Subject interface for retinal imaging system

Abstract

A subject interface including bellows for a retinal imaging system and a retinal imaging are described. In an embodiment, the subject interface comprises a headrest shaped to couple with a forehead of a subject, the headrest comprising a rim defining a headrest aperture; and a bellows comprising an outer circumference coupled to the rim; and an inner circumference defining a bellows aperture overlapping with the headrest aperture. In an embodiment, the bellows is configured to move the inner circumference relative to the outer circumference through deformation of the bellows. In an embodiment, the inner circumference is configured to move relative to the outer circumference to displace the bellows aperture primary axis relative to the headrest aperture primary axis. In an embodiment, the bellows defines one or more waves, shaped to unfold as the bellows aperture primary axis is displaced relative to the headrest primary axis.

Description

SUBJECT INTERFACE FOR RETINAL IMAGING SYSTEMCROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional Application No. 63 / 678,702, filed on August 2, 2024, the contents of which are incorporated herein by reference.TECHNICAL FIELD

[0002] This disclosure relates generally to a subject interface, and. in particular but not exclusively, relates to a subject interface 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. Bright illumination of the retina through the pupil improves image fidelity.

[0004] However, stray light from outside the retinal imaging system can deteriorate retinal images. Further, dust, dirt, and moisture within the retinal imaging system can degrade the retinal imaging system over time and degrade retinal imaging. Additionally, there is a need to protect the internal camera system from the entry of larger foreign objects or accidental contact with fingers, for example.BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Non-limiting and non-exhaustive embodiments of the claimed subj ect 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.

[0006] FIG. 1A is a perspective view of a subject interface according to an embodiment of the present disclosure.

[0007] FIG. IB is another perspective view of the subject interface of FIG. 1 A according to an embodiment of the present disclosure.

[0008] FIG. 1C is a top-down plan view of the subject interface of FIG. 1A according to an embodiment of the present disclosure.

[0009] FIG. ID is a side view of the subject interface of FIG. 1 A according to an embodiment of the present disclosure.

[0010] FIG. IE is a perspective view of the subject interface of FIG. 1A according to an embodiment of the present disclosure.

[0011] FIG. IF is a cross-section view of the subject interface of FIG. IA according to an embodiment of the present disclosure.

[0012] FIG. 1G is another cross-section view of the subject interface of FIG. 1A according to an embodiment of the present disclosure.

[0013] FIG. 1H is a front view of the subject interface of FIG. 1A according to an embodiment of the present disclosure.

[0014] FIG. II is an exploded view of the subject interface of FIG. 1A according to an embodiment of the present disclosure.

[0015] FIG. 2A is a perspective view of a retinal imaging system according to an embodiment of the present disclosure.

[0016] FIG. 2B is another perspective view of the retinal imaging system of FIG. 2A according to an embodiment of the present disclosure.

[0017] FIG. 2C is a top-down plan view of the retinal imaging system of FIG. 2A according to an embodiment of the present disclosure.

[0018] FIG. 2D is a side view of the retinal imaging system of FIG. 2A according to an embodiment of the present disclosure.

[0019] FIG. 2E is a side view of the retinal imaging system of FIG. 2A according to an embodiment of the present disclosure.

[0020] FIG. 3 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.

[0021] FIG. 3B is another functional component diagram of the retinal imaging system of FIG. 3A. in accordance with an embodiment of the disclosure.DETAILED DESCRIPTION

[0022] Embodiments of subject interface including bellows for a retinal imaging system and a retinal imaging are described herein. In the following description numerous specific details are set forth to provide a thorough understandingof 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 show n or described in detail to avoid obscuring certain aspects.

[0023] 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.

[0024] In an aspect the present disclosure provides a subject interface for a retinal imaging system. As described in greater detail herein, in an embodiment, the subject interface comprises a bellows, such as to provide a seal between a head rest and internal components of the retinal imaging system and to allow imaging components of the retinal imaging system to align with an eye of a subject.

[0025] Most bellows designs are suitable for one primary linear axis of travel with minimal ability to tolerate large displacements in additional linear axes of travel. As described further herein, alignment of a retinal image sensor with an eye of a subj ect can include aligning the retinal image sensor along multiple orthogonal axes. Accordingly, aligning a retinal image sensor with an eye of a subject using most bellows designs w ould place portions of the bellows under tension. Over time and with use, such tension can tend to degrade the integrity of the bellows and create tears or holes, which would allow stray light, dust, dirt, and moisture into internal portions of the retinal imaging system. As discussed further herein, such stray light, dust, dirt, and moisture can tend to degrade retinal image quality and retinal imaging system components. Additionally, the tension places a large amount of force on the moving lens assembly which the motors and gantry system must overcome.

[0026] When trying to prevent ingress of dirt, dust, or splashes of moisture a good seal and non-porous material is important to preventing very' deformable materials such as a cloth from being suitable in many cases, recommending a molded shape that is tolerant of significant deformation in multiple axes, as described further herein.

[0027] To address these and related challenges, the present disclosure provides a subject interface including a bellows allowing travel along multiple axes for alignment of an eye with a retinal image sensor, such as without placing the bellows under tension. In this regard, the subject interface 100 of FIGS. 1A-1I will now be discussed. FIG. 1A is a perspective view of a subject interface 100 according to an embodiment of the present disclosure. FIG. IB is another perspective view of the subject interface 100. FIG. 1C is a top-down plan view of the subject interface 100. FIG. ID is a side view of the subject interface 100. FIG. IE is a perspective view of the subject interface 100. FIG. IF is a cross-section view of the subject interface 100. FIG. 1G is another cross-section view of the subject interface 100. FIG. 1H is a front view of the subject interface 100. FIG. II is an exploded view of the subject interface 100 of FIG. 1A according to an embodiment of the present disclosure.

[0028] As shown, the subject interface 100 includes head rest and a bellows 112 coupled to the headrest 104. The headrest 104 is generally shaped to accommodate the face of a subject or portions thereof to allow imaging of one or more eyes of the subj ect. In this regard, in an embodiment, the headrest 104 shaped to couple with a forehead of a subject. In particular, as illustrated, the headrest 104 is shaped to couple with a portion of the face of the subject encompassing both eye sockets. By encompassing, encircling, or otherwise enclosing the eye sockets of the subject, the headrest 104 can both accommodate or couple to the face of the subject, but also block stray light when the face of the subject is coupled to the headrest 104.

[0029] As shown, the headrest 104 comprises a rim 108 defining a headrest aperture 110. As discussed further herein, in an embodiment, the headrest aperture 110 is shaped or otherwise configured to allow imaging of eyes of a subject when the face of the subject is placed against the head rest. As also shown, the headrest 104 comprises a bracket 156 shaped to couple with a retinal imaging system. See, for example, FIGS. 2A-2E.

[0030] In the illustrated embodiment, the bellows 112 comprises an outer circumference 114 coupled to the rim 108; and an inner circumference 1 16 defining a bel lows aperture 118 overlapping with the headrest aperture 110. As discussed further herein, the bellows 112 is configured to move the inner circumference 116 relative to the outer circumference 114 through deformation of the bellow s 112.

[0031] In an embodiment, the headrest 104 defines a curvature 132 shaped to couple to the forehead of the subject. As discussed further herein, in an embodiment,the subject interface 100 is shaped or otherwise suitable to image both eyes of a subject. In this regard, by coupling, such as at an outer circumference, the forehead of the subject, both eye sockets are viewable through the headrest 104. Accordingly, in an embodiment, the outer circumference 114 defines an ovoid shape 136, wherein apexes 138 of the outer circumference 114 extend farther away from a portion of the headrest 104 shaped to couple with a center of the forehead when the headrest 104 is coupled to the forehead.

[0032] As discussed further herein, the subject interface 100 is shaped to allow imaging of the eyes of a subject, such as through the bellows aperture 118 and the headrest aperture 110 when the face of the subject is placed against the head rest. Such imaging can occur through a bellows aperture primary axis 122. Furthermore, the bellows 112 is configured to allow translation of the inner circumference 116, such as where the inner circumference 116 is coupled to an eyepiece lens assembly, to align the eyepiece lens assembly with an eye of the subject. In this regard, the inner circumference 116 is configured to move relative to the outer circumference 114 to displace the bellows aperture primary axis 122 relative to a headrest aperture primary axis 120.

[0033] As shown, the inner circumference 116 is shown to define a circular circumference. In an embodiment, the bellows aperture 118 is disposed as a center of the circle. As shown and as discussed further herein, in an embodiment, the rim 108 defines an ovoid shape 136 or an ellipse. In an embodiment, the headrest aperture primary axis 120 is disposed at a center of the oval or ellipse.

[0034] As discussed further herein with respect to the retinal imaging system 202 of FIGS. 2A-2E, the bellows 112 is configured to deform, such as deform elastically or through folding or flexing, as the inner circumference 116 moves relative to the out circumference in aligning the eyepiece lens assembly with an eye of the subject. Through such translation of the inner circumference 116 of the bellows 112 and deformation thereof, the bellows 112 generally do not deform plastically in moving the inner circumference 116 relative to the outer circumference 114 in aligning optical components with an eye of the subject. In such embodiments, the bellow-s 112 are not under tension as the inner circumference 116, such as the bellows aperture primary axis 122, is aligned with the eye. By avoiding tension in the bellows 112, tears or other damage to the bellows 112 can be reduced, as well as the force on the associated gantry system and motors.

[0035] In an embodiment and as shown, the bellow s 112 defines one or more waves 124, shaped to unfold as the bellows aperture primary- axis 122 is displaced relative to the headrest primary axis. In this regard, the one or more w aves 124 provide additional material that can unfold, thereby avoiding tension in the bellows 112 material. In this regard, and as discussed further herein with respect to FIGS. 3A and 3B, in an embodiment, a line length 152 of the bellows 112 between the outer circumference 114 and the inner circumference 116 is at least equal to a distance between the headrest aperture primary- axis 120 and the bellows aperture primary axis 122 when the bellows aperture primary axis 122 is aligned with an eye.

[0036] As shown, the bellows 112 or a portion thereof defines a cross section of a torus taken orthogonally to the bellows aperture primary axis 122. Such a toroidal portion can allow- translation of the inner circumference 116 relative to the outer circumference 114 in several directions, including along the bellows aperture primaryaxis 122 and in directions orthogonal to the bellows aperture primary- axis 122. Additionally, as above, the bellows 112 can comprise the one or more waves 124, which are shown here as generally sinusoidal waves 124 in the toroidal portion of the bellows 112. While generally sinusoidal waves 124 are shown, it will be understood that other shapes allowing unfolding are possible and within the scope of the present disclosure.

[0037] Such one or more waves 124 are distinct from an accordion-style bellows configured to compress or collapse along a primary axis of the bellows. Likew ise, such compression or collapsing is distinct from unfolding or unfurling of the one or more waves 124 as discussed here, which occurs as the inner circumference 116 moves relative to the outer circumference 114, whether along the bellows aperture primary axis 122 or orthogonal to the bellows aperture primary axis 122.

[0038] The bellow s 112 can comprise a flexible membrane, elastomer, or other flexible material suitable to unfold as described herein. In an embodiment, the bellow s 112 material is opaque to light, such as to block stray light from entering a retinal imaging system attached thereto. In an embodiment, the bellows 112 material is waterproof or w ater-resistant, such as to prevent ingress of moisture into the retinal imaging system and to allow- w-ashing of the bellow s 112 material. In an embodiment, the bellows 112 material is an elastomeric material such as silicone rubber and has a Shore A durometer in a range of about 30A to about 40A. In an embodiment, the bellow s 112 material has a thickness of about 1.0 mm to about 1.5 mm.

[0039] In another aspect, the present disclosure provides a retinal imaging system for imaging a retina of a subject. In this regard, attention is directed to FIGURES 2A-2E in which a retinal imaging system 202 according to an embodiment of the present disclosure is illustrated. FIG. 2A is a perspective view of the retinal imaging system 202. FIG. 2B is another perspective view of the retinal imaging system 202. FIG. 2C is a top-down plan view of the retinal imaging system 202. FIG. 2D is a side view of the retinal imaging system 202. FIG. 2E is a side view of the retinal imaging system 202. As shown, a top of the retinal imaging system 202 is shown removed to illustrate internal components of the retinal imaging system 202, such as components disposed within the box 258.

[0040] In the illustrated embodiment, the retinal imaging system 202 is shown to include an eyepiece lens assembly 228, a subject interface 200, and a retinal image sensor 242. In an embodiment, the subject interface 200 is a subject interface according to any embodiment of the present disclosure. In an embodiment, the subject interface 200 is an example of subject interface 100 discussed further herein with respect to FIGS. 1A-1I. In this regard, in an embodiment, the subject interface 200 comprises a headrest 204 shaped to couple with a forehead of a subject, the headrest 204 comprising a rim 208 defining a headrest aperture; and a bellows 212 comprising an outer circumference coupled to the rim 208; and an inner circumference defining a bellows aperture (such as bellow aperture 118) overlapping with the headrest aperture (such as headrest aperture 110), wherein the bellows 212 is configured to move the inner circumference (such as inner circumference 116) relative to the outer circumference (such as outer circumference 114) through deformation of the bellow s 212. See, for example, FIGS. 1A-1I.

[0041] The headrest 204 is shown to include a bracket 256 configured to couple the headrest 204 to the box 258.

[0042] Referring again to FIGS. 2A-2C, the retinal imaging system 202 is shown to include a retinal image sensor 242 optically coupled to the eyepiece lens assembly 228 positioned to acquire a retinal image of an eye through the eyepiece lens assembly 228 and the subject interface 200. As shown, the retinal image sensor 242 is positioned to receive light from the eyepiece lens assembly 228, such as may be reflected by a retina of an eye of a user, where the face of the user is placed against the subject interface 200.

[0043] As shown, the bellows 212 are coupled to a rim 208 of the headrest 204. Further, on an opposing end, such as through an inner circumference, the bellows 212 is shown coupled to the eyepiece lens assembly 228. In this regard, the subject interface 200 limits stray light, dust, dirt, and moisture from entering an inner portion of the retinal imaging system 202, such as defined in part by the box 258. As discussed further herein, by limiting stray light from entering the box 258, retinal image quality can be improved. Further, by limiting ingress of dust, dirt, and moisture into the box 258, internal components, particularly moving or otherwise sensitive parts, are protected and their usable life can be extended.

[0044] In an embodiment, the bellows 212 comprises an optically opaque material. In an embodiment, the bellows 212 comprises a water-resistant or waterproof material, and may be wiped or otherwise cleaned, such as before or after use by a subject.

[0045] In the illustrated embodiment, the retinal imaging system 202 is shown to include an alignment motor 246 configured to move the retinal image sensor 242 relative to the headrest 204. As shown, the retinal imaging system 202 includes comprising a controller 248 operatively coupled to the retinal image sensor 242 and the alignment motor 246. In an embodiment, the controller 248 comprises logic that, when executed by the controller 248, causes the retinal imaging system 202 to perform operations. In an embodiment, such operations comprise moving, with the alignment motor 246, the retinal image sensor 242 to align the retinal image sensor 242 with an eye of the subject; and obtaining, with the retinal image sensor 242, an image of the eye.

[0046] In an embodiment, moving, with the alignment motor 246, the retinal image sensor 242 to align the retinal image sensor 242 with an eye of the subject causes the bellow s 212 to deform elastically, such as where moving, w ith the alignment motor 246, the retinal image sensor 242 to align the retinal image sensor 242 with an eye of the subject does not plastically deform the bellows 212. As discussed further herein, by deforming elastically the bellows 212, such as without plastically deforming the bellow-s 212, such deformation avoids stressing bellows 212 material, which can cause tears or other breaks in the bellow s 212. Such breaks would allow ingress of light, dust, dirt, and moisture into the retinal imaging system 202.

[0047] As discussed further herein with respect to FIGS. 1A-1I. in an embodiment, the bellows aperture defines a bellows aperture primary axis. In anembodiment, moving, with the alignment motor 246, the retinal image sensor 242 to align the retinal image sensor 242 with the eye of the subject comprises one or more of moving the retinal image sensor 242 along the bellows aperture primary axis, and moving the retinal image sensor 242 orthogonally to the bellows aperture primary axis. In this regard, the retinal image sensor 242 can be moved to place a focal point of the retinal imaging system 202 within an eyebox of the subject including a retinal of the eye. The bellows 212 are configured to unfold, such as by unfolding one or more waves 224 of the bellows 212, to accommodate the movement of the movement of the retinal image sensor 242 along or orthogonally to the bellows aperture primary' axis.

[0048] FIGS. 3A and 3B are functional component diagrams illustrating a retinal imaging system 302 with a subject interface 300, in accordance with an embodiment of the disclosure. The illustrated embodiment of retinal imaging system 302 includes the subject interface 300, an illuminator 305, an image sensor 310 (also referred to as a retinal image sensor), a controller 315, a user interface 321, a display 325. alignment tracking camera(s) 830. and an optical relay system. The illustrated embodiment of the optical relay system includes lens assemblies 335, 340. 345 and a beam splitter 350. The illustrated embodiment of illuminator 305 comprises illuminator arrays 365 and a center aperture 355.

[0049] The optical relay system serves to direct (e.g., pass or reflect) illumination light 380 output from illuminator 305 along an illumination path through the pupil of eye 344 to illuminate retina while also directing image light 385 of retina (i.e., the retinal image) along an imaging path to image sensor 310. Image light 385 is formed by the scattered reflection of illumination light 380 off the retina. In the illustrated embodiment, the optical relay system further includes beam splitter 350, which passes at least a portion of image light 385 to image sensor 310 while also optically coupling fixation target 391 to eyepiece lens assembly 335 and directing display light 390 output from display 325 to eye 344. Beam splitter 350 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 335, 340, and 345, to focus the various light paths as needed. For example, lens 335 may include one or more lensing elements that collectively form an eyepiece lens assembly 335 that is housed within a lens tube (not illustrated in FIGS. 3A and 3B). The eyepiece lens 335 is displaced from the cornea of eye 344 by an eye relief 395during operation. Lens 340 may include one or more lens elements for bringing image light 385 to a focus on image sensor 310. Lens 345 may include one or more lens elements for focusing display light 390. 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. 3 A and 3B.

[0050] In one embodiment, display light 390 output from display 325 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 391). The fixation target not only can aid with obtaining fine or precise alignment between eyepiece lens 335 and eye 344 by providing visual feedback to the patient, but also gives the patient a fixation target upon which to accommodate and stabilize their vision. Display 325 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 ).

[0051] The illustrated embodiment is shown to include a subject interface 300 comprising a headrest 304 shaped to couple with a forehead of a subject, the headrest 304 comprising a rim 308 defining a headrest aperture 311; and a bellows 312 coupled to the headrest 304, the bellows 312 comprising an outer circumference 314 coupled to the rim 308; and an inner circumference 316 coupled to the eyepiece lens assembly 335. As discussed further herein with respect, for example, to FIGS. 1A-1I, the bellows 312 is configured to move the inner circumference 316 relative to the outer circumference 314 through deformation of the bellows 312.

[0052] As shown, the retinal imaging system 302 is shown to include an alignment motor 346 configured to move the retinal image sensor 310 relative to the headrest 304. As also shown, the alignment motor 346 is operatively coupled to the controller 315. In operation, the controller 315 choreographs operation of the alignment motor 346 to move, with the alignment motor 346, the retinal image sensor 310 to align the retinal image sensor 310 with an eye 344 of the subject; and obtain, with the retinal image sensor 310, an image of the eye 344. In an embodiment such moving, with the alignment motor 346, the retinal image sensor 310 to align the retinal image sensor 310 with an eye 344 of the subject causes the bellows 312 todeform elastically, such as without plastically deforming the bellows 312. As shown, one or more waves 324 defined by the bellows 312 deforms or otherwise unfolds on a side to allow movement of the retinal image sensor 310 relative to the subject interface 300 without plastic deformation.

[0053] In the illustrated embodiment, the headrest aperture 311 defines a headrest aperture primary axis 320, and the bellows aperture 318 defines a bellows aperture primary axis 322. In an embodiment, a line length 352 of the bellows 312 between the outer circumference 314 and the inner circumference 316 is at least equal to a distance 354 between the headrest aperture primary axis 320 and the bellows aperture primary axis 322 when the bellows aperture primary' axis 322 is aligned with the eye 344. Because the line length 352 is at least equal to the distance 354 between the headrest aperture primary axis 320 and the bellows aperture primary' axis 322 when the bellows aperture primary axis 322 is aligned with the eye 344, the bellows 312 can unfold, such as unfold the one or more waves 324 without placing the bellows 312 under tension. In an embodiment, the line length 352 is at least 5% greater. 10% greater, 15% greater, 20% greater than the distance 354 between the headrest aperture primary axis 320 and the bellows aperture primary axis 322 when the bellows aperture primary' axis 322 is aligned with the eye 344.

[0054] As shown, the headrest 304 is shaped to couple with a portion of the face of the subject encompassing both eye sockets 331. Additionally, the headrest 304 defines a curvature 332 shaped to couple to the forehead 334 of the subject. In an embodiment, the outer circumference 314 defines an ovoid shape (see FIG. II), wherein apexes of the outer circumference 314 extend farther away from a portion of the headrest 304 shaped to couple with a center of the forehead 334 when the headrest 304 is coupled to the forehead 334.

[0055] In this regard, the headrest 304 is shaped to allow imaging of both eyes 344 and 351, while forming a light-tight seal between the headrest 304 and the face of the user. Accordingly, in an embodiment, the controller 315 further comprises logic that, when executed by the controller 315. causes the retinal imaging system 302 to perform operations comprising moving, with the alignment motor 346, the headrest 304 to align a second eye 351 of the subject with the eyepiece lens assembly 335; and obtaining, with the retinal image sensor 310, an image of the second eye 351, as illustrated in FIG. 3B.

[0056] In the illustrated embodiment, the subject interface 300 is shown to accommodate alignment tracking cameras 330.

[0057] Image sensor 310 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 one embodiment, image sensor 310 includes an onboard memory’ buffer or attached memory to store / buffer retinal images.

[0058] Alignment tracking camera(s) 330 operate to track lateral and eye relief offset alignment (or misalignment) between retinal imaging system 302 and eye 344, and in particular, between eyepiece lens assembly 335 and eye 344. Alignment tracking camera 330 may operate using a variety of different techniques to track the relative position of eye 344 to retinal imaging system 302 including pupil tracking, iris tracking, or otherwise. In the illustrated embodiment, alignment tracking camera 330 includes tw o cameras disposed on either side of eyepiece lens assembly 335 to enable triangulation and obtain X, Y, and Z position information about the pupil or iris. In one embodiment, alignment tracking camera 330 includes one or more infrared (IR) emitters to track eye 344 via IR light while retinal images are acquired with visible spectrum light, and in some cases, w ith IR light as well.

[0059] Eye position, including lateral alignment and / or eye relief offset alignment, may be measured and tracked using retinal images acquired by image sensor 310 for precise alignment tracking, or separately / additionally, by alignment tracking camera(s) 330. Alignment tracking camera(s) 330 provide coarse alignment tracking via the pupil or iris. In the illustrated embodiment, alignment tracking camera(s) 330 are positioned externally to view eye 344 from outside of eyepiece lens assembly 335. In other embodiments, alignment tracking camera(s) 330 may be optically coupled via the optical relay components to view’ and track eye 344 through eyepiece lens assembly 335.

[0060] Controller 315 is coupled to image sensor 310, display 325, illuminator 305. alignment tracking camera 330, and visual guidance indicator 301 to choreograph their operation. Controller 315 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. 3 A illustrates controller 315 as a distinct functional element, the logical functions performed by controller 315 may be decentralized acrossa number hardware elements. Controller 315 may further include input / output (I / O ports), communication systems, or otherwise. Controller 315 is coupled to user interface 321 to receive user input and provide user control over retinal imaging system 302. User interface 321 may include one or more buttons, dials, feedback displays, indicator lights, etc.

[0061] During operation, controller 315 operates illuminator 305 and retinal image sensor 310 to capture one or more retinal images. Illumination light 380 is directed through the pupil of eye 344 to illuminate retina 375. The scattered reflections from retina 375 are directed back along the image path through aperture 355 to image sensor 310. When eye 344 is properly aligned within the eyebox of system 302, aperture 355 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 315 operates visual guidance indicator 301 and alignment tracking camera(s) 330 to provide real-time visual feedback to eye 344 to achieve coarse alignment, at which point the user can see the fixation target. Controller 315 further operates display 325 to output a fixation target image 391 to guide the patient's gaze into fine or precise alignment. Once fine alignment is achieved, controller 315 deems eye 344 to be within the eyebox of retinal imaging system 302, and thus acquires a retinal image with image sensor 310.

[0062] 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.

[0063] 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 ).

[0064] The above description of illustrated embodiments of the invention, including what is described in the Abstract, is not intended to be exhaustive or to limitthe 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.

[0065] 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 subject interface for a retinal imaging system, the subject interface comprising: a headrest shaped to couple with a forehead of a subject, the headrest comprising a rim defining a headrest aperture; and a bellows comprising: an outer circumference coupled to the rim; and an inner circumference defining a bellows aperture overlapping with the headrest aperture, wherein the bellows is configured to move the inner circumference relative to the outer circumference through deformation of the bellows.

2. The subject interface of Claim 1, wherein the headrest aperture defines a headrest aperture primary axis, wherein the bellows aperture defines a bellows aperture primary axis.

3. The subject interface of Claim 2. wherein the inner circumference is configured to move relative to the outer circumference to displace the bellows aperture primary axis relative to the headrest aperture primary axis.

4. The subject interface of Claim 2, wherein the bellows defines one or more waves, shaped to unfold as the bellows aperture primary axis is displaced relative to the headrest primary axis.

5. The subject interface of Claim 2, wherein the bellows defines a cross section of a torus taken orthogonally to the bellows aperture primary axis.

6. The subject interface of Claim 1, wherein the inner circumference is shaped to couple with an eyepiece lens assembly of the retinal imaging system.

7. The subject interface of Claim 1, wherein the headrest is shaped to couple with a portion of the face of the subject encompassing both eye sockets.

8. The subject interface of Claim 1, the headrest defines a curvature shaped to couple to the forehead of the subject.

9. The subject interface of Claim 1, wherein the outer circumference defines an ovoid shape, wherein apexes of the outer circumference extend farther away from a portion of the headrest shaped to couple with a center of the forehead when the headrest is coupled to the forehead.

10. A retinal imaging system comprising: an eyepiece lens assembly; subject interface comprising: a headrest shaped to couple with a forehead of a subject, the headrest comprising a rim defining a headrest aperture; and a bellows coupled to the headrest, the bellows comprising: an outer circumference coupled to the rim; and an inner circumference coupled to the eyepiece lens assembly, the inner circumference defining a bellows aperture overlapping with the headrest aperture. wherein the bellows is configured to move the inner circumference relative to the outer circumference through deformation of the bellows, and a retinal image sensor optically coupled to the eyepiece lens assembly positioned to acquire a retinal image of an eye through the eyepiece lens assembly and the subject interface.

11. The retinal imaging system of Claim 10, further comprising an alignment motor configured to move the retinal image sensor relative to the headrest.

12. The retinal imaging system of Claim 11 , further comprising a controller operatively coupled to the retinal image sensor and the alignment motor, the controller comprising logic that, when executed by the controller, causes the retinal imaging system to perform operations comprising: moving, with the alignment motor, the retinal image sensor to align the retinal image sensor with an eye of the subject; and obtaining, with the retinal image sensor, an image of the eye.

13. The retinal imaging system of Claim 12, wherein moving, with the alignment motor, the retinal image sensor to align the retinal image sensor with an eye of the subject causes the bellows to deform elastically.

14. The retinal imaging system of Claim 12, wherein moving, with the alignment motor, the retinal image sensor to align the retinal image sensor with an eye of the subject does not plastically deform the bellows.

15. The retinal imaging system of Claim 12, wherein the headrest aperture defines a headrest aperture primary axis, wherein the bellows aperture defines a bellows aperture primary axis, wherein a line length of the bellows between the outer circumference and the inner circumference is at least equal to a distance between the headrest aperture primary axis and the bellows aperture primary axis when the bellows aperture primary axis is aligned with the eye.

16. The retinal imaging system of Claim 12, wherein the bellows aperture defines a bellows aperture primary axis, and wherein moving, with the alignment motor, the retinal image sensor to align the retinal image sensor with the eye of the subject comprises one or more of: moving the retinal image sensor along the bellows aperture primary axis, and moving the retinal image sensor orthogonally to the bellows aperture primary axis.

17. The retinal imaging system of Claim 12, wherein the controller further comprises logic that, when executed by the controller, causes the retinal imaging system to perform operations comprising: moving, with the alignment motor, the headrest to align a second eye of the subject with the eyepiece lens assembly; and obtaining, with the retinal image sensor, an image of the second eye.

18. The retinal imaging system of Claim 10, wherein the bellows defines one or more waves, shaped to unfold as the bellows aperture primary axis is displaced relative to the headrest primary axis.

19. The retinal imaging system of Claim 10. wherein the headrest is shaped to couple with a portion of the face of the subject encompassing both eye sockets.

20. The retinal imaging system of Claim 10, the headrest defines a curvature shaped to couple to the forehead of the subject.

21. The retinal imaging system of Claim 10, wherein the outer circumference defines an ovoid shape, wherein apexes of the outer circumference extend farther away from a portion of the headrest shaped to couple with a center of the forehead when the headrest is coupled to the forehead.

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