# US 9,775,508 B1 · Depolarizing region identification in the retina > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,775,508 B1 - Document ID: US9775508B1 - Status: Granted - Kind: B1 - Application number: 15/148,795 - Filed: 2016-05-06 - Granted: 2017-10-03 - Earliest claimed: 2016-05-06 - Assignees: Canon Kabushiki Kaisha - Applicants: Canon Kabushiki Kaisha - Inventors: Andrew Docherty; Barry James Drake - Web page: https://patentgrep.com/patent/US9775508B1 ## CPC - A61B 3/0025: {characterised by electronic signal processing, e.g. eye models} - A61B 3/102: {for optical coherence tomography [OCT]} - A61B 3/1225: {using coherent radiation} - G06F 18/24137: {Distances to cluster centroïds} - G06T 7/0012: {Biomedical image inspection} - G06V 10/42: Global feature extraction by analysis of the whole pattern, e.g. using frequency domain transformations or autocorrelation - G06V 10/764: using classification, e.g. of video objects - G06V 20/698: {Matching; Classification} - G06T 2207/10072: Tomographic images - G06T 2207/10101: Optical tomography; Optical coherence tomography [OCT] - G06T 2207/30041: Eye; Retina; Ophthalmic - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL - G06V: IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING ## Abstract A computer-implementable method of analyzing tissues of a retina. A polarization-sensitive (PS-OCT) image data set of the retina is received from a polarization-sensitive device, each element in the polarization-sensitive image data set being associated with an intensity value ({I1, . . . , IL}) and a polarization direction ({P1, . . . , PL}). A likelihood score is determined for each element of the polarization-sensitive image data set based on the intensity value of the element and a degree of divergence (μ*TP or D2) of the polarization direction associated with the element from a reference polarization direction (μ*) associated with the polarization sensitive image data set, wherein the likelihood score indicates whether said element is drawn from a directionally polarized distribution or a depolarizing distribution, Elements of the polarization-sensitive image data set are classified using the determined likelihood scores to analyze tissues of the retina. ## Claims ### Claim 1 A computer-implementable method of analysing tissues of a retina, the method comprising: receiving a polarization-sensitive (PS-OCT) image data set of the retina from a polarization-sensitive device, each element in the polarization-sensitive image data set being associated with an intensity value ({I1, . . . , IL}) and a polarization direction ({P1, . . . , PL}); determining a likelihood score for each element of the polarization-sensitive image data set based on the intensity value of the element and a degree of divergence (μ*TP or D2) of the polarization direction associated with the element from a reference polarization direction (μ*) associated with the polarization sensitive image data set, wherein the likelihood score indicates whether said element is drawn from a directionally polarized distribution or a depolarizing distribution; and classifying elements of the polarization-sensitive image data set using the determined likelihood scores to analyse tissues of the retina. ### Claim 2 (depends on 1) The method of claim 1, further comprising displaying a representation of the classified elements of the polarization-sensitive image data. ### Claim 3 (depends on 1) The method of claim 1, wherein the reference polarization direction is a dominant polarization direction determined by determining normalized average of polarization directions associated with the elements in the polarization-sensitive image data set. ### Claim 4 (depends on 1) The method of claim 1, wherein the polarizing distribution is characterised by a predetermined probability density distribution function having at least one control parameter dependent on an intensity value (I) of the element, the control parameter defining the concentration (κ) of the polarizing distribution. ### Claim 5 (depends on 4) The method of claim 4, wherein dependence of the control parameter on the intensity value is determined by fitting a function to estimated values of the control parameter (κ*) for a plurality of polarization-sensitive images having different intensity parameters. ### Claim 6 (depends on 5) The method of claim 5, wherein the control parameters are stored in memory in association with corresponding intensity values. ### Claim 7 (depends on 1) The method of claim 1, further comprising determining the polarizing distribution using intensity values of the elements of the polarization-sensitive image data set and the reference polarization direction associated with the polarization-sensitive image data set. ### Claim 8 (depends on 1) The method of claim 1, wherein the polarization direction is determined by weighting polarization data associated with the element based on corresponding intensity value. ### Claim 9 (depends on 1) The method of claim 1, further comprising smoothing the likelihood scores in the classified polarization-sensitive image data set using a linear filter. ### Claim 10 (depends on 1) The method of claim 1, wherein the polarization-sensitive image data set is formed by a plurality of A-scans, each of which representing imaging signal produced by an polarization-sensitive device capable of penetrating beyond the retinal pigment epithelium (RPE) of the eye. ### Claim 11 (depends on 1) The method of claim 1, wherein the polarization-sensitive image data set represents a region in a B-scan corresponding to a subset of A-scans which form the B-scan. ### Claim 12 (depends on 1) The method of claim 1, wherein the polarization-sensitive image data set corresponds to a single A-scan, and the mean polarisation direction is determined as a sliding window over a plurality of neighbouring A-scans. ### Claim 13 (depends on 1) The method of claim 1, wherein the directionally polarized distribution is determined (1500) by selecting, from a test polarization-sensitive image data set, a first subset of elements associated with the likelihood score exceeding at least a first predetermined threshold. ### Claim 14 (depends on 1) The method of claim 1, wherein the depolarizing distribution is determined by selecting, from the test polarization-sensitive image data set, a second subset of elements associated with the likelihood score below a second predetermined threshold. ### Claim 15 A system for analysing tissues of a retina, the system comprising: a memory for storing data and a computer program; a processor coupled to the memory for storing data and a computer program, the computer program comprising instructions for: receiving a polarization-sensitive (PS-OCT) image data set of the retina from a polarization-sensitive device, each element in the polarization-sensitive image data set being associated with an intensity value ({I1, . . . , IL}) and a polarization direction ({P1, . . . , PL}); determining a likelihood score for each element of the polarization-sensitive image data set based on the intensity value of the element and a degree of divergence (μ*TP or D2) of the polarization direction associated with the element from a reference polarization direction (μ*) associated with the polarization sensitive image data set, wherein the likelihood score indicates whether said element is drawn from a directionally polarized distribution or a depolarizing distribution; and classifying elements of the polarization-sensitive image data set using the determined likelihood scores to analyse tissues of the retina. ### Claim 16 An apparatus for analysing tissues of a retina, the apparatus comprising: means for receiving a polarization-sensitive (PS-OCT) image data set of the retina from a polarization-sensitive device, each element in the polarization-sensitive image data set being associated with an intensity value ({I1, . . . , IL}) and a polarization direction ({P1, . . . , PL}); means for determining a likelihood score for each element of the polarization-sensitive image data set based on the intensity value of the element and a degree of divergence (μ*TP or D2) of the polarization direction associated with the element from a reference polarization direction (μ*) associated with the polarization sensitive image data set, wherein the likelihood score indicates whether said element is drawn from a directionally polarized distribution or a depolarizing distribution; and means for classifying elements of the polarization-sensitive image data set using the determined likelihood scores to analyse tissues of the retina. ### Claim 17 A computer readable medium having a computer program stored thereon for analysing tissues of a retina, the program comprising: code for receiving a polarization-sensitive (PS-OCT) image data set of the retina from a polarization-sensitive device, each element in the polarization-sensitive image data set being associated with an intensity value ({I1, . . . , IL}) and a polarization direction ({P1, . . . , PL}); code for determining a likelihood score for each element of the polarization-sensitive image data set based on the intensity value of the element and a degree of divergence (μ*TP or D2) of the polarization direction associated with the element from a reference polarization direction (μ*) associated with the polarization sensitive image data set, wherein the likelihood score indicates whether said element is drawn from a directionally polarized distribution or a depolarizing distribution; and code for classifying elements of the polarization-sensitive image data set using the determined likelihood scores to analyse tissues of the retina. ### Claim 18 A computer-implementable method of determining physical properties of tissues of a retina, the method comprising: receiving a polarization-sensitive image data set of the retina from a polarization-sensitive device, each element in the polarization-sensitive image data set being associated with an intensity value and polarization data; determining, for each element of the polarization-sensitive image data set, a likelihood score (D) that said element is drawn from a polarization scrambling signal based on a reference polarization direction (μ*) associated with the polarization-sensitive image data set, the intensity value and the polarization data of the element; and classifying the elements of the polarization-sensitive image data set using the determined likelihood scores to determine physical properties of tissues of the retina.