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EP-4736738-A1 - AN OCT APPARATUS FOR OPTORETINOGRAPHY

EP4736738A1EP 4736738 A1EP4736738 A1EP 4736738A1EP-4736738-A1

Abstract

An OCT apparatus for acquiring optoretinography data, comprising: an optical system which applies an optical stimulus confined to a portion of a retina of the eye whose location is controllable; an OCT imaging system which acquires OCT data from the retina; and a controller which: acquires a duration of a physiological response of the retina in the optoretinography data to be acquired; acquires target locations on the retina and uses these to control the optical system to apply the optical stimulus to respective first portions of the retina at the respective target locations; controls the OCT imaging system to acquire, for each first portion, respective OCT data of the respective second portion of the retina over the duration indicated by the first indicator, which second portion is stimulated by the optical stimulus applied to the first portion; and generates the ORG data based on the acquired OCT data.

Inventors

  • Rycroft, Ewan
  • PRECIADO, Miguel
  • NORMAND, Margaret

Assignees

  • Optos plc

Dates

Publication Date
20260506
Application Date
20241031

Claims (15)

  1. An optical coherence tomography, OCT, apparatus (100) arranged to acquire optoretinography, ORG, data (150) that is indicative of a physiological response of a retina of an eye (160) of a subject to an optical stimulus, the OCT apparatus (100) comprising: an optical system (120) operable to apply the optical stimulus to the retina such that an illumination of the retina by the optical stimulus is confined to a portion of the retina, the optical system (120) being controllable to vary a location on the retina at which the optical stimulus is to be applied; an OCT imaging system (130) operable to acquire OCT data (135) by imaging a portion of the retina of the eye (160); and a controller (140) arranged to: acquire (S51) a first indicator (141) which is indicative of a duration of the physiological response indicated by ORG data that is to be acquired by the OCT apparatus (100); acquire (S54) a number, N, of second indicators (142), each second indicator being indicative of a respective target location on the retina at which the optical stimulus is to be applied by the optical system (120), wherein N is dependent on the first indicator (141) such that N decreases as the duration indicated by the first indicator (141) increases; use (S55) the second indicators (142) to control the optical system (120) to apply the optical stimulus to respective first portions of the retina at the respective target locations; control (S56) the OCT imaging system (130) to acquire, for each of the first portions of the retina, respective OCT data (135) of a respective second portion of N second portions of the retina over the duration indicated by the first indicator (141), wherein at least a part of the respective second portion of the retina is disposed in relation to the respective first portion of the retina so as to be stimulated by the applied optical stimulus during acquisition of at least some of the respective OCT data (135); and process (S57) the respective OCT data (135) of each second portion of the retina to generate respective ORG data (150) indicative of a respective physiological response of the second portion of the retina to the optical stimulus applied to the corresponding first portion of the retina.
  2. The OCT apparatus (100) according to Claim 1, wherein the controller (140) is arranged to acquire the first indicator (141) by selecting a value from a group of values comprising: a first value indicative of a duration less than 20 ms of the physiological response indicated by ORG data (150) that is to be acquired by the OCT apparatus (100); and a second value indicative of a duration greater than 20 ms of the physiological response indicated by ORG data (150) that is to be acquired by the OCT apparatus (100).
  3. The OCT apparatus (100) according to Claim 1 or Clam 2, wherein the N second indicators (142) are indicative of respective target locations on the retina that are one of: distributed around a circle centred on a fovea of the eye (160), at which target locations the optical stimulus is to be applied by the optical system (120); located within respective grid cells of an Early Treatment Diabetic Retinopathy Study, ETDRS, grid centred on a fovea of the eye (160), at which target locations the optical stimulus is to be applied by the optical system (120); and distributed along a straight line passing through a fovea of the eye (160), at which target locations the optical stimulus is to be applied by the optical system (120).
  4. The OCT apparatus (100) according to any preceding claim, wherein the optical system (120, 300) comprises a light source (301) arranged to generate light which provides the optical stimulus, and one or more scanning elements (312, 314; 363, 364) arranged to direct the light to the retina, and the controller (140) is arranged to use the N second indicators (142) to control the one or more scanning elements (312, 314; 363, 364) to direct the light to each of the first portions of the retina which is at the respective target location.
  5. The OCT apparatus (100) according to Claim 4, wherein the OCT imaging system (130, 320) comprises: an interferometer (322) having a sample arm (324) and a reference arm (325); and a detector (323) arranged to detect an interference between sample OCT light (L o ) propagating along the sample arm (324) after having been scattered from the retina, and reference OCT light (L r ) propagating along the reference arm (325), and at least one of the one or more scanning elements (312, 314) is further arranged to direct the sample OCT light (L o ) toward each of the N second portions of the retina, and the sample OCT light (L o ) scattered from each of the N second portions of the retina toward the detector (323).
  6. The OCT apparatus (100) according to Claim 4, wherein the OCT imaging system (120, 361) comprises: an interferometer (322) having a sample arm (324) and a reference arm (325); one or more scanning elements (312, 314); and a detector (323) arranged to detect an interference between sample OCT light (L o ) propagating along the sample arm (324) after having been scattered from the retina, and reference OCT light (L r ) propagating along the reference arm (325), wherein the one or more scanning elements (312, 314) are arranged to direct the sample OCT light (L o ) toward each of the N second portions of the retina, and the sample OCT light (L o ) scattered from each of the N second portions of the retina toward the detector (323), and the one or more scanning elements (363, 364) of the optical system (120, 360) are different from the one or more scanning elements (312, 314) of the OCT imaging system (120, 361).
  7. The OCT apparatus (100) according to Claim 6, wherein the controller (140) is arranged to use the N second indicators (142) to control the one or more scanning elements (363, 364) of the optical system (130, 361) independently from the one or more scanning elements (312, 314) of the OCT imaging system (120, 360).
  8. The OCT apparatus (100) according to any preceding claim, wherein the controller (140) stores a third indicator (143) which is indicative of a period of time over which the optical system (120) is to apply the optical stimulus to respective first portions of the retina and the OCT imaging system (130) is to acquire, for each of the first portions of the retina, the respective OCT data (135) of the respective second portion of the retina over the duration indicated by the first indicator (141), and the controller (140) is arranged to determine, based on the first indicator (141) and the third indicator (143), the number, N, of second indicators (142) to be acquired such that, within the period of time indicated by the third indicator (143): the controller (140) uses the N second indicators (142) to control the optical system (120) to apply the optical stimulus to the respective first portions of the retina; and the controller (140) controls the OCT imaging system (130) to acquire the respective OCT data (135) for each of the first portions of the retina.
  9. The OCT apparatus (100) according to Claim 8, wherein the controller (140) is arranged to update the third indicator (143) based on a size of the pupil of the eye (160) such that the period of time indicated by the third indicator (143) increases as the size of the pupil increases.
  10. The OCT apparatus (100) according to Claim 8 or Claim 9, wherein the period of time indicated by the third indicator (143) does not exceed 300 ms.
  11. A computer-implemented method of controlling an optical coherence tomography, OCT, apparatus (100) to acquire optoretinography, ORG, data (150) that is indicative of a physiological response of a retina of an eye (160) to an optical stimulus, the OCT apparatus (100) comprising: an optical system (120) operable to apply the optical stimulus to the retina such that an illumination of the retina by the optical stimulus is confined to a portion of the retina, the optical system (120) being controllable to vary a location on the retina at which the optical stimulus is to be applied; and an OCT imaging system (130) operable to acquire OCT data (135) by imaging a portion of the retina of the eye (160), the method comprising: acquiring (S51) a first indicator (141) which is indicative of a duration of the physiological response indicated by ORG data that is to be acquired by the OCT apparatus (100); acquiring (S54) a number, N, of second indicators (142), each second indicator being indicative of a respective target location on the retina at which the optical stimulus is to be applied by the optical system (120), wherein N is dependent on the first indicator (141) such that N decreases as the duration indicated by the first indicator (141) increases; using(S55) the second indicators (142) to control the optical system (120) to apply the optical stimulus to respective first portions of the retina at the respective target locations; controlling (S56) the OCT imaging system (130) to acquire, for each of the first portions of the retina, respective OCT data (135) of a respective second portion of N second portions of the retina over the duration indicated by the first indicator (141), wherein at least a part of the respective second portion of the retina is disposed in relation to the respective first portion of the retina so as to be stimulated by the applied optical stimulus during acquisition of at least some of the respective OCT data (135); and processing (S57) the respective OCT data (135) of each second portion of the retina to generate respective ORG data (150) indicative of a respective physiological response of the second portion of the retina to the optical stimulus applied to the corresponding first portion of the retina.
  12. The computer-implemented method according to Claim 11, wherein the first indicator (141) is acquired by selecting a value from a group of values comprising: a first value indicative of a duration less than 20 ms of the physiological response indicated by ORG data (150) that is to be acquired by the OCT apparatus (100); and a second value indicative of a duration greater than 20 ms of the physiological response indicated by ORG data (150) that is to be acquired by the OCT apparatus (100).
  13. The computer-implemented method according to Claim 11 or Claim 12,further comprising: storing (S52) a third indicator (143) which is indicative of a period of time over which the optical system (120) is to apply the optical stimulus to respective first portions of the retina and the OCT imaging system (130) is to acquire, for each of the first portions of the retina, the respective OCT data (135) of the respective second portion of the retina over the duration indicated by the first indicator (141); and determining (S53), based on the first indicator (141) and the third indicator (143), the number, N, of second indicators (142) to be acquired such that, within the period of time indicated by the third indicator (143): the N second indicators (142) are used to control the optical system (120) to apply the optical stimulus to the respective first portions of the retina; and the OCT imaging system (130) is controlled to acquire the respective OCT data (135) for each of the first portions of the retina.
  14. A computer program (445) comprising computer-readable instructions that, when executed by a processor (420) which is arranged to control the optical coherence tomography, OCT, apparatus (100) according to any of Claims 1 to 10, cause the processor (420) to control the OCT apparatus (100) in accordance with the method according to any of Claims 11 to 13.
  15. A non-transitory computer-readable storage medium storing the computer program according to Claim 14.

Description

[Field] Example aspects herein generally relate to the field of optical coherence tomography (OCT) imaging systems and, in particular, to OCT imaging systems for acquiring optoretinography (ORG) data indicative of a physiological response of a retina of an eye of a subject to an optical stimulus. [Background] Optical coherence tomography (OCT) is an imaging technique based on low-coherence interferometry, which is widely used to acquire high-resolution two- and three-dimensional images of optical scattering media, such as biological tissue. OCT imaging systems can be classified as being time-domain OCT (TD-OCT) or Fourier-domain OCT (FD-OCT) (also referred to as frequency-domain OCT), depending on how depth ranging is achieved. In TD-OCT, an optical path length of a reference arm of the imaging system's interferometer is varied in time during the acquisition of a reflectivity profile of the scattering medium being imaged by the OCT imaging system (referred to herein as the "imaging target"), the reflectivity profile being commonly referred to as a "depth scan" or "axial scan" ("A-scan"). In FD-OCT, a spectral interferogram resulting from an interference between light in the reference arm and light in the sample arm of the interferometer at each A-scan location is Fourier transformed to simultaneously acquire all points along the depth of the A-scan, without requiring any variation in the optical path length of the reference arm. FD-OCT can allow much faster imaging than scanning of the sample arm mirror in the interferometer, as all the back-reflections from the sample are measured simultaneously. Two common types of FD-OCT are spectral-domain OCT (SD-OCT) and swept-source OCT (SS-OCT). In SD-OCT, a broadband light source delivers many wavelengths to the imaging target, and all wavelengths are measured simultaneously using a spectrometer as the detector. In SS-OCT (also referred to as time-encoded frequency-domain OCT), the light source is swept through a range of wavelengths, and the temporal output of the detector is converted to spectral interference. Modern FD-OCT imaging systems are often phase-stable. For example, SD-OCT imaging systems are inherently phase-stable due to the simultaneous acquisition of all the spectral sampling points with a line-scan camera. SS-OCT imaging systems may also be phase-stable by employing phase-stabilization techniques well-known to those versed in the art. OCT imaging systems can also be classified as being point-scan (also known as "point detection" or "scanning point"), line-scan or full-field, depending on how the imaging system is configured to acquire OCT data at locations on the imaging target. A point-scan OCT imaging system acquires OCT data by scanning a focused sample beam across the surface of the imaging target, typically along a single line (which may be straight, or alternatively curved so as to define a circle or a spiral, for example) or along a set of (usually substantially parallel) lines on the surface of the imaging target, and acquiring an axial depth profile (A-scan) for each of a plurality of points along the line(s), one single point at a time, to build up OCT data comprising a one- or two-dimensional array of A-scans representing a two-dimensional (i.e. a B-scan) or three-dimensional (i.e. a C-scan or volumetric scan) reflectance profile of the sample. A line-scan OCT imaging system acquires OCT data by scanning a focused line of light across the surface of the imaging target. Measured reflectance from the imaging target is used to generate OCT data comprising a two-dimensional reflectance profile (i.e. a B-scan) of the sample. By scanning the focused line of light across a plurality of locations on the imaging target, OCT data comprising a three-dimensional reflectance profile (i.e. a C-scan or volumetric scan) of the sample can be obtained. Typically, the focused line of light is straight and is scanned in a direction perpendicular to it, although in some instances it may be curved with the scanning direction adjusted accordingly. A full-field OCT imaging system acquires OCT data by projecting a beam of light onto the imaging target to acquire OCT data comprising a three-dimensional reflectance profile (i.e. a C-scan or volumetric scan) of the sample. Optoretinography (ORG) generally refers to the detection of a physiological response of a retina of an eye to an optical stimulus (i.e. light-induced functional activity of the retina). ORG techniques include the non-invasive optical imaging of this physiological response of the retina. For example, OCT imaging systems can be used to image retinal neurons thought to be exhibiting a change in dimension (size) in response to excitation by the optical stimulus. These changes in dimension have been shown to be detectable by OCT imaging systems and are typically changes in length of the outer segments of cone photoreceptors or rod photoreceptors in the retina that are detected by measuring the change