title: Identification of intraocular lens materials using confocal Raman spectroscopy.
abstract: OBJECTIVE
  To develop and test a noninvasive method to identify intraocular lens (IOL) materials in vitro.
  
  
  METHODS
  Center for Biomedical Engineering and the Department of Ophthalmology, University of Texas Medical Branch, Galveston, Texas, USA.
  
  
  METHODS
  A laser confocal Raman spectroscopy system (Conforam) was used for the noninvasive assessment of Raman spectra in the lower and the higher spectral regions (299.1 to 1833.7 cm-1 and 2633.8 to 3819.6 cm-1, respectively) of 4 IOL materials: silicone, poly(methyl methacrylate) (PMMA), acrylic, and hydrogel.
  
  
  RESULTS
  Each lens material showed a distinctive spectrum in both the higher and the lower spectral regions. Most materials had unique peaks and a distinct profile using 1 mW of laser power and a 1 second exposure time. All materials still had a unique spectrum in both the higher and the lower region that allowed 1 material to be distinguished from the others.
  
  
  CONCLUSIONS
  A Conforam differentiated silicone, PMMA, acrylic, and hydrogel lenses in vitro. Raman spectroscopy using the Conforam may provide a fast, safe, and reliable noninvasive method to gain information about the material of an implanted IOL and the stability of lens materials and their coatings.
authors.affiliation: University of Texas Medical Branch, Galveston, USA.
authors.forename: E E
authors.initials: EE
authors.lastname: Smit
authors.forename: R J
authors.initials: RJ
authors.lastname: Erckens
authors.forename: F
authors.initials: F
authors.lastname: Hendrikse
authors.forename: M
authors.initials: M
authors.lastname: Motamedi
authors.forename: J P
authors.initials: JP
authors.lastname: Wicksted
authors.forename: W F
authors.initials: WF
authors.lastname: March
mesh_terms: D000179:Acrylates / Q000737:chemistry*; D007910:Lenses, Intraocular; D008689:Methacrylates / Q000737:chemistry*; D019904:Polymethyl Methacrylate / Q000737:chemistry*; D012826:Silicone Elastomers / Q000737:chemistry*; D013059:Spectrum Analysis, Raman / Q000379:methods*
chemical_list: D000179:Acrylates; D008689:Methacrylates; D012826:Silicone Elastomers; C005044:hydroxyethyl methacrylate; D019904:Polymethyl Methacrylate; C036658:acrylic acid