# US 2017/0280992 A1 · Fast absolute-reflectance method for the determination of tear film lipid layer thickness > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0280992 A1 - Document ID: US20170280992A1 - Status: Published application - Kind: A1 - Application number: 15/627,077 - Filed: 2017-06-19 - Published: 2017-10-05 - Earliest claimed: 2014-06-06 - Assignees: Abbott Medical Optics Inc. - Applicants: Abbott Medical Optics Inc. - Inventors: Stanley W. Huth; Denise Tran - Web page: https://patentgrep.com/patent/US20170280992A1 ## CPC - A61B 3/101: {for examining the tear film} - A61B 3/0025: {characterised by electronic signal processing, e.g. eye models} - A61B 3/1005: {for measuring distances inside the eye, e.g. thickness of the cornea (A61B3/11 takes precedence)} - G01B 11/06: for measuring thickness {; e.g. of sheet material (thickness measurement by thermal means G01B21/085)} - G01J 3/45: Interferometric spectrometry - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N) ## Abstract A method for determining reflectivity of a tear film lipid layer of a patient and recommending a course of treatment based on the same. The method includes 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; comparing the calculated absolute reflectance spectrum to a theoretical absolute lipid reflectance spectrum to determine a tear film lipid layer thickness; and determining a reflectivity value for the tear film lipid layer thickness at a first wavelength of light corresponding to ultraviolet, violet, or blue light. ## Claims ### Claim at position 1 1-38. (canceled) ### Claim 39 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. ### Claim 40 (depends on 39) The method of claim 39, wherein identifying a correct lipid layer thickness based on the standard error comprises identifying a correct lipid layer thickness when the standard error is minimized. ### Claim 41 (depends on 39) The method of claim 39, wherein identifying a correct lipid layer thickness based on the standard error comprises identifying a correct lipid layer thickness when the standard error is less than 0.1. ### Claim 42 (depends on 39) The method of claim 39, wherein iteratively comparing the calculated absolute reflectance spectrum to a plurality of theoretical absolute reflectance lipid spectra comprises minimizing a sum of least squares differences between the calculated absolute reflectance spectrum and the theoretical absolute reflectance lipid spectra. ### Claim 43 (depends on 39) The method of claim 39, wherein iteratively comparing the calculated absolute reflectance spectrum to a plurality of theoretical absolute reflectance lipid spectra comprises starting the iteration using a first lipid layer thickness value estimate. ### Claim 44 (depends on 43) The method of claim 43, wherein the first lipid layer thickness value estimate is 65 nm. ### Claim 45 (depends on 43) The method of claim 43, wherein, if the standard error is greater than 0.1, the method further comprises restarting the iteration using a second lipid layer thickness value estimate different from the first lipid layer thickness value estimate. ### Claim 46 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. ### Claim 47 (depends on 46) The method of claim 46, wherein iteratively comparing the calculated absolute reflectance spectrum to a plurality of theoretical absolute reflectance lipid spectra comprises minimizing a sum of least squares differences between the calculated absolute reflectance spectrum and the theoretical absolute reflectance lipid spectra. ### Claim 48 (depends on 46) The method of claim 46, wherein iteratively comparing the calculated absolute reflectance spectrum to a plurality of theoretical absolute reflectance lipid spectra comprises starting the iteration using a first lipid layer thickness value estimate. ### Claim 49 (depends on 48) The method of claim 48, wherein the first lipid layer thickness value estimate is 65 nm. ### Claim 50 (depends on 48) The method of claim 48, wherein, if the standard error is greater than 0.1, the method further comprises restarting the iteration using a second lipid layer thickness value estimate different from the first lipid layer thickness value estimate.