# US 10,117,571 B2 · 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 10,117,571 B2 - Document ID: US10117571B2 - Status: Granted - Kind: B2 - Application number: 15/627,077 - Filed: 2017-06-19 - Published: 2017-10-05 - Granted: 2018-11-06 - Earliest claimed: 2014-06-06 - Assignees: Johnson & Johnson Surgical Vision, Inc. - Applicants: Johnson & Johnson Surgical Vision, Inc. - Inventors: Stanley W. Huth; Denise Tran - Web page: https://patentgrep.com/patent/US10117571B2 ## 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 1 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 2 (depends on 1) The method of claim 1, wherein identifying the correct lipid layer thickness based on the standard error comprises identifying the correct lipid layer thickness when the standard error is minimized. ### Claim 3 (depends on 1) The method of claim 1, wherein identifying the correct lipid layer thickness based on the standard error comprises identifying the correct lipid layer thickness when the standard error is less than 0.1. ### Claim 4 (depends on 1) The method of claim 1, wherein iteratively comparing the calculated absolute reflectance spectrum to the plurality of theoretical absolute reflectance lipid spectra comprises minimizing a sum of least squares differences between the calculated absolute reflectance spectrum and the plurality of theoretical absolute reflectance lipid spectra. ### Claim 5 (depends on 1) The method of claim 1, wherein iteratively comparing the calculated absolute reflectance spectrum to the plurality of theoretical absolute reflectance lipid spectra comprises starting the iteration using a first lipid layer thickness value estimate. ### Claim 6 (depends on 5) The method of claim 5, wherein the first lipid layer thickness value estimate is 65 nm. ### Claim 7 (depends on 5) The method of claim 5, 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 8 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 9 (depends on 8) The method of claim 8, wherein iteratively comparing the calculated absolute reflectance spectrum to the plurality of theoretical absolute reflectance lipid spectra comprises minimizing a sum of least squares differences between the calculated absolute reflectance spectrum and the plurality of theoretical absolute reflectance lipid spectra. ### Claim 10 (depends on 8) The method of claim 8, wherein iteratively comparing the calculated absolute reflectance spectrum to the plurality of theoretical absolute reflectance lipid spectra comprises starting the iteration using a first lipid layer thickness value estimate. ### Claim 11 (depends on 10) The method of claim 10, wherein the first lipid layer thickness value estimate is 65 nm. ### Claim 12 (depends on 10) The method of claim 10, 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.