Identification of intraocular lens materials using confocal Raman spectroscopy.
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.
Smit
E E
EE
University of Texas Medical Branch, Galveston, USA.
Erckens
R J
RJ
Hendrikse
F
F
Motamedi
M
M
Wicksted
J P
JP
March
W F
WF
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*
D000179:Acrylates; D008689:Methacrylates; D012826:Silicone Elastomers; C005044:hydroxyethyl methacrylate; D019904:Polymethyl Methacrylate; C036658:acrylic acid