Patent ID: 7139598

Claim:
A method of determining a tissue state of the tissue of an individual, comprising: a. Illuminating a portion of the tissue of the individual with excitation light; b. Detecting light emitted from the tissue by fluorescence of a chemical within the tissue, where the tissue is not the lens of the eye; c. Determining the tissue state from the detected light and a model relating fluorescence and a tissue state, wherein detecting light emitted from the tissue comprises: d. Determining a tissue reflectance characteristic at an excitation light wavelength; e. Detecting light returned from the tissue in response to illumination at the excitation wavelength; f. Determining a corrected fluorescence measurement from the detected light and the tissue reflectance characteristic; g. And wherein determining a tissue state comprises determining the tissue state from the corrected fluorescence measurement and a model relating fluorescence and tissue state.