irvine, California 92612, USA.
authors.forename: S
authors.initials: S
authors.lastname: Yang
authors.forename: H
authors.initials: H
authors.lastname: Makker
authors.forename: F R
authors.initials: FR
authors.lastname: Christ
mesh_terms: D007910:Lenses, Intraocular; D019563:Mechanics; D055095:Optics and Photonics; D012826:Silicone Elastomers / Q000737:chemistry / Q000528:radiation effects*; D013499:Surface Properties; D013997:Time Factors; D014466:Ultraviolet Rays
chemical_list: D012826:Silicone Elastomers