Visual indicator for alignment for retinal imaging system

Abstract

A retinal camera and related methods of use are described. In an example, the retinal camera comprises a lens tube; a face rest shaped to steady a face of a user when the face is placed against the face rest; a light baffle positioned to conceal internal components of the retinal imaging system, wherein the light baffle defines a slit; and an alignment indicator positioned to be visible through the slit when an eye of the face is within an initial alignment zone of the retinal imaging system. In an example, the face rest defines a horizontal axis, and wherein the slit is parallel to the horizontal axis. In an example, the slit is positioned to align with a line between two eyes of the user when the face is placed against the face rest.

Description

VISUAL INDICATOR FOR ALIGNMENT FOR RETINAL IMAGING SYSTEMCROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional Application No.63 / 711,501, filed on October 24, 2024, the contents of which are incorporated herein by reference.TECHNICAL FIELD

[0002] This disclosure relates generally to alignment indicators for retinal imaging systems, and, in particular but not exclusively, relates to visual alignment indicators for a retinal imaging system.BACKGROUND INFORMATION

[0003] Retinal imaging is a part of basic eye exams for screening, field diagnosis, and progress monitoring of many retinal diseases. A high-fidelity retinal image is important for accurate screening, diagnosis, and monitoring.

[0004] Aligning a patient's eye with the optics of a retinal imaging system can been challenging. Some retinal cameras have an automated process for finding a user's pupils. However, some such cameras require the pupil to be in a position reasonably aligned initially with retinal imaging system optics, such as a lens tube and a retinal image sensor. Such coarse alignment is not straightforward, as in some retinal imaging systems where there is no clear indicator for when the user brings their face toward the retinal imaging system. Such coarse alignment can consume a lot of screening time, and can also heavily rely on operator experience to bring a user into coarse alignment with the retinal image system. Certain cameras rely on communication between operator and users to make this adjustment.

[0005] Some retinal cameras heavily rely on camera affordances to guide the patient, but this approach can be inaccurate due to the individual facial structures and subjective nature of comfort levels.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Non-limiting and non-exhaustive embodiments of the claimed subject matter are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified.Not all instances of an element are necessarily labeled so as not to clutter the drawings where appropriate. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles being described.

[0007] FIG. 1A is a front view of a retinal imaging system according to an embodiment of the present disclosure.

[0008] FIG. IB is a side view of the retinal imaging system of FIG. 1A, according to an embodiment of the present disclosure.

[0009] FIG. 1C is a partial view of internal components of the retinal imaging system of FIG. 1A, according to embodiments of the present disclosure.

[0010] FIG. 2A-2C are schematic illustrations of alignment of an eye in an initial alignment zone of a retinal imaging system (top row), visibility of alignment indicators (middle row), and alignment of a face of a user relative to a retinal imaging system (bottom row), according to embodiments of the present disclosure.

[0011] FIG. 3A is a front view of a partial assembly of a retinal imaging system, according to embodiments of the present disclosure.

[0012] FIG. 3B is an exploded view of the partial assembly of FIG. 3A. according to embodiments of the present disclosure.

[0013] FIG. 3C is another exploded view of a partial assembly of a retinal imaging system according to an embodiment of the present disclosure.

[0014] FIG. 4 provides examples of shapes of alignment indicators according to embodiments of the present disclosure.

[0015] FIG. 5 A is a functional component diagram illustrating a retinal imaging system with a subject interface for accommodating a face of a subject, in accordance with an embodiment of the disclosure.

[0016] FIG. 5B is another functional component diagram of the retinal imaging system of FIG. 5 A, in accordance with an embodiment of the disclosure.DETAILED DESCRIPTION

[0017] Embodiments of visual alignment structures for a retinal camera are described herein. In the following description numerous specific details are set forth to provide a thorough understanding of the embodiments. One skilled in the relevant art will recognize, however, that the techniques described herein can be practiced without one or more of the specific details, or with other methods, components, materials, etc.In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring certain aspects.

[0018] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0019] High-fidelity retinal images are important for screening, diagnosing, and monitoring many retinal diseases.

[0020] To capture a retinal image with a retinal imaging system, a lens tube (including the eyepiece lens) should be precisely aligned with a subject's eye (usually to a tolerance of just a few millimeters). In order to achieve this precise alignment, some retinal cameras include some sort of fixation target in the optical path that is visible when looking directly into the eyepiece lens. Among other purposes, the fixation target provides feedback about where to look during alignment. However, due to the optical properties of some lens tubes, even just getting one's eye to the region in space where the fixation target is visible is often challenging. Without visual feedback to facilitate a coarse alignment, a grossly misaligned user is often unsure how to move relative to the eyepiece lens to gain visual contact with the fixation target, at which point fine or precise alignment can begin using the fixation target

[0021] To address these and related challenges, the present disclosure provides a retinal imaging system comprising alignment indicators that, when visible, such as when entirely visible, through a slit provide a visual indication that an eye or eyes of a user are within an initial alignment zone of the retinal imaging system. In embodiments, the alignment indicator provides a visual reference to guide the eye into a coarse alignment with the retinal imaging system, such as with an eyepiece lens to observe a fixation target or other aide in finer alignment.

[0022] By placing an eye or eyes within an initial alignment zone of the retinal imaging zone, the retinal imaging system can automatically adjust alignment of optical components of the retinal imaging system within a smaller eyebox of the retinal imaging system to obtain a retinal imaging of the user’s eye. Without such course alignment of the retinal imaging system to place the user’s eyes within the initialalignment zone, it may be challenging or even impossible to obtain the fine alignment used to obtain a retinal image.

[0023] Embodiments described herein enable fully automated retinal camera systems that can be used without a skilled technician's intervention, thereby opening up a variety7of new uses cases and environments of operation.

[0024] In this regard, attention is directed to FIGS. 1A-1C in which a retinal imaging system 100, according to an embodiment of the present disclosure, is illustrated. FIG. 1A is a front view of the retinal imaging system 100. FIG. IB is a side view of the retinal imaging system 100. FIG. 1C is a partial view of internal components 108 of the retinal imaging system 100.

[0025] The retinal imaging system 100 is shown to include a lens tube 102. a face rest 104, a light baffle 106 positioned to conceal internal components 108 (such as the retinal image sensor 138, see FIG. 1C) of the retinal imaging system 100, and an alignment indicator 112.

[0026] As show n, the face rest 104 is shaped to steady a face of a user when the face is placed against the face rest 104. such as by providing a surface against which the user may rest a portion of their face, such as a forehead and cheeks. In the illustrated embodiment, the face rest 104 is shown to define a curved surface, such as defined by an outer periphery of the face rest 104, shaped to generally conform to a corresponding surface of the face of a user. By conforming to portions of the face of the user, the face rest 104 is shaped to stabilize or steady the face of the user, such that the face, and correspondingly eye(s) of the user, is steady and suitable for retinal imaging, such as through the lens tube 102.

[0027] As shown, the lens tube 102 protrudes through a light baffle 106, and is generally directed through an aperture of the face rest 104, such as to image an eye of a user placing their face against the face rest 104. The light baffle 106 is positioned to conceal internal components 108 of the retinal imaging system 100, such as to prevent or limit stray light, dust, moisture, and the like from entering into an internal portion of the retinal imaging system 100. such as within the case 146. In an embodiment, the light baffle 106 comprises a material that is opaque to light, such as to visible light, such that stray light (i.e., light not emanating from an internal portion of the retinal imaging system 100) does not pass through the face rest 104 and into the internal portion of the retinal imaging system 100. Such stray light can deteriorate or degrade retinal images, such as where stray light impinges upon a retinal image sensor 138.

[0028] The light baffle 106 is further shown to define a slit 110, shown here as a horizontal slit 110, in the light baffle 106. Also shown are an alignment indicator 112 positioned to be visible through the slit 110, such as when an eye of the face is within an initial alignment zone of the retinal imaging system 100.

[0029] As shown, the slit 110 defines a cut out portion of the light baffle 106 defined by two straight edges. While a slit 110 is illustrated, it will be understood that other shapes in the light baffle 106 may be possible, such as curved slits or apertures, and are within the scope of the present disclosure, such as where the shapes are positioned such that the alignment indicator 112 is visible when a user’s eye is visible through the shape.

[0030] In an embodiment, an alignment indicator of a retinal imaging system is positioned to be visible through a slit of a light baffle when an eye of a user’s face is within an initial alignment zone of a face rest. In this regard, attention is directed to FIGS. 2A-2C, in which alignment and misalignment of an eye 214 within an initial alignment zone 216 of a retinal imaging system 200, according to embodiments of the present disclosure, is shown FIG. 2A-2C are schematic illustrations of alignment of an eye 214 in an initial alignment zone 21 of a retinal imaging system 200 (top row-), visibility of alignment indicators 212 (middle row ), and alignment of a face of a user relative to a retinal imaging system 200 (bottom row), according to embodiments of the present disclosure.

[0031] In an embodiment, the retinal imaging system 200 is an example of the retinal imaging system 100 discussed further herein with respect to FIGS. 1A-1C.

[0032] As shown, the retinal imaging system 200 comprises a face rest 204 shaped to steady a face of a user when the face is placed against the face rest 204. The retinal imaging system 200 is also shown to include a lens tube 202, a light baffle 206, configured to block light, and defining a slit 210, and an alignment indicator 212 positioned to be visible through the slit 210. In particular, as shown in FIG. 2A (top row), when the eye 214 of the user is within an initial alignment zone 216 of the face rest 204, the alignment indicator 212 is visible by the aligned eye 214 through the slit 210. In an embodiment, the initial alignment zone 216 is a three-dimensional space positioned, for example, within the face rest 204 defining a range of potential focal points of the retinal imaging system 200. In particular, as discussed further herein, the lens tube 202 can be moved, such as with an alignment motor (such as alignment motor 546 discussed further herein with respect to FIGS. 5A and 5B) relative to the face rest204 to direct optical components of the retinal imaging system 200 within the three-dimensional space.

[0033] In an embodiment, the initial alignment zone 216 is defined, at least in part, by a range of motion of the alignment motor, such as can be used to effect positions of the lest tube 202 to adjust the focal points. In another embodiment, the size of the initial alignment zone 216 is controlled by a size and position of the slit 210 and a size and position of the alignment indicator 212. In this regard, a smaller slit 210. such as a smaller slit 210 that is positioned farther from an alignment indicator 212, will generally result in a smaller initial alignment zone 216. Conversely, a larger slit 210 positioned closer to an alignment indicator 212, particularly a smaller alignment indicator 212, will provide a larger initial alignment zone 216.

[0034] In particular embodiments, all of the alignment indicator 212 is positioned to be visible through the slit 210 when the eye 214 is within the initial alignment zone 216 of the face rest 204. In this regard, the alignment indicator 212 is shaped and positioned to guide a user into alignment with the optics of the retinal imaging system 200. In particular embodiment, the alignment indicator 212 is positioned to provide an indication to a user that the user’s eye 214 is within an initial alignment zone 216 when the alignment indicator 212 is visible, such as entirely visible, through the slit 210.

[0035] In contrast to the embodiment illustrated in FIG. 2 A. where the eye 214 of the user is not within an initial alignment zone 216 of the retinal imaging system 200, either because the eye 214 is too high (FIG. 2C) or too low (FIG. 2B), the alignment indicator 212 will not be visible, or will not be entirely visible, by the unaligned eye 214 through the slit 210. The retinal imaging system 200. and in particular the slit 210 and alignment indicator 212, is, thus, configured to guide a user in a direction to move their eye 214 to attain initial alignment with optical components of the retinal imaging system 200.

[0036] In an embodiment, the retinal imaging systems of the present disclosure include a face rest shaped to encompass a portion of a face of the user comprising tw o eye sockets. In this regard, attention is directed to FIGS. 3A-3C in which a partial assembly of a retinal imaging system including a face rest 304, according to embodiments of the present disclosure, is illustrated. FIG. 3A is a front view- of the partial assembly of the retinal imaging system. FIG. 3B is an exploded view of thepartial assembly. FIG. 3C is another exploded view of a partial assembly of the retinal imaging system.

[0037] In an embodiment, the partial assembly can be used or is part of the retinal imaging systems 100 and 200 illustrated in and discussed further herein with respect to FIGS. 1A-1C and FIGS. 2A-C, respectively.

[0038] In the illustrated embodiment, the face rest 304 is shaped to encompass or encircle a portion of a face of the user comprising two eye sockets, such as including two eyes 314. As discussed further herein, retinal imaging systems according to the present disclosure can be configured to move the lens tube 302 relative to the face rest 304, such as relative also to the eyes 314 of the subject, to align with individual eyes 314, such as while the face of a user remains relatively stationary within the face rest 304 once within an initial alignment zone of the retinal imaging system. In an embodiment, the face rest 304 is configured to prevent light from outside of the face rest 304 from entering the lens tube 302 when the face is placed against the face rest 304. Such stray light could deteriorate retinal image quality, such as if the stray light were to impinge upon a retinal image sensor. Additionally, a relatively dark environment tends to induce a larger pupil, which can be beneficial for retinal image capture.

[0039] As shown, the partial assembly comprises a lens tube 302; a face rest 304 shaped to steady a face of a user when the face is placed against the face rest 304; a light baffle 306 positioned to conceal internal components of the retinal imaging system, wherein the light baffle 306 defines a slit 310; and an alignment indicator 312 positioned to be visible through the slit 310 when an eye 314 of the face is within an initial alignment zone of the retinal imaging system.

[0040] In an embodiment, the light baffle 306 is configured to block light, whereas, in an embodiment, the slit 310 defined by the light baffle 306 is configured to allow light to pass through the slit 310, such that the alignment indicator 312 may be visible by a user, such as depending upon a viewing angle of the user relative to the slit 310 and the alignment indicator 312.

[0041] In the illustrated embodiment, the slit 310 generally crosses or bisects the light baffle 306 and / or an interior portion of the face rest 304, such as horizontally crosses or bisects the light baffle 306 and / or the interior portion of the face rest 304. Accordingly, in an embodiment, the face rest 304 defines a horizontal axis 318, such as a horizontal axis 318 positioned roughly between a top portion positioned to contact aforehead of the user and a bottom portion of the face rest 304 positioned to contact cheeks of the user. In an embodiment, the slit 310 is parallel to the horizontal axis 318. In this regard, in an embodiment, the slit 310 is shaped and positioned to align with a line 320 between two eyes 314 of the user when the face is placed against the face rest 304. Such a configuration can be suitable in aligning eyes 314 of the user in an initial alignment zone so that the alignment indicator 312 is viewable by both eyes 314 of the subject through the slit 310.

[0042] As shown, the alignment indicator 312 includes portions visible on two lateral sides of the lens tube 302. In the illustrated embodiment, the face rest 304 defines a vertical axis 326, such as a vertical axis 326 positioned between a side of the face rest 304 shaped and positioned to contact a left cheek of the user and a side of the face rest 304 shaped and positioned to contact a right cheek of the user when the user places their face against the face rest 304. In an embodiment, the vertical axis 326 thus vertically divides or bisects the face rest 304. As shown, the alignment indicator 312 comprises a first portion 328 on a first side 330 of the vertical axis 326 and a second portion 332 on a second side 334 of the vertical axis 326. In an embodiment, the first portion 328 of the alignment indicator 312 and the second portion 332 of the alignment indicator 312 are equidistant from the vertical axis 326.

[0043] By having portions of the alignment indicator 312 on two sides of the lens tube 302 (i.e., on either side of the vertical axis 326), the first portion 328 can be visible by a first eye 314 of a user and a second portion 332 can be visible by a second eye 314 of the user when the user places their face against the face rest 304. In this regard, the alignment indicator 312 is configured to give a visual indication to the user whether their first eye 314 and their second eye 314 are both within the initial alignment zone. With an alignment indicator 312 on only a single side of the lens tube 302, a user could view the alignment indicator 312 and, nevertheless, have a yaw misalignment about a lens tube primary axis 322, which could make fine alignment of the retinal image sensor with one or both eyes 314 challenging or impossible, such as depending upon a degree of such misalignment. In this regard, by having an alignment indicator 312 on both sides of the lens tube 302, the system 300 has an improved fine alignment success rate for both eyes.

[0044] As above, the partial assembly is shown to include, and the retinal imaging systems of the present disclosure generally include, a lens tube 302. In the illustrated embodiment, the lens tube 302 is shown protruding through a portion of thelight baffle 306 defining the slit 310. Such a configuration is shaped to provide an initial alignment zone that positions the eye 314 generally aligned with the lens tube 302 and, thus, viewable through the lens tube 302.

[0045] In an embodiment, the slit 310 passes through a center of the lens tube 302. In the illustrated embodiment, the lens tube 302 defines a lens tube primary' axis 322 along a length of the lens tube 302, such as defined by a central or rotational axis of the lens tube 302. In the illustrated embodiment, the slit 310 defines a slit primary axis 324, such as a slit primary axis 324 in a center of the slit 310 defined by an upper edge and a lower edge of the slit 310.

[0046] As shown, the slit 310 passes through an aperture in the light baffle 306 shaped to receive the lens tube 302. Accordingly, in an embodiment, the slit primary axis 324 passes through the lens tube primary axis 322. Such a configuration is suitable to image a central portion of an aligned eye 314, such as a central portion of a retina of the eye 314) as the alignment indicator 312 is positioned to provide a visual indication of rough alignment when the eye 314 is generally aligned with a lens tube primary axis 322. Alternatively, in an embodiment, the sht primary axis 324 does not pass through the lens tube primary' axis 322, such as when imaging of a different portion of a retina is desired.

[0047] In the illustrated embodiment of FIG. 3B, the alignment indicator 312 comprises a light source, such as a light source configured to emit light through the slit 310 visible to an eye 314 within an initial alignment zone. In the illustrated embodiment of FIG. 3C, the partial assembly is shown to include a light source 336 positioned to emit light onto the alignment indicator 312. As shown in FIG. 3C, the light source 336 is positioned on a side of the light baffle 306 opposite the face rest 304 such that the light source 336 is not visible by a user through the slit 310. By illuminating the alignment indicator 312 with the light source 336, a periphery of the alignment indicator 312 may be more easily view able by a user than if the alignment indicator 312 itself comprises a light source 336, such as a bright light source 336. In an embodiment, the illumination is switched off during fine alignment and retinal image capture to reduce distraction.

[0048] As discussed elsewhere herein, in an embodiment, all of the alignment indicator 312 is positioned to be visible through the sht 310 when the eye 314 is within the initial alignment zone of the face rest 304. In this regard, it can be advantageous to have an alignment indicator 312 comprising outer portions or peripheries easily andclearly viewable by a user so that the user can determine if all of the alignment indicator 312 is viewable.

[0049] FIG. 4 provides examples of shapes of alignment indicators according to embodiments of the present disclosure. As discussed elsewhere herein, in an embodiment, the retinal imaging systems of the present disclosure comprise a slit and an alignment indicator, wherein all of the alignment indicator is positioned to be visible through the slit when the eye is within the initial alignment zone of the face rest. Accordingly, it can be advantageous to have alignment indicators shaped such that it is clear to the user that the user is viewing all of the alignment indicator shape or only a portion thereof.

[0050] In an embodiment, the alignment indicators of the present disclosure define shapes that are rotationally symmetric about a rotational axis. In an embodiment, the alignment indicator defines a shape comprising an order of rotational symmetry that is greater than 3, such as a triangle (such as an equilateral triangle), square, pentagon (such as a regular pentagon), hexagon (such as a regular hexagon), etc. In an embodiment, the alignment indicator defines a shape that is a regular polygon. In an embodiment, the alignment indicator defines a shape that is a circle. Such shapes provide an easy visual indication of whether a subject is viewing all or only a portion of the alignment indicator. For example, it is relatively easy for a subject to determine whether they are viewing all or only a portion of a circle, as a portion of a circle would present a flat upper or lower edge, such as where a portion of the light baffle occludes a portion of the alignment indicator. By contrast, it may be difficult for a subject to determine whether the subject is viewing all or a portion of a rectangle, as a portion of the rectangle not obscured by the edge of the light baffle defining the slit may not be easily differentiable from the whole rectangle.

[0051] FIGS. 5A and 5B are functional component diagrams illustrating a retinal imaging system 502 with a face rest 508, in accordance with an embodiment of the disclosure. The illustrated embodiment of retinal imaging system 502 includes the face rest 508, an illuminator 505. an image sensor 510 (also referred to as a retinal image sensor), a controller 515, a user interface 521, a display 525, alignment tracking camera(s) 530, and an optical relay system. The illustrated embodiment of the optical relay system includes lens assemblies 535, 540, 545 and a beam splitter 550. The illustrated embodiment of illuminator 505 comprises illuminator arrays 565 and a center aperture 555.

[0052] As above, the retinal imaging system 502 can also include a face rest 508 shaped to steady a face of a user when the face is placed against the face rest 508; a light baffle (not shown, see for example, FIGS. 2A-2C and 3A-3C) positioned to conceal internal components of the retinal imaging system 502, wherein the light baffle defines a slit (see FIG. 3A); and an alignment indicator (see FIG. 3A) positioned to be visible through the slit when an eye of the face is within an initial alignment zone of the retinal imaging system 502. In an embodiment, the lens tube, face rest 508. light baffle, and alignment indicator are those described further herein with respect to FIGS.1A-1C, 2A-2C, 3A-3C, and 4.

[0053] In an embodiment, all or a portion of the optical relay system is housed or disposed in the lens tube, as passes through the light baffle (see, for example, FIGS.3A-3C). In this regard, in an embodiment, the optical relay system disposed in the lens tube can be moved, such as through operation of the alignment motor 546, to align with an eye of the user. In an embodiment, the alignment motor 546 is configured to move such components including the optical relay, such as all system 502 components other than the controller 515 and user input 521. relative to the face rest 508 to align the optical relay, and, in particular, the retinal image sensor 510, with an eye of the user.

[0054] The optical relay system serves to direct (e.g., pass or reflect) illumination light 580 output from illuminator 505 along an illumination path through the pupil of eye to illuminate retina while also directing image light 585 of retina (i.e.. the retinal image) along an imaging path to image sensor 510. Image light 585 is formed by the scattered reflection of illumination light 580 off the retina. In the illustrated embodiment, the optical relay system further includes beam splitter 550, which passes at least a portion of image light 585 to image sensor 510 while also optically coupling fixation target 591 to eyepiece lens assembly 535 and directing display light 590 output from display 525 to eye. Beam splitter 550 may be implemented as a polarized beam splitter, a non-polarized beam splitter (e.g., 90% transmissive and 10% reflective. 50 / 50 beam splitter, etc.), a dichroic beam splitter, or otherwise. The optical relay system includes a number of lenses, such as lenses 535.540, and 545, to focus the various light paths as needed. For example, lens 535 may include one or more lensing elements that collectively form an eyepiece lens assembly 535 that is housed within a lens tube (not illustrated in FIGS. 5A and 5B, see FIG. IB). The eyepiece lens 535 is displaced from the cornea of eye by an eye relief during operation. Lens 540 may include one or more lens elements for bringing imagelight 585 to a focus on image sensor 510. Lens 545 may include one or more lens elements for focusing display light 590. It should be appreciated that optical relay system may be implemented with a number and variety of optical elements (e.g., refractive lenses, reflective surfaces, diffractive surfaces, etc.) and may vary from the configuration illustrated in FIGS. 5A and 5B.

[0055] In one embodiment, display light 590 output from display 525 represents a fixation target. The fixation target may be an image of a plus-sign, a bullseye, a cross, a target, or other shape (e g., see demonstrative fixation target images 591). The fixation target not only can aid with obtaining fine or precise alignment between eyepiece lens 535 and the eye by providing visual feedback to the patient, but also gives the patient a fixation target upon which to accommodate and stabilize their vision. Display 525 may be implemented with a variety of technologies including a liquid crystal display (LCD), light emitting diodes (LEDs), various illuminated shapes (e.g., an illuminated cross or concentric circles), or otherwise. Of course, the fixation target may be implemented in other manners than a virtual image on a display. For example, the fixation target may be a physical object (e.g., crosshairs, etc.).

[0056] The illustrated embodiment is shown to include a face rest 508. As discussed further herein, in an embodiment, the face rest 508 is shaped to steady a face of a user when the face is placed against the face rest 508.

[0057] As shown, the retinal imaging system 502 includes an alignment motor 546 configured to move the retinal image sensor 510 relative to the face rest 508. As also shown, the alignment motor 546 is operatively coupled to the controller 515. In operation, the controller 515 choreographs operation of the alignment motor 546 to move, with the alignment motor 546, the retinal image sensor 510 to align the retinal image sensor 510 with an eye of the subject; and obtain, with the retinal image sensor 510, an image of the eye. In an embodiment, such moving, with the alignment motor 546, the retinal image sensor 510 to align the retinal image sensor 510 with an eye of the subject through a lens tube (such as shown in FIG. IB). In an embodiment, the alignment motor 546 is coupled to and configured to move the optical relay components, such as components disposed in a lens tube (see FIG. 1C) to align the retinal image sensor 510 with an eye of the user.

[0058] Image sensor 510 may be implemented using a variety of imaging technologies, such as complementary metal-oxide-semiconductor (CMOS) image sensors, charged-coupled device (CCD) image sensors, or otherwise. In oneembodiment, image sensor 510 includes an onboard memory' buffer or attached memory to store / buffer retinal images.

[0059] Alignment tracking camera(s) 530 operate to track lateral and eye relief offset alignment (or misalignment) between retinal imaging system 502 and eye, and in particular, between eyepiece lens assembly 535 and eye. Alignment tracking camera 530 may operate using a variety of different techniques to track the relative position of eye to retinal imaging system 502 including pupil tracking, iris tracking, or otherwise. In the illustrated embodiment, alignment tracking camera 530 includes two cameras disposed on either side of eyepiece lens assembly 535 to enable triangulation and obtain X, Y, and Z position information about the pupil or iris. In one embodiment, alignment tracking camera 530 includes one or more infrared (IR) emitters to track e e via IR light while retinal images are acquired with visible spectrum light, and in some cases, with IR light as well.

[0060] Eye position, including lateral alignment and / or eye relief offset alignment, may be measured and tracked using retinal images acquired by image sensor 510 for precise alignment tracking, or separately / additionally, by alignment tracking camera(s) 530. Alignment tracking camera(s) 530 provide coarse alignment tracking via the pupil or iris. In the illustrated embodiment, alignment tracking camera(s) 530 are positioned externally to view eye from outside of eyepiece lens assembly 535. In other embodiments, alignment tracking camera(s) 530 may be optically coupled via the optical relay components to view and track eye through eyepiece lens assembly 535.

[0061] Controller 515 is coupled to image sensor 510, display 525, illuminator 505, alignment tracking camera 530, and visual guidance indicator 501 to choreograph their operation. Controller 515 may include software / firmware logic executing on a microcontroller, hardware logic (e.g., application specific integrated circuit, field programmable gate array, etc.), or a combination of software and hardware logic. Although FIG. 5 A illustrates controller 515 as a distinct functional element, the logical functions performed by controller 515 may be decentralized across a number of hardware elements. Controller 515 may further include input / output (I / O ports), communication systems, or otherwise. Controller 515 is coupled to user interface 521 to receive user input and provide user control over retinal imaging system 502. User interface 521 may include one or more buttons, dials, feedback displays, indicator lights, etc.

[0062] During operation, controller 515 operates illuminator 505 and retinal image sensor 510 to capture one or more retinal images. Illumination light 580 is directed through the pupil of eye to illuminate retina 575. The scattered reflections from retina 575 are directed back along the image path through aperture 555 to image sensor 510. When the eye is properly aligned within the eyebox of system 502, aperture 555 operates to block deleterious reflections and light scattering that would otherwise malign the retinal image while passing the image light itself. Prior to capturing the retinal image, controller 515 operates display 525 and alignment tracking camera(s) 530 to provide real-time visual feedback to eye to achieve coarse alignment, at which point the user can see the fixation target. Controller 515 further operates display 525 to output a fixation target image 591 to guide the patient's gaze into fine or precise alignment.

[0063] Once fine alignment is achieved, controller 515 deems the eye to be within the eyebox of retinal imaging system 502, and thus acquires a retinal image with image sensor 510.

[0064] In embodiments, operation can include moving, with the motor 546. the lens tube, thereby aligning the retinal image sensor 510 with the eye; and obtaining, with the retinal image sensor 510, a retinal image of the eye.

[0065] While operation of the alignment tracking cameras 530 and display 525 to provide real-time visual feedback can be used, such operation may be optional, such as where the user interface 521 is utilized to receive a user input of coarse alignment. Accordingly, in an embodiment, the user interface 521 is configured to receive input from a user and generate an alignment signal indicative of alignment of the face in the initial alignment zone. In operation, moving, with the motor 546. the lens tube, and obtaining, with the retinal image sensor, the retinal image based on receipt of the alignment signal.

[0066] In an aspect, the present disclosure provides methods of obtaining a retinal image of an eye with a retinal imaging system. In an embodiment, the retinal imaging system is according to any embodiment of the present disclosure. In an embodiment, the retinal imaging system is an example of a retinal imaging system as discussed herein with respect to FIGS. 1A-1C, 2A-2C, and 5 A and B, such as may include the partial assemblies discussed herein with respect to FIGS. 3A-3C or the alignment indicators of FIG. 4. In an embodiment, the methods comprise generating, with a user interface, an alignment signal based on a user input indicating that analignment indicator is visible through a slit of a light baffle of the retinal imaging system: moving, with a motor of the retinal imaging system, lens tube, thereby aligning a retinal image sensor with an eye of the user: and obtaining, with a retinal image sensor of the retinal imaging system, a retinal image of the eye. In an embodiment, the method comprises illuminating the alignment indicator, such as where the alignment indicator does not itself comprise a light source. In an embodiment, the illumination is switched off during fine alignment and retinal image capture to reduce distraction.

[0067] The order in which some or all of the process steps are described should not be deemed limiting. Rather, one of ordinary skill in the art having the benefit of the present disclosure will understand that some of the process steps may be executed in a variety of orders not illustrated, or even in parallel. Additionally, some of the blocks may be optional.

[0068] The processes explained above are described in terms of computer software and hardware. The techniques described may constitute machine-executable instructions embodied within a tangible or non-transitory machine (e.g.. computer) readable storage medium, that when executed by a machine will cause the machine to perform the operations described. Additionally, the processes may be embodied within hardware, such as an application specific integrated circuit ("ASIC") or otherwise.

[0069] A tangible machine-readable storage medium includes any mechanism that provides (i.e., stores) information in anon-transitory form accessible by a machine (e.g., a computer, network device, personal digital assistant, manufacturing tool, any device with a set of one or more processors, etc.). For example, a machine-readable storage medium includes recordable / non-recordable media (e.g., read only memory (ROM), random access memory (RAM), magnetic disk storage media, optical storage media, flash memory devices, etc.).

[0070] The above description of illustrated embodiments of the invention, including what is described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize.

[0071] These modifications can be made to the invention in light of the above detailed description. The terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification. Rather,the scope of the invention is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.

Claims

CLAIMSWhat is claimed is:

1. A retinal imaging system comprising:a lens tube;a face rest shaped to steady a face of a user when the face is placed against the face rest;a light baffle positioned to conceal internal components of the retinal imaging system, wherein the light baffle defines a slit; andan alignment indicator positioned to be visible through the slit when an eye of the user is within an initial alignment zone of the retinal imaging system.

2. The retinal imaging system of Claim 1, wherein the face rest defines a horizontal axis, and wherein the slit is parallel to the horizontal axis.

3. The retinal imaging system of Claim 1, wherein the slit is positioned to align with a line between two eyes of the user when the face is placed against the face rest.

4. The retinal imaging system of Claim 1, wherein the lens tube defines a lens tube primary' axis along a length of the lens tube, and wherein the slit defines a slit primary' axis.

5. The retinal imaging system of Claim 4, wherein the slit primary' axis passes through the lens tube primary' axis.

6. The retinal imaging system of Claim 4. wherein the slit primary’ axis does not pass through the lens tube primary axis.

7. The retinal imaging system of Claim 1, wherein the lens tube protrudes through the light baffle.

8. The retinal imaging system of Claim 7, wherein the lens tube passes through a portion of the light baffle comprising the slit.

9. The retinal imaging system of Claim 1. wherein all of the alignment indicator is positioned to be visible through the slit when the eye is within the initial alignment zone of the face rest.

10. The retinal imaging system of Claim 1, wherein the face rest defines a vertical axis, and wherein the alignment indicator comprises a first portion on a first side of the vertical axis and a second portion on a second side of the vertical axis.

11. The retinal imaging system of Claim 1, wherein the alignment indicator comprises a light source.

12. The retinal imaging system of Claim 1, wherein the retinal imaging system further comprises a light source positioned to emit light onto the alignment indicator.

13. The retinal imaging system of Claim 1, wherein the alignment indicator defines a shape comprising an order of rotational symmetry that is greater than 3.

14. The retinal imaging system of Claim 1. wherein the alignment indicator defines a shape selected from a regular polygon and a circle.

15. The retinal imaging system of Claim 1, wherein the face rest is shaped to encompass a portion of a face of the user comprising two eye sockets.

16. The retinal imaging system of Claim 1, wherein the face rest is configured to prevent light from outside of the face rest from entering the lens tube when the face is placed against the face rest.

17. The retinal imaging system of Claim 1, further comprising:a retinal image sensor optically coupled to the lens tube and positioned to acquire a retinal image of an eye through the lens tube; anda motor configured to move the lens tube to align with the eye.

18. The retinal imaging system of Claim 17, further comprising a controller operatively coupled to the retinal image sensor and the motor, the controller including logic that when executed by the controller causes the retinal imaging system to perform operations including:moving, with the motor, the lens tube, thereby aligning the retinal image sensor with the eye; andobtaining, with the retinal image sensor, a retinal image of the eye.

19. The retinal imaging system of Claim 18, further comprising a user interface configured to receive input from a user and generate an alignment signal indicative of alignment of the face in the initial alignment zone,wherein the controller is operably coupled to the user interface, the controller further comprising logic that that when executed by the controller causes the retinal imaging system to perform operations including:moving, with the motor, the lens tube, and obtaining, with the retinal image sensor, the retinal image based on receipt of the alignment signal.

20. A method of obtaining a retinal image of an eye with a retinal imaging system, the method comprising:generating, with a user interface, an alignment signal based on a user input indicating that an alignment indicator is visible through a slit of a light baffle of the retinal imaging system;moving, with a motor of the retinal imaging system, lens tube, thereby aligning a retinal image sensor with an eye of the user; andobtaining, with a retinal image sensor of the retinal imaging system, a retinal image of the eye.

21. The method of Claim 20, further comprising illuminating the alignment indicator.

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