Fluorescence/Raman intensity measurements, pioneered by Dr. Yu of Georgia Institute of Technology, have been used to provide artifact free measurements of the various long wavelength lens chromophore fluorescences in the excised lens. These lens fluorescence measurements provide a quantitation of changes in lens biochemistry and metabolism leading to cataract formation in the aging and diabetic lens. This collaborative proposal describes the first incorporation of this unique methodology into a clinical instrument capable of making these measurements from the living human lens. The clinical instrument will be based on a modified slit lamp design developed by Dr. Bursell at the Joslin Diabetes Center and currently used to make non-invasive quasi- elastic light scattering (QELS) measurements from the lenses of diabetic patients. This measurement provides information on the changes in size or environment of the lens proteins which can lead to increased lens scatter and the development of opacities and cataracts. This research will focus primarily on using the yellow (568.2 nm) krypton laser line to simultaneously excite two different lens fluorophores exhibiting fluorescent peaks at 591 nm (orange) and 633 nm (near red). Preliminary results have indicated that these fluorophores are associated with metabolic abnormalities in the lens. The advantage of using this excitation wavelength is that is provides both Raman and fluorescence spectra in lenses up to 70 years of age. Thus changes in lens metabolism and chemistry can be quantitated using a single illumination wavelength. We shall, however, not restrict ourselves to only this region but will investigate fluorescences ranging from green fluorescence (excited by blue (441.6 nm) light) and far red fluorescence (excited by red 647.1 nm) light) which are also implicated in lens changes associated with aging and diabetes. The instrument will initially be developed at the Georgia Institute of Technology. Initial testing and optimization will be performed then using the available laser and Raman spectroscopy facilities. The clinical measurements will be performed at the Joslin Diabetes Center using the available diabetic population as a short term aging model for monitoring lens changes associated with cataract formation. The fluorescence/Raman intensity measurements will be performed together with QELS measurements using the same with changes in lens protein conformation and/or environment to quantitate the primary causes of cataract formation. In the face of active commercial and academic interests from Japan (Prof. A. Mizuno, Jikei University, Tokyo, and Kowa Optical Inc.) it is important for us not to lost the initiatives in this area of research. It thus becomes imperative to concentrate our established research expertise into developing a sensitive non- invasive instrument to be used in early in vivo detection of the primary molecular changes associated with cataract formation. Thus these measurements will enhance our ability to prevent cataracts from forming and rapidly monitor the effectiveness of treatments to slow down or reverse cataractogenesis.
