Patient alignment system for an ophthalmic imaging device

Abstract

An ultra-wide angle ophthalmic imaging scanner is provided.SOLUTION: An ultra-wide-angle ophthalmic imaging scanner includes a rotatable mirror for scanning a light beam over a fundus via an elliptical mirror having the rotatable mirror at a first focus and a pupil of an eye at a second focus, a stereoscopic imaging device for acquiring a stereoscopic image of the pupil via the rotatable mirror and the elliptical mirror, and a processor for controlling the stereoscopic imaging device to acquire the stereoscopic image via the rotatable mirror and the elliptical mirror when the rotatable mirror is in a predetermined orientation, and for processing the stereoscopic image to generate an alignment signal to an imaging location of the pupil for ultra-wide-angle image acquisition of the fundus. The processor then controls the imaging scanner to scan the beam on the fundus via the elliptical mirror by rotating the rotatable mirror to obtain an ultrawide-angle image.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD OF THE INVENTION Exemplary aspects herein relate generally to the field of ophthalmic imaging scanners, and more particularly to a system for positioning a subject's eye for fundus image acquisition by an ophthalmic imaging scanner. [Background technology]

[0002] Ophthalmic imaging scanners use a variety of technologies to image different portions of a subject's eye, which are used by clinicians to diagnose and manage various eye conditions. Ophthalmic imaging scanners acquire images of the fundus and other parts of the eye by scanning a light beam over the eye and detecting light returning from the eye. To acquire high-quality images of the fundus of the eye, ophthalmic imaging scanners, such as scanning laser ophthalmoscopy (SLO) and optical coherence tomography (OCT) scanners, often require that the exit pupil of the ophthalmic imaging scanner be located within a predetermined distance from the eye's pupil for acquisition of such images. Pupil alignment is particularly important for wide-angle (WF) and ultra-wide-angle (UWF) ophthalmic imaging scanners, which rely on light passing through the pupil to and from the fundus at angles of incidence that vary significantly relative to the pupil plane.

[0003] To measure the distance to the eye, stereoscopic distance measurement techniques using stereoscopic cameras are often used. For example, some ophthalmic imaging scanners include a so-called pupil alignment module (PAM). This is configured to include a stereoscopic camera for acquiring stereoscopic images of the eye, locating the centers of the pupils in the stereoscopic images, and determining the distance between the PAM and the pupils based on the distance between the pupil centers located in the stereoscopic images. Visual feedback based on the determined distance is provided to guide the subject to position the eyes appropriately for imaging.

[0004] PAM stereoscopic cameras are typically mounted on ophthalmic imaging scanners and have a direct visual path to the subject's eyes (i.e., no intervening optical elements). However, in WF or UWF ophthalmic imaging scanners, the mirror-based WF / UWF optics often used for WF or UWF image acquisition, which typically use elliptical mirrors to transmit scans to and from the eye, make it difficult or impossible to provide such a direct visual path. The alternative of using additional optical elements within the WF / UWF optics to direct light from the eyes to the stereoscopic camera increases system complexity and can present significant technical challenges, such as addressing spurious reflections caused by the additional optical elements that can appear as artifacts in the acquired images. Summary of the Invention [Problem to be solved by the invention]

[0005] It would therefore be desirable to find a way to accommodate a stereoscopic imaging device for acquiring stereoscopic images of the pupil within a mirror-based WF or UWF ophthalmic imaging scanner that at least partially addresses the above-mentioned challenges. [Means for solving the problem]

[0006] According to a first exemplary aspect of the present disclosure, there is provided an ultra-wide-angle (UWF) ophthalmic imaging device configured to acquire an ultra-wide-angle (UWF) image of the fundus of a subject's eye by scanning a light beam over the fundus, the device comprising: a light source that emits a light beam; a rotatable mirror configured to scan the light beam over the fundus; and an elliptical mirror having a first focus and a second focus through which the rotatable mirror scans the light beam over the fundus, wherein the rotatable mirror is configured to scan the light beam over the elliptical mirror via the first focus, and the pupil of the eye is positioned at the second focus when the ultra-wide-angle ophthalmic imaging device is in use. The UWF ophthalmic imaging device includes a stereoscopic imaging device configured to acquire stereoscopic images of a pupil via a rotatable mirror and an ellipsoidal mirror, and a processor configured to generate signals for positioning the pupil of the eye within a target range for acquiring an ultra-wide-angle image of the fundus based on the stereoscopic images of the pupil in a patient alignment mode, and subsequently control the ultra-wide-angle ophthalmic imaging device to acquire an ultra-wide-angle image of the fundus in a fundus imaging mode. In the patient alignment mode, the processor is configured to control the rotatable mirror to remain stationary in a predetermined orientation, control the stereoscopic imaging device to acquire stereoscopic images of the pupil via the rotatable mirror and the ellipsoidal mirror while the rotatable mirror remains stationary in the predetermined position, and process the stereoscopic images of the pupil to generate signals for aligning the pupil of the eye to an imaging position. In the fundus imaging mode, the processor is configured to control the ultra-wide-angle ophthalmic imaging device to acquire an ultra-wide-angle image of the fundus by controlling a light source to emit a light beam and controlling the rotatable mirror to scan the light beam over the fundus via the ellipsoidal mirror.

[0007] In some exemplary embodiments, the rotatable mirror is configured to reflect the light beam onto the elliptical mirror at the first focus. In other exemplary embodiments, the UWF ophthalmic imaging device further comprises a second elliptical mirror through which the rotatable mirror is configured to scan the light beam onto the fundus, the second elliptical mirror having a first focus and a second focus, the rotatable mirror is configured to reflect the light beam at the first focus of the second elliptical mirror, the second focus of the second elliptical mirror coinciding with the first focus of the elliptical mirror.

[0008] The rotatable mirror is configured to reflect the light beam onto the elliptical mirror at a first focus of the elliptical mirror, and the stereoscopic imaging device can be positioned between the rotatable mirror and the elliptical mirror in a region that the light beam does not pass through when acquiring UWF images of the fundus. In the exemplary embodiment including the second elliptical mirror described above, the stereoscopic imaging device can be positioned between the rotatable mirror and the second elliptical mirror in a region that the light beam does not intersect when acquiring UWF images of the fundus.

[0009] The predetermined orientation of the rotatable mirror may be such that when the ultra wide angle ophthalmic imaging device begins acquiring UWF images of the fundus, the rotatable mirror begins to rotate from the predetermined orientation.

[0010] Additionally or alternatively, the stereoscopic imaging device may be positioned between the rotatable mirror and the elliptical mirror so that deviation from circularity of each pupil representation in a stereoscopic image of the pupil acquired by the stereoscopic imaging device when the rotatable mirror is in a predetermined orientation is minimized. In some exemplary embodiments, the elliptical mirror may have a plane of symmetry including a first focus and a second focus, and a normal direction of the rotatable mirror at the first focus may form a predetermined angle with the plane of symmetry when the rotatable mirror is in a predetermined orientation. The stereoscopic imaging device may include a first camera and a second camera. The first camera and the second camera are positioned equidistant from and on opposite sides of a second plane including the first focus and the second focus. The normal direction of the rotatable mirror and the second plane form an angle at the first focus that is less than twice the predetermined angle. In these exemplary embodiments, the first camera may have a first optical axis, and the second camera may have a second optical axis parallel to the first optical axis. The stereoscopic imaging device may further include a Fresnel lens disposed between the rotatable mirror and both the first and second cameras. The Fresnel lens is configured to refract light from the eye reflected by the rotatable mirror (e.g., at a first focal point of the elliptical mirror) to propagate along a first and second optical axis. In some other exemplary embodiments, the stereoscopic imaging device may include a first camera having a first optical axis and a second camera having a second optical axis parallel to the first optical axis. The Fresnel lens is disposed between the rotatable mirror and both the first and second cameras. The Fresnel lens is configured to refract light from the eye reflected by the rotatable mirror (at a first focal point of the elliptical mirror, if the rotatable mirror is positioned to reflect a light beam at the first focal point) to propagate along the first and second optical axes.

[0011] The UWF ophthalmic imaging device of the first exemplary aspect or exemplary embodiments thereof described above further includes a fixation target light source configured to project a fixation light onto the fundus via a rotatable mirror and an elliptical mirror, and in a patient alignment mode, the processor controls the fixation target light source to project the fixation light onto the rotatable mirror at a predetermined orientation, and the fixation target light source is positioned relative to the rotatable mirror so that the fixation light is projected onto the fundus via the elliptical mirror to fix the gaze direction of the eye. In some exemplary embodiments, where the rotatable mirror is configured to reflect the light beam at a first focal point and the stereoscopic imaging device is positioned in a region between the rotatable mirror and the elliptical mirror through which the light beam does not pass when acquiring UWF images of the fundus, the fixation target light source can also be positioned in that region. In this case, the predetermined orientation of the rotatable mirror may be such that the rotatable mirror begins to rotate from the predetermined orientation when the ultra-wide-angle ophthalmic imaging device starts acquiring UWF images of the fundus. For example, the fixation target light source is configured to project a fixation light onto the rotatable mirror from a position such that when the rotatable mirror is in a predetermined orientation, the fixation light enters the eye in the direction of the eye's central gaze fixation.

[0012] In the UWF ophthalmic imaging device of the first exemplary aspect or exemplary embodiment thereof described above, the signal for positioning the pupil of the eye within a target range for acquiring a UWF image of the fundus may include projecting light of a first color (e.g., blue) onto the eye when the subject should move the eye toward the UWF ophthalmic imaging device to orient the pupil toward the target range, projecting light of a second color (e.g., red) onto the eye when the subject should move the eye away from the UWF ophthalmic imaging device to orient the pupil toward the target range, and projecting light of a third color (e.g., green) onto the eye when the pupil is within a target range suitable for UWF image acquisition, wherein the first color, the second color, and the third color are different from each other. Additionally or alternatively, the signal for positioning the pupil of the eye within a target range for acquiring a UWF image of the fundus may include a first sound (e.g., a tone or sound) when the subject should move their eye toward the UWF ophthalmic imaging device to orient the pupil toward the target range, a second sound (e.g., a tone or sound) when the subject should move their eye away from the UWF ophthalmic imaging device to orient the pupil toward the target range, and a third sound (e.g., a tone or sound) when the pupil is within a target range suitable for UWF image acquisition, wherein the first sound, second sound, and third sound are different from one another.

[0013] The UWF ophthalmic imaging device of the first exemplary aspect or any exemplary embodiment thereof described above may further comprise an illumination light source configured to illuminate the eye with light via the rotatable mirror and the elliptical mirror to obtain a stereoscopic image of the pupil by the stereoscopic imaging device, and may comprise, for example, an ultra-wide angle scanning laser ophthalmoscope.

[0014] According to a second exemplary aspect of the present disclosure, there is provided a method for controlling an UWF ophthalmic device configured to acquire UWF images of an eye's fundus by scanning a light beam over the fundus. The ultra-wide-angle ophthalmic imaging device includes a light source that emits a light beam, a rotatable mirror configured to scan the light beam over the fundus, and an elliptical mirror having a first focus and a second focus, through which the rotatable mirror scans the light beam over the fundus. The rotatable mirror is configured to scan the light beam over the elliptical mirror through the first focus, and a pupil of the eye is positioned at the second focus when the ultra-wide-angle ophthalmic imaging device is in use. A stereoscopic imaging device is also configured to acquire stereoscopic images of the pupil via the rotatable mirror and the elliptical mirror. The method includes generating a signal to position the pupil of the eye within a target range for acquiring an ultra-wide-angle image of the fundus, by controlling a stereoscopic imaging device to hold a rotatable mirror stationary in a predetermined orientation that enables imaging of the pupil via the rotatable mirror and the elliptical mirror, controlling the stereoscopic imaging device to acquire a stereoscopic image of the pupil via the rotatable mirror and the elliptical mirror while the rotatable mirror is in the predetermined orientation, and processing the stereoscopic image of the pupil to generate a signal. After generating the signal, the method further includes controlling a light source to emit a light beam, and controlling the ultra-wide-angle ophthalmic imaging device to rotate the rotatable mirror to scan the light beam over the fundus via the elliptical mirror to acquire an ultra-wide-angle image of the fundus.

[0015] In some exemplary embodiments, the UWF ophthalmic imaging device further includes a fixation target light source configured to project fixation light onto the fundus via the rotatable mirror and the elliptical mirror, and the method further includes controlling the fixation target light source to project the fixation light onto the rotatable mirror when the rotatable mirror is in a predetermined orientation and the stereoscopic imaging device is controlled to acquire a stereoscopic image of the pupil, and the fixation target light source is positioned relative to the rotatable mirror such that the fixation light is projected onto the fundus via the elliptical mirror to fix the gaze direction of the eye.

[0016] Also provided is a computer program according to a third exemplary aspect of the present specification, comprising computer-readable instructions, which, when executed by a processor of the UWF ophthalmic imaging device of the aforementioned first exemplary aspect or any exemplary embodiment thereof, causes the processor to perform the method of the aforementioned second exemplary aspect or any embodiment thereof. The computer program may be stored on a non-transitory computer-readable storage medium (e.g., a computer hard disk or CD, etc.) or carried by a computer-readable signal.

[0017] Exemplary embodiments of the invention will now be described in detail, by way of non-limiting example only, with reference to the accompanying drawings, in which like reference symbols appearing in different drawings may represent identical or functionally similar elements, unless otherwise stated, and in which: [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic diagram of an ultra-wide-angle ophthalmic imaging device according to an example embodiment herein. [Figure 2] FIG. 2 is a schematic diagram of programmable signal processing hardware that can be configured to perform the functions of processor 50 described herein. [Figure 3] Figure 3 is a schematic diagram showing a cross-sectional view of the elliptical mirror 32 of this exemplary embodiment in a plane perpendicular to the symmetry axis of the elliptical mirror and including the first focus 32-1, as well as a top view along the symmetry axis of the stereoscopic imaging device 40 and fixation target light source 80 of this exemplary embodiment. [Figure 4] 4 is a schematic diagram of an ultra-wide-angle ophthalmic imaging device according to a modified example of an exemplary embodiment herein, which includes two elliptical mirrors with a common focal point, a rotating mirror 30 at the other focal point of one of the elliptical mirrors, and scans a linear illumination across the fundus 12 through a pupil 14 located at the other focal point of the other elliptical mirror. [Figure 5]5 is a schematic diagram of an exemplary embodiment of a pupil alignment module (PAM) of a UWF ophthalmic imaging device as viewed from a rotatable mirror 30. The PAM includes the stereoscopic imaging system 40 and modified fixation target light source 80 included in the exemplary embodiment of FIG. [Figure 6] FIG. 6 is a flow diagram illustrating how the processor 50 controls the UWF ophthalmic imaging device of the exemplary embodiment to acquire a UWF image 55 of the fundus 12 of the eye 10. DETAILED DESCRIPTION OF THE INVENTION

[0019] 1 is a schematic diagram of an ophthalmic imaging device 100 according to a first exemplary embodiment, which is operable to image a portion of a subject's eye 10 by scanning a light beam over the eye 10. The imaged portion, in this exemplary embodiment, may be a region of the fundus 12 of the eye 10. The fundus 12 is the inner layer of the eye 10 opposite the lens and includes the retina, macula, optic disc, fovea, choroid, and blood vessels. The ophthalmic imaging device 100 may also image other regions of the eye 10, such as at least a portion of the anterior segment of the eye 10.

[0020] The ophthalmic imaging device 100 may be a wide-angle (WF) ophthalmic imaging device operable to acquire a WF image of the fundus 12. A WF image of the fundus 12 is defined as a single captured image centered on the fovea of ​​the eye 10, which images the mid-peripheral retinal anatomical features located posterior to the vortex vein ampulla in all four quadrants of the eye 10 (i.e., superior, inferior, nasal, and buccal). A WF ophthalmic imaging device is therefore capable of acquiring a single captured image covering the retinal region from the fovea to the posterior edge of the vortex vein ampulla, and is defined as having a field of view (FoV) ranging from 60 to 100 degrees. Here, the FoV is expressed in terms of ocular angle, which is the angle subtended by the imaged retinal region at the ocular center of the eye 10, i.e., the intersection of the vertical diameter of the eye and the visual axis.

[0021] The ophthalmic imaging device 100, as in this exemplary embodiment, is provided in the form of an ultra-wide-field (UWF) ophthalmic imaging device, which has a larger FoV than a WF device and is operable to acquire UWF images of the fundus 12, covering a wider portion of the fundus 12. A UWF image of the fundus 12 is defined as a single image centered on the fovea of ​​the eye 10 and capturing peripheral retinal anatomical features anterior to the vortex vein ampulla in all four quadrants. A UWF ophthalmic imaging device is therefore defined as being capable of acquiring a single UWF image covering the retinal region extending from the fovea to the anterior edge of the vortex vein ampulla and down to the pars plana, and having a field of view (expressed in eye angles) ranging from 110 to 220 degrees. As an example, the Optos Daytona® is capable of acquiring UWF images (so-called Optomap® images) covering up to 200 degrees of the fundus in a single image (i.e., approximately 82% of the retina).

[0022] It should be noted that the techniques described herein are not limited in their application to WF and UWF ophthalmic imaging devices, but may also be applied to small FoV ophthalmic imaging devices and may be beneficial to any scanning ophthalmic imaging device that uses one or more elliptical mirrors to scan light across a portion of the eye 10 to image that portion.

[0023] In this exemplary embodiment, the ophthalmic imaging device 100 includes a UWF combined scanning laser ophthalmoscope (SLO) and optical coherence tomography (OCT) device and is configured to acquire OCT images of the fundus 12 using well-known interferometric imaging techniques, as well as fundus images in one or more additional modes. Examples of such additional imaging modes include pseudocolor imaging, fundus autofluorescence (FAF), fundus fluorescein photography (FA), and indocyanine green angiography (ICGA). As an example, the Optos Monaco® is a combined SLO-OCT system capable of acquiring green or red (or a combination of green and red) laser images, green laser autofluorescence images, and OCT images. However, the ophthalmic imaging device 100 need not be a combined SLO-OCT system; instead, it may be an OCT imager capable of acquiring only OCT images, or a UWF SLO capable of operating in one or more of the aforementioned (or other) SLO imaging modes, excluding the OCT mode. The Optos Daytona® is an example of such a multi-mode UWF SLO.

[0024] As shown schematically in FIG. 1, an ophthalmic imaging device 100 emits at least one light beam L for imaging an eye 10. T (which may be understood as a projection in any direction), and an optical system including a rotatable mirror 30 and an ellipsoidal mirror 32. A stereoscopic imaging device 40 (described in more detail below) is provided to assist in positioning the eye 10 so that it can be imaged by the ophthalmic imaging device 100. The optical system directs at least one light beam L T scans the eye 10, and the light beam L T The light L returning from the area of ​​the eye 10 illuminated with R It is configured to collect and guide the return light L R is the light beam L reflected or scattered by the eye 10. T or may be part of the light beam L, e.g., in the case of FAF and ICGA imaging modes. T The light may be excited by

[0025] The ophthalmic imaging device 100 further comprises a processor (or controller) 50, and as in this exemplary embodiment, may also comprise a beam splitter 60 or a photodetector 70. The beam splitter 60 splits the returning light L R A part of the return light L is separated. Rto a photodetector 70. A UWF image 55 of the eye 10 is acquired by the ophthalmic imaging device 100 (e.g., processor 50) by processing the output of the photodetector 70 using well-known techniques.

[0026] The optical system may also include a drive mechanism 34, for example comprising a galvanometer, controlled by a processor 50 to impart a predetermined rotational movement to the rotatable mirror 30, thereby rotating the light beam L. T This can involve, as in the present exemplary embodiment, a predetermined oscillatory rotational motion in which the rotatable mirror 30 rotates alternately clockwise and counterclockwise through a predetermined angle (or, stated another way, the rotatable mirror 30 repeatedly rotates about the mirror's axis of rotation through a defined angular range, reversing the direction of rotation at each end of the angular range).

[0027] The light source 20 is generally configured to generate light in one or more wavelength ranges, such as the visible spectrum (e.g., red and green light) and / or the near-infrared spectrum, suitable for imaging the fundus 12 (or, in some cases, other portions of the eye 10). The light source 20 may include, for example, one or more laser diodes or one or more superluminescent diodes (or a combination of one or more laser diodes and one or more superluminescent diodes), and may also include one or more optical components, such as a collimator, an aperture, and a lens, configured to generate one or more light beams. The optical system (described below) may be configured to illuminate an area of ​​the fundus 12 using a (moving) point of light, or a line of light (if the ophthalmic imaging device 100 is a linear (i.e., line-scanning) system), generated using a cylindrical lens or other known components or optical assemblies for generating line illumination.

[0028] In an exemplary embodiment in which the ophthalmic imaging device 100, such as the present example, is operable in OCT imaging mode, OCT imaging can be provided with a swept light source (if the ophthalmic imaging device 100 is a swept-source OCT (SS-OCT) system) or a broadband light source (if the ophthalmic imaging device 100 is a spectral-domain OCT (SD-OCT) system).

[0029] The configuration of the photodetector 70 is not limited, and the photodetector 70 may be, for example, a balanced photodetector configuration consisting of two reverse-biased photodiodes. The output photocurrents are canceled, and the canceled current signal is converted to a voltage detection signal by a transimpedance amplifier. In embodiments where the ophthalmic imaging device 100 is provided in the form of a line-scanning SLO, the photodetector 70 may be configured as a one-dimensional or two-dimensional array of light-sensing elements. In exemplary embodiments where the ophthalmic imaging device 100 features an OCT imaging mode, such as this embodiment, a spectrometer (in the case of an SD-OCT configuration) or a photodiode detector (in the case of a SS-OCT configuration) may be provided to detect the interference light from the sample arm and reference arm of the interferometer.

[0030] The optical system of this exemplary embodiment directs light L from the light source 20 onto the area of ​​the fundus 12 that is to be illuminated in a point scan. T The optical system is configured to perform two-dimensional point scanning with a ray of light L and to collect light from the illuminated area during the point scanning. The optical system is configured to direct the light beam L onto the fundus 12 in part via an ellipsoidal mirror 32. T The optical system further comprises a scanner 36 and a curved mirror 38, which scans the light beam L. T The scanner 36 is configured to scan the light beam L in a first direction across the elliptical mirror 32 via the rotatable mirror 30. The scanner 36, as in this exemplary embodiment, is in the form of a polygon scanner. TThe scanner 36 comprises a plurality of (e.g., 16) facets arranged around the periphery of a wheel that rotates at high speeds (typically greater than 30,000 revolutions per minute) to perform high-frequency repetitive scanning of the ellipsoidal mirror 32. However, the scanner 36 can take other forms, such as a galvanometer scanner, a microelectromechanical system (MEMS) scanning mirror, or a resonant scanning mirror. Alternatively, if the optical system is a linear system, it can be replaced by a cylindrical lens or other means that includes a "fan" of light rays that form a line of light when projected onto a flat surface. When the ophthalmic imaging device 100 has an OCT imaging mode, as in this exemplary embodiment, a second galvanometer scanner (not shown in FIG. 1 ) can be provided to scan the OCT sample beam in a first direction across the ellipsoidal mirror 32 via the rotatable mirror 30.

[0031] Light beam L T The light is reflected successively by the scanner 36, the curved mirror 38, the rotatable mirror 30, and the elliptical mirror 32 before passing through the pupil 14 of the eye 10 and onto the fundus 12. The light from the illuminated area of ​​the fundus 12 follows the same optical path as the light beam that entered the optical system, but in reverse order, and is directed by the beam splitter 60 to a photodetector 70.

[0032] Light beam L T a scanner 36 for scanning the light beam L in a first (e.g., vertical) direction on the area of ​​the fundus 12; and a scanner 36 for rotating about its rotation axis for scanning the light beam L TThe two-dimensional point scan is performed by a rotating mirror 30 that scans the ellipsoidal mirror 32 in a second (e.g., horizontal) direction over the area of ​​the fundus 12 (which may be orthogonal to the first direction, as in this exemplary embodiment). The ellipsoidal mirror 32 has a first focal point 32-1 and a conjugate second focal point 32-2, and may be in the form of a spherical mirror having rotational symmetry, particularly an axis of rotational symmetry centered on a principal axis passing through the focal points, as in this exemplary embodiment. More generally, any form of curved mirror having a curvature that can transmit light rays incident on the first focal point of the curved mirror to the conjugate second focal point of the curved mirror can be used in the exemplary embodiment as a generalization of the ellipsoidal mirror 32. In some exemplary embodiments, the ellipsoidal mirror 32 may have a substantially spherical shape, which allows the ophthalmic imaging device 100 to acquire WF or UWF images of the fundus 12 even with slight deviations in curvature from a spherical shape. The axis of rotation of the rotatable mirror 30 may be parallel to the axis of circular symmetry of the spherical mirror, as in this exemplary embodiment. The first focal point 32-1 and the light beam L incident thereon as the beam is scanned by the rotation of the rotatable mirror 30 are T The optical path length between the path T3 on the elliptical mirror 32 followed by the scanner 36 is therefore constant. The scanning performed by the scanner 36 and the rotatable mirror 30 is coordinated by a processor 50 or scanning system controller (not shown) to synchronize the optical beam L T can scan over the fundus 12 according to a predetermined scanning pattern.

[0033] The curved mirror 38 (also referred to as a slit mirror) may be an elliptical mirror, as in this exemplary embodiment. The curved mirror 38 and the elliptical mirror 32 each have a first focal point and a conjugate second focal point. The scanner 36 scans the light beam L at the first focal point of the curved mirror 38. T 38, which is positioned to reflect the beam L T The curved mirror 38 causes the projection of the incident light beam L to follow the trajectory T1 shown in FIG. T towards its second focal point, and the rotatable mirror 30 reflects the light beam L at the second focal point of the curved mirror 38. TThe rotatable mirror 30 is positioned to reflect the beam L at a first focal point 32-1 of the elliptical mirror 32. T The pupil 14 of the eye 10 is positioned at the second focal point 32-2 of the elliptical mirror 32. T is scanned onto the curved mirror 38, the beam L T is reflected from there via a rotatable mirror 30 onto an elliptical mirror 32. T 1 along the so-called "vertical" (or "fast") scan direction on the elliptical mirror 32 during each so-called "vertical scan." As the rotatable mirror 30 rotates, adjacent vertical scans move relative to each other along the so-called "horizontal" (or "slow") scan direction. Thus, points of the vertical scans having the same height are located along the path T3 shown in FIG. 1.

[0034] The processor 50 may be provided in any suitable form, such as the processor 220 of programmable signal processing hardware 200 of the type shown generally in FIG. 2. The programmable signal processing hardware 200 includes a communications interface (I / F) 210 for communicating control signals and / or data with the light source 20, a drive mechanism 34, a stereoscopic imager 40, a photodetector 70, and a fixation target light source, as described herein. The signal processing hardware 200 includes a processor 220 (e.g., a central processing unit, CPU, and / or a graphics processing unit, GPU), a working memory 230 (e.g., random access memory), and an instruction store 240 that stores a computer program 245 of computer-readable instructions that, when executed by the processor 220, cause the processor 220 to perform the various functions of the processor 50 described herein.

[0035] The working memory 230 stores information used by the processor 220 during the execution of the computer program 245. The instruction storage unit 240 may consist of a ROM (e.g., in the form of an Electrically Erasable Programmable Read-Only Memory (EEPROM) or flash memory) on which computer-readable instructions are pre-stored. Alternatively, the instruction storage unit 240 may comprise a RAM or similar type of memory, into which the computer-readable instructions for the computer program 245 may be input from a computer program product, such as a non-transitory computer-readable storage medium 250, in the form of a CD-ROM, DVD-ROM, etc., or from a computer-readable signal 260 carrying the computer-readable instructions. In any event, the computer program 245, when executed by the processor 220, causes the processor 220 to perform the functions of the processor 50 described herein. More generally, the processor 50 of the present exemplary embodiment may include one or more instances of the computer processor 220 and one or more instances of the memory 240 that store the computer-readable instructions. The computer-readable instructions, when executed by the computer processor 220, cause the computer processor 220 to perform the functions of the processor 50 described herein. If multiple processors 220 are provided, the processors 220 may be in communication with each other via any computer network.

[0036] It should be noted, however, that processor 50 may be implemented with non-programmable hardware, such as an ASIC, FPGA, or other integrated circuit dedicated to performing the functions of processor 50 described above, or a combination of such non-programmable hardware and programmable hardware as described with reference to FIG. 2.

[0037] 1 , stereoscopic imaging device 40, which may form part of a so-called pupil alignment module (PAM), includes first and second cameras 42, 44 configured to acquire, via rotatable mirror 30 and elliptical mirror 32, stereoscopic images 46-1, 46-2, respectively, of pupil 14 and a peripheral portion of eye 10 (including at least a portion of the iris, and typically also a portion of the sclera). In this exemplary embodiment, stereoscopic imaging device 40 also includes an illumination source 47 that illuminates eye 10 via rotatable mirror 30 and elliptical mirror 32. Reflections of this light from eye 10 are then detected by first and second cameras 42, 44 to acquire, respectively, stereoscopic images 46-1, 46-2, of pupil 14. Illumination is typically in the infrared (IR) band for patient comfort and to avoid pupil constriction, and may be provided by illumination source 47, for example, in the form of an IR light-emitting diode (LED). The stereo cameras 42, 44 may use complementary metal-oxide semiconductor (CMOS) sensors and fast lenses with fixed focal lengths to compensate for the sensors' relatively low sensitivity to IR illumination typically provided by illumination sources. The ophthalmic imaging device 100, as in this exemplary embodiment, further includes a fixation target light source 80 (e.g., as part of the PAM) that includes one or more light sources, such as, for example, light-emitting diodes (LEDs). The fixation target light source 80 directs fixation light L via a rotatable mirror 30 and an elliptical mirror 32. F The fixation target light L F The projection of the fixation light L onto the fundus 12 has a predetermined shape selected to help the subject maintain a stable gaze direction, which may include, for example, one or more crosshairs, a dot, a disk, or a circle. F The color of may be variable by processor 50 as described below.

[0038] In the patient alignment mode, the processor 50 is configured to control the drive mechanism 34 to rotate the rotatable mirror 30 to a predetermined orientation (if the rotatable mirror 34 is not already in that orientation) and to keep the rotatable mirror 30 stationary in the predetermined orientation while controlling the stereoscopic imaging device 40 to simultaneously acquire stereoscopic images 46-1 and 46-2 of the pupil 14 via the rotatable mirror 30 and the ellipsoidal mirror 32 (or with a small enough delay between acquisitions of the two images that does not significantly affect the stereoscopic distance measurement). The processor 50 controls the stereoscopic imaging device 40 to continue acquiring stereoscopic images of the pupil 14 throughout operation in the patient alignment mode. The processor 50 is further configured to process the acquired stereoscopic images to generate a signal S for positioning the pupil 14 within a target range suitable for acquiring an UWF image 55 of the fundus 12.

[0039] When the rotatable mirror 30 is stationary at a predetermined orientation in the patient alignment mode (also referred to herein as the fixation mode or the patient alignment and fixation mode), the processor 50 controls the fixation target light source 80 to emit the fixation light L F onto the rotatable mirror 30, specifically onto the first focal point 32-1 of the elliptical mirror 32. The fixation target light source 80 is disposed relative to the rotatable mirror when the rotatable mirror is in a predetermined orientation, and projects the fixation light L F is projected onto the fundus 12 via the rotatable mirror 30 and the elliptical mirror 32 to fixate the gaze direction of the eye 10. Then, based on the signal S, the eye 10 is maintained fixated while the pupil 14 is positioned within a target range suitable for acquiring an ultra-wide-angle image 55 of the fundus 12. The fixation target light source 80, as in this exemplary embodiment, emits fixation light L F onto the rotatable mirror 30, and when the rotatable mirror 30 is in a predetermined orientation, the fixation light L F However, the light is made to enter the eye 10 in a direction that will fix the gaze direction of the eye 10 in the central gaze direction that the subject takes when looking straight ahead. However, as will be described later with reference to Figure 5, the fixation target light source 80 may be configured to fix the gaze in a gaze direction other than the central gaze direction.

[0040] In the patient alignment mode, as in this exemplary embodiment, the processor 50 can process the stereoscopic images acquired by the stereoscopic imaging device 40 using any known stereoscopic distance measurement technique that uses concepts of parallax and triangulation to estimate distance, to determine an indication of the distance d between the exit pupil of the ophthalmic imaging device 100 and the pupil 14 of the eye 10. For example, the processor 50 can determine the indication of the distance d by processing each of the acquired stereoscopic images 46-1 and 46-2 to locate the pupil centers of each of the pupils in the image (e.g., by determining a pupil outline using edge detection and fitting a circle to the outline to find the circle center), mapping the located pupil centers to a common image frame, determining a spacing between the pupil centers in the common image frame, and using the determined spacing, which is inversely related to the distance d, to determine the indication of the distance d. The processor 50 can then compare the indication of the determined distance d to a predetermined threshold to determine whether the pupil 14 is too close to the exit pupil location of the ophthalmic imaging device 100, too far from the exit pupil location, or whether the distance from the exit pupil location is within a predetermined range acceptable for image capture. The processor 50 can then generate a signal S that controls the fixation target light source 80 to output a fixation light of a color indicative of the result of the comparison, as in this exemplary embodiment. For example, the fixation light source 80 may be controlled by the processor 50 to emit a fixation light of a first color (e.g., blue) when the distance between the exit pupil E of the ophthalmic imaging device 100 and the pupil 14 is greater than a threshold indicating the end of range R and the pupil 14 is on the side of range R that is farther from the ophthalmic imaging device 100, to emit a fixation light of a second, different color (e.g., red) when the distance between the exit pupil E and the pupil 14 is greater than the threshold and the pupil 14 is on the opposite side of range R that is closer to the ophthalmic imaging device 100, and to emit a fixation light of a still different color (e.g., green) when the distance between the exit pupil E and the pupil 14 is less than the threshold. Although the exit pupil position is described here, any other reference point on the image capture device 2 near which the pupil 14 needs to be located in order to capture an image 5 of the fundus 12 of the eye 10 could instead be used.

[0041] Additionally or alternatively, the processor 50 may generate a control signal S to control a speaker (not shown in FIG. 1 ) to generate a sound (e.g., a varying tone or sound) indicative of the comparison. For example, the speaker may be controlled by the processor 50 to generate a first (e.g., low-pitched) tone or sound indication when the distance between the exit pupil E of the ophthalmic imaging device 100 and the pupil 14 is greater than a threshold value and the pupil 14 is on the far side of the range R of the ophthalmic imaging device 100, a different second (e.g., high-pitched) tone or sound indication when the distance between the exit pupil E and the pupil 14 is greater than the threshold value and the pupil 14 is on the nearer side of the range R of the ophthalmic imaging device 100, and yet another (e.g., mid-pitched) tone or sound indication when the distance between the exit pupil E and the pupil 14 is less than the threshold value.

[0042] By processing each acquired pair of stereoscopic images as described above, the patient is guided to move the eye 10 backward (away from the ophthalmic imaging device 100) or forward (toward the ophthalmic imaging device 100) as appropriate. The patient then observes the fixation light turn green (as appropriate) and / or hears a mid-pitched tone or audio indication that the pupil 14 of the eye 10 is close enough to the exit pupil (or other reference point) of the ophthalmic imaging device 100 that UWF imaging of the fundus 12 can begin.

[0043] If the distance between the position of the exit pupil and the pupil 14 is determined to be less than the threshold, the processor 50 is configured to start operating in a fundus imaging mode and control the ophthalmic imaging device 100 to acquire an UWF image 55 of the fundus 12. The processor 50 controls the light source to emit a light beam L T and controls the ophthalmic imaging device 100 to transmit the light beam L through the elliptical mirror 32 by controlling the scanner 36 and the rotatable mirror 30. T This is done by scanning the light beam L over the fundus 12 to obtain a UWF image 55 of the fundus 12. The processor 50 T and controls the scanner 36 and the rotatable mirror 30 to emit the light beam L via the elliptical mirror 32. TThis is done by controlling the ophthalmic imaging device 100 to acquire a UWF image 55 of the fundus 12 by scanning the light beam L across the fundus 12. The processor 50 controls the fixation target light source 80 (when the light source 20 emits the light beam L T before or after emitting the fixation light L F Preferably, the emission of the UWF signal is stopped to reduce artifacts and otherwise improve the quality of the UWF image 55. To reduce the risk of misalignment of the eye 10 with respect to the ophthalmic imaging device 100, in this exemplary embodiment the processor 50 automatically initiates operation in a fundus imaging mode in response to determining that the distance d between the exit pupil of the ophthalmic imaging device 100 and the pupil 14 is less than a threshold value. However, in alternative embodiments, this switch in operational mode may be commanded by an operator of the ophthalmic imaging device 100, for example, by the operator clicking a mouse button or pressing a key on a computer keyboard communicatively coupled to the processor 50, in response to visual, audio, and / or tactile feedback based on the signal S.

[0044] The stereoscopic imaging device 40, as in this exemplary embodiment, transmits the light beam L between the rotatable mirror 30 and the elliptical mirror 32 during acquisition of the UWF image 55 of the fundus 12. T , which is not intersected by the ellipsoidal mirror 32. The fixation target light source 80 can also be located in region R, as in this exemplary embodiment. The stereoscopic imaging device 40 and the fixation target light source 80 can therefore be housed in an area not used for light propagation within the bowl of the ellipsoidal mirror 32. This configuration can be advantageous because by placing the stereoscopic imaging device 40 and the fixation target light source 80 in an otherwise unused area of ​​the ophthalmic imaging device 100, the ophthalmic imaging device 100 can be made more compact.

[0045] Furthermore, housing the stereoscopic imaging device 40 and fixation target light source 80 in region G provides the option of orienting the rotatable mirror 30 in the patient alignment mode (i.e., selecting the aforementioned predetermined orientation). This allows the rotatable mirror 30 to start rotating from the predetermined orientation as soon as the UWF ophthalmic imaging device 100 starts acquiring UWF images 55 while the processor 50 is operating in fundus imaging mode. This avoids delays in the start of image acquisition that may occur due to rotating the rotatable mirror 30 from the predetermined orientation used in the patient alignment mode to a (different) starting orientation for image acquisition, and reduces the risk of changing the gaze direction of the eye 10. However, if this advantage outweighs easy access to the stereoscopic imaging device 40 or fixation target light source 80, for example, for maintenance and / or adjustment, the stereoscopic imaging device 40 and fixation target light source 80 can alternatively be located outside the bowl of the elliptical mirror 32 in some embodiments. Again, the predetermined orientation of the rotatable mirror 30 used in the patient alignment mode is set to allow the stereoscopic imaging device 40 to acquire stereoscopic images 46-1 and 46-2 of the pupil 14 via the rotatable mirror 30 and the elliptical mirror 32 while the eye 10 remains fixed. For example, the stereoscopic imaging device 40 and the fixation target light source 80 could be positioned above the edge of the elliptical mirror 32 (e.g., similar to the curved mirror 38 in FIG. 1 ) so that they each have a line of sight to the rotatable mirror 30. Alternatively, the stereoscopic imaging device 40 and the fixation target light source 80 could be positioned on the non-reflective side of the elliptical mirror 32. One or more holes could be drilled in the elliptical mirror 32 to allow light to pass through the elliptical mirror 32 to the stereoscopic imaging device 40 and from the fixation target light source 80.

[0046] When the UWF ophthalmic imaging device 100 begins acquiring the UWF image 55, regardless of whether the rotatable mirror 30 allows the rotatable mirror 30 to begin rotating from a predetermined orientation in the patient alignment mode, it may be advantageous to position the stereoscopic imaging device 40 between the rotatable mirror 30 and the elliptical mirror 32 in a position that minimizes deviation from circularity in the respective representations of the pupil 14 in the stereoscopic images 46-1 and 46-2 of the pupil 14 acquired by the stereoscopic imaging device 40 when the rotatable mirror 30 is in the predetermined orientation. Such a position of the stereoscopic imaging device 40, which allows the viewpoint of the stereoscopic imaging device 40 to be as close as possible to the central gaze direction of the eye 10 and therefore allows the pupil 14 in the images 46-1 and 46-2 to be as circular as possible, may facilitate the process of locating the pupil center and therefore accurately calculating the distance between the pupil 14 and the exit pupil of the ophthalmic imaging device 100.

[0047] As an example, the elliptical mirror 32 in this exemplary embodiment has a plane of symmetry P that includes the first focal point 32-1 and the second focal point 32-2. A normal direction N of the rotatable mirror 30 at the first focal point 32-1 forms a predetermined angle θ with the plane of symmetry P when the rotatable mirror 30 is in a predetermined orientation as shown in FIG. 3 . For clarity, the magnitude of the angle θ and the angle α discussed below are exaggerated in FIG. 3 . The first camera 42 and the second camera 44 are disposed symmetrically about a second plane P2 that passes through the first focal point 32-1 and the second focal point 32-2. As in this exemplary embodiment, the first camera 42 and the second camera 44 include respective camera lenses having respective optical axes 48-1 and 48-2 that are parallel to each other and equidistant from each other on opposite sides of the second plane P2. However, in another exemplary embodiment, both the optical axes 48-1 and 48-2 may be within the second plane P2. It has been found that when the normal direction N of the rotatable mirror 30 and the second plane P2 form an angle α at the first focal point 32-1 that is less than twice the predetermined angle θ, the deviation from circularity of the representation of each pupil 14 in the stereoscopic images 46-1, 46-2 of the pupil 14 obtained using this arrangement is small enough to achieve satisfactory pupil alignment.

[0048] The rotatable mirror 30 rotates the light beam L at a first focal point 32-1 of the elliptical mirror 32. T onto the ellipsoidal mirror 32, the optical system of the ophthalmic imaging device 100 is such that the rotatable mirror 30 otherwise reflects the beam L through a first focal point 32-1. T 4 is a schematic diagram of a line-scanning UWF ophthalmic imaging device 300 according to a variant of the exemplary embodiment, which in addition to the elliptical mirror 32 comprises a second elliptical mirror 39 through which the rotatable mirror 30 directs the light beam L in the form of a line of light onto the fundus 12. T In this case, the light beam L T ' projects a line on a plane (i.e., cross-section) perpendicular to its propagation direction, which can be generated using a cylindrical lens to generate a light beam with a point-like cross-section (such as that generated by light source 20), or can be generated using other optical configurations for generating line-shaped illumination known to those skilled in the art (e.g., a back-illuminated slit aperture). As shown in FIG. 4, second elliptical mirror 39 has a first focal point 39-1 and a second focal point 39-2, and rotatable mirror 30 rotates light beam L at first focal point 39-1 of second elliptical mirror 39. T The second focal point 39-2 of the second elliptical mirror 39 coincides with the first focal point 32-1 of the elliptical mirror 32.

[0049] Linear lighting L T 4, which replaces the light source 20, scanner 36, and curved mirror 38 of the exemplary embodiment of FIG. 1. The line-scanning UWF ophthalmic imaging device 300 includes the remaining components of the UWF ophthalmic imaging device 100, although these are not shown in FIG. 4 to more clearly illustrate the different scan transfer configuration, including the two elliptical mirrors 32, 39. The line-scanning UWF ophthalmic imaging device 300 also directs returning light from the fundus 12 to a photodetector for detecting the returning linear illumination, although this is also omitted from FIG. 4 for simplicity.

[0050] In the line-scanning UWF ophthalmic imaging device 300, the stereoscopic imaging device 40 and the fixation target light source 80 (if present) are configured to transmit the light beam LT The stereoscopic imaging device 40 and the fixation target light source 80 (if any) are arranged relative to the rotatable mirror 30 and are configured to operate as described above, except that the light propagating from the eye 10 to the stereoscopic imaging device 40 and the fixation light L propagating from the fixation target light source 80 to the eye 10 are F propagates through elliptical mirror 39 as well as elliptical mirror 32.

[0051] Alternatively, if there is insufficient space within the bowl of second elliptical mirror 39, one or both of stereoscopic imaging device 40 and fixation target light source 80 can be located in region G2' on the non-reflective side of the bowl of second elliptical mirror 39. One or more holes can be drilled in second elliptical mirror 39 to allow light to pass through elliptical mirror 29 to stereoscopic imaging device 40 and from fixation target light source 80.

[0052] Regardless of whether the stereoscopic imaging device 40 is housed in region G (or region G2 in the modified embodiment of FIG. 4 ), the stereoscopic imaging device 40 may further include a Fresnel lens 49 disposed between the rotatable mirror 30 and both the first camera 42 and the second camera 44, as in the present exemplary embodiment. In the exemplary embodiment of FIG. 1 , the Fresnel lens 49 is configured to refract light from the eye 10 reflected by the rotatable mirror 30 at the first focal point 32-1 of the elliptical mirror 32 so that the light propagates along a first optical axis 48-1 of the first camera 42 and a second optical axis 48-2 of the second camera 44. The Fresnel lens 49 enables the first camera 42 and the second camera 44 to be easily mounted on a supporting circuit board or other flat substrate, with their respective optical axes perpendicular to the substrate surface. This avoids the time-consuming process of carefully aligning the optical axes of the first camera 42 and the second camera 44 so that they pass through the first focal point 32-1 of the ellipsoidal mirror 32, which would otherwise have to be done to improve stereoscopic ranging, thereby resulting in easier and faster manufacture of the stereoscopic imaging device 40. Similarly, in the alternative embodiment described with reference to FIG. 4 , a Fresnel lens 49 can be positioned between the rotatable mirror 30 and both the first camera 42 and the second camera 44 in region G2, and is configured to refract light from the eye 10 that is reflected by the rotatable mirror 30 at the first focal point 39-1 of the second ellipsoidal mirror 39 to propagate along the first optical axis 48-1 of the first camera 42 and the second optical axis 48-2 of the second camera 44.

[0053] The fixation target light source 80 projects fixation light L from a single location onto the rotatable mirror 30 for centerline fixation in the exemplary embodiment and its variations described above. F Alternatively, fixation target light source 80 may be operable to project fixation light L onto rotatable mirror 30 from selected positions of a plurality of positions on fixation target light source 80, each positioned in a different direction from first focal point 32-1 of elliptical mirror 32 (or from first focal point 39-1 of second elliptical mirror 39 in the modified embodiment of FIG. 4). F may be configured to project

[0054] FIG. 5 is a schematic diagram of a PAM 400 including the stereoscopic imaging system 40 and an improved fixation target light source 80 included in the exemplary embodiment of FIG. 1, as viewed from the rotatable mirror 30. As shown in FIG. 5, the PAM 400 includes a flat substrate 410 on which are mounted a first camera 42, a second camera 44, and an IR illumination light source 47 for illuminating the eye 10 so that it can be imaged by the stereoscopic cameras 42, 44. The fixation target light source 80 includes a plurality of separate fixation light sources in the form of LEDs, labeled 80-1 through 80-9 in FIG. 5. Each of these fixation target light sources is capable of generating at least three colors of visible light, e.g., red, green, and blue. In the example of FIG. 5, the LEDs 80-1 through 80-9 are RGB LEDs, each capable of emitting red, green, and blue light under the control of the processor 50. There are nine such light sources, arranged as shown in the example of FIG. 5, but the number and arrangement of the light sources is not so limited. PAM 400 may also include the aforementioned Fresnel lens 49, as in this embodiment, which is overlaid on top of stereo cameras 42 and 44, IR illumination source 47, and LEDs 80-1 through 80-9 and positioned between these components and rotatable mirror 30.

[0055] LEDs 80-1 through 80-9 are provided at different locations, each located in a different direction from first focal point 32-1 in the exemplary embodiment of FIG. 1 (or first focal point 39-1 of second elliptical mirror 39 in the modified embodiment of FIG. 4), and eye 10 can be directed in different directions by gazing at light from a selected one of the LEDs relayed to eye 10 via rotatable mirror 30 and elliptical mirror 32 (and second elliptical mirror 39 in the modified embodiment of FIG. 4). In the example of FIG. 5, LED 80-5 is positioned to provide central fixation, and the remaining LEDs are positioned to guide the patient to look left, right, directly upward, upper left, upper right, directly downward, lower left, and lower right.

[0056] However, the fixation target light source 80 is arranged in a different manner, and the fixation light L is projected onto the rotatable mirror 30 from a selected position among a plurality of positions on the fixation target light source 80 arranged in different directions from the first focal point 32-1 of the elliptical mirror 32 (or the first focal point 39-1 of the elliptical mirror 39 in the modified embodiment of FIG. 4). F It should be noted that fixation light source 80 may alternatively be provided in the form of at least one display screen (such as a liquid crystal display (LCD), an LED display screen, or an organic LED (OLED) display screen), which may be controllable by processor 50 to project fixation light L from selected ones of a plurality of separate portions on the display screen. F , possibly in a color selected from a plurality of available colors. As another example, fixation light source 80 can be provided in the form of an array of optical fibers, which emerge from substrate 410 at the same locations as LEDs 80-1 through 80-9 and project light directed therethrough toward rotatable mirror 30. Here, an optical switch or other means controllable by processor 50 is provided to control fixation light L. F is allowed to enter the rotatable mirror 30 from the selected optical fiber.

[0057] In the patient alignment mode, the processor 50 selects one of a plurality of different gaze directions in which the gaze direction of the eye 10 should be fixed, and uses the selected gaze direction to determine a corresponding position from a plurality of positions from which the fixation target light source 80 projects the fixation light L onto the rotatable mirror 30. F In the embodiment of FIG. 5, the processor 50 can select one of the LEDs 80-1 to 80-9, which corresponds to the selected gaze direction. The processor 50 then controls the fixation target light source 80, for example, by driving only the selected LED to project the target fixation light L. F By projecting the fixation light L F can be projected from the determined position onto the rotatable mirror 30 to fix the gaze direction of the eye 10 in the selected gaze direction.

[0058] The plurality of different gaze directions may include a central gaze direction, and the plurality of positions on the fixation target light source 80 may include a central position (i.e., the position of LED 80-5 in the embodiment of FIG. 5). F When the light beam L is projected from the center position onto the fundus 12 via the rotatable mirror 30 in a predetermined direction and via the elliptical mirror 32, the Fresnel lens 49 fixes the gaze direction of the eye 10 in the central gaze direction. F , which, when emitted from that position, propagate towards a common point on the rotatable mirror 30. This common point is the first focal point of the elliptical mirror in the above exemplary embodiment, and corresponds to the first focal point 39-1 of the second elliptical mirror 39 in the modified embodiment described with reference to Figure 4. The Fresnel lens 49 is therefore configured to refract the light returning from the eye 10, which is used to form the stereoscopic images 46-1, 46-2, and the fixation light L, which is used to fixate the gaze direction of the eye 10. F The optical system can provide the necessary light collection for both the stereoscopic imaging device 40 and the fixation target light source 80, thereby eliminating the need to provide separate optical systems for the stereoscopic imaging device 40 and the fixation target light source 80.

[0059] Figure 6 is a flow diagram summarizing the operations performed by the processor 50 to control the ophthalmic imaging device 100 as described above to acquire UWF images 55 of the fundus 12. For clarity, some acts and processes that may be performed / executed in the context of the operations previously described will not be described again here, but will be understood to form optional features of the operations described below with reference to Figure 6. The processor 50 may similarly control the ophthalmic imaging device 300 to acquire UWF images 55 of the fundus 12.

[0060] In the patient alignment mode, the processor 50 operates to generate a signal S for positioning the pupil 14 of the eye 10 within a target range for acquiring a UWF image 55 of the fundus 12. To this end, the processor 50 first controls the rotatable mirror 30 to remain stationary in a predetermined orientation that enables the stereoscopic imaging device 40 to image the pupil 14 via the rotatable mirror 30 and the elliptical mirror 32 (S10 in FIG. 6). Next, the processor 50 controls and turns on the illumination light source of the stereoscopic imaging device 40, thereby enabling illumination of the eye 10 with IR light via the rotatable mirror 30 and the elliptical mirror 32 (and the second elliptical mirror 39 in the modified embodiment of FIG. 4).

[0061] Next, in S20 of Figure 6, the processor 50 controls the stereoscopic imaging device 40 to acquire stereoscopic images 46-1, 46-2 of the pupil 14 via the rotatable mirror 30 and the elliptical mirror 32 while the rotatable mirror 30 is in a predetermined orientation. In the context of the modified embodiment of Figure 4, the processor 50 controls the stereoscopic imaging device 40 in S20 to acquire stereoscopic images 46-1, 46-2 of the pupil 14 via the rotatable mirror 30, the second elliptical mirror 39, and the elliptical mirror 32 while the rotatable mirror 30 is in a predetermined orientation. While the rotatable mirror 30 is in a predetermined orientation and the stereoscopic imaging device 40 is controlled to acquire stereoscopic images 46-1, 46-2 of the pupil 14, the processor 50 controls the fixation target light source 80 to emit fixation light L (as an optional part of process S20 of Figure 6). F is projected onto the rotatable mirror 30. Here, the fixation target light source 80 is disposed relative to the rotatable mirror 30, and the fixation light L F is projected onto the fundus 12 via an elliptical mirror 32 in order to fix the line of sight of the eye 10.

[0062] At S30 of FIG. 6, the processor processes the stereoscopic images 46-1, 46-2 of the pupil 14 to generate the signal S as previously described.

[0063] In optional process S35, the processor 50 can determine whether a predefined condition is met. The predefined condition may be, for example, that the processor 50 has received a command from the operator of the ophthalmic imaging device 100, who is receiving visual and / or audio feedback based on the signal S, to begin imaging the fundus 12. As another example, the predefined condition may be that the distance between the exit pupil of the ophthalmic imaging device 100 and the pupil 14 (as determined by the processor 50 based on the stereoscopic images 46-1, 46-2) is within a target range suitable for acquiring a UWF image 55 of the fundus 12. As a further alternative, the predefined condition may be that a predetermined time has elapsed since the processor 50 began operating in the patient alignment mode, during which the distance between the exit pupil of the ophthalmic imaging device 100 and the pupil 14 is likely to be within the target range. If the processor determines that the predefined condition is not yet met, the process loops back to S20. Otherwise, the process proceeds to S40 of FIG. 6 . Process S35 can be omitted.

[0064] In S40 of FIG. 6, the processor 50 controls the light source 20 to generate the light beam L T and controlling the ophthalmic imaging device 100 to rotate the rotatable mirror 30 to emit the light beam L T is scanned over the fundus 12 via the elliptical mirror 32 (or via the second elliptical mirror 39 in the modified embodiment of FIG. 4 ), thereby acquiring a UWF image 55 of the fundus 12. Before acquiring the UWF image 55, the processor 50 preferably turns off the fixation target light source 80 and the IR illumination light source 47.

[0065] In the preceding description, exemplary aspects have been described with reference to several exemplary embodiments. Accordingly, this specification should be considered illustrative, and not restrictive. Similarly, the shapes shown in the drawings, which highlight features and advantages of the exemplary embodiments, are presented for illustrative purposes only. The architecture of the exemplary embodiments is sufficiently flexible and configurable to be utilized in ways other than those shown in the accompanying figures.

[0066] Some aspects of the examples presented herein, such as the functionality of the processor 50, may be provided as computer programs or software, such as one or more programs having instructions or sequences of instructions. These, in one embodiment, are contained in or stored on an article of manufacture such as a machine-accessible or machine-readable medium, instruction store, or computer-readable storage device, each of which may be non-transitory. The programs or instructions on the non-transitory machine-accessible medium, machine-readable medium, instruction store, or computer-readable storage device may be used to program a computer system or other electronic device. Machine-readable or computer-readable media, instruction stores, and storage devices may include, but are not limited to, optical and magneto-optical disks, or other types of media / machine-readable media / instruction stores / storage devices suitable for storing or transmitting electronic instructions. The techniques described herein are not limited to any particular software configuration; they may find applicability in any computing or processing environment. As used herein, the terms "computer-readable," "machine-accessible medium," "machine-readable medium," "instruction store," and "computer-readable storage device" are intended to include any medium capable of storing, encoding, or transmitting instructions or sequences of instructions for execution by a machine, computer, or computer processor, and causing the machine / computer / computer processor to perform any of the methods described herein.

[0067] The computer program product may be provided in the form of a storage medium, instruction store, or storage device having instructions stored thereon that can be used to control or cause a computer or computer processor to perform any of the procedures of the exemplary embodiments described herein. The storage medium / instruction store / storage device may include, by way of example and not limitation, optical disks, ROM, RAM, EPROM, EEPROM, DRAM, VRAM, flash memory, flash cards, magnetic cards, optical cards, nanosystems, molecular memory integrated circuits, RAID, remote data storage / archive / warehousing, and / or any other type of device suitable for storing instructions and / or data.

[0068] Some implementations stored on computer-readable media, instruction storage, or storage devices include software that controls the system's hardware and enables the system or microprocessor to interact with a human user or other mechanisms that utilize the results of the exemplary embodiments described herein. Such software may include, but is not limited to, device drivers, operating systems, and user applications. Ultimately, such computer-readable media or storage devices further include software for carrying out the exemplary aspects of the present invention as described above.

[0069] The programming and / or system software includes software modules for performing the procedures described herein. In some exemplary embodiments herein, the modules include software, although in other exemplary embodiments herein, the modules include hardware or a combination of hardware and software.

[0070] While this specification contains details of many specific embodiments, these should not be construed as limiting the scope of any invention or claimed subject matter, but rather as descriptions of features unique to the specific embodiments described herein. Certain features described herein in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable subcombination. Furthermore, even if features are described above as acting in a particular combination and initially claimed as such, one or more features from a claimed combination may, in some cases, be deleted from that combination, and the claimed combination may be directed to a subcombination or a variation of a subcombination.

[0071] Multitasking and parallel processing may also be advantageous under certain circumstances. Furthermore, it should be understood that the separation of various components in the above embodiments does not require such separation in all embodiments, and that the above program elements and systems may generally be integrated into a single software product or packaged into multiple software products.

[0072] Having now described several exemplary embodiments and implementations, it should be apparent that the foregoing has been presented by way of example and not limitation. In particular, while many of the examples presented herein include particular combinations of device or software elements, these elements may be combined in different ways to achieve the same purpose. Acts, elements, and features discussed only in connection with one embodiment are not intended to be excluded from a similar role in other embodiments.

Claims

1. Light beam (L Ｔ 1. An ultra-wide-angle ophthalmic imaging device (100; 300) configured to acquire an ultra-wide-angle image (55) of a fundus (12) of an eye (10) by scanning a 3D imager (100; 300) over the fundus (12), comprising: Light beam (L Ｔ ;L Ｔ a light source (20; 20′) configured to emit a light beam (20; 20′); Light beam (L Ｔ ;L Ｔ a rotatable mirror (30) configured to scan the ocular fundus (12) with the ocular fundus (12); A rotatable mirror (30) passes through it and directs the light beam (L Ｔ ;L Ｔ an elliptical mirror (32) configured to scan the ocular fundus (12) with an ellipsoidal mirror (32) The elliptical mirror (32) has a first focal point (32-1) and a second focal point (32-2), The rotatable mirror (30) directs the light beam (L) through the first focal point (32-1). Ｔ ;L Ｔ ') onto the elliptical mirror (32), an elliptical mirror, the pupil (14) of the eye (10) being at the second focus (32-2) when the ultra-wide-angle ophthalmic imaging device (100) is in use; a stereoscopic imaging device (40) configured to acquire stereoscopic images (46-1; 46-2) of the pupil (14) through the rotatable mirror (30) and the elliptical mirror (32); A processor (50), and in a patient alignment mode, generating a signal (S) based on the stereoscopic image (46-1; 46-2) of the pupil (14) to position the pupil (14) of the eye (10) within a target range for acquiring an ultra-wide-angle image (55) of the fundus (12); subsequently operating in a fundus imaging mode to control the ultra-wide-angle ophthalmic imaging device (100) to acquire the ultra-wide-angle image (55) of the fundus (12); a processor (50) configured to: wherein: In the patient alignment mode, the processor (50) Controlling the rotatable mirror (30) so that it remains stationary in a predetermined direction; controlling the stereoscopic imaging device (40) to acquire the stereoscopic images (46-1; 46-2) of the pupil (14) through the rotatable mirror (30) and the elliptical mirror (32) while the rotatable mirror (30) is stationary in a predetermined position; processing the stereoscopic images (46-1; 46-2) of the pupil (14) to generate the signal (S) for aligning the pupil (14) of the eye (10) to an imaging position; It is configured as follows: In the fundus imaging mode, the processor (50) The light beam (L Ｔ ;L Ｔ controlling said light source (20; 20') to emit a The rotatable mirror (30) is controlled to rotate the light beam (L Ｔ ;L Ｔ controlling the ultra-wide-angle ophthalmic imaging device (100; 300) to acquire the ultra-wide-angle image (55) of the fundus (12) by scanning a ray of light (′) over the fundus (12) via the elliptical mirror (32); An ultra-wide-angle ophthalmic imaging device (100; 300) configured as follows.

2. The rotatable mirror (30) directs the light beam (L) at the first focal point (32-1). Ｔ ), and the stereoscopic imaging device (40) is configured to reflect the light beam (L) when acquiring the ultra-wide-angle image (55) of the fundus (12). Ｔ 2. The ultra-wide-angle ophthalmic imaging device (100) of claim 1, wherein the rotatable mirror (30) is positioned in a region (R) between the rotatable mirror (30) and the elliptical mirror (32) that is not intersected by the ellipsoidal mirror (32).

3. 3. The ultra-wide-angle ophthalmic imaging device (100) of claim 2, wherein the predetermined orientation of the rotatable mirror (30) is such that the rotatable mirror (30) begins to rotate from the predetermined orientation when the ultra-wide-angle ophthalmic imaging device (100) begins acquiring the ultra-wide-angle image (55) of the fundus (12).

4. The ultra-wide-angle ophthalmic imaging device (100) of claim 2 or claim 3, wherein the stereoscopic imaging device (40) is located between the rotatable mirror (30) and the elliptical mirror (32) and is positioned such that, when the rotatable mirror (30) is in the predetermined orientation, deviation from circularity of the representation of each of the pupils (14) in the stereoscopic images (46-1; 46-2) of the pupils (14) acquired by the stereoscopic imaging device (40) is minimized.

5. The elliptical mirror (32) has a plane of symmetry (P) that includes the first focal point (32-1) and the second focal point (32-2), a normal direction of the rotatable mirror (30) at the first focal point (32-1) forms a predetermined angle with respect to the plane of symmetry (P) when the rotatable mirror (30) is in a predetermined orientation; 5. The ultra-wide-angle ophthalmic imaging device (100) of claim 4, wherein the stereoscopic imaging device (40) comprises a first camera (42) and a second camera (44), the first camera (42) and the second camera (44) being arranged equidistantly on opposite sides of a second plane (P2) including the first focal point (32-1) and the second focal point (32-2), and wherein a normal direction of the rotatable mirror (30) and the second plane (P2) form an angle at the first focal point (32-1) that is less than twice the predetermined angle.

6. The first camera (42) has a first optical axis (48-1), and the second camera (44) has a second optical axis (48-2) parallel to the first optical axis (48-1); The stereoscopic imaging device (40) further includes a Fresnel lens (49) disposed between the rotatable mirror (30) and both the first camera (42) and the second camera (44); 6. The ultra-wide-angle ophthalmic imaging device (100) of claim 5, wherein the Fresnel lens (49) refracts light from the eye (10) reflected by the rotatable mirror (30) at the first focal point (32-1) of the elliptical mirror (32) to propagate along the first optical axis (48-1) and the second optical axis (48-2).

7. The stereoscopic imaging device (40) a first camera (42) having a first optical axis (48-1), and a second camera (44) having a second optical axis (48-2) parallel to the first optical axis (48-1); a Fresnel lens (49) disposed between the rotatable mirror (30) and both the first camera (42) and the second camera (44), the Fresnel lens (49) refracting light from the eye (10) reflected by the rotatable mirror (30) to propagate along the first optical axis (48-1) and the second optical axis (48-2); The ultra-wide-angle ophthalmic imaging device (100) of any one of claims 1 to 4, comprising:

8. A fixation light (L) is projected onto the fundus (20) through the rotatable mirror (30) and the elliptical mirror (32). Ｆ a fixation target light source (80) configured to project a In the patient alignment mode, the processor (50) controls the fixation target light source (80) to adjust the fixation light (L Ｆ ) onto the rotatable mirror (30) in the predetermined orientation, and the fixation target light source (80) projects the fixation light (L Ｆ 8. The ultra-wide-angle ophthalmic imaging device (100) of claim 1, wherein the rotatable mirror (30) is positioned relative to the rotatable mirror (30) such that a 3D image of the fundus (12) is projected through the elliptical mirror (32) onto the fundus (12) to fix the line of sight of the eye (10).

9. The fixation target light source (80) is configured to fixate the light beam (L) between the rotatable mirror (30) and the elliptical mirror (32) when acquiring the ultra-wide-angle image (55) of the fundus (12). Ｔ 9. The ultra-wide-angle ophthalmic imaging device (100) according to claim 8 dependent on claim 2, wherein the ultra-wide-angle ophthalmic imaging device (100) is arranged in a region (R) where the .lambda.

10. The ultra-wide-angle ophthalmic imaging device (100) of claim 9, wherein the predetermined orientation is such that the rotatable mirror (30) begins to rotate from the predetermined orientation when the ultra-wide-angle ophthalmic imaging device (100) begins acquiring the ultra-wide-angle image (55) of the fundus (12).

11. The fixation target light source (80) emits the fixation light (L Ｆ The fixation light (L) is projected onto the rotatable mirror (30) from a position such that the fixation light (L) is incident on the eye (10) in the direction of the central gaze fixation of the eye (10). Ｆ 11. The ultra-wide angle ophthalmic imaging device (100) of claim 10, configured to project a

12. 12. The ultra-wide-angle ophthalmic imaging device (100) of claim 1, further comprising an illumination light source (47) configured to illuminate the eye (10) with light via the rotatable mirror (30) and the elliptical mirror (32) in order to obtain the stereoscopic images (46-1; 46-2) of the pupil (14) by the stereoscopic imaging device (40).

13. The ultra-wide-angle ophthalmic imaging device (100) of any one of claims 1 to 12, wherein the ultra-wide-angle ophthalmic imaging device (100) comprises an ultra-wide-angle scanning laser ophthalmoscope.

14. Light beam (L Ｔ ;L Ｔ 1. A method for controlling an ultra-wide-angle ophthalmic imaging device (100; 300) configured to acquire an ultra-wide-angle image (55) of a fundus (12) of an eye (10) by scanning a 3D imager (100; 300) over the fundus (12), comprising: The ultra-wide-angle ophthalmic imaging device (100) comprises: The light beam (L Ｔ ;L Ｔ a light source (20; 20′) configured to emit a light beam (20; 20′); The light beam (L Ｔ ;L Ｔ a rotatable mirror (30) configured to scan the ocular fundus (12) with the ocular fundus (12); Through which the rotatable mirror (30) directs the light beam (L Ｔ ;L Ｔ an elliptical mirror (32) configured to scan the light beam (L′) on the fundus (12), the elliptical mirror (32) having a first focus (32-1) and a second focus (32-2), the rotatable mirror (30) directing the light beam (L′) through the first focus (32-1); Ｔ ;L Ｔ an elliptical mirror configured to scan a second focal point (32-2) of the eye (10) with a second focal point (32-3) of the pupil (14) of the eye (10) when the ultra-wide-angle ophthalmic imaging device (100) is in use; a stereoscopic imaging device (40) configured to acquire stereoscopic images (46-1; 46-2) of the pupil (14) via the rotatable mirror (30) and the elliptical mirror (32); Equipped with The method comprises: a signal (S) for positioning the pupil (14) of the eye (10) within a target range for acquiring the ultra-wide-angle image (55) of the fundus (12); A step (S10) of controlling the stereoscopic imaging device (40) so that the rotatable mirror (30) is stationary in a predetermined orientation that enables imaging of the pupil (14) via the rotatable mirror (30) and the elliptical mirror (32); a step (S20) of controlling the stereoscopic imaging device (40) to acquire the stereoscopic images (46-1; 46-2) of the pupil (14) through the rotatable mirror (30) and the elliptical mirror (32) while the rotatable mirror (30) is in the predetermined orientation; processing (S30) said stereoscopic images (46-1; 46-2) of said pupil (14) to generate said signal (S); and generating the After generating the signal (S), the light beam (L Ｔ ;L Ｔ and controlling the light source (20; 20') to emit the light beam (L'), and rotating the rotatable mirror (30). Ｔ ;L Ｔ controlling the ultra-wide-angle ophthalmic imaging device (100) to acquire the ultra-wide-angle image (55) of the fundus (12) by scanning the ellipsoidal mirror (32) with the ellipsoidal mirror (32) over the fundus (12) (S40); 20. A method for controlling an ultra-wide angle ophthalmic imaging device (100; 300), comprising:

15. The ultra-wide-angle ophthalmic imaging device (100) transmits fixation light (L) via the rotatable mirror (30) and the elliptical mirror (32). Ｆ a fixation target light source (80) configured to project a fixation target light onto the fundus (20); The method further comprises: when the rotatable mirror (30) is in the predetermined orientation and the stereoscopic imaging device (40) is controlled to acquire the stereoscopic images (46-1; 46-2) of the pupil (14), Ｆ ) onto the rotatable mirror (30), wherein the fixation target light source (80) is configured to project the fixation light (L Ｆ 15. The method of claim 14, wherein the ellipsoidal mirror is positioned relative to the rotatable mirror so that a ray of light projected from the ellipsoidal mirror onto the fundus fixes the direction of gaze of the eye.

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