Purpose. A confocal Raman spectroscopy (Conforam) system has been developed to study biochemical properties of ocular tissue in-vivo. To assess the ability of this instrument to characterize the biochemical structure of ocular tissue, pre-clinical animal studies and preliminary human trials have been conducted. Methods. Our setup consists of the Conforam working in a 180° backscattered mode with diffraction limited optics. A long working distance objective acts as entrance and collection lens. A fiber collects the Raman light, acts as the confocal pinhole and permits flexible coupling with the monochromator. The CCD array used, allows for rapid scanning and low laser power. Either the 514.5 nm of a CW Argon ion laser or the 632.8 nm line of a CW Helium-Neon laser is used as excitation light. The axial resolution differs per setup and can range from ∼10 to 150 μm. The eyes of 9 anesthetized NZW rabbits (2.5-3.0 kg) were investigated in-vivo with our Conforam. Also cornea scans were made from two blind human eyes. Results. The Conforam a lows for low laser power (5-25 mW) and short integration times (1-10 s) to get a good S/N ratio. In-vivo, specific Raman signatures from various molecules can be seen in different rabbit ocular tissue layers (cornea, aqueous humor and lens). These include modes from OH, CH, SH, Amide I and III, and from aminoacids, lactate, urea and other metabolites. With high axial resolution, z-scans from cornea and lens in axial direction can be made. Practical in-vivo probing proved attainable in humans. Conclusion. In-vivo non-invasive detection of biochemical properties of the eye is possible with our Conforam system. Specific Raman signatures can be distinguished from cornea, aqueous humor and lens. Application of this promising technology to non-invasively study human eyes seems feasible.
|Original language||English (US)|
|Journal||Investigative Ophthalmology and Visual Science|
|State||Published - Feb 15 1996|
ASJC Scopus subject areas
- Sensory Systems
- Cellular and Molecular Neuroscience