title: Etiology of surface light scattering on hydrophobic acrylic intraocular lenses.
abstract: OBJECTIVE
  To study the etiology of surface light scattering on hydrophobic acrylic intraocular lenses (IOLs).
  
  
  METHODS
  Alcon Research Laboratories, Fort Worth, Texas, USA.
  
  
  METHODS
  Experimental study.
  
  
  METHODS
  Intraocular lenses were obtained from clinical explantations (n = 5), from human cadavers (n = 8), and from finished-goods inventory (controls). Surface light scattering was measured and imaged with the IOLs in various hydration states (dry, short-term wetted, and long-term hydrated) before and after proteins were quantified and removed. Selected IOL samples were analyzed with x-ray photoelectron spectroscopy, scanning electron microscopy (SEM) with energy-dispersion x-ray analysis, Fourier-transform infrared spectroscopy with attenuated total reflectance, and cryogenic SEM with a focused ion beam.
  
  
  RESULTS
  No inorganic deposits or organic changes were observed on any IOL surface. Under clinically relevant hydrated conditions, surface light-scattering intensity was independent of proteinaceous biofilm state (P≥.11). Instead, the hydration state of the IOLs significantly contributed to the intensity of surface light scattering (P<.001); clinically explanted and cadaver-eye IOLs (but not control IOLs) exhibited minimal scatter when dry, intermediate scatter when wetted, and maximum scatter when hydrated. Subsurface nanoglistenings with diameters less than a micron and with locations up to 120 μm from the surface of the IOLs were characterized by SEM with a focused ion beam and were identified as the source of the hydration-related surface light scattering.
  
  
  CONCLUSIONS
  Surface light scattering on hydrophobic IOLs was predominantly caused by hydration-related subsurface nanoglistenings within the acrylic IOL material.
authors.affiliation: Alcon Research, Ltd., Fort Worth, Texas 76134, USA. marcia.ong@alconlabs.com
authors.forename: Marcia D
authors.initials: MD
authors.lastname: Ong
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Callaghan
authors.forename: Ron
authors.initials: R
authors.lastname: Pei
authors.forename: Mutlu
authors.initials: M
authors.lastname: Karakelle
mesh_terms: D000180:Acrylic Resins; D003459:Crystallins / Q000032:analysis / Q000378:metabolism; D003720:Densitometry; D020878:Device Removal; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007910:Lenses, Intraocular; D008027:Light; D008855:Microscopy, Electron, Scanning; D056951:Photoelectron Spectroscopy; D011485:Protein Binding; D012542:Scattering, Radiation; D013052:Spectrometry, X-Ray Emission; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water / Q000737:chemistry*
chemical_list: D000180:Acrylic Resins; D003459:Crystallins; D014867:Water