Raman Spectroscopy for Non-Invasive Characterization of Ocular Tissue: Potential for Detection of Biological Molecules

The ability of Raman spectroscopy to remotely characterize ocular tissues using a rapid fibre-optic-based system was explored in this study. An argon ion laser operating at 514.5 nm and a charge-coupled-device-based Raman system were used. Raman spectra from aqueous humour specimens of rabbits and humans, as well as spectra from biological molecules obtained through fresh excised rabbit corneas, were obtained. Prominent peaks were observed which qualitatively matched the known locations of biological molecular peaks such as glucose, lactate and urea. In the rabbit aqueous humour spectra, peak positions were also observed indicative of amino acids and proteins. Raman spectra were also obtained from the rabbit lens showing peak positions indicative of amide I and III modes, sulphydryl and CH stretching modes and amino acids. This study demonstrated that it may be possible to characterize ocular tissue structures and to determine in a qualitative manner the presence of various biological molecules in aqueous humour by means of a Raman-based fibre optic instrument.