Patient alignment system for ophthalmic imaging devices

Abstract

Acquisition of a WF or UWF fundus image relies on light passing through the pupil, towards the fundus at angles of incidence that vary widely relative to the pupil plane, and back from the fundus. [Solution] An ultra-wide-angle ophthalmic imaging device for acquiring ultra-wide-angle images of the fundus of a subject's eye includes a patient alignment device that monitors the position of the eye's pupil relative to the device's exit pupil and compares that position with a distance range from the exit pupil to determine whether the pupil is within an adjustable distance range. If the pupil is outside the distance range, the patient alignment device generates a signal based on the monitored position to guide the patient to change the distance between the eye and the device to bring the pupil closer to the range. If the pupil is within the distance range, the patient alignment device generates an indication that the pupil is in a suitable position for image acquisition. The device automatically acquires the image in response to the generated indication.

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, ophthalmic imaging scanners, such as scanning laser ophthalmoscopy (SLO) and optical coherence tomography (OCT) scanners, often require that the position of the eye's pupil be within a predetermined distance range suitable for image acquisition from the exit pupil (or other reference position) of the ophthalmic imaging scanner. Pupil alignment is particularly important for wide-angle (WF) and ultra-wide-angle (UWF) ophthalmic imaging scanners, where acquisition of a WF or UWF fundus image relies on light passing through the pupil, toward the fundus, and returning from the fundus at angles of incidence that vary significantly relative to the pupil plane.

[0003]

[0003] Stereoscopic distance measurement techniques using stereo cameras are often used to measure the distance to the eyes. For example, some ophthalmic imaging scanners include a so-called pupil alignment module (PAM), which is equipped with a stereo camera for acquiring stereo images of the eyes and is configured to determine the distance between the PAM and the pupils based on the distance between the pupil centers in the stereo images. Visual feedback based on the determined distance is provided to guide the subject to position their eyes appropriately for eye imaging. Summary of the Invention

[0004] According to a first exemplary aspect of the present disclosure, an ultra-wide-angle ophthalmic imaging device is provided. The device includes an image capture device configured to capture ultra-wide-angle images of a fundus of a subject's eye through an exit pupil of the image capture device; and a patient alignment device configured to monitor the position of the pupil of the eye relative to the exit pupil of the image capture device and compare the position with a distance range from the exit pupil suitable for capturing images of the fundus to determine whether the pupil is within the distance range from the exit pupil. The distance range (R) used in the comparison is adjustable. If the pupil is determined to be outside the distance range, the patient alignment device is configured to generate a signal to guide the subject, based on the monitored position, to change the distance between the eye and the image capture device and move the pupil toward the distance range from the exit pupil. If the pupil is determined to be within the distance range, the patient alignment device is configured to generate an indication that the pupil is in a position suitable for capturing images of the fundus. The ultra-wide-angle ophthalmic imaging device further includes a controller configured to control the image capture device to automatically capture ultra-wide-angle images of the fundus in response to the patient alignment device generating the indication.

[0005] According to a second exemplary aspect of the present disclosure, there is provided a method for operating an ultra-wide-angle ophthalmic imaging device to acquire an ultra-wide-angle image of a fundus of a subject's eye, the method including: monitoring (S10) a position of a pupil of the eye relative to an exit pupil of the ultra-wide-angle ophthalmic imaging device; comparing the position with a distance range from the exit pupil suitable for acquiring an image of the fundus to determine whether the pupil is within a distance range from the exit pupil, where the distance range used for the comparison is adjustable; if it is determined that the pupil is outside the distance range, generating a signal to induce the subject to change a distance between the eye and the ultra-wide-angle ophthalmic imaging device based on the monitored position to bring the pupil closer to the distance range from the exit pupil; if it is determined that the pupil is within the distance range, generating an indication that the pupil is in a suitable position for acquiring an image of the fundus; and automatically controlling the ultra-wide-angle ophthalmic imaging device to acquire an ultra-wide-angle image of the fundus in response to generating the indication.

[0006] 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]

[0007] [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 an example implementation of the ultra-wide angle ophthalmic imaging device of the exemplary embodiment of FIG. [Figure 3] FIG. 3 is a schematic diagram of programmable signal processing hardware that can be configured to perform the functions of processor 50 described herein. [Figure 4] Figure 4 is a schematic diagram showing a cross-sectional view of the elliptical mirror 32 of this 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 of the stereoscopic imaging device 40 and fixation target light source 80 of this embodiment along the symmetry axis. [Figure 5] 5 is a schematic diagram of an ultra-wide-angle ophthalmic imaging device according to a variation of an example 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 6] 6 is a schematic diagram of an example embodiment of a pupil alignment device for a UWF ophthalmic imaging device as viewed from rotatable mirror 30. The pupil alignment device includes a stereoscopic imaging system 40 and a modified fixation target light source 80 included in the example embodiment of FIG. [Figure 7] FIG. 7 is a flow diagram illustrating a method of operating a UWF ophthalmic imaging device to acquire UWF fundus images, according to an exemplary embodiment. [Figure 8]FIG. 8 is a flow diagram illustrating an example of a method for comparing the position of the pupil with a distance range from the exit pupil appropriate for acquiring a fundus image to determine whether the pupil is within that distance range. [Figure 9] FIG. 9 is a schematic diagram of an alternative implementation of the patient alignment device of the exemplary embodiment. [Figure 10] FIG. 10 is a schematic diagram of a further alternative implementation of the patient alignment device of the exemplary embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] 1 is a schematic diagram of an ophthalmic imaging device 1 that includes an image capture device 2 configured to capture an image 5 of a fundus 12 of a subject's eye 10 through an exit pupil E of the image capture device 2. 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.

[0009] The ophthalmic imaging device 1 further comprises a patient alignment device 4 (also referred to herein as a patient alignment module (PAM) or pupil alignment module), which is configured to monitor the position of the pupil 14 of the eye 10 relative to the exit pupil E of the image capture device 2. Although the exit pupil E is mentioned 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 alternatively be used. The patient alignment device 4 is capable of measuring the position of the pupil 14 along the optical axis (the so-called "z-axis") of the image capture device 2, which passes through the exit pupil E. The patient alignment device 4 can do this in a variety of different ways, and several example implementations are described herein, including an implementation based on stereoscopic ranging, which is described below with reference to FIG. 2.

[0010] The patient alignment device 4 determines whether the pupil 14 is within a distance range R from the exit pupil E by comparing the measured position with a distance range R along the z-axis from the exit pupil E within which the pupil 14 can be imaged by the image capture device 2. The distance range R used in this comparison is defined by a value stored in the memory of the patient alignment device 4 and can be adjusted in a number of different ways, as described in more detail below. The adjustable distance range R used in this comparison allows the sensitivity of the automatic capture mechanism described herein to displacement along the z-axis to be varied depending on the size of the pupil 14, specifically, allowing for a looser alignment of the pupil 14 with the exit pupil E. This is acceptable when the pupil 14 is dilated (e.g., by administering eye drops containing a mydriatic drug) compared to when the pupil 14 is not dilated, resulting in a higher-quality fundus image being captured more quickly and with less discomfort for dilated patients who are more sensitive to light.

[0011] If the pupil 14 is determined to be outside the distance range R, the patient alignment device 4 is configured to generate, based on its monitored position, a stimulus signal S (i.e., an alert such as a different color, a different sound, and / or a different form of tactile feedback) to induce the subject to change the distance between the eye 10 and the image capture device 2 to move the pupil 14 closer to, and ultimately within, the distance range R from the exit pupil E. If the pupil 14 is determined to be within the distance range R, the patient alignment device 4 is configured to generate an indication I that the pupil 14 is in a suitable position for capturing an image 5 of the fundus 12.

[0012] Ophthalmic imaging device 1 further includes a controller 6 configured to control image capture device 2, which automatically captures an image of fundus 12, in response to patient alignment device 4 generating display I. Patient alignment device 4 and controller 6 thus provide an automatic capture mechanism for automatically capturing an image of fundus 12 when pupil 14 is sufficiently close to exit pupil E for image capture 5. As will be explained below, this can be particularly useful in wide-angle and ultra-wide-angle ophthalmic imaging devices, where imprecise alignment of the patient's pupil with respect to the device's exit pupil can result in the fundus image being clipped by the pupil, potentially capturing less of the fundus than would be possible with more precise pupil alignment.

[0013] Figure 2 is a schematic diagram of an ophthalmic imaging device 100, an example implementation of the ophthalmic imaging device of Figure 1. The ophthalmic imaging device 100 is capable of imaging a portion of the fundus 12 by steering a light beam across the eye 10. The ophthalmic imaging device 100 is also capable of imaging other portions of the eye 10, such as at least a portion of the anterior segment of the eye 10.

[0014] 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 captures the anatomical features of the mid-peripheral retina 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 defined as being capable of acquiring a single captured image that covers the retinal region from the fovea to the posterior edge of the vortex vein ampulla and has 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 captured 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.

[0015] 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 that cover a wider portion of the fundus 12. A UWF image of the fundus 12 is defined as a single captured 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. Thus, a UWF ophthalmic imaging device is capable of acquiring a single UWF image that covers the retinal region extending from the fovea to the anterior edge of the vortex vein ampulla and into the pars plana, and is defined as having an FoV (expressed in eye angles) ranging from 110 degrees to 220 degrees. As an example, the Optos Daytona® can capture UWF images (so-called Optomap® images) that cover up to 200 degrees of the fundus (i.e., approximately 82% of the retina) in a single capture.

[0016] In this exemplary embodiment, the ophthalmic imaging device 100 includes a UWF combined scanning laser ophthalmoscope (SLO) and optical coherence tomography (OCT) device 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), fluorescein fundus 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 without an OCT mode. The Optos Daytona® is an example of such a multi-mode UWF SLO.

[0017] The image capture device 2 emits at least one light beam L for imaging the eye 10, as in the example embodiment of FIG.T The image capture device 2 may comprise a light source 20 configured to emit a light beam L (which may be understood as a projection in any direction), a rotatable mirror 30 and an elliptical mirror 32. Using these components, the image capture device 2 generates at least one light beam L T is scanned over the eye 10, and the light beam L T The light L returning from the area of ​​the eye 10 illuminated with R 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

[0018] 2, the patient alignment device 4 includes a stereoscopic imaging device 40 (described in more detail below) and a processor 50 that assist in bringing the eye 10 closer to a position that can be imaged by the ophthalmic imaging device 100. The stereoscopic imaging device 40 is configured to acquire stereoscopic images 46-1, 46-2 of the pupil 14, and the processor 50 is configured to process the stereoscopic images 46-1, 46-2 using any well-known stereoscopic distance calculation algorithm to monitor the position of the pupil 14 relative to the exit pupil E of the image capture device 2. The processor 50 is further configured to generate a signal S, based on the monitored position, to prompt the subject to change the distance between the eye 10 and the image capture device 2 to bring the pupil 14 closer to the distance range R from the exit pupil E if the pupil 14 is outside the range R. It should be noted, however, that the patient alignment device 4 need not rely on stereoscopic ranging, but could instead use any other means for determining the position of the pupil 14 relative to the exit pupil E of the image capture device 2, such as a laser distance sensor or a device that relies on analysis of the corneal specular reflection as described in European Patent Application No. 24165816.0, the entire contents of which are incorporated herein by reference and protection may be claimed for any features disclosed therein.

[0019] In this exemplary embodiment, the processor 50 may be further configured to determine a dimensional representation of the pupil 14 based on one or both of the stereoscopic images 46-1, 46-2 of the pupil 14, for example, by locating the image of the pupil 14 in the image using edge detection or other techniques (e.g., thresholding pixel values) and determining a measurement of the pupil's size, such as the diameter, circumference, or area of ​​the pupil 14. The processor 50 may further be configured to use the determined dimensional representation of the pupil 14 to adjust a stored distance range R used in the comparison between the aforementioned position of the pupil 14 and the aforementioned distance range R, such that the range R used in the comparison increases with increasing size of the pupil 14. The stored range R may thus be varied from a first value (e.g., approximately 0.5 mm) required to generate a UWF image 55 with a small, undilated pupil 14 (e.g., 2 mm diameter) to a second value (e.g., approximately 2 mm) required to generate a UWF image 55 with a fully dilated pupil 14 (e.g., 8 mm diameter). The processor 50 can compare the pupil size indicated by the determined indication with a predetermined threshold (e.g., 5 mm) and switch to select a first value of range R if the pupil size is less than the predetermined threshold, or a second value of range R if the pupil size is greater than the predetermined threshold. The processor 50 can alternatively vary range R in one or more steps between the first and second values, or continuously (e.g., linearly) between the first and second values ​​as a function of pupil size. In the latter case, the distance range R can be determined as a function of pupil size by any suitable method, such as by using a look-up table or by calculating a function of pupil size.

[0020] The processor 50 of Figure 2 also provides an example implementation of the controller 6 of Figure 1. However, the controller 6 may also be implemented as a separate processor. The ophthalmic imaging device 100 may include a beam splitter 60 and a photodetector 70, as in this example embodiment. 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.

[0021] The image capture device 2 may also include a drive mechanism 34, for example comprising a galvanometer, controlled by a processor 50 to cause the rotatable mirror 30 to undergo a predetermined rotational movement, thereby aligning 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 differently, the rotatable mirror 30 repeatedly rotates through a defined angular range about the mirror's axis of rotation, reversing the direction of rotation at each end of the angular range).

[0022] 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 image capture device 2 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. 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).

[0023] 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.

[0024] In this embodiment, the image acquisition device 2 scans light L from the light source 20 onto the area of ​​the fundus 12 that is illuminated by point scanning. TThe image acquisition device 2 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 image acquisition device 2 is configured to direct the light beam L onto the fundus 12 in part via an ellipsoidal mirror 32. T Furthermore, the image acquisition device 2 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, in this example embodiment, is in the form of a polygon scanner. T The 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 field system, it can be replaced by a cylindrical lens or other means that produces a beam consisting of a "fan" of light rays that form a line of light when projected onto a flat surface. If the ophthalmic imaging device 100 has an OCT imaging mode, as in this exemplary embodiment, a second galvanometer scanner (not shown in FIG. 2 ) can be provided to scan the OCT sample beam in a first direction across the ellipsoidal mirror 32 via the rotatable mirror 30.

[0025] 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 and onto the fundus 12. The light from the illuminated area of ​​the fundus 12 follows the same optical path through the image capture device 2 as the light beam entering the optical system, but in reverse order, and is then directed by the beam splitter 60 to the photodetector 70.

[0026] 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 scanning 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 embodiments 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 point along path T3 on elliptical mirror 32 followed by scanner 36 is therefore constant. The scanning performed by scanner 36 and rotatable mirror 30 is coordinated by processor 50 or a scanning system controller (not shown) to synchronize light beam L T can scan over the fundus 12 according to a predetermined scanning pattern.

[0027] 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 , and directs the beam L onto a curved mirror 38. 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 on the curved mirror 38, the beam L T is reflected from there via a rotatable mirror 30 onto an elliptical mirror 32. T 2 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. 2.

[0028] The processor 50 may be provided in any suitable form, for example as a processor 220 of programmable signal processing hardware 200 of the type shown schematically in FIG. The programmable signal processing hardware 200 includes a communication 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 various functions of the processor 50 described herein.

[0029] 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 exemplary embodiment may include one or more computer processors 220 and one or more memories 240 for storing 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.

[0030] It should be noted, however, that processor 50 may be implemented in non-programmable hardware, such as an ASIC, FPGA, or other integrated circuit dedicated to performing the functions of processor 50 described above, or in a combination of such non-programmable hardware and programmable hardware as described with reference to FIG. 3.

[0031] 2 , stereoscopic imaging device 40 includes first and second cameras 42, 44 configured to capture, 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 capture, 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 can be provided by illumination source 47, for example, in the form of an IR light-emitting diode (LED). The stereoscopic 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 patient alignment device 4) that includes one or more light sources, such as, for example, light-emitting diodes (LEDs). The fixation target light source 80 transmits 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, and / or a circle or two or more concentric circles. F The color of may be variable by processor 50 as described below.

[0032] 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 acquisition 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) distance range R from the exit pupil E suitable for acquiring an UWF image 55 of the fundus 12.

[0033] When the rotatable mirror 30 is stationary in a predetermined orientation in the patient alignment mode, the processor 50 controls the fixation target light source 80 to emit a 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 30 when the rotatable mirror 30 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, thus maintaining fixation of the eye 10 while the pupil 14 is positioned within a target range suitable for acquiring a UWF 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 6, the fixation target light source 80 may be configured to fix the gaze in a gaze direction other than the central gaze direction.

[0034] In the patient alignment mode, as in this exemplary embodiment, the processor 50 can process the stereoscopic images 46-1, 46-2 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, 46-2 to locate the pupil center 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 an indication of the distance d. The processor 50 can then compare the determined indication of the distance d to a predetermined threshold to determine whether the pupil 14 is too close to the exit pupil E, too far from the exit pupil E, or whether the distance from the exit pupil E is within a predetermined range R that is acceptable for image capture.

[0035] 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 comparison result, as in this exemplary embodiment. For example, the fixation target light source 80 can 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 an even different color (e.g., green) when the distance between the exit pupil E and the pupil 14 is less than the threshold.

[0036] However, visual feedback indicating that the patient needs to move forward or backward to position the pupil 14 relative to the exit pupil properly for fundus imaging is provided by the fixation light L F It does not have to be done with any other visible light visible to the patient, e.g., fixation light L FNote that the signal S may be provided with background illumination of 100 to 2000 nm. Thus, the signal S more generally includes projecting light of a first color (e.g., blue) onto the eye 10 when the subject should move the eye 10 toward the image capture device 100 to move the pupil 14 toward a distance range R from the exit pupil E, projecting light of a second color (e.g., red) onto the eye 10 when the subject should move the eye 10 away from the image capture device 100 to move the pupil 14 toward a distance range R from the exit pupil E, and projecting light of a third color (e.g., green) onto the eye 10 when the pupil 14 is within a distance range R from the exit pupil E suitable for capturing a UWF image 55 of the fundus 12, where the first color, second color, and third color are different from one another.

[0037] Additionally or alternatively, the processor 50 may generate a signal S that controls a speaker (not shown in FIG. 2 ) to generate a sound (e.g., a varying tone or voice) 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 voice 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 from the ophthalmic imaging device 100, a different second (e.g., high-pitched) tone or voice indication when the distance between the exit pupil E and the pupil 14 is greater than the threshold value and the pupil 14 is closer to the ophthalmic imaging device 100 and on the opposite side of the range R, and a further (e.g., mid-pitched) tone or voice indication when the distance between the exit pupil E and the pupil 14 is less than the threshold value.

[0038] By processing each pair of acquired stereoscopic images as described above, the subject 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 subject then observes the fixation light turn green and / or hears a mid-pitched tone or audio indication (as appropriate), which indicates to the subject that the pupil 14 of the eye 10 is close enough to the exit pupil E to begin UWF imaging of the fundus 12.

[0039] If the distance between the exit pupil E and the pupil 14 is determined to be less than the threshold, the processor 50 begins operation in a fundus imaging mode and is configured to control the ophthalmic imaging device 100 to acquire an UWF image 55 of the fundus 12. The processor 50 controls the light source 20 to emit a light beam L T , and control the image capture device 2 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 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 , reducing artifacts and otherwise improving the quality of the UWF image 55. To reduce the risk of misalignment of the eye 10 with the ophthalmic imaging device 100, as in the present exemplary embodiment, the processor 50 automatically initiates operation in fundus imaging mode in response to determining that the distance between the exit pupil E of the ophthalmic imaging device 100 and the pupil 14 is less than a threshold. However, in other embodiments, this switch in operational mode may be commanded by an operator of the ophthalmic imaging device 100, for example, by clicking a mouse (as an example of a user interface that can be used for this purpose) or pressing a key on a computer keyboard, in response to visual, auditory, and / or tactile feedback based on the signal S.

[0040] The stereoscopic imaging device 40, as in this exemplary embodiment, uses the light beam L between the rotatable mirror 30 and the elliptical mirror 32 during the acquisition of the UWF image 55. T , and the fixation target light source 80 may be located within region G, as in this exemplary embodiment. The stereoscopic imaging device 40 and the fixation target light source 80 may therefore be housed within an area not used for light propagation within the bowl of the elliptical mirror 32. This configuration may be advantageous because by locating 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 may be made more compact.

[0041] Furthermore, housing the stereoscopic imaging device 40 and fixation target light source 80 in region G provides an option for orienting the rotatable mirror 30 in the patient alignment mode (i.e., selecting the aforementioned predetermined orientation). This allows the rotatable mirror 30 to begin rotating from the predetermined orientation as soon as the processor 50 starts acquiring UWF images 55 with the UWF ophthalmic imaging device 100 during operation in fundus imaging mode. This avoids delays in the start of image acquisition and reduces the risk of changing the gaze direction of the eye 10, which 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. 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 (e.g., similar to the curved mirror 38 in FIG. 1 ) so that each has 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.

[0042] 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 of the images 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 E.

[0043] 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. The 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. 4. For clarity, the magnitude of the angle θ and the angle α discussed below are exaggerated in FIG. 4. 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 each include a camera lens having an optical axis 48-1 and an optical axis 48-2, which 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 images of the respective pupils 14 in the stereoscopic images 46-1, 46-2 of the pupils 14 obtained using this arrangement is small enough to achieve satisfactory pupil alignment.

[0044] 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 5 is a schematic diagram of a line-scanning UWF ophthalmic imaging device 300 according to a variation of the example embodiment of FIG. 2, which, in addition to the elliptical mirror 32, includes 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 5, the second elliptical mirror 39 has a first focal point 39-1 and a second focal point 39-2, and the rotatable mirror 30 projects a line onto a plane (i.e., cross-section) perpendicular to its propagation direction, which can be generated by a light beam having a point-like cross-section (such as that generated by the light source 20) using a cylindrical lens, or by another optical configuration for generating line-shaped illumination known to those skilled in the art (e.g., a back-illuminated slit aperture). As shown in FIG. 5, the second elliptical mirror 39 has a first focal point 39-1 and a second focal point 39-2, and the rotatable mirror 30 projects the light beam L at the first focal point 39-1 of the 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.

[0045] Linear lighting L T 5 shows a light source 20' generating a line of illumination ', which replaces the light source 20, scanner 36, and curved mirror 38 of the exemplary embodiment of FIG. 2. 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. 5 to more clearly show the different scanning transmission configuration, including the two elliptical mirrors 32, 39. The line-scanning UWF ophthalmic imaging device 300 also includes a beam splitter that directs returning light from the fundus 12 to a photodetector for detecting the returning linear illumination, although this is also omitted in FIG. 5 for simplicity.

[0046] 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 L T 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.

[0047] 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.

[0048] Regardless of whether the stereoscopic imaging device 40 is housed in region G (or region G2 in the modified embodiment of FIG. 5 ), 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. 2 , the Fresnel lens 49 is configured to refract light from the eye 10 that is 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 to pass through the first focal point 32-1 of the elliptical mirror 32, which may otherwise be necessary to improve stereoscopic ranging. As a result, manufacturing of the stereoscopic imaging device 40 is simplified and expedited. Similarly, in the modified embodiment described with reference to FIG. 5 , 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 elliptical mirror 39 to propagate along a first optical axis 48-1 of the first camera 42 and a second optical axis 48-2 of the second camera 44.

[0049] The fixation target light source 80 projects fixation light L from a single location onto the rotatable mirror 30 for central gaze 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. 5). F may be configured to project

[0050] FIG. 6 is a schematic diagram of a patient alignment system 400 including the stereoscopic imaging system 40 and an improved fixation target light source 80 included in the example embodiment of FIG. 2, as viewed from the rotatable mirror 30. As shown in FIG. 6, the patient alignment device 400 includes a flat substrate 410 on which are mounted a first camera 42, a second camera 44, and an IR illumination 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. 6, 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. 6, but the number and arrangement of the light sources is not so limited. The patient alignment device 400 may also include the aforementioned Fresnel lens 49, as in this embodiment, which is overlaid on the stereo cameras 42 and 44, the IR illumination source 47, and the LEDs 80-1 through 80-9 and positioned between these components and the rotatable mirror 30.

[0051] 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 example embodiment of FIG. 2 (or first focal point 39-1 of second elliptical mirror 39 in the variation of FIG. 5), and eye 10 can be directed in different directions by gazing at light from a selected LED relayed to eye 10 via rotatable mirror 30 and elliptical mirror 32 (and second elliptical mirror 39 in the variation of FIG. 5). In the example of FIG. 6, 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.

[0052] 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. 5). 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 depending on the displacement of pupil 14 from exit pupil E. The background color of the display screen may also be varied to indicate the need for the subject to move eye 10 back and forth (or not move at all) to bring pupil 14 within distance range R, as previously described. As another example, fixation light source 80 may be provided in the form of an array of optical fibers, emerging from substrate 410 at the same locations as LEDs 80-1 through 80-9 and projecting light directed therethrough toward rotatable mirror 30. Here, an optical switch or other means controllable by processor 50 may be provided to control fixation light L. F is allowed to enter the rotatable mirror 30 from the selected optical fiber.

[0053] 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. 6, processor 50 can select one of LEDs 80-1 through 80-9, which corresponds to the selected gaze direction. Processor 50 then controls fixation target light source 80, for example, by driving only the selected LED to project the appropriate color 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.

[0054] 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 the LED 80-5 in the embodiment of FIG. 6). 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 5. The Fresnel lens 49 is therefore configured to refract the light returned 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.

[0055] Figure 7 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 7. The processor 50 may similarly control the ophthalmic imaging device 300 to acquire UWF images 55 of the fundus 12.

[0056] When operating in patient alignment mode to generate signal S for positioning pupil 14 of eye 10 within a target range for acquiring UWF image 55, processor 50 first controls rotatable mirror 30 to rest in a predetermined orientation that enables stereoscopic imaging device 40 to image pupil 14 via rotatable mirror 30 and elliptical mirror 32. Processor 50 then controls the illumination light source of stereoscopic imaging device 40 to turn on, thereby illuminating eye 10 with IR light via rotatable mirror 30 and elliptical mirror 32 (and second elliptical mirror 39 in the modified embodiment of FIG. 5 ).

[0057] In process S10 of Figure 7, the processor 50 monitors the position of the pupil 14 relative to the exit pupil E of the UWF ophthalmic imaging device 100. In this exemplary embodiment, the processor 50 can monitor this position by the process shown in the flow diagram of Figure 8, specifically by acquiring stereoscopic images 46-1, 46-2 of the pupil 14 in process S12 and processing the stereoscopic images 46-1, 46-2 in process S14, e.g., as previously described, to monitor the position of the pupil 14 relative to the exit pupil E of the UWF ophthalmic imaging device 100.

[0058] 7, in process S20, the processor 50 compares the position with an appropriate distance range R from the exit pupil E for acquiring a UWF image 55 of the fundus 12 to determine whether the pupil 14 is within the distance range from the exit pupil E. Here, the distance range R used in this comparison has been adjusted in advance. The distance range R used by the processor 50 for the comparison in S20 is adjusted in advance, for example, in optional processes S2 and S4 shown in FIG. 7. Specifically, the processor 50 determines a dimensional representation (e.g., diameter, circumference, area) of the pupil 14 based on at least one of the stereoscopic images 46-1, 46-2 of the pupil 14 (process S2), and adjusts the distance range R used for comparison based on the determined dimensional representation of the pupil 14 (process S4), thereby adjusting the distance range R used for comparison in S20 so that it increases as the size of the pupil 14 increases. Alternatively, if the patient alignment device includes a single (non-stereo) camera 4c as described herein with reference to FIG. 9, processor 50 may determine the dimensional representation of pupil 14 based on the image of pupil 14 captured by camera 4c (rather than one or both of stereo images 46-1, 46-2) in S2 of FIG. 7. However, adjustment of range R is not limited to these examples and may be performed in other ways, such as by providing a patient alignment device with a user interface as described herein with reference to FIG. 10 and configuring processor 50 to perform process S6 of FIG. 7 instead of processes S2 and S4. Here, processor 50 adjusts distance range R used in the comparison according to user input provided via user interface 4d. In this case, the user knows the dilated state of the pupil and can manually adjust distance range R as needed.

[0059] If in S20 it is determined that the pupil 14 is outside the distance range R ("No" in S25), in process S30 of FIG. 7, the processor 50 generates a signal S to guide the subject to change the distance between the eye 10 and the UWF ophthalmic imaging device 100 based on the monitored position to bring the pupil 14 closer to the distance range R from the exit pupil E. These signals include projecting a first color of light onto the eye 10 when the subject must move the eye 10 toward the UWF ophthalmic imaging device 100 to bring the pupil 14 closer to a distance range R from the exit pupil (E), projecting a second color of light onto the eye 10 when the subject must move the eye 10 away from the UWF ophthalmic imaging device 100 to bring the pupil 14 closer to a distance range R from the exit pupil, and projecting a third color of light onto the eye 10 when the pupil 10 is within a distance range R from the exit pupil E suitable for capturing a UWF image 55 of the fundus 12, where the first color, second color, and third color are different from each other.

[0060] If the pupil 14 is within the distance range R in S20 ("Yes" in S25), the processor 50 generates an indication I in process S40 of FIG. 7 that the pupil 14 is in a suitable position to acquire a UWF image 55. In response to the indication I generated in process S40, the processor 50 automatically controls the UWF imaging device 100 to acquire a UWF image 55 of the fundus 12 (process S50 of FIG. 7). The processor 50 controls the light source 20 to emit a 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. 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.

[0061] In the exemplary embodiment described above, the patient alignment device 4 includes a stereoscopic imaging device 40 and a processor 50 configured to determine a dimensional representation of the pupil 14 based on one or both of the stereoscopic images 46-1, 46-2 of the pupil 14 captured by the stereoscopic imaging device 40, and to adjust the distance range R used for the comparison based on the determined dimensional representation of the pupil 14. However, the patient alignment device is not limited to this, and may be configured to adjust the distance range R used for the comparison in other ways.

[0062] 9 is a schematic diagram of a variation 4-2 of the patient alignment device, which measures the distance L to the eye 10 and generates a measurement signal S indicative of the measured distance L. M The distance sensor 4a may comprise, for example, a laser distance sensor, which may be configured to measure the distance to the pupil 14, for example using laser triangulation. The patient alignment device 4-2 is configured to generate a measurement signal S M The patient alignment device 4-2 also includes a processor 4b configured to monitor the position of the pupil 14 relative to the exit pupil E of the image capture device 2 based on stereo images 46-1 and / or 46-2. The patient alignment device 4-2 further includes a camera 4c configured to capture images M of the pupil 14. The processor 4b is then further configured to determine a dimensional representation of the pupil 14 based on the captured images M of the pupil 14 (similar to processor 50 based on stereo images 46-1 and / or 46-2), and to adjust the distance range R used for comparison based on the determined dimensional representation of the pupil 14, increasing the distance range R used for comparison with increasing dimensions of the pupil 14, as described above.

[0063] 10 is a schematic diagram of another variation of the patient alignment device 4-3, which includes a user interface 4d that allows the distance range R used in the comparison to be adjusted by a user of the UWF ophthalmic imaging device 100. The user interface 4d can be included in any of the previously described exemplary embodiments and variations thereof, allowing the user to override the ongoing automatic adjustment of the range R, if desired.

[0064] In the preceding description, exemplary aspects have been described with reference to several exemplary embodiments. Accordingly, the present specification should be considered illustrative rather than restrictive. Similarly, the shapes shown in the figures, 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.

[0065] 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.

[0066] 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 steps of the exemplary embodiments described herein.

Claims

1. An ultra-wide-angle ophthalmic imaging device (1; 100; 300), comprising: an image capture device (2) configured to capture an ultra-wide-angle image (55) of a fundus (12) of a subject's eye (10) through an exit pupil (E) of the image capture device (2); a patient alignment device (4; 4-2; 4-3) configured to monitor the position of a pupil (14) of the eye (10) relative to the exit pupil (E) of the image capture device (2) and to compare said position with a distance range (R) from the exit pupil (E) suitable for capturing the image (55) of the fundus (12) to determine whether the pupil (14) is within said distance range (R) from the exit pupil (E), the distance range (R) used in the comparison is adjustable; if it is determined that the pupil (14) is outside the distance range (R), the patient alignment device (4; 4-2; 4-3) is configured to generate, based on the monitored position, a signal (S) to guide the subject to change the distance between the eye (10) and the image capture device (2) to move the pupil (14) toward the distance range (R) from the exit pupil (E); a patient alignment device (4; 4-2; 4-3) configured to generate an indication (I) that the pupil (14) is in a suitable position for acquiring the image (55) of the fundus (12) if the pupil (14) is determined to be within the distance range (R); a controller (6) configured to control the image capture device (2) to automatically capture the ultra-wide-angle image (55) of the fundus (12) in response to the patient alignment device (4; 4-2; 4-3) generating the display (I); and An ultra-wide-angle ophthalmic imaging device (1; 100; 300) comprising:

2. The patient alignment device (4) comprises: a stereoscopic imaging device (40) configured to acquire stereoscopic images (46-1; 46-2) of the pupil (14); a processor (50) configured to process the stereoscopic images (46-1; 46-2) to monitor the position of the pupil (14) relative to the exit pupil (E) of the image capture device (2); 2. The ultra-wide-angle ophthalmic imaging device (100; 300) of claim 1, comprising:

3. 3. The ultra-wide-angle ophthalmic imaging device of claim 2, wherein the processor is further configured to determine a dimensional representation of the pupil based on at least one of the stereoscopic images of the pupil, and to adjust, based on the determined dimensional representation of the pupil, the distance range used in the comparison such that the distance range increases with increasing size of the pupil.

4. The image acquisition device (2) projects a light beam (L Ｔ ) to acquire the ultra-wide-angle image (55) of the fundus (12), 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 ... 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 (32) 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; Equipped with the controller (6) is configured to cause the patient alignment device (4) to monitor the position of the pupil (14) relative to the exit pupil (E) of the image capture device (2) in a patient alignment mode, and to control the image capture device (2) to capture the ultra-wide-angle image (55) of the fundus (12) in a fundus imaging mode; the stereoscopic imaging device (40) is configured to acquire the stereoscopic images (46-1; 46-2) of the pupil (14) via the rotatable mirror (30) and the elliptical mirror (32); In the patient alignment mode, the controller (6) Controlling the rotatable mirror (30) so that it remains stationary in a predetermined orientation, and 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 the predetermined orientation; In the fundus imaging mode, the controller (6) 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 4. The ultra-wide-angle ophthalmic imaging device (100; 300) of claim 2 or 3, wherein the image capture device (2) is controlled to capture the ultra-wide-angle image (55) of the fundus (12) by scanning the ellipsoidal mirror (32) with a hologram (31) of the fundus (12).

5. The patient alignment device (4-2) The distance (L) to the eye (10) is measured, and a measurement signal (S) indicating the measured distance (L) is generated. Ｍ ), wherein the patient alignment device (4-2) is configured to generate the measurement signal (S Ｍ a distance sensor (4 a) configured to monitor the position of the pupil (14) relative to the exit pupil (E) of the image capture device (2) based on a camera (4c) configured to take an image (M) of said pupil (14); Equipped with 2. The ultra-wide-angle ophthalmic imaging device (1;100;300) of claim 1, wherein the patient alignment device (4-2) is configured to determine a size representation of the pupil (14) based on a captured image (M) of the pupil (14), and to adjust the distance range (R) used in the comparison based on the determined size representation of the pupil (14) such that the distance range (R) used in the comparison increases with increasing size of the pupil (14).

6. An ultra-wide-angle ophthalmic imaging device (1; 100; 300) as described in any one of claims 1 to 5, wherein the patient alignment device (4-3) is provided with a user interface (4d) whereby the distance range (R) used in the comparison can be adjusted by a user of the ultra-wide-angle ophthalmic imaging device (1; 100; 300).

7. a signal (S) for inducing the subject to change the distance between the eye (10) and the image capture device (2) to move the pupil (14) closer to the distance range (R) from the exit pupil (E), projecting light of a first color onto the eye (10) when the subject must move the eye (10) towards the image capture device (2) to bring the pupil (14) closer to the distance range (R) from the exit pupil (E); projecting light of a second color onto the eye (10) when the subject must move the eye (10) away from the image capture device (2) to bring the pupil (14) closer to the distance range (R) from the exit pupil (E); projecting light of a third color onto the eye (10) when the pupil (14) is within the distance range (R) from the exit pupil (E) suitable for acquiring an image of the fundus (12); 7. An ultra-wide-angle ophthalmic imaging device (1; 100; 300) according to any one of claims 1 to 6, comprising:

8. The ultra-wide-angle ophthalmic imaging device (1; 100; 300) of claim 7, wherein the patient alignment device (4; 4-2; 4-3) further comprises a fixation target light source (80) configured to project light of the first color, light of the second color, and light of the third color, respectively, to fixate the gaze direction of the eye (10) in a predetermined direction.

9. 9. The ultra-wide-angle ophthalmic imaging device (1; 100; 300) of claim 8, wherein the fixation target light source (80) is configured to project light of the first color, light of the second color, and light of the third color, respectively, so as to have a projection on the fundus (12) of the eye (10) comprising at least one of a crosshair, a dot, a circle, or one or more concentric circles.

10. The ultra-wide-angle ophthalmic imaging device (1; 100; 300) of any one of claims 1 to 9, wherein the ultra-wide-angle ophthalmic imaging device (100) comprises an ultra-wide-angle scanning laser ophthalmoscope.

11. 1. A method of operating an ultra-wide angle ophthalmic imaging device (100; 300) to acquire an ultra-wide angle image (55) of a fundus (12) of an eye (10) of a subject, comprising: monitoring (S10) the position of the pupil (14) of the eye (10) relative to the exit pupil (E) of the ultra-wide-angle ophthalmic imaging device (100; 300); a step (S20) of comparing the position with a distance range (R) from the exit pupil (E) suitable for acquiring the image (55) of the fundus (12) to determine whether the pupil (14) is within the distance range (R) from the exit pupil (E), wherein the distance range (R) used in the comparing step (S20) is adjustable; If it is determined that the pupil (14) is outside the distance range (R), a step (S30) is performed to generate a signal (S) for instructing the subject to change the distance between the eye (10) and the ultra-wide-angle ophthalmic imaging device (100; 300) based on the monitored position so that the pupil (14) approaches the distance range (R) from the exit pupil (E); If the pupil (14) is determined to be within the distance range (R), generating (S40) an indication that the pupil (14) is in a suitable position for acquiring the image (55) of the fundus (12); automatically controlling (S50) the ultra-wide-angle ophthalmic imaging device (100; 300) to acquire the ultra-wide-angle image (55) of the fundus (12) in response to generating the display; A method comprising:

12. A stereoscopic image (46-1; 46-2) of the pupil (14) is acquired (S12), processing (S14) stereoscopic images (46-1; 46-2) of the pupil (14) to monitor the position of the pupil (14) relative to the exit pupil (E) of the ultra-wide-angle ophthalmic imaging device (100; 300); 12. The method of claim 11, wherein the position of the pupil (14) relative to the exit pupil (E) of the ultra-wide angle ophthalmic imaging device (100; 300) is monitored by:

13. determining (S2) a dimensional representation of the pupil (14) based on at least one of the stereoscopic images (46-1; 46-2) of the pupil (14); adjusting (S4) the distance range (R) used in the comparison (S20) based on the determined size representation of the pupil (14) such that the distance range (R) used in the comparison (S20) increases with increasing size of the pupil (14); The method of claim 12 further comprising:

14. 12. The method of claim 11, wherein the ultra-wide-angle ophthalmic imaging device (100; 300) includes a user interface (4d), and the method further includes adjusting the distance range (R) used in the comparison (S20) according to user input provided via the user interface (4d).

15. a signal (S) for inducing the subject to change the distance between the eye (10) and the ultra-wide-angle ophthalmic imaging device (100; 300) to move the pupil (14) closer to the distance range (R) from the exit pupil (E), projecting light of a first color onto the eye (10) when the subject must move the eye (10) towards the ultra-wide-angle ophthalmic imaging device (100; 300) to bring the pupil (14) closer to the distance range (R) from the exit pupil (E); projecting light of a second color onto the eye (10) when the subject must move the eye (10) away from the ultra-wide-angle ophthalmic imaging device (100; 300) to bring the pupil (14) closer to the distance range (R) from the exit pupil (E); and projecting light of a third color onto the eye (10) when the pupil (14) is within the distance range (R) from the exit pupil (E) suitable for acquiring an image (55) of the fundus (12); wherein the first color, the second color, and the third color are different from each other.

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