Patent ID: 12201360

DETAILED DESCRIPTION

In the following description, various embodiments of the present invention will be described. For purposes of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the embodiments. However, it will also be apparent to one skilled in the art that the present invention may be practiced without the specific details. Furthermore, well-known features may be omitted or simplified in order not to obscure the embodiment being described.

INTRODUCTION

Many patients with retinal diseases are treated with intra-ocular injection per general guidelines based on the average patient. Progression of a retinal disease in any specific patient, may progress differently than in the average patient. Moreover, the specific patient may respond differently to treatment than the average patient. Accordingly, there is a strong clinical need to monitor the progression of a retinal disease in some patients on a continual basis so that the patient can receive treatment based on their own disease progression. Ophthalmic imaging devices employing optical coherence tomography (OCT) imaging are often employed in eye clinics to image a patient's retina to monitor the progression of a retinal disease. Having to travel to an eye clinic, however, may prevent sufficient continual monitoring of some patients. As a result, there is a need for affordable OCT based ophthalmic imaging devices that can be used by a patient at home to continually monitor the progression of the patient's retinal disease. Such retinal disease may be chorio-retinal eye diseases, such as AMD, ocular hystoplasmosis, myopia, central serous retinopathy, central serous choroidopathy, glaucoma, diabetic retinopathy, retintis pigmentosa, optic neuritis, epiretinal membrane, vascular abnormalities and/or occlusions, choroidal dystrophies, retinal dystrophies, macular hole, or choroidal or retinal degeneration.

OCT imaging of a retina often includes focusing a sample arm light beam onto the retina to enhance the resolution of the OCT image of the retina. Typically, OCT imaging of a retina is accomplished with the subject not wearing glasses or contacts. Variations between the optical characteristics of different eyes results in different amounts of focus correction being applied to the sample arm light beam for different subjects. Additionally, OCT imaging of a retina often includes the subject fixating on a fixation target so as to control eye orientation and accommodation level during an imaging session. The focus correction is typically applied so as to also focus the fixation target for the subject.

Many existing OCT systems apply a focus correction to the sample arm light beam using an approach that adds to the complexity of the system and/or requires a trained technician to operate the OCT system. For example, some existing OCT systems employ movement of an objective lens (i.e., a coupling optics lens located closest to the eye of the subject) relative to the eye to apply the focus correction. In some existing OCT systems, moving the objective lens relative to the eye is accomplished by a technician moving the OCT system relative to the eye. In some existing OCT systems, the OCT system moves the objective lens relative to the eye. Some existing OCT systems employ a focus detector, such as a fundus camera, that generates output indicative of how the sample arm light beam is currently focused on the retina for use in controlling the amount of focus correction applied to the sample arm light beam. Some existing OCT systems employ a coupling optics assembly, such as a telescope assembly, that includes two lenses, and varies the amount of focus correction applied to the sample arm light beam by varying the distance between the two lenses of the telescope assembly. A notable advantage of the approach used in many existing OCT systems to apply the focus correction to the sample arm light beam is that the same focus mechanism both focuses the sample arm light beam onto the retina and focuses the fixation target for the subject. In many existing systems, once the focus correction is applied, the length of the reference arm optical path is varied to search for the length of the reference arm optical path for which the OCT detector generates a signal from which an OCT image of the retina can be generated.

Added system complexity and/or the requirement for a trained technician to operate an OCT system, however, is undesirable in a home OCT system. For example, moving the objective lens relative to the retina may require movement of the OCT system relative to the retina, which complicates the operation of the OCT system. As another example, the use of a focus detector adds to the system complexity and cost.

Retinal Imaging OCT Systems for Use in a Non-Clinical Environment

Affordable retinal imaging OCT systems and related methods are described herein that are suitable for use in a non-clinical environment (e.g., at a patient's home), thereby serving to reduce the cost associated with monitoring of progression of a patient's retinal disease. Referring now to the drawings, in which like reference numerals represent like parts throughout the several views,FIG.1shows a user12looking into a view port14of a viewing assembly16of a retinal imaging OCT system10, in accordance with many embodiments. In many embodiments, the viewing assembly16is configured to approximately position one eye of the user12on an optical axis20of the OCT system10. For example, in the configuration shown inFIG.1, the viewing assembly16is configured to approximately position the right eye of the user12on the optical axis20. In many embodiments, the viewing assembly16is repositionable relative to the optical axis20so as to reconfigure the viewing assembly16to approximately position the left eye of the user12on the optical axis20. Accordingly, each of the right eye and the left eye of the user12can be selectively approximately positioned on the optical axis20of the OCT system10for imaging of the respective eye by the retinal imaging OCT system10. In embodiments described herein, final positioning and alignment of the optical axis of the respective eye of the user12with the optical axis20of the imaging system10is accomplished by the user12adjusting the user's position relative to the view port14in response to feedback provided to the user12by the OCT system10.

FIG.2is a simplified schematic illustration of components and associated optical paths of an OCT imaging device30of the OCT system10. The OCT imaging device30includes a broadband light source32, a beam splitter34, a reference arm optical path36, a reference arm optical path length adjustment mechanism38, a sample arm light beam focus mechanism40, a scanning unit42, a first dichroic mirror44, a coupling optics assembly46that includes a fixed position objective lens48and a fixed position rear lens50, a second dichroic mirror52, a display device54, a display device focus mechanism56, a pupil camera58, an eye illuminator60, and an OCT image detector62. In the illustrated embodiment, the OCT imaging device30is a spectral domain OCT imaging device that operates in a wavelength range of 800 nm to 900 nm. The eye illuminator60illuminates an eye64of the user12using a suitable wavelength of light (e.g., a wavelength of light above 920 nm). The display device54can project light between any suitable wavelength (e.g., from 400 nm to 700 nm). The first dichroic mirror44transmits the display device wavelength range and reflects the OCT wavelength. The second dichroic mirror52transmits the OCT wavelength and the display wavelength range (400 nm to 900 nm) and reflects the illumination wavelength (e.g., greater than 920 nm) to the pupil camera58.

In operation, the broadband light source32emits a light beam having the OCT wavelength. The light beam propagates from the light source32to the beam splitter34. The beam splitter splits the light beam into a sample arm light beam and a reference arm light beam.

The reference arm light beam propagates over a reference arm optical path36and then back to the beam splitter34. The reference arm optical path36includes a reference arm optical path length adjustment module38that is operable, under the control of a control unit64(seeFIG.3), to selectively vary the length of the reference arm optical path36. The reference arm optical path length adjustment module38can have any suitable configuration. For example, the reference arm optical path length adjustment module38can include a motorized movable mirror that is controllably displaceable.

The sample arm light beam propagates from the beam splitter34to the sample arm light beam focus mechanism40. The sample arm light beam focus mechanism40is operable, under the control of the control unit64, to selectively apply a focus correction to the sample arm light beam so as to focus the sample arm light beam onto the retina of the eye64. The sample arm light beam focus mechanism40provides focusing of the sample arm light beam onto the user's retina so as to account for the specific focusing characteristics of the user's eye64.

The sample arm light beam, with the applied focus correction, propagates from the sample arm light beam focus mechanism40to the scanning unit42. The scanning unit42is operable, under the control of the control unit64, to scan the sample arm light beam in two dimensions transverse to the direction of propagation of the sample arm light beam. The scanning unit42can have any suitable configuration. For example, in many embodiments, the scanning unit42includes dual axis scanning mirrors.

The scanned sample arm light beam propagates from the scanning unit42to the first dichroic mirror44. The scanned sample arm light beam is reflected by the first dichroic mirror44so as to propagate through the coupling optics assembly46by propagating through the fixed position rear lens50, the second dichroic mirror52, and the fixed position objective lens48. The scanned sample arm light beam propagates from the fixed position objective lens48into the eye64and onto the retina of the eye64.

A returned portion of the scanned sample arm light beam propagates back from the retina and through the fixed objective lens48, the second dichroic mirror52, and the fixed rear lens50. The returned portion of sample arm light beam is reflected by the first dichroic mirror44back to the scanning unit42. The returned portion of the sample arm light beam is redirected by the scanning unit42back through the sample arm light beam focus mechanism40to the beam splitter34. The returned portion of the sample arm light beam and the reference arm light beam are recombined by the beam splitter34to form a recombined light beam. The recombined light beam propagates to the OCT image detector62.

The OCT image detector62generates and outputs an OCT image signal that is processed using known techniques to build up a three-dimensional OCT image of layers of the retina. In many embodiments, the OCT image detector62detects interference between the returning sample arm light and the reference arm light only if the time travelled by light in the reference and sample arms is nearly equal. In many embodiments, the reference arm optical path length adjustment module38includes a mirror that is mounted to a motorized mechanism that is controllable to vary the position of the mirror, thereby controllably varying the length of the reference arm optical path36. The ability to vary the length of the reference arm optical path36enables the OCT imaging device30to be used to generate OCT images of any user's retina of a desired population of users even though each user's retina can be at a different distance from the fixed objective lens48when the user's head is engaged with the viewer assembly16due to corresponding anatomical variations between user's heads, as well as variation in the relative position between the user's head and the viewer assembly16.

In many embodiments, the eye illuminator60, the pupil camera58, and the display device54are used to provide feedback to the user12by which the user12self-aligns the eye64with the optical axis of the OCT imaging device30. The display device54displays a fixation target that is viewed by the user so as to align the eye64with the fixation target. The display device focus mechanism56is operable, under the control of the control unit64, to selectively apply a focus correction light emitted by the display device54so that the fixation target displayed by the display device54is in focus for the user12even when the imaging of the user's retina is accomplished without the user12wearing glasses or contacts. Similar to the sample arm light beam focus mechanism40, the display device focus mechanism56provides focusing of items displayed by the display device54(e.g., the fixation target) onto the user's retina so as to account for the specific focusing characteristics of the user's eye64.

In many embodiments, the OCT imaging device30is configured to automatically control components/modules of the OCT imaging device30during an imaging session during which an OCT image of a user's retina is generated. In many embodiments, the OCT imaging device30includes a suitable control unit that is operatively connected to components/modules of the OCT imaging device30and configured to communicate and/or control the components/modules. For example,FIG.3is a simplified schematic diagram illustrating components/modules of an embodiment of the OCT imaging device30that includes the control unit64operatively coupled with the components/modules. The control unit64includes a processor66and a data storage device68. The data storage device68stores program instructions executable by the processor66to accomplish the acts described herein. The data storage device68can also stores user specific data that can be used by the processor66to customize its control of the operation of the OCT imaging device30to the specific user as described.

The control unit64is operatively connected to a user interface70to receive input from the user12via the user interface70and/or to display output to the user12via the user interface70. Any suitable user interface70can be employed including, but not limited to, one or more push buttons, a display, a touch display, one or more indicator lights, and/or a speaker. The user interface70can be configured to enable a user to input an identification of the user for an imaging session so that the control unit30can employ parameters stored in the data storage device68when controlling the components/modules of the OCT imaging device30during an imaging session of a retina of the user12.

The control unit64is operatively connected to the eye illuminator60, the pupil camera58, and the display device54. The control unit64can turn the eye illuminator60on at the start of an imaging session and off at the end of an imaging session. In many embodiments, the control unit64turns the pupil camera58on at the start of the imaging session, receives image data from the pupil camera58, processes the image data to track the position of the optical axis of the eye64relative to the optical axis of the OCT imaging device30, and turns the pupil camera58off at the end of the imaging session. In many embodiments, the control unit64turns the display device54on at the start of the imaging session, generates and displays feedback to the user12on the display device54(e.g., the fixation target) to enable the user12to reposition the user's head relative to the viewer assembly16to sufficiently align the user's eye64with the optical axis of the OCT imaging device30for the generation of an OCT image of the user's retina, and turns the display device54of that the end of the imaging session.

The control unit64is operatively connected to the broadband light source32, the reference arm optical path length adjustment module38, the sample arm light beam focus mechanism40, the scanning unit42, the display device focus mechanism56, and the OCT image detector62to control operation of and/or receive input from these components/modules during an OCT imaging session of a retina of the user12. The control unit64can turn the broadband light source32on to begin transmission of the OCT wavelength light beam over the sample and reference arms at the beginning of the OCT scanning portion of the imaging session, and can turn the light source32off at the end of the imaging session. The control unit64can control the reference arm optical path length adjustment module38to vary the length of the reference arm optical path to search for the length of the reference arm optical path for which the OCT image detector62generates a suitable OCT signal for use in generating an OCT image of the user's retina. For example, the control unit64can receive and process the OCT signal generated by the OCT image detector62to monitor the suitability of the OCT signal to generate an OCT image of the user's retina while the control unit64controls the reference arm optical path length adjustment module38to vary the length of the reference arm optical path.

Following the identification of a suitable length of the reference arm optical path for use in generating an OCT image of the retina, the control unit64can control the sample arm light beam focus mechanism40to vary the amount of a focus correction applied to the sample arm light beam to search for a suitable focus correction for the user12. In many embodiments, the control unit64monitors a strength of the OCT image signal generated by the OCT image detector62while varying the amount of focus correction applied to the sample beam to identify the focus correction that maximizes the monitored strength of the OCT image signal, thereby identifying a focus correction that results in the sample arm light beam being focused on the retina of the user12. In some embodiments, an operational parameter of the sample arm light beam focus mechanism40is varied by the control unit64, thereby resulting in a corresponding variation in the applied focus correction. In some embodiments, the data storage device68stores a data lookup table that provides correspondence between the varied operational parameter of the sample arm light beam focus mechanism and the diopter correction of the respective focus corrections. The sample arm light beam focus mechanism40can be operable to vary the amount of the applied focus correction over a suitable range to accommodate any user within a target population of users. For example, the sample arm light beam focus mechanism40can be configured to be operable to vary the amount of the applied focus correction over at least a 15 diopter range. The sample arm light beam focus mechanism40can have any suitable configuration. For example, in some embodiments, the sample arm light beam focus mechanism40includes a liquid lens that is controllable by the control unit64to vary the applied focus correction to identify the optimum focus correction for use during the OCT imaging session of the retina of the user12. In some embodiments, the control unit64monitors output of the pupil camera58to monitor alignment of the user's pupil with the optical axis of the OCT imaging device30. In some embodiments, the control unit64monitors output of the pupil camera58to monitor whether the user's eyelid is sufficiently open for the sample arm light beam to reach the retina. In some embodiments, the control unit64suspends the search for the focus correction to be applied by the sample arm light beam focus mechanism40while there is insufficient alignment of the user's eye with the optical axis of the OCT imaging device30or if the user's eyelid is not sufficiently open for the sample arm light beam to reach the retina.

Following the identification of a focus correction to be applied by the sample arm light beam focus mechanism40for the user12, the control unit64can control operation of the display device focus mechanism56to apply a corresponding focus correction so that items displayed by the display device54(e.g., the fixation target) are in focus for the user12. For example, if a 2.5 diopter focus correction is identified to be the focus correction to be applied by the sample arm light beam focus mechanism40, the control unit64can control operation of the display device focus mechanism56to also apply a 2.5 diopter focus correction.

FIG.4AandFIG.4Bshow a simplified schematic block diagram of acts of a method100of imaging a retina by an OCT system, in accordance with embodiments. Any suitable OCT imaging system, such as the OCT system10described herein, can be used to practice the method100.

In act102, a light beam is emitted from a broadband light source. For example, in the OCT imaging device30of the OCT system10, the control unit64can control operation of the broadband light source32to emit the light beam.

In act104, the light beam is split into a sample arm light beam and a reference arm light beam. For example, in the OCT imaging device30, the beam splitter34splits the light beam into the sample arm light beam and the reference arm light beam.

In act106, the sample arm light beam propagates through a sample arm light beam focus mechanism to apply a focus correction to the sample arm light beam. For example, in the OCT imaging device30, the sample arm light beam propagates through sample arm light beam focus mechanism40, which applies the focus correction to the sample arm light beam.

In act108, the sample arm light beam (with the focus correction applied) is scanned, by a scanning unit, in two dimensions transverse to a direction of propagation of the sample arm light beam to produce a scanned sample arm light beam. For example, in the OCT imaging device30, the scanning unit42scans the sample arm light beam (with the focus correction applied by the sample arm light beam focus mechanism40) in two dimensions transverse to a direction of propagation of the sample arm light beam.

In act110, the user's head is restrained by a viewer assembly so that the scanned sample arm light beam is incident upon the retina. For example, in the OCT system10, the user's head is restrained by the viewer assembly16assembly so that the scanned sample arm light beam is incident upon the retina. In many embodiments, the user's head is restrained by the viewer assembly16so that the eye64is maintained at a fixed distance from the fixed position objective lens48.

In act112, the reference arm light beam propagates over a reference arm light beam optical path. For example, in the OCT imaging device30, the reference arm light beam propagates from the beam splitter34to the reference arm optical path length adjustment mechanism38and back to the beam splitter34.

In act114, a returned portion of the scanned sample arm light beam and the reference arm light beam are recombined to produce a recombined light beam. For example, in the OCT imaging device30, the beam splitter34recombines a returned portion of the scanned sample arm light beam and the reference arm light beam to produce the recombined light beam.

In act116, the recombined light beam propagates to an OCT image detector. For example, in the OCT imaging device30, the recombined light beam propagates from the beam splitter34to the OCT image detector62.

In act118, the OCT image detector generates an OCT signal for the recombined light beam. For example, in the OCT imaging device30, the OCT image detector62generates an OCT signal for the recombined light beam.

In act120, the OCT signal is monitored by a control unit. For example, in the OCT imaging device30, the control unit64monitors the OCT signal.

In act122, a reference arm optical path length adjustment mechanism is controlled, by the control unit, to vary the length of the reference arm optical path to identify a length of the reference arm optical path for which the OCT signal corresponds to an OCT image of the retina. For example, in the OCT imaging device30, the reference arm optical path length adjustment mechanism38is controlled, by the control unit64, to vary the length of the reference arm optical path36to identify a length of the reference arm optical path36for which the OCT signal corresponds to an OCT image of the retina of the eye64.

In act124, an operational parameter of the sample arm light beam focus mechanism is varied, by the control unit, over a range, while maintaining the length of the reference arm optical path for which the OCT signal corresponds to the OCT image of the retina, to identify a focus correction for the user, based on the OCT signal, for application to the sample arm light beam. For example, in the OCT imaging device30, an operational parameter of the sample arm light beam focus mechanism38is varied, by the control unit64, over a range, while maintaining the length of the reference arm optical path36for which the OCT signal corresponds to the OCT image of the retina of the eye64, to identify a focus correction for the user, based on the OCT signal, for application to the sample arm light beam.

FIG.5athroughFIG.5hshow a sequence of example OCT images generated during a search for a reference arm path length for which the OCT signal corresponds to an OCT image of a strong eye retina. The sequence of example OCT images shown illustrate aspects of the OCT images that can be identified using any suitable image processing approach to identify a reference arm path length for which the OCT signal corresponds to an OCT image of a strong eye retina.

FIG.5ashows an example OCT image126at time (0) (arbitrary units (AU)) and the reference arm adjustable mirror position equal to 100 AU. The OCT image126includes an auto correlation signal128from the retina that can be ignored.

FIG.5bshows an example OCT image130at time (1) AU and the reference arm adjustable mirror position equal to 90 AU. The OCT image130includes a cross correlation signal132from the retina. The cross correlation signal132is a ghost or an artifact that can be ignored.

FIG.5cshows an example OCT image134at time (2) AU and the reference arm adjustable mirror position equal to 80 AU. The OCT image134includes a cross correlation signal136from the retina. The cross correlation signal136is a ghost or an artifact that can be ignored.

FIG.5dshows an example OCT image138at time (3) AU and the reference arm adjustable mirror position equal to 70 AU. The OCT image138includes a cross correlation signal140from the retina. The cross correlation signal140is a ghost or an artifact that can be ignored.

FIG.5eshows an example OCT image142at time (4) AU and the reference arm adjustable mirror position equal to 60 AU. The OCT image142includes a cross correlation signal144from the retina. The cross correlation signal144is a “real” signal from the retina and the corresponding reference arm optical path length and/or the position of the reference arm adjustable mirror position can be stored.

FIG.5fshows an example OCT image146at time (5) AU and the reference arm adjustable mirror position equal to 50 AU. The OCT image146includes a cross correlation signal148from the retina. The cross correlation signal148is a “real” signal from the retina and the corresponding reference arm optical path length and/or the position of the reference arm adjustable mirror position can be stored.

FIG.5gshows an example OCT image150at time (6) AU and the reference arm adjustable mirror position equal to 53 AU. The OCT image150includes a cross correlation signal152from the retina. The cross correlation signal152is a “real” signal from the retina and the corresponding reference arm optical path length and/or the position of the reference arm adjustable mirror position can be stored.

FIG.5hshows an example OCT image154at time (7) AU and the reference arm adjustable mirror position equal to 58 AU. The OCT image154includes a cross correlation signal156from the retina. The cross correlation signal156is a “real” signal from the retina and the corresponding reference arm optical path length and/or the position of the reference arm adjustable mirror position can be stored.

FIG.6shows an example OCT image158at a time (20) AU and the reference arm adjustable mirror position equal to 53 AU. The OCT image158was generated with a user specific focus correction applied to the sample arm light beam. The OCT image158includes a cross correlation signal160from the retina. The cross correlation signal160is a “real” signal from the retina. The reference arm adjustable mirror position and the user specific focus correction applied to the sample arm beam used to generate the OCT image158can be used to generate an OCT image of the strong eye retina.

FIG.7athroughFIG.7cshow example OCT images generated during a search for a reference arm path length for which the OCT signal corresponds to an OCT image of a week eye retina. The sequence of example OCT images shown illustrate aspects of the OCT images that can be identified using any suitable image processing approach to identify a reference arm path length for which the OCT signal corresponds to an OCT image of a week eye retina.FIG.7ashows an example OCT image162that does not include a cross correlation signal.FIG.7bshows an example OCT image164that includes a cross correlation signal166from the retina. The cross correlation signal166is a “real” signal from the retina and the corresponding reference arm optical path length and/or the position of the reference arm adjustable mirror position can be stored.FIG.7cshows an example OCT image168that includes a cross correlation signal170from the retina. The cross correlation signal170is a “real” signal from the retina and the corresponding reference arm optical path length and/or the position of the reference arm adjustable mirror position can be stored.

FIG.8shows an example OCT image172that was generated with a user specific focus correction applied to the sample arm light beam. The OCT image172includes a cross correlation signal174from the retina. The cross correlation signal174is a “real” signal from the retina. The reference arm adjustable mirror position and the user specific focus correction applied to the sample arm beam used to generate the OCT image172can be used to generate an OCT image of the strong eye retina.

FIG.9shows a simplified schematic block diagram of a process200that can be used to identify a reference arm optical path length for which the OCT image corresponds to an OCT image of the retina. The process200can be used to accomplish act122of the method100.

In act202, while applying a default focus correction (e.g., 0 diopter) to the sample arm light beam, the reference arm optical path length adjustment mechanism is controlled to vary the reference arm optical path length. For example, in the OCT imaging device30, the control unit64controls the sample arm light beam focus mechanism40to apply the default focus correction to the sample arm path light beam. While the default focus correction is applied to the sample arm path light beam, the control unit64control the reference arm optical path length adjustment mechanism38to vary the length of the reference arm optical path36.

In act204, a reference arm search B-scan (a.k.a. cross-sectional tomography) is generated and stored for each of a selection of reference arm optical path lengths. The reference arm search B-scan can have any suitable number of reference arm search A-scans (a.k.a. axial depth scan). For example, in some embodiments, the reference arm search B-scan includes 500 reference arm search A-scans. In contrast, an imaging B-scan can be formed from the same number of A-scans as there are pixels in the OCT image detector, which can, for example, have 1024 pixels. For example, in the OCT imaging device30, the control unit64processes an OCT signal generated by the OCT image detector62to generate a reference arm search B-scan for each of a selection of lengths of the reference arm optical path36. The control unit64generates the reference arm search B scan by laterally combining a series of reference arm search A-scans. The control unit64controls the reference arm optical path length adjustment mechanism38to vary the reference arm optical path length around the respective selected reference arm optical path length so that the OCT image detector62generates an OCT signal that is processed by the control unit64to generate each of the reference arm search A-scans. Each reference arm search A-scan is indicative of the amount of the sample arm light beam that is reflected back from the location along the sample arm optical path corresponding to the respective reference arm optical path lengths. Accordingly, each reference arm search A-scan is indicative of a reflectively profile of the locations on the sample arm light beam corresponding to the reference arm search A-scan.

Any suitable approach can be used to generate each of the reference arm search A-scans. For example, in the OCT imaging device30, each spectrum output by the OCT image detector62can be processed by the control unit64using a Fast Fourier Transformation (FFT) to form a respective reference arm search A-scan.FIG.10shows an example spectrum on which a FFT is done to generate a respective reference arm search A-scan. In some embodiments, computational time is reduced during generation of the reference arm search A-scans by not including linearization and dispersion compensation.

In act206, an intensity number is determined for each reference arm search B-scan by summing the gray level of each of the reference arm search A-scans in the respective reference arm search B-scan. For example, in the OCT imaging device30, the control unit64determines an intensity number for each reference arm search B-scan by summing the gray level of each of the reference arm search A-scans in the respective reference arm search B-scan. In some embodiments, the intensity number has arbitrary units (AU).

In act208, the reference arm optical path length is set to match the reference arm optical path length of the reference arm search B-scan with the highest intensity number. For example, in the OCT imaging device30, the control unit64controls the reference arm optical path length adjustment mechanism38to set the reference arm optical path length to match the reference arm optical path length of the reference arm search B-scan with the highest intensity number.

In act210, the reference arm optical path length is adjusted to fine tune the position of the image of the retina within predetermined boundaries. For example, in the OCT imaging device30, the control unit64controls the reference arm optical path length adjustment mechanism38to fine tune the position of the image of the retina within predetermined boundaries.FIG.11shows an example OCT image during fine tuning of the reference arm optical path length to fine tune the position of the image of the retina within predetermined boundaries212,214. Any suitable approach can be used to detect the position of the image of the retina within the predetermined boundaries212,214. For example, a suitable image processing approach can be used that employs edge detection that is applied to a group of A scans to detect the position of the image of the retina relative to the predetermined boundaries212,214. The group of A-scans can include any suitable selection of A-scans. For example, in some embodiments, A-scans covering 10 different sections216are averaged to increase the reliability of edge detection based on the averaged A-scans. Any suitable number of A-scans can be included in each of the sections216. For example, in some embodiments, 50 A-scans are included in each of the sections216, and the 50 A-scans are averaged to detect an edged of the image of the retina. The sections216can be located relative to the predetermined boundaries212,214so that when a corresponding edge of the image of the retina is disposed on the sections216, the image of the retina is suitably located between the predetermined boundaries212,214. The direction of movement of the image of the retina for a change in the reference arm optical path length can be used to assess whether the image of the retina is a mirror image.

FIG.12shows a simplified schematic block diagram of acts of a process220that can be used in the method100to identify a user specific focus correction. The process220can be used to accomplish act124of the method100.

In act222, using the fine-tuned reference arm optical path length, the sample arm light beam focus mechanism is controlled to vary the applied focus correction through a selection of focus corrections. For example, in the OCT imaging device30, the control unit64controls the sample arm light beam focus mechanism40to vary the focus correction applied to the sample arm light beam through a selection of focus corrections.

In act224, a focus search B-scan is generated and stored for each of a selection of applied focus corrections. The focus search B-scan can have any suitable number of focus search A-scans (a.k.a. axial depth scan). For example, in some embodiments, the focus search B-scan includes 500 focus search A-scans. For example, in the OCT imaging device30, the control unit64processes an OCT signal generated by the OCT image detector62to generate a focus search B-scan for each of a selection of lengths of the reference arm optical path36. The control unit64generates the focus search B scan by laterally combining a series of focus search A-scans.

Any suitable approach can be used to generate each of the focus search A-scans. For example, in the OCT imaging device30, each spectrum output by the OCT image detector62can be processed by the control unit64using a Fast Fourier Transformation (FFT) to form a respective focus search A-scan. In some embodiments, computational time for generating each focus search A-scan is reduced by not including linearization and dispersion compensation.

In act226, an intensity score is determined for each focus search B-scan by summing the gray level of each of the focus search A-scans in the respective focus search B-scan. For example, in the OCT imaging device30, the control unit64determines an intensity score for each focus search B-scan by summing the gray level of each of the focus search A-scans in the respective focus search B-scan. In some embodiments, the intensity score for each focus search B-scan has arbitrary units (AU).

In act228, the sample arm light beam focus mechanism is controlled to apply the focus correction corresponding to the focus search B-scan with the highest intensity number. In some embodiments, interpolation using any suitable approach is employed to identify the best focus correction to apply when the amount of change in the intensity number between successive focus B-scans indicates that the best focus correction lies in between adjacent evaluated focus corrections.

FIG.13shows a simplified schematic block diagram of acts of a process300that can be accomplished in conjunction with the method100. The process300can be used to operate a display device focus mechanism based on the identified focus correction for the user applied by the sample arm light beam focus mechanism that best focuses the sample arm light beam onto the retina.

In act302, light is propagated from a display device to the retina through a display device focus mechanism. For example, in the OCT imaging device30, light is propagated from the display device54through the display device focus mechanism56.

In act304, a focus setting of the display device focus mechanism is determined, by the control unit, based on the identified focus correction for the user applied via the sample arm light beam focus mechanism. For example, in the OCT imaging device30, the control unit64determines a focus setting of the display device focus mechanism56based on the identified focus correction for the user applied via the sample arm light beam focus mechanism40.

In act306, the control unit controls the display device focus mechanism to operate at the focus setting for the display device focus mechanism. For example, in the OCT imaging device30, the control unit64controls the display device focus mechanism56to operate at the focus setting for the display device focus mechanism56.

Many of the features and approaches employed in the OCT imaging systems and related processes described herein provide benefits such as reduced cost and/or ease of operation. For example, the use of the sample arm light beam focus mechanism and acts described herein can be used in conjunction with a coupling optics assembly (e.g., a telescope) that has no moving parts. Additionally, the distance between the eye and the objective lens of the OCT imaging system can be fixed. For example, the distance between the eye and the objective lens can be defined by facial features (for example forehead-eye distance) engaged with a viewer assembly. Further, the use of the sample arm light beam focus mechanism and acts described herein can be used without the use of an additional detector that functions as a focus detector. The use of two separate focus mechanisms (i.e., a sample arm light beam focus mechanism and a display device focus mechanism) as described in conjunction with the OCT imaging systems and related processes described herein is believed to be counterintuitive in view of the use of a single focus mechanism (e.g., a coupling optics controllable to vary the focus) in many existing OCT imaging systems.

Many of the features and approaches employed in the OCT imaging systems and related processes described herein can be employed in combination with storage and reuse of user specific imaging parameters. For example, the reference arm optical path length and the applied focus correction identified and used during an initial imaging of a specific user's retina can be stored and used during subsequent imaging of the specific user's retina so as to reduce the range of the reference arm optical path lengths and the range of applied focus corrections searched during the subsequent imaging, thereby reducing the time required to conduct the subsequent imaging session. Any suitable approach can be used to store and reuse the user specific imaging parameters, such as the approaches described in U.S. Pat. No. 10,595,722, entitled AUTOMATIC OPTICAL PATH ADJUSTMENT IN HOME OCT, the entire content of which is hereby incorporated herein by reference.

Other variations are within the spirit of the present invention. Thus, while the invention is susceptible to various modifications and alternative constructions, certain illustrated embodiments thereof are shown in the drawings and have been described above in detail. It should be understood, however, that there is no intention to limit the invention to the specific form or forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention, as defined in the appended claims.

The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. The term “connected” is to be construed as partly or wholly contained within, attached to, or joined together, even if there is something intervening. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate embodiments of the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.