Identification of intraocular lens materials using confocal Raman spectroscopy

Purpose: To develop and test a noninvasive method to identify intraocular l ens (IOL) materials in vitro. Setting: Center for Biomedical Engineering and the Department of Ophthalmol ogy, 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 sp ectral regions (299.1 to 1833.7 cm(-1) and 2633.8 to 3819.6 cm(-1), respect ively) of 4 IOL materials. silicone, poly(methyl methacrylate) (PMMA), acry lic, and hydrogel. Results: Each lens material showed a distinctive spectrum in both the highe r and the lower spectral regions. Most materials had unique peaks and a dis tinct profile using 1 mW of laser power and a 1 second exposure time. AU ma terials 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 hydroge l lenses in vitro. Raman spectroscopy using the Conforam may provide a fast , safe, and reliable noninvasive method to gain information about the mater ial of an implanted IOL and the stability of lens materials and their coati ngs, J Cataract Refract Surg 1999. 25. 1498-1504 (C) 1999 ASCRS and ESCRS.