Fast absolute-reflectance method for the determination of tear film lipid layer thickness

A method of determining tear film lipid layer thickness, comprising the steps of:

• measuring a tear film aqueous plus lipid layer relative reflectance spectrum using a wavelength-dependent optical interferometer;
• converting the measured tear film aqueous plus lipid layer relative reflectance spectrum to a calculated absolute reflectance spectrum;
• iteratively comparing the calculated absolute reflectance spectrum to a plurality of theoretical absolute reflectance lipid spectra to generate a tear film lipid layer thickness estimate;
• determining a standard error for the tear film lipid layer thickness estimate;
• and
• identifying a correct lipid layer thickness based on the standard error.

A method of determining tear film lipid layer thickness, comprising the steps of:

• measuring a tear film aqueous plus lipid layer relative reflectance spectrum using a wavelength-dependent optical interferometer;
• converting the measured tear film aqueous plus lipid layer relative reflectance spectrum to a measured lipid layer relative reflectance spectrum;
• converting the measured lipid layer relative reflectance spectrum to a calculated absolute reflectance spectrum;
• and
• iteratively comparing the calculated absolute reflectance spectrum to a plurality of theoretical absolute reflectance lipid spectra to generate a tear film lipid layer thickness estimate.