Systems and methods for detecting physical characteristics of a multilayered tissue of a subject, such as a tear film including analyzing received detector-output indicative of optical properties of light reflected or deflected from the respective multilayered tissue, to determine spectral properties of the multilayered tissue; and determining physical characteristics of the multilayered tissue by using multiple spectral models of the of the multilayered tissue, each model being associated with spectral properties indicative of different tissue characteristics, wherein physical characteristics of the multilayered tissue are determined by hierarchal determination of a best-fit model from the multiple spectral models.