# US 2018/0020915 A1 · System and Method for Eye Tracking During Retinal Imaging > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0020915 A1 - Document ID: US20180020915A1 - Status: Published application - Kind: A1 - Application number: 15/722,784 - Filed: 2017-10-02 - Published: 2018-01-25 - Earliest claimed: 2016-07-01 - Assignees: Canon Kabushiki Kaisha - Applicants: Canon Kabushiki Kaisha - Inventors: Koji NOZATO - Web page: https://patentgrep.com/patent/US20180020915A1 ## CPC - A61B 3/152: {for aligning} - A61B 3/0025: {characterised by electronic signal processing, e.g. eye models} - A61B 3/1025: {for confocal scanning} - A61B 3/113: for determining or recording eye movement - A61B 3/1225: {using coherent radiation} - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) ## Abstract A method, a, controller, a non-transitory computer readable storage medium encoded with instructions; each of which control an apparatus to produce multiple images of an area of an eye in parallel. Selecting one of the images for estimating a change in position of the area to be used for tracking the area of the eye being imaged. ## Claims ### Claim 1 A method of controlling an ophthalmic apparatus to produce images of an area of an eye, wherein the apparatus scans light on the area, divides return light from the area into a first portion of light and a second portion of light, generates a first image based on the first portion of the return light, and generates a second image based on the second portion of return light, the method comprising: receiving the first image and the second image; comparing the first image and the second image; selecting the first image or the second image based on a result of the comparing step as a position detection image; and estimating a change in position of the area based on the position detection image. ### Claim 2 (depends on 1) The method according to claim 1 further comprising sending instructions to the apparatus to adjust an imaging area based on the estimated change in position of the area. ### Claim 3 (depends on 1) The method according to claim 1, wherein: the first portion of the return light has a first range of wavelengths; the second portion of the return light has a second range of wavelengths; and the first range of wavelengths is different from the second range of wavelengths. ### Claim 4 (depends on 1) The method according to claim 1, wherein the first portion of the return light is fluorescence light; and the second portion of the return light is not fluorescence light. ### Claim 5 (depends on 1) The method according to claim 1, wherein the first portion of the return light does not pass through a confocal pinhole before being detected by a first detector to generate the first image; and the second portion of the return light passes through a first confocal pinhole before being detected by a second detector to generate the second image. ### Claim 6 (depends on 1) The method according to claim 1, wherein selecting the first image or the second image as the position detection image comprises: estimating a first cross correlation value based on the first image and a previous first image; estimating a second cross correlation value based on the second image and a previous second image; selecting the first image as the position detection image if the first cross correlation is greater than second cross correlation image; and selecting the second image as the position detection image if the second cross correlation is greater than first cross correlation image. ### Claim 7 (depends on 1) The method according to claim 1, wherein selecting the first image or the second image as the position detection image comprises: selecting the first image as the position detection image if the average signal strength of the first image is greater than average signal strength of the second image; and selecting the second image as the position detection image if the average signal strength of the second image is greater than average signal strength of the first image. ### Claim 8 (depends on 1) The method according to claim 1, wherein selecting the first image or the second image as the position detection image comprises: estimating a first difference based on a difference between a focus position of the first image relative to a set focus position; estimating a second difference based on a difference between a focus position of the second image relative to the set focus position; and selecting the first image as the position detection image if the first difference is less than second difference. ### Claim 9 (depends on 1) The method according to claim 1, wherein the position detection image is set as a reference image which is used as a point of comparison for image tracking in subsequent position tracking during a second period of time after a first period of time, wherein the first period of time and the second period of time are same time for one scan of the area. ### Claim 10 (depends on 9) The method according to claim 9, further comprising replacing the reference image with a new reference image. ### Claim 11 (depends on 10) The method according claim 10, wherein replacing the reference image with the new reference image further comprises: selecting the new reference image from a plurality of images. ### Claim 12 (depends on 11) The method according to claim 11, wherein the new reference image is selected based on the average intensity of each of the plurality of images. ### Claim 13 (depends on 11) The method according to claim 11 wherein the new reference image is selected based on a distribution of intensity of pixels within each of the plurality of images. ### Claim 14 (depends on 11) The method according to claim 11, wherein the new reference image is selected based on cross correlation coefficients calculated among the plurality of images. ### Claim 15 (depends on 10) The method according to claim 10, wherein the new reference image is constructed from an average of a plurality of images. ### Claim 16 A controller that is configured to control an ophthalmic apparatus to produce images of an area of an eye, wherein the apparatus scans light on the area, divides return light from the area into a first portion of light and a second portion of light, generates a first image based on the first portion of the return light, and generates a second image based on the second portion of the return light, the controller comprising: a processor; and a memory; wherein the processor receives the first image and the second image; wherein the processor compares the first image and the second image; wherein the processor selects the first image or the second image based on the comparing result as a position detection image; and wherein the processor estimates a change in position of the area based on the position detection image. ### Claim 17 (depends on 16) The controller according to claim 16, further comprising the ophthalmic apparatus. ### Claim 18 (depends on 17) The ophthalmic of claim 17 further comprising: one or more light sources to provide the light that is scanned on the area; and a scanner for scanning the light on the area. ### Claim 19 A non-transitory computer readable storage medium encoded with instructions for performing a method of controlling an ophthalmic apparatus to produce images of an area of an eye, wherein the apparatus scans light on the area, divides return light from the area into a first portion of light and a second portion of light, generates a first image based on the first portion of the return light, and generates a second image based on the second portion of the return light, the instructions may comprise: instructions for receiving the first image and the second image; instructions for comparing the first image and the second image; instructions for selecting the first image or the second image based on the compared result as a position detection image; and instructions for estimating a change in position of the area based on the position detection image.