Control of a height-adjustable patient interface for an ophthalmic imaging device

Abstract

To provide a height-adjustable patient interface.SOLUTION: A control system 130 comprises: at least one camera 132 arranged to acquire one or more images 138 of at least a portion of a head 103 of a subject 102; and a processor 134. The processor is arranged to: process the one or more images to generate a value of a first indicator which is indicative of a height at which the at least a portion of the head is disposed; use at least one mapping M to map the value of the first indicator to a value of a second indicator which is indicative of a target height; and generate a control signal for adjusting a height at which a height-adjustable contact surface of an ophthalmic imaging device is disposed to the target height at which the contact surface is to contact the head of the subject during imaging of the eye of the subject by the ophthalmic imaging device.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] Exemplary aspects of the present specification relate generally to the field of ophthalmic imaging devices, and more particularly to mechanisms for adjusting the height of a patient interface of an ophthalmic imaging device, such as a chin rest, head rest, eyecup(s), or the like, against which the patient's head contacts to stabilize the head during imaging. [Background technology]

[0002] Ophthalmic imaging devices use various imaging techniques to image different parts of the eye and are used by clinicians to diagnose and manage various ocular conditions. Ophthalmic imaging devices include (but are not limited to) (among others) scanning laser ophthalmoscopes (SLOs), optical coherence tomography (OCT) imaging devices, fundus cameras, microperimetry devices, and corneal topography devices, or a combination of two or more such devices. Ophthalmic imaging devices typically include a height-adjustable patient interface (also called a face interface), such as a chin rest, head rest, or eyecup, having a contact surface that the patient's head contacts during imaging of the patient's eye. Such a contact surface allows the eye to be positioned approximately correctly relative to the ophthalmic imaging device and helps keep the patient's head stable during imaging, thereby reducing artifacts in the acquired images caused by movement of the patient's head relative to the device.

[0003] Because patients imaged with an ophthalmic imaging device typically have a range of different heights, the height of the patient interface is typically adjusted to suit each patient being imaged. Adjusting the patient interface to a height appropriate for the patient is particularly important for ophthalmic imaging devices, such as microperimeter and optical coherence tomography (OC) imaging devices, which require relatively long imaging sessions that can last from tens of seconds to minutes (depending on the device) (eye movement during imaging can result in motion artifacts in the acquired eye images). If the patient interface is not set at a height comfortable for the patient, the patient will be more likely to move during imaging, thereby exacerbating the problem of imaging artifacts in the acquired images. This tends to be particularly problematic for elderly patients, who typically have a relatively limited range of body positions they can comfortably maintain for the duration of an imaging session. If an elderly patient is set in an uncomfortable position, the patient may not be able to properly engage with the patient interface, and an image of the eye may not even be captured at all.

[0004] Adjusting the height of an ophthalmic imaging device's patient interface (so-called "macroalignment") is typically performed manually by an operator who monitors the patient's eye line while adjusting the height of the patient interface using a mechanical or electromechanical mechanism to approximate eye level. This is typically a time-consuming process that the operator must repeat for every patient they need to treat. This adjustment can be particularly time-consuming and difficult to perform accurately for operators with limited skill and / or experience. Once macroalignment is complete and the patient is engaged with the patient interface, the ophthalmic imaging device can perform an automated microalignment process to align its scan head with the patient's eye. Summary of the Invention

[0005] According to a first exemplary aspect of the present disclosure, there is provided a control system configured to generate a control signal for adjusting a height at which a height-adjustable contact surface of an ophthalmic imaging device is positioned to a target height at which the contact surface should contact the patient's head during imaging of the patient's eye with the ophthalmic imaging device. The control system includes at least one camera configured to acquire one or more images of at least a portion of the patient's head when the patient is positioned next to the ophthalmic imaging device to bring the head into contact with the contact surface when the contact surface is at the target height, and a processor. The control system further includes a processor configured to process the one or more images to generate a value of a first indicator indicative of a height at which at least a portion of the head was positioned when the one or more images were acquired, map the value of the first indicator to a value of a second indicator indicative of a target height at which the contact surface should contact the head during imaging using at least one mapping, and generate a control signal for adjusting the height at which the contact surface is positioned to the target height indicated by the value of the second indicator.

[0006] In an exemplary embodiment, the height of the contact surface is adjustable by a user of the control system, and the control system further comprises a user interface for providing instructions to the user for adjusting the height of the contact surface. The user interface may comprise, for example, at least one of a display for providing visual instructions to the user for adjusting the height of the contact surface and a speaker for providing audio instructions to the user for adjusting the height of the contact surface. In an exemplary embodiment, the processor is configured to control the user interface using the generated control signal to provide instructions to the user for adjusting the height of the contact surface to a target height.

[0007] In another exemplary embodiment, the height of the contact surface of the ophthalmic imaging device is automatically adjustable by a height adjustment mechanism, and the generated control signal is configured to cause the height adjustment mechanism to automatically adjust the height of the contact surface to a target height.

[0008] In any of the above exemplary embodiments, the value of the first indicator may indicate a height at which the patient's eye was positioned when the one or more images were acquired, and the at least one mapping may map each value of the first indicator to a corresponding value of the second indicator such that the height of the imaging axis of the ophthalmic imaging device when the contact surface is positioned at the target height indicated by the value of the second indicator is less than the height indicated by the value of the first indicator. The at least one mapping may be dependent on the patient's age such that, for each value of the first indicator, the respective target height indicated by the corresponding value of the second indicator increases as the patient's age increases, and the processor may be further configured to receive an indication of the patient's age and map the value of the first indicator to the value of the second indicator using the received indication of age and the at least one mapping. Additionally or alternatively, the at least one mapping may depend on the patient's distance from the contact surface when the patient is in a position next to the ophthalmic imaging device, such that for each value of the first indicator, a distinct target height indicated by a corresponding value of the second indicator decreases as the patient's distance from the contact surface increases, and the processor may be further configured to obtain an indication of the patient's distance and map the value of the first indicator to a value of the second indicator using the obtained indication of distance and the at least one mapping. The processor may be configured to obtain the indication of distance by processing at least some of the one or more images obtained by the at least one camera. Alternatively, the control system may further include a distance sensor configured to measure the patient's distance from the contact surface when the patient is in a position next to the ophthalmic imaging device, and the processor may be configured to obtain the indication of distance by receiving the measured distance from the distance sensor.

[0009] In an exemplary embodiment, where the value of the first indicator indicates a height at which the patient's eye was positioned when the one or more images were acquired, and at least one mapping maps each value of the first indicator to a corresponding value of the second indicator such that the height of the imaging axis of the ophthalmic imaging device when the contact surface is positioned at the target height indicated by the value of the second indicator is less than the height indicated by the value of the first indicator, the at least one camera may be configured to acquire one or more images while the patient is sitting in a seated position on a seat next to the ophthalmic imaging device, and the at least one mapping may be dependent on the seat height such that for each value of the first indicator, the individual target height indicated by the corresponding value of the second indicator increases as the seat height increases, and the processor may be further configured to acquire an indication of the seat height and map the value of the first indicator to a value of the second indicator using the acquired indication of the seat height and the at least one mapping.

[0010] In a first exemplary aspect of any of the exemplary embodiments or variations thereof described above, the contact surface may be movable laterally toward the patient's head, and the control system may be further configured to generate a second control signal for moving the contact surface along the lateral axis to a target lateral position where the contact surface should contact the patient's head during imaging of the patient's eye by the ophthalmic imaging device, and the processor may be further configured to process one or more images to generate a third indicator value indicative of a separation along the lateral axis between the contact surface and a first lateral position where at least a portion of the patient's head is located when the patient is sitting in a seated position on a seat next to the ophthalmic imaging device, map the value of the third indicator using at least one second mapping to a fourth indicator value indicative of the target lateral position where the contact surface should contact the patient's head during imaging of the patient's eye by the ophthalmic imaging device, and generate a second control signal for moving the contact surface to the target lateral position indicated by the value of the fourth indicator. Alternatively, the contact surface may be movable laterally toward the patient's head, and the control system may be further configured to generate a second control signal for moving the contact surface along the lateral axis to a target lateral position where the contact surface should contact the patient's head during imaging of the patient's eye with the ophthalmic imaging device, and the control system may further include a distance sensor configured to generate a value of a third indicator indicative of a separation along the lateral axis between the contact surface and a first lateral position where at least a portion of the patient's head is located when the patient is sitting in a seated position on a seat next to the ophthalmic imaging device, and the processor may be further configured to map, using at least one second mapping, the value of the third indicator to a value of a fourth indicator indicative of the target lateral position where the contact surface should contact the patient's head during imaging of the patient's eye with the ophthalmic imaging device, and to generate a second control signal for moving the contact surface along the lateral axis to the target lateral position indicated by the value of the fourth indicator.In either case, the at least one second mapping may map values ​​of the third indicator to corresponding values ​​of the fourth indicator, and the at least one second mapping may be dependent on the patient's age such that for each value of the first indicator, the individual target lateral position indicated by the corresponding value of the fourth indicator approaches the first lateral position with increasing age, and the processor may be further configured to receive an indication of the patient's age and map values ​​of the third indicator to values ​​of the fourth indicator using the received indication of the patient's age and the at least one second mapping.

[0011] According to a second exemplary aspect of the present disclosure, there is provided a system for imaging a patient's eye. The system includes an ophthalmic imaging device configured to image the patient's eye, the ophthalmic imaging device including a height-adjustable contact surface configured to contact the patient's head during imaging of the eye. The system further includes a movement mechanism configured to adjust a height at which the height-adjustable contact surface is positioned to a target height at which the contact surface should contact the patient's head during imaging of the eye. The system further includes a control system according to the first exemplary aspect of the present disclosure, configured to generate a control signal for controlling the movement mechanism to adjust the height to the target height. The movement mechanism can include a height-adjustable table configured to support the ophthalmic imaging device.

[0012] The system may further include at least one sensor of the object, each sensor being one of a distance sensor configured to measure a distance to the object and a proximity sensor configured to detect the object when the object is within a detection range of the proximity sensor, and the at least one sensor and control system are configured to determine whether at least one of the height-adjustable table or the ophthalmic imaging device has been moved within a predetermined distance of the object, and in response to determining that at least one of the height-adjustable table or the ophthalmic imaging device has been moved within the predetermined distance of the object, generate a command to stop the height adjustment to the target height being made by the movement mechanism. Alternatively, the system may further include at least one distance sensor configured to measure a distance to the object, and the at least one distance sensor and control system are configured to determine whether at least one of the height-adjustable table or the ophthalmic imaging device should be moved within the predetermined distance of the object during adjustment of the height to the target height by the movement mechanism, and in response to determining that at least one of the height-adjustable table or the ophthalmic imaging device should be moved within the predetermined distance of the object during the adjustment, generate a warning to the user.

[0013] Additionally or alternatively, the system may further include at least one sensor of the object, each sensor being one of a distance sensor configured to measure the distance to the object and a proximity sensor configured to detect the object when the object is within the detection range of the proximity sensor, and the at least one sensor and control system configured to determine whether the patient is within a predetermined distance of the ophthalmic imaging device and, in response to determining that the patient is within the predetermined distance of the ophthalmic imaging device, control at least one camera of the control system to acquire one or more images.

[0014] Exemplary embodiments will now be described in detail, by way of non-limiting example only, with reference to the accompanying figures described below, in which like reference numbers appearing in different figures of the figures may indicate identical or functionally similar elements, unless otherwise indicated. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram of a system for imaging a patient's eye, according to an exemplary embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic diagram of a control system according to an exemplary embodiment of the present disclosure. [Figure 3A] FIG. 3A is a schematic illustration of a patient sitting next to a system for imaging the patient's eye before a chin rest of an ophthalmic imaging device is moved to a target position suitable for the patient, according to an exemplary embodiment of the present specification. [Figure 3B] FIG. 3B is a schematic illustration of a patient sitting next to an exemplary embodiment of the system after the chin rest has been moved to a target position. [Figure 3C] FIG. 3C is a schematic illustration of the exemplary embodiment system in the same state as FIG. 3B, and the patient before and after moving to engage the chin rest. [Figure 4] FIG. 4 is a schematic diagram of programmable signal processing hardware that can be configured to perform the functions of the processor described herein. [Figure 5] FIG. 5 is a flow diagram illustrating a process by which a processor of a control system generates a first control signal in an exemplary embodiment of the present disclosure. [Figure 6] FIG. 6 is a schematic representation of the first mapping described herein in exemplary form of a table. [Figure 7] FIG. 7 is a flow diagram illustrating a process by which a processor of a control system generates a second control signal in an exemplary embodiment of the present disclosure. [Figure 8] FIG. 8 is a schematic representation of the second mapping described herein in exemplary form of a table. DETAILED DESCRIPTION OF THE INVENTION

[0016] To address the above-mentioned problems, the inventors have devised, according to an exemplary embodiment, a control system configured to generate control signals for adjusting a height at which a height-adjustable contact surface of an ophthalmic imaging device is positioned to a target height at which the contact surface should contact the patient's head during imaging of the patient's eye with the ophthalmic imaging device. The control system includes at least one camera configured to acquire one or more images of at least a portion of the patient's head when the patient is positioned next to the ophthalmic imaging device to bring the head into contact with the contact surface when the contact surface is at the target height. The control system also includes a processor configured to process the one or more images to generate a value of a first indicator indicative of a height at which the at least a portion of the head was positioned when the one or more images were acquired. Instead of automating the traditional approach to adjusting patient interface height, in which the difference in height between the patient interface and the head is determined by an operator and minimized by the operator repeatedly adjusting the height of the patient interface and evaluating the height difference resulting from the previous adjustment, the processor of the exemplary embodiment can obtain the target height at which the contact surface should contact the head during imaging in a faster, non-iterative manner by using a mapping M to map values ​​of a first indicator to values ​​of a second indicator indicative of a target height of the contact surface, and generating a control signal to adjust the height at which the contact surface is positioned to the target height indicated by the value of the second indicator. The mapping M may be provided, for example, in the form of a look-up table (LUT) that associates values ​​of the first indicator with corresponding values ​​of the second indicator, and the processor may use the value of the first indicator to look up the corresponding value of the second indicator in the LUT, indicative of the target height of the contact surface.

[0017] In some exemplary embodiments, the mapping may depend on how far the patient is sitting or standing from the ophthalmic imaging device (which may be measured, estimated, or assumed) to allow the patient to lean forward and comfortably engage the contact surface by adjusting the height of the contact surface to a target height indicated by the value of the second indicator. This may help the patient maintain eye position more consistently during imaging of the eye with the ophthalmic imaging device, thereby reducing motion artifacts in the acquired image(s). The mapping may also or alternatively depend on the patient's age, reflecting the observation that older patients tend to have less mobility than younger patients and, particularly, have very limited ability to adjust eye height once settled into a particular seated position when engaging the contact surface of an ophthalmic imaging device, compared to younger patients. Therefore, using such a mapping to set the height of the contact surface of an ophthalmic imaging device may enable patients, particularly older patients, to maintain eye position more stably during imaging, thereby reducing motion artifacts in the acquired images.

[0018] 1 is a schematic diagram of a system 100 for imaging an eye 101 of a (human) patient 102. The system 100 comprises an ophthalmic imaging device 110, a movement mechanism 120, and a control system (also called a guidance system) 130.

[0019] The ophthalmic imaging device 110 is configured to image the eye 101 of the patient 102. The ophthalmic imaging device 110 may be an optical coherence tomography (OCT) imaging device in the form of a swept-source OCT (SS-OCT) imaging device, as in this exemplary embodiment. However, the ophthalmic imaging device 110 may also be another type of Fourier-domain OCT (FD-OCT) imaging device, such as a spectral-domain OCT (SD-OCT) imaging device, or alternatively a time-domain OCT (TD-OCT) imaging device. However, the ophthalmic imaging device 110 is not limited thereto and may also be any other type of ophthalmic imaging device for imaging the posterior segment of the eye 101, such as, for example, a scanning laser ophthalmoscope (SLO) or a fundus camera. Furthermore, the ophthalmic imaging device 110 need not be limited to imaging the posterior portion of the eye 101, but may alternatively or additionally be configured to image the anterior portion of the eye 101.

[0020] The OCT imaging device 110 may include well-known components, such as a light beam generator, a scanning system, an interferometer, a photodetector, OCT data processing hardware, and a scan head (not shown). The scanning system may be configured to perform one-dimensional and / or two-dimensional point scans of a light beam across the retina of the eye 101 and collect light scattered by the retina during the point scans. Thus, the OCT imaging device 110 may acquire A-scans at respective scan locations distributed across the surface of the retina by sequentially irradiating the scan locations with a light beam, one scan location at a time, and collecting at least a portion of the light scattered by the retina at each scan location. The OCT imaging system 110 may be configured to acquire OCT images in the form of B-scans, for example, by performing point scans to acquire successive A-scans along a straight line. However, the OCT imaging system 110 may instead be configured to acquire B-scans by a scanning system performing line scans, using hardware well known to those skilled in the art. More generally, the OCT imaging system 110 may be configured to acquire OCT images in the form of B-scans or C-scans by performing point or line scans using predetermined scan patterns (e.g., spiral scans) known to those skilled in the art, or by using a full-field setup.

[0021] The ophthalmic imaging device 110 includes a height-adjustable patient interface 111 having a contact surface 112 configured to contact the head 103 of the patient 102 and help keep the head 103 stable during imaging of the eye 101. A patient interface 111 useful for this purpose may take one of many different forms.

[0022] For example, the patient interface 111 may be provided in the form of a chin rest having an upwardly facing contact surface 112 on which the patient 102 rests his or her chin while the eye 101 is imaged by the ophthalmic imaging device 110, as in this exemplary embodiment.

[0023] As another example, the patient interface 111 may be provided in the form of a forehead rest (which may also be referred to as a head rest). In some exemplary embodiments, the forehead rest may be configured to contact only the forehead of the patient 102 when the patient 102 engages the forehead rest. In other exemplary embodiments, the forehead rest may be shaped to contact not only the patient's forehead when the patient 102 engages the forehead rest, but also the portion of the patient's face surrounding the eye sockets, thereby helping to reduce side-to-side movement of the head 103 as well as front-to-back movement of the head 103 when the patient's head 103 engages the forehead rest. In such other exemplary embodiments, the forehead rest may be shaped to fit around the patient's eye sockets and over the bridge of the nose to provide a contact surface for the patient's head 103 similar in shape to that of, for example, a ski mask or snorkel mask.

[0024] As some further examples, the patient interface 111 may be provided in the form of a combination chin rest and forehead rest as described above, or in the form of one or two eyecups (among other possibilities).

[0025] The height h of the contact surface 112 may be adjustable relative to some of the remaining components of the ophthalmic imaging device 110. However, in this exemplary embodiment, the height h of the contact surface 112 relative to the rest of the ophthalmic imaging device 110 is fixed and is adjustable by vertical movement of the entire ophthalmic imaging device 110, specifically by up and down movement (along the z-axis in FIG. 1 ) of the top surface of a height-adjustable table on which the ophthalmic imaging device 110 rests. The height h is measured relative to a reference height, such as ground level 200, which may be the floor of a room housing the ophthalmic imaging device 110. The contact surface 112 may also be horizontally movable (along the x-axis in FIG. 1 ) toward and away from the patient 102 to change its lateral position, as in this exemplary embodiment, as described in more detail below, although in some exemplary embodiments, such horizontal adjustability of the contact surface 112 may not be available.

[0026] The movement mechanism 120 is configured to adjust the height h at which the height-adjustable contact surface 112 is positioned to a target height at which the contact surface 112 should contact the head 103 of the patient 102 during imaging of the eye 101. The movement mechanism 120 may, as in this exemplary embodiment, be further configured to move the contact surface 112 horizontally to a target lateral position at which the contact surface 112 should contact the head 103 of the patient 102 during imaging.

[0027] The movement mechanism 120 may, as in this exemplary embodiment, comprise a height-adjustable table configured to support the ophthalmic imaging device 110 on a table top. Thus, the ophthalmic imaging device 110 rests on the height-adjustable table. The height of the height-adjustable table top is therefore adjustable and, as in this exemplary embodiment, may be horizontally movable toward and away from the head 103 of the patient 102. Thus, in exemplary embodiments such as the present invention in which the contact surface 112 is fixed relative to the rest of the ophthalmic imaging device 110, vertical adjustment to change the height of the table top and horizontal adjustment to change its lateral position result in corresponding adjustments of the height and lateral position of the contact surface 112, respectively. Any suitable height-adjustable table (e.g., an Optos® table) may be used to support and, optionally, horizontally move the ophthalmic imaging device 110 toward and away from the patient 102. A height-adjustable table may have a motorized movement mechanism that is controllable by an operator (e.g., via a button on the table or handset that the operator can press) to adjust the height of the table top and, optionally, its lateral position as well.

[0028] However, the movement mechanism 120 may be provided in other forms, such as a height-adjustable wall mount (e.g., a height-adjustable wall mount arm) that is attached to a wall of a room and configured to support the ophthalmic imaging device 110 on a height-adjustable upper surface of the wall mount. The upper surface of the height-adjustable wall mount that supports the ophthalmic imaging device 110 may also be horizontally movable toward and away from the head 103 of the patient 102. Thus, if the contact surface 112 is fixed relative to the rest of the ophthalmic imaging device 110, vertical adjustment to change the height of the upper surface of the wall mount and horizontal adjustment to change its lateral position result in corresponding adjustments of the height of the contact surface 112 and its lateral position, respectively. The height-adjustable wall mount may comprise a motorized movement mechanism controllable by an operator (e.g., via a button on the wall mount or a handset that the operator can press) to adjust the height of the upper surface of the wall mount, and optionally also its lateral position.

[0029] Although adjustments to the height and optionally the lateral position of the contact surface 112 have been described above as being achieved by movement of the entire ophthalmic imaging device 110 by the movement mechanism 120 that supports the ophthalmic imaging device 110, these adjustments of the contact surface 112 may be performed in other ways. For example, the position of the contact surface 112 may be fixed relative to a portion of the ophthalmic imaging device 110 that comprises the scan head and scanning system, which portion may be configured to have an adjustable height relative to the remaining components of the ophthalmic imaging device 110, including the interferometer, detector, light source, and OCT data processing hardware. Such an arrangement may be achieved, for example, by optically coupling the scanning system to the interferometer with optical fiber and providing a mechanism that uses stepper motors or the like to move the scanning system, with the scan head and patient interface 111 comprising the contact surface 112 relative to the remaining components of the ophthalmic imaging device 110.

[0030] The control system 130 is configured to generate a first control signal S1 to adjust the height h to a target height. The control system 130 may be further configured to generate a second control signal S2 to move the contact surface 112 horizontally to a target lateral position where the contact surface 112 should contact the head 103 of the patient 102 and change its lateral position while the eye 101 is being imaged by the ophthalmic imaging device 110, as in this exemplary embodiment. However, the generation of the second control signal S2 by the control system 130 is optional and may be omitted in some exemplary embodiments.

[0031] 2 is a schematic diagram showing details of control system 130. Control system 130 includes at least one camera 132, at least one processor 134, and may further include one or more sensors 136, which are described in more detail below.

[0032] In this exemplary embodiment, the control system 130 includes a single camera 132 configured to acquire an image 138 of at least a portion 104 of the head 103 of the patient 102, the patient 102 being in a suitable body position next to the ophthalmic imaging device 110 for contacting the head 103 with the contact surface 112 when the contact surface 112 is at a target height, for example, by the patient 102 leaning forward to engage the patient interface 111 and contacting the head 103 with the contact surface 112. The camera 132 may be a camera in an automatic pupil alignment module (also known as a patient alignment module, PAM) of the ophthalmic imaging device 110, which functions to automatically align the imaging beam of the imaging device 110 with the pupil during micro-alignment, or may be a dedicated digital camera for the control system 130. The patient 102 may be in a seated position, for example, on a seat next to the ophthalmic imaging device 110, from which position the patient 102 can move their head 103 forward by tilting it toward the ophthalmic imaging device 110 to bring the contact surface 112 into contact with the head 103 after the contact surface 112 has moved to the target height. Alternatively, and typically if the patient 102 is a child, the patient 102 may be standing (i.e., in a standing position), for example, next to the ophthalmic imaging device 110, from which the patient 102 can move their head 103 forward by tilting it toward the ophthalmic imaging device 110 to bring the contact surface 112 into contact with the head 103 after the contact surface 112 has moved to the target height. The imaged portion 104 of the head 103 may be the portion of the head 103 that is within the field-of-view (FoV) of the camera 132 (or, in an exemplary embodiment, within the combined FoV of two or more cameras if more than one camera 132 is present) when the patient 102 is in a body position next to the ophthalmic imaging device 110 so as to bring the head 103 into contact with the contact surface 112 when the contact surface 112 is set to a target height.

[0033] 3A-3C are schematic illustrations of a patient 102 seated next to an ophthalmic imaging device 110 of the system 100 at different stages of the macro-alignment process described herein. As noted above, the movement mechanism 120 of the system 100, in this exemplary embodiment, is provided in the exemplary form of a height-adjustable table, shown at 300 in FIGS. 3A-3C. Components of the control system 130, including the camera 132, the processor 134, and sensors 136-1, 136-2, and 136-3 (as examples of the one or more sensors 136 of FIG. 2), are also shown in FIGS. 3A-3C. These figures also schematically illustrate a user interface 113 configured to be controlled by the processor 134 to guide an operator (user) of the ophthalmic imaging device 110 to set the height of the contact surface 112 to a target height and the lateral position of the contact surface 112 to a target lateral position for imaging.

[0034] As shown in FIG. 3A , the patient 102 is initially seated in a seated position on a seat 400 next to the ophthalmic imaging device 110, ready to image the eye 101 while seated in the seat 400. In this exemplary embodiment, the seat 400 is provided in the form of a chair, but in other exemplary embodiments, it may be, for example, the patient's wheelchair. With the patient 102 seated in this manner, the camera 132 acquires an image 138 of the patient's 102's head 103, for example, in response to a start command entered into the control system 130 by an operator, or automatically in response to the patient's 102's presence being detected, as described below. The camera 132 is configured so that its field of view captures the patient's 102's head 103, preferably while avoiding any part of the ophthalmic imaging device 110, such as the patient interface 111.

[0035] The processor 134 is configured to generate a first control signal S1 and, optionally, a second control signal S2 based on the acquired image 138. The process by which the processor 134 can generate the first control signal S1 and the second control signal S2 is described in detail below with reference to Figures 5 and 7, respectively.

[0036] The height h of the contact surface 112 and its lateral position may be adjustable by the operator, as in this exemplary embodiment, using any known type of mechanical or operator-controlled electrical drive mechanism for moving the top of the height-adjustable table 300 vertically (along the z-axis) and horizontally (i.e., along the x-axis) toward and away from the patient 102. In either case, the user interface 113 (which may include a screen viewable by the operator) is controlled by the processor 134 using first and second control signals S1 and S2 to provide instructions to the operator, e.g., in the form of “up,” “down,” “front,” and “back” directional indicators (e.g., in the form of arrows or triangles), for setting the height and lateral position of the contact surface 112 to target heights and lateral positions, respectively. In some exemplary embodiments, the user interface 113 may include a display of the ophthalmic imaging device 110 used to control the ophthalmic imaging device 110 and to view acquired images. The user interface 113 may additionally or alternatively include a speaker for providing voice commands to the user for adjusting the height h and lateral position d of the contact surface 112 .

[0037] The control system 130 can instead use the first control signal S1 and the second control signal S2 to automatically control one or more electric actuators (e.g., electric motors) that may be included in the height-adjustable table 300 to adjust the height h at which the height-adjustable contact surface 112 is positioned from an initial height h0 to a target height hT at which the contact surface 112 should contact the head 103 of the patient 102 during imaging of the eye 101, and to adjust the lateral position of the contact surface 112 (which can be expressed as the distance d of a point on the contact surface 112 from a stationary reference point on the height-adjustable table 300 in a direction along the x-axis toward the patient 102) from an initial position of distance d0 to a target lateral position of distance dT. Thus, the control system 130 can guide the patient interface 111 to a position suitable for comfortable engagement with the patient 102.

[0038] 3B illustrates the result of the operator adjusting the height and lateral position of the top of the height-adjustable table 300 according to instructions provided by the control system 130 via the display and / or speaker of the user interface 113 to adjust the height and lateral position of the contact surface 112 to correspond to a target height hT and a target lateral position of distance dT, respectively. The user interface 113 can indicate to the operator that the target height and lateral position of the contact surface 112 has been reached based on vertical and horizontal movement of the top of the height-adjustable table 300, which may be monitored by the control system 130. The patient 102 may be instructed to maintain a seated position while movement of the height-adjustable table 300 occurs to reduce the risk of the height-adjustable table 300 or the ophthalmic imaging device 110 thereon colliding with the patient 102 during macro-alignment.

[0039] Once the contact surface 112 has been moved to the target height and lateral position during macro-alignment, the patient 102 aligns with the patient interface 111 (in this embodiment, the chin rest) by leaning forward to engage the patient interface 111, so that the chin contacts the contact surface 112 on the chin rest, as shown in FIG. 3C . The patient 102 maintains the resulting seated position until imaging of the eye 101 with the ophthalmic imaging device 110 is complete (and any prior micro-alignments that may have been performed by the ophthalmic imaging device 110 to more closely align the eye 101 (e.g., pupil center) with the imaging axis 114). During imaging of the eye 101 with the ophthalmic imaging device 110, there is no further movement of the height-adjustable table 300, and the patient 102 remains as still as possible. The patient's 102 buttocks typically remain substantially in the same place while the patient 102 leans forward, and the seat 400 also remains in place. Alternatively, the seat 400 may be moved forward by the patient 102, as described further below.

[0040] Once the contact surface 112 is adjusted to the target height hT, the patient 102 can assume a seated position next to the ophthalmic imaging device 110 from which the patient 102 can bring their head 103 into contact with the contact surface 112 by leaning forward to engage the patient interface 111; however, the patient need not be seated and can instead remain in a standing position during the macro-alignment process and subsequent micro-alignment (if any) and imaging by the ophthalmic imaging device 110. For example, if the ophthalmic imaging device 110 is used to image a child's eye, the ophthalmic imaging device 110 may be used with the patient 102 assuming a standing position next to the ophthalmic imaging device 110 suitable for bringing their head 103 into contact with the contact surface 112 when the contact surface 112 is at the target height. Thus, when the contact surface 112 is set at a target height, a standing patient 102 may lean forward and contact the contact surface 112 for the duration of imaging of the eye 101 by the ophthalmic imaging device 110.

[0041] 2, the processor 134, as in this exemplary embodiment, may be further configured to receive an indication Iage of the age of the patient 102, the use of which will be described below. The indicator Iage may be entered into the processor 134 by an operator, for example, or may be received from an external computer (e.g., a PC or server) as part of the patient's patient record.

[0042] The processor 134 may be further configured to obtain an indication of the distance I of the patient 102 from the contact surface 112 while the patient 102 is in the aforementioned position next to the ophthalmic imaging device 110, as in this exemplary embodiment. For example, the processor 134 may be configured to obtain the distance indication I by processing at least some of the one or more images acquired by the at least one camera 134. If the control system 130 includes a single camera 132, the processor 134 may use known object detection techniques based on machine learning, such as a Haar cascade classifier, to identify the pupils of the patient's eyes in the images acquired by the camera 132, use the identified pupil locations to determine the interpupillary distance (in pixels) in the images, and then convert the determined interpupillary distance in pixels into an estimate of the distance of the patient's eyes from the contact surface 112. This conversion may be performed using, for example, a mapping in the form of a conversion function or look-up table obtained by measuring the individual distances (in pixels) in each image of a set of images captured by the camera 132 of a calibration board showing two markers spaced approximately 63 mm (the average interpupillary distance in adults) positioned at different known distances from the contact surface 112 in the set of images. The estimate may be refined using the measured interpupillary distance of the patient 102 if entered by an operator or otherwise made available to the processor 134 (e.g., from the patient record of the patient 102 retrieved from a remote data store). In other exemplary embodiments, if the control system 130 includes a stereoscopic system having two cameras with separated, parallel optical axes configured to acquire stereoscopic images of the head 103 of the patient 102, the processor 134 can estimate the distance of the patient 102 from the cameras (and therefore from the contact surface 112) by processing the images using well-known techniques for distance estimation from stereoscopic vision.

[0043] As a further alternative, the control system 130 may, as in this exemplary embodiment, further comprise a distance sensor as one of the sensors 136, configured to measure the distance of the head 103 or torso of the patient 102 from the contact surface 112 (e.g., a reference point on the contact surface, such as the closest point on the contact surface to the patient 102) when the patient 102 is in the above-mentioned position next to the ophthalmic imaging device 110. The processor 134 may be configured to obtain the indication Idist by receiving the measured distance from the distance sensor, as shown at 136-1 in FIGS. 3A-3C , which will be described in more detail below. The distance sensor 136-1 may be of any known type, such as, for example, an ultrasonic sensor, an infrared (IR) distance sensor, or a light detection and ranging (LIDAR) sensor. The distance sensor 136-1 may be positioned next to the patient interface 111 to measure the distance dDS between the distance sensors 136-1, and therefore equivalently between the contact surface 112 of the patient interface 111 and the head 103 or torso of the patient 102, as in this exemplary embodiment. In this case, the processor 134 may be configured to obtain an indication Idist of the distance dDS by receiving the measured distance from the distance sensor 136-1. However, the distance sensor 136-1 may be positioned elsewhere on the ophthalmic imaging device 110, and the processor 134 may be configured to correct the distance measured by the distance sensor 136-1 to determine the distance dDS using the distance along the x-axis between the distance sensor 136-1 and the contact surface 112 (e.g., the aforementioned reference point on the contact surface 112).

[0044] 2, processor 134, as in this exemplary embodiment, may be further configured to obtain an indication, Iseat_h, of the height of seat 400, the use of which will be described below. This indication, Iseat_h, may be entered into processor 134 by an operator, or may be obtained from a seat height sensor in control system 130 (not shown), which is configured to measure the height of seat 400 above ground level 200 and transmit this to processor 134.

[0045] The one or more sensors 136 of the control system 130 shown in FIG. 2 , as in this exemplary embodiment, can include at least one sensor of the object, each sensor being a distance sensor configured to measure the distance to the object or a proximity sensor configured to detect the object when the object is within the detection range of the proximity sensor. The distance sensor may be of any known type, such as an ultrasonic sensor, an infrared (IR) distance sensor, or a light detection and ranging (LIDAR) sensor. The distance sensor may alternatively include a digital camera configured to capture an image including the object and another object and a processor configured to process the image using any known technique to estimate the distance between the objects. The proximity sensor may be of any known type, such as a contact switch or a non-contact proximity sensor, such as an IR or ultrasonic proximity sensor.

[0046] In this exemplary embodiment, three such object sensors are provided: distance sensor 136-1, as described above, and proximity sensors 136-2 and 136-3, as shown in Figures 3A-3C. Each object sensor and processor 134 of control system 130, as in this exemplary embodiment, may be configured to determine whether one or both of height-adjustable table 300 or ophthalmic imaging device 110 has moved within a predetermined distance of an object (e.g., a portion (e.g., a leg) of patient 102, or, if patient 102 is seated in seat 400, a portion (e.g., an armrest) of seat 400). Distance sensor 136-1 is used by processor 134 to determine whether the portion of ophthalmic imaging device 110 closest to patient 102 (e.g., patient interface 112) has moved within a first predetermined distance of patient 102 (by comparing the distance value measured by distance sensor 136-1 to a first predetermined threshold), proximity sensor 136-2 is configured to sense whether height-adjustable table 300 has moved within a second predetermined distance of patient 102 or seat 400, and proximity sensor 136-3 is configured to sense whether height-adjustable table 300 has moved within a third predetermined distance of patient 102 or seat 400. The first, second, and third predetermined distances may be different from one another, although two or more of these predetermined distances may be the same. Each of the proximity sensors 136-2 and 136-3 is further configured to send a respective signal to the processor 134 in response to detecting that the height-adjustable table 300 or (as the case may be) the ophthalmic imaging device 110 has moved within a respective predetermined distance of the patient 102 or (as the case may be) the seat 400.

[0047] Similarly, processor 134 compares the distance value reported by distance sensor 136-1 with a first predetermined threshold and generates instructions to stop adjusting the height of height-adjustable table 300 when the reported distance becomes less than the first threshold.

[0048] In response to determining, based on signals received from the object sensors, that at least one of the height-adjustable table 300 and (optionally) the ophthalmic imaging device 110 has moved within a predetermined distance of the object, the processor 134 can generate instructions to stop the height adjustment to the target height being made by the movement mechanism 120. For example, the processor 134 can compare the distance value reported by the distance sensor 136-1 to a first predetermined threshold and generate instructions when the reported distance becomes less than the first threshold. The instructions can be displayed on the user interface 113, where an operator adjusts the height of the height-adjustable table 300 by manipulating a mechanical drive mechanism or controlling an electromechanical drive mechanism. Alternatively, the control system 130 can use the instructions to automatically control one or more electric actuators (e.g., electric motors) that may be included in the height-adjustable table 300.

[0049] In addition to, or instead of, its use in collision avoidance as described above, distance sensor 136-1 can be used to initiate imaging of patient's head 103 by camera 132. More specifically, processor 134 of control system 130 can be configured to determine whether patient 102 is within a predetermined distance of ophthalmic imaging device 110 and, in response to determining that patient 102 is within the predetermined distance of ophthalmic imaging device 110, control camera 132 to capture image 138. Imaging of patient's head 103 by camera 132 can alternatively be initiated by a proximity sensor configured to trigger imaging when patient 102 is detected within its detection range.

[0050] Instead of a reactive approach to avoiding a collision between at least one of the height-adjustable table 300 and the ophthalmic imaging device 110 and an object (e.g., a portion of the patient 102 or a portion of the seat 400), a predictive approach to collision avoidance may be taken. In this case, at least one distance sensor, such as distance sensor 136-1 configured to measure a distance to an object, such as the patient 102, may be provided, and the distance sensor and control system 130 is configured to determine whether at least one of the height-adjustable table 300 or the ophthalmic imaging device 110 should be moved within a predetermined distance of the object during adjustment of the height h of the contact surface 112 to the target height hT by the movement mechanism 120, and to generate a warning to an operator in response to determining that at least one of the height-adjustable table 300 or the ophthalmic imaging device 110 should be moved within the predetermined distance of the object during the adjustment. The warning may be communicated to the operator, for example, via one or both of the display and speaker of the user interface 113 described above.

[0051] 2 are exemplified by sensors 136-1, 136-2, and 136-3 shown in Figures 3A-3C, but the disclosure is not limited to these examples and any number of sensors of the types described above or similar types may be used. In particular, multi-directional distance sensors may be used to reduce the total number of sensors required.

[0052] Processor 134 may be provided in any suitable form, for example as processor 520 of programmable signal processing hardware 500 of the type shown schematically in Figure 4. Components of programmable signal processing hardware 500 may be included within control system 130. Programmable signal processing device 500 comprises a communications interface (I / F) 510 for receiving image 138 from camera 132 (or multiple images from multiple cameras in other exemplary embodiments), and optionally at least one of the instructions Iage, Idist, and Iseat_h described above, and, if provided, a second control signal S2 to user interface 113 or movement mechanism 120 for automatic adjustment of the height and lateral position of contact surface 112, as described above. The signal processing hardware 500 further comprises a processor 520 (e.g., a central processing unit CPU and / or a graphics processing unit GPU), a working memory 530 (e.g., a random access memory), and an instruction store 540 that stores a computer program 545 containing computer-readable instructions that, when executed by the processor 520, cause the processor 520 to perform various functions of the processor 134 described herein.

[0053] The working memory 530 stores information used by the processor 520 during execution of the computer program 545, including a mapping M for mapping the value of a first indicator indicative of the height at which the head 103 (or an anatomical feature thereof) was positioned when the image 138 was acquired to a corresponding value of a second indicator indicative of the target height hT of the contact surface 112. The working memory 530 may also store further mappings, described below, for converting y-axis components of pixel locations of pixels in the image 138 to the height of the anatomical feature represented by the pixel. The working memory 530 may alternatively store a mapping that can be used to directly map y-axis components of pixel locations of pixels in the image 138 representing anatomical features, such as the eye 101, to the corresponding value of the second indicator indicative of the target height hT of the contact surface 112, instead of the mappings described above.

[0054] The instruction store 540 may comprise a ROM (e.g., in the form of an electrically erasable programmable read-only memory (EEPROM) or flash memory) pre-loaded with computer-readable instructions. Alternatively, the instruction store 540 may comprise a RAM or similar type of memory, and the computer-readable instructions of the computer program 545 may be input thereto from a computer program product, such as a non-transitory computer-readable storage medium 550 in the form of a CD-ROM, DVD-ROM, or the like, or from a computer-readable signal 560 carrying the computer-readable instructions. In either case, the computer program 545, when executed by the processor 520, causes the processor 520 to perform the functions of the processor 134 described herein. In other words, the processor 134 of the present exemplary embodiment may comprise the computer processor 520 and a memory 540 storing computer-readable instructions that, when executed by the computer processor 520, cause the computer processor 520 to perform the functions of the processor 134 described herein.

[0055] It should be noted, however, that the processor 134 may alternatively be implemented with non-programmable hardware, such as an ASIC, FPGA, or other integrated circuit dedicated to performing the functions of the processor 134 described herein, or a combination of such non-programmable and programmable hardware as described above with reference to Figure 4. Furthermore, in some exemplary embodiments, the programmable signal processing hardware 500 may further perform at least one of the functions of the OCT data processing hardware if the ophthalmic imaging device 110 is an OCT imaging device, or the functions of a controller for the movement mechanism 120, if provided.

[0056] 5 is a flow diagram illustrating a process by which processor 134 generates a first control signal S1 for adjusting the height h at which contact surface 112 is located to a target height hT. Note that processor 134 may, for example, first receive image 138 and any additional images of head 103 (or a portion thereof) from camera 132 via I / F 510.

[0057] In process S10 of FIG. 5 , processor 134 processes one or more images acquired by camera(s) of control system 130 to generate a value of a first indicator that indicates the height at which head 103 (or a portion thereof) was positioned in the image(s) when the image(s) was acquired. While processor 134 may generate the value of the first indicator by first identifying eye 101 of patient 102, as in this exemplary embodiment, in other exemplary embodiments, processor 134 may identify another anatomical feature of head 103, such as patient 102's eyebrows, mouth, ears, or chin. This can be achieved through the use of object detection algorithms of a type well known to those skilled in the art. For example, processor 134 can use known object detection techniques based on machine learning, such as a Haar cascade classifier, to identify eyes in image 138 acquired by camera 132 and thus provide pixel coordinates of eyes 101 in image 138.

[0058] The y-axis component of the pixel coordinate is converted to the height of the eye 101 (e.g., relative to the camera 132 or ground level 200) using a mapping that can be obtained by using the camera 132 to acquire a calibration image of a calibration board having a series of markers spaced vertically (e.g., at regular intervals of, e.g., 1 cm) and positioned at a distance from the camera 132 equal to the typical distance that the head 103 of the patient 102 would be positioned at when the patient 102 is in position and ready to image the eye 101. The y-axis component of each pixel location in the calibration image that corresponds to a respective one of the markers on the calibration board can then be correlated with the height (e.g., relative to the (usually horizontal) optical axis of the camera 132 or ground level 200) of the respective marker on the calibration board. If, as in this exemplary embodiment, the control system 130 includes a distance sensor 136-1 for measuring the distance dDS between it (and therefore, equivalently, the contact surface 112) and the head 103 or torso of the patient 102, a set of such calibration images of the calibration board at different distances along the x-axis from the distance sensor / patient interface 111 may be captured by the camera 132 to obtain a set of mappings of the type described above, and the most appropriate mapping from among these mappings used to convert the y-axis component of the pixel position of a pixel in the image 138 to the relative height of the part of the patient's face represented by the pixel may be selected depending on the distance dDS measured by the distance sensor 136-1 during the macro-alignment process described above.

[0059] It should be noted that the value of the first indicator may generally indicate the height of a single anatomical feature (e.g., mouth or chin) obtained as described above, or the average height of two anatomical features (e.g., eyes or ears) in the image 138. Furthermore, the height of the anatomical feature of the head 103 determined as described above (which may be taken to provide a measurement of the height of the head 103) may be used to estimate the height of another anatomical feature on the patient's face using the average height difference between the features, which may be derived from a sample of the population. This estimate may be useful to make when the anatomical feature of interest, e.g., the height of the chin, is more difficult to determine from the image 138 than other features, e.g., the eyes 101, which may have greater contrast in the image 138.

[0060] 5, the processor 134 uses at least one mapping M to map values ​​of the first indicator to values ​​of a second indicator that indicate a target height hT at which the contact surface 112 should contact the head 103 during imaging of the eye 101. FIG. 6 is a schematic illustration of an exemplary mapping M in the form of a table 600. The table 600 includes a first column 601 with values ​​X1, X2, ... XN of the first indicator and a second column 602 with corresponding values ​​Y1, Y2, ... YN of the second indicator. However, the form of the mapping M is not so limited and may instead be provided as a function of multiple variables or a multi-dimensional look-up table, for example, as described in more detail below.

[0061] The mapping M may map each value Xi of the first indicator to a corresponding value Yi of the second indicator such that, as in this exemplary embodiment, when the contact surface 112 is positioned at a target height hT indicated by the value of the second indicator, the height of the imaging axis 114 of the ophthalmic imaging device 110 is less than the height of the eye 101 indicated by the value of the first indicator. For example, a respective value Yi of the second indicator corresponding to each value Xi of the first indicator may indicate a target height hT of the headrest of the ophthalmic imaging device such that the patient's eye will be approximately aligned with the imaging axis 114 (in other words, at a height suitable for obtaining an image of the eye 101 with the ophthalmic imaging device 110, or at a height suitable for micro-aligning the ophthalmic imaging device 110 and the eye 101 so that the eye 101 can then be imaged) when the patient leans forward and places their chin on a headrest set at the target height hT, thereby lowering the eye height relative to the height indicated by the value Xi of the first indicator. Such mapping may be based, for example, on the average height difference between the eyes and chin derived from a population sample. The height of the imaging axis 114 above the contact surface 112 may similarly be set to correspond to such average height difference. The difference between the height indicated by the value of the first indicator Xi and the height of the patient's eyes (or imaging axis 114) when the patient's chin is resting on the chin rest at the target height hT can be set to a predetermined value, which may be in the range of 2 to 10 cm, preferably 3 to 8 cm, and more preferably 5 cm, to reflect the natural downward movement of the head 103 when leaning forward, as shown in FIG. 3C, in a manner and degree that is comfortable for the patient (assumed to be of average height and mobility in this case), i.e., in a manner and degree that does not require straining to place the head in a position other than a relaxed forward leaning movement to a pose that can be comfortably maintained for the duration of the imaging session.

[0062] The degree to which a patient can lean forward to assume a pose that can be comfortably maintained for the duration of an imaging session may depend on the patient's age, as older patients (e.g., those over 50) tend to have more limited mobility than younger patients and therefore often cannot lean forward very far while remaining comfortable. More specifically, the degree of hip flexion tends to decrease with age beyond middle age, which can reduce the degree to which a person can lean forward and comfortably maintain the resulting position for the duration of eye imaging, and consequently, the amount of head height loss as the patient leans forward.

[0063] To account for the resulting variability in the ideal target height hT of the contact surface 112 between patients of the same or similar height but different ages, the mapping M may, as in this exemplary embodiment, depend on the age of the patient 102, such that for each value of the first indicator, the individual target height hT indicated by the corresponding value of the second indicator increases with increasing age of the patient 102, at least when the age is within a predetermined range, e.g., 50 years or older. This dependency of the mapping M on the age of the patient 102 may therefore allow the patient interface 111 to be set at a height that allows the patient to assume an inclined position more closely adapted to their needs, which may be more comfortable and therefore may further reduce the incidence of motion artifacts in images of the eye 101 acquired by the ophthalmic imaging device 110. As an example, for patients between 50 and 60 years old, the difference between the height indicated by the value Xi of the first indicator and the height of the patient's eyes (or imaging axis 114) when the patient's chin is resting on the headrest at the target height hT may be 75% of the difference for patients under 50 years old, for patients between 60 and 70 years old, the difference between the height indicated by the value Xi of the first indicator and the height of the patient's eyes (or imaging axis 114) when the patient's chin is resting on the headrest at the target height hT may be 50% of the difference for patients under 50 years old, and for patients over 70 years old, the difference between the height indicated by the value Xi of the first indicator and the height of the patient's eyes (or imaging axis 114) when the patient's chin is resting on the chinrest at the target height hT may be 30% of the difference for patients under 50 years old.

[0064] The mapping M may also depend on the distance dDS such that, for each value of the first indicator, when the patient 102 is positioned next to the ophthalmic imaging device 110, the individual target height hT indicated by the corresponding value of the second indicator decreases as the distance dDS of the patient 102 from the contact surface 112 increases, as in this exemplary embodiment. As the distance dDS of the patient 102 from the contact surface 112 increases, the amount the patient 102 must lean forward to contact the contact surface 112 also increases, so the target height hT of the contact surface 112 should be lowered to account for the arc-shaped trajectory of the head 103 as the patient 102 leans forward (as shown in FIG. 3C ). This allows the target height hT of the contact surface 112, which is determined by the position of the seat 400, to account for different starting positions of the patient 102. This is particularly useful when the seat 400 is a wheelchair, as attempting to position the wheelchair in a predetermined position relative to the ophthalmic imaging device 110 each time the ophthalmic imaging device 110 is used can be time consuming and inaccurate. As noted above, the distance sensors 136-1 may be positioned next to the patient interface 111, as in this exemplary embodiment, to measure the distance dDS between the distance sensors 136-1, and therefore equivalently between the contact surface 112 of the patient interface 111 and the head 103 or torso of the patient 102.

[0065] If the camera 132 is configured to acquire the image 138 while the patient 102 is seated in a seated position on the seat 400 next to the ophthalmic imaging device 110, as in this exemplary embodiment, the mapping M may depend on the height of the seat 400 such that, for each value of the first indicator, the individual target height hT indicated by the corresponding value of the second indicator decreases as the height of the seat 400 increases. For a given value of the first indicator, the higher the seat 400, the shorter the patient 102's spine is likely to be. When the patient 102 pivots about their hips when leaning forward from a seated position, a shorter spine provides a higher hip pivot point than a longer spine. Thus, the target height hT indicated by the value of the second indicator is higher for higher seat 400 to reflect the smaller head drop of a patient with a shorter spine when leaning forward compared to a patient with a longer spine. This may enable the processor 134 to determine a target height hT for the contact surface 112 that does not require a patient with a relatively short spine to lean forward unnecessarily far, and thus may help establish a comfortable position for the patient 102 during imaging of the eye 101 by the ophthalmic imaging device 110. This may further reduce the incidence of motion artifacts in images of the eye 101 acquired by the ophthalmic imaging device 110.

[0066] Thus, in step S20, the processor 134 can map the value of the first indicator to the value of the second indicator using the received indication of the age Iage of the patient 102, the acquired indication of the distance dDS Idist, and the acquired indication of the height Iseat_h of the seat 400, each of which is described above with reference to FIG. 2 , as well as at least one mapping M, as in the present exemplary embodiment. However, each of the dependencies of the mapping M described above is an optional refinement to the mapping M, and one or more of them may be omitted. For example, the mapping M may depend on the height of the seat 400 rather than the distance dDS of the patient 102 from the contact surface 112 and the age of the patient 102, and thus the processor 134 may map the value of the first indicator to the value of the second indicator using only the acquired indication of the height Iseat_h of the seat 400 and the mapping M. In such a case, the processor 134 may not receive the indication of the age Iage of the patient 102 or acquire the indication of the distance dDS Idist as described with reference to FIG. 2 .

[0067] 5, the processor 220 generates a first control signal S1 for adjusting the height h at which the contact surface 112 is positioned to a target height hT indicated by the value of the second indicator. The first control signal S1 can be used to adjust the height h at which the contact surface 112 is positioned to the target height hT, as described above with respect to FIG.

[0068] 7 is a flow diagram illustrating a process by which the processor 134 generates a second control signal S2 to move the contact surface 112 along the horizontal axis (x-axis) to a target lateral position dT where the contact surface 112 should contact the head 103 of the patient 102 while the ophthalmic imaging device 110 is imaging the eye 101 of the patient 102, as in this exemplary embodiment. The process illustrated in FIG. 7 may be performed in parallel with the process illustrated in FIG. 5, or alternatively, may be performed after the process of FIG. 5 is completed.

[0069] In process S100 of Figure 7, the processor 134 receives from the distance sensor 136-1 a value of a third indicator indicating the separation along the horizontal axis (x-axis) between the contact surface 112 and a first lateral position at which the head 103 is positioned when the patient 102 is sitting in a seated position on the seat 400 next to the ophthalmic imaging device 110.

[0070] 7 , which may be implemented in an exemplary embodiment in which the control system 130 includes a stereoscopic system having two cameras with parallel optical axes separated from one another, and in which the stereoscopic system is configured to acquire a stereoscopic image of the head 103 of the patient 102, the processor 134 may process the images to generate a value of a third indicator indicative of a separation along a horizontal axis (x-axis) between the contact surface 112 and a first lateral position at which the imaged portion 104 of the head 103 is located when the patient 102 is seated in a seated position on the seat 400 next to the ophthalmic imaging device 110. The processor 134 may estimate the distance of the patient 102 from the cameras (and therefore from the contact surface 112) by processing the images using well-known techniques for distance estimation from stereoscopic vision.

[0071] In process S200 of FIG. 7 , the processor 134 uses one or more second mappings to map values ​​of the third indicator to values ​​of a fourth indicator that indicate a target lateral position dT at which the contact surface 112 should contact the head 103 of the patient 102 during imaging of the eye 101 of the patient 102 by the ophthalmic imaging device 110. The one or more second mappings map values ​​of the third indication to corresponding values ​​of the fourth indicator. FIG. 8 is a schematic diagram of an exemplary second mapping in the form of a table 800. The table 800 includes a first column 801 having values ​​A1, A2, ... A-N of the third indicator and a second column 802 having corresponding values ​​B1, B2, ... B-N of the fourth indicator. However, the form of the second mapping is not so limited and may instead be provided as a function of multiple variables or a multidimensional lookup table, for example.

[0072] It should be noted that the first mapping(s) and the second mapping(s) may form part of a common mapping. That is, in some example embodiments, one or more mappings may receive a first indicator value and a third indicator value received as input and output a second indicator value and a fourth indicator value. In this case, the mapping of the first indicator value to the second indicator value may be a function of the third indicator value. Additionally or alternatively, the mapping of the third indicator value to the fourth indicator value may be a function of the first indicator value.

[0073] The at least one second mapping may similarly depend on the age of the patient 102, such that for each value of the third indicator, the individual target lateral position dT indicated by the corresponding value of the fourth indicator approaches the first lateral position with increasing age. Thus, the processor 134 may use the received indication of the age I of the patient 102, as described with reference to FIG. 2, and the at least one second mapping to map values ​​of the third indicator to values ​​of the fourth indicator.

[0074] The at least one second mapping may similarly depend on the height of the seat 400 such that, for each value of the third indicator, the individual target lateral position dT indicated by the corresponding value of the fourth indicator approaches the first lateral position with increasing height of the seat 400. Thus, the processor 134 may use the obtained indication of the height of the seat 400 Iseat_h and the at least one second mapping as described with reference to FIG.

[0075] 7, the processor 134 generates a second control signal S2 for moving the contact surface 112 to a target lateral position indicated by the value of the fourth indicator. The second control signal S2 can be used to move the contact surface 112 to the target lateral position indicated by the value of the fourth indicator, as described above with reference to FIG.

[0076] The foregoing description describes exemplary aspects with reference to several exemplary embodiments. Accordingly, the present specification should be considered illustrative rather than restrictive. Similarly, the diagrams shown in the drawings are intended to highlight the functionality and advantages of the exemplary embodiments and 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.

[0077] Some aspects of the examples shown herein, such as the functionality of processor 134, may be provided as computer programs or software, such as one or more programs having instructions or instruction sequences 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 in one example embodiment. 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- or computer-readable medium, instruction store, and storage device may include, but is not limited to, floppy diskettes, optical disks, and optical-magnetic disks, or other types of media / machine-readable medium / instruction store / storage device 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 that can store, encode, or transmit instructions or sequences of instructions for execution by a machine, computer, or computer processor, and that cause the machine / computer / computer processor to perform any one of the methods described herein. Furthermore, it is common in the art to refer to software in some form (e.g., program, procedure, process, application, module, unit, logic, etc.) that performs an action or causes a result. Such expressions are merely a shorthand way of stating that execution of the software by a processing system causes the processor to perform an operation to produce a result.

[0078] Some or all of the functionality of processor 134 may also be implemented by the fabrication of application specific integrated circuits, field programmable gate arrays, or by interconnecting an appropriate network of conventional component circuits.

[0079] The computer program product may be provided in the form of one or more storage media, instruction store(s), or storage device(s) having stored thereon instructions that can be used to cause a computer or computer processor to control or execute any of the procedures of the example embodiments described herein. The storage media / instruction store / storage device may include, by way of example and not limitation, optical disks, ROM, RAM, EPROM, EEPROM, DRAM, VRAM, flash memory, flash cards, magnetic cards, optical cards, nanosystems, molecular memory integrated circuits, RAID, remote data storage devices / archives / warehouses, and / or any other type of device suitable for storing instructions and / or data.

[0080] Some implementations include software stored on one or more computer-readable media, one or more instruction store(s), or storage device(s) for controlling both the system hardware and enabling the system or microprocessor to utilize the results of the exemplary embodiments described herein to interact with a human user or other mechanism. Such software can include, but is not limited to, device drivers, operating systems, and user applications. Finally, such computer-readable media or storage device(s) further include software for carrying out exemplary aspects of the present invention, as described above.

[0081] The programming and / or software of the system includes software modules for performing the procedures described herein. In some exemplary embodiments herein, the modules include software, while in other exemplary embodiments herein, the modules include hardware or a combination of hardware and software.

[0082] While various exemplary embodiments of the present invention have been described above, it should be understood that they are presented by way of example, not limitation. Various changes in form and detail will be apparent to those skilled in the art. Accordingly, the present invention should not be limited by any of the exemplary embodiments described above, but should be defined only in accordance with the following claims and their equivalents. It should be understood that the steps recited in the claims do not have to be performed in the order presented.

[0083] While this specification contains details of many specific embodiments, these should not be construed as limitations on the scope of any invention or what may be claimed, but rather as descriptions of features unique to the particular embodiments described herein. Certain features described herein in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable subcombination. Furthermore, while features may be described above as acting in particular combinations and initially claimed as such, one or more features from a claimed combination may, in some cases, be deleted from the combination, and a claimed combination may be directed to a subcombination or variations of a subcombination.

[0084] In certain circumstances, multitasking and parallel processing may be advantageous. Furthermore, the separation of various components in the above embodiments should not be understood to require such separation in all embodiments, and the described program components and systems may generally be integrated together in a single software product or packaged in multiple software products.

[0085] Many of the examples shown herein involve particular combinations of device or software elements, but those elements may be combined in other ways to achieve the same purpose. Acts, elements, and features discussed only in connection with one embodiment are not intended to be excluded from similar roles in other embodiments or embodiments.

Claims

1. a control system (130) configured to generate a control signal (S1) for adjusting a height (h) at which a height-adjustable contact surface (112) of an ophthalmic imaging device (110) is positioned to a target height (hT) at which the contact surface (112) should contact a head (103) of the patient (102) during imaging of the eye (101) of the patient (102) by the ophthalmic imaging device, at least one camera (132) configured to acquire one or more images (138) of at least a portion (104) of the patient's head (103) when the patient (102) is positioned next to the ophthalmic imaging device (110) to bring the head (103) into contact with the contact surface (112) when the contact surface (112) is at the target height (hT); a processor (134) comprising: processing the one or more images (138) to generate a value of a first indicator indicative of a height at which the at least a portion of the head (103) was located when the one or more images (138) were acquired; using at least one mapping (M) to map the value of the first indicator to a value of a second indicator indicative of the target height (hT) at which the contact surface (112) should contact the head (103) during the imaging; a processor configured to generate a control signal to adjust the height (h) at which the contact surface (112) is positioned to the target height (hT) indicated by the value of the second indicator.

2. the height (h) of the contact surface (112) is adjustable by a user of the control system (130); the control system (130) further comprises a user interface (113) for providing instructions to the user for adjusting the height (h) of the contact surface (112); the processor (134) is configured to control the user interface (113) using the generated control signal (S1) to provide instructions to the user to adjust the height (h) of the contact surface (112) to the target height (hT). The control system (130) of claim 1.

3. 2. The control system (130) of claim 1, wherein the height (h) of the contact surface (112) of the ophthalmic imaging device (110) is automatically adjustable by a height adjustment mechanism, and the generated control signal (S1) is configured to cause the height adjustment mechanism to automatically adjust the height (h) of the contact surface (112) to the target height (hT).

4. the value of the first indicator indicates a height at which the eye (101) of the patient (102) was positioned when the one or more images (138) were acquired; the at least one mapping (M) maps each value of the first indicator to a corresponding value of the second indicator such that a height of an imaging axis (114) of the ophthalmic imaging device (110) when the contact surface (112) is positioned at the target height (hT) indicated by the value of the second indicator is less than the height indicated by the value of the first indicator; A control system (130) according to any one of claims 1 to 3.

5. the at least one mapping (M) is dependent on the age of the patient (102) such that for each value of the first indicator, the individual target height (hT) indicated by the corresponding value of the second indicator increases as the patient's age increases; the processor (134) is further configured to receive an indication of the age (Iage) of the patient (102) and map the value of the first indicator to the value of the second indicator using the received indication of age (Iage) and the at least one mapping. The control system (130) of claim 4.

6. the at least one mapping (M) is dependent on a distance (dDS) of the patient (102) from the contact surface (112) such that, for each value of the first indicator, the respective target height (hT) indicated by the corresponding value of the second indicator decreases as the distance (dDS) of the patient (102) from the contact surface (112) increases when the patient (102) is in the position next to the ophthalmic imaging device (110); the processor (134) is further configured to obtain an indication (Idist) of the distance (dDS), and to map the value of the first indicator to the value of the second indicator using the obtained indication (Idist) of the distance (dDS) and the at least one mapping. The control system (130) of claim 4.

7. 7. The control system (130) of claim 6, wherein the processor (134) is configured to obtain the indication (Idist) of the distance (dDS) by processing at least some of the one or more images (138) acquired by the at least one camera (132).

8. a distance sensor (136-1) configured to measure the distance (dDS) of the patient (102) from the contact surface (112) when the patient (102) is in the position next to the ophthalmic imaging device (110); the processor (134) is configured to obtain the indication (Idist) of the distance (dDS) by receiving the measured distance from the distance sensor (136-1); The control system (130) of claim 6.

9. the at least one camera (132) is configured to acquire the one or more images (138) while the patient (102) is seated in a seated position in a seat (400) next to the ophthalmic imaging device (110); the at least one mapping (M) is dependent on the height of the seat (400) such that for each value of the first indicator, the respective target height (hT) indicated by the corresponding value of the second indicator increases as the height of the seat (400) increases; the processor (134) is further configured to obtain an indication of the height (Iseat_h) of the seat (400) and to map the value of the first indicator to the value of the second indicator using the obtained indication of the height (Iseat_h) of the seat (400) and the at least one mapping (M). The control system (130) of claim 4.

10. the contact surface (112) is movable along a horizontal axis (x) toward the head (103) of the patient (102); the control system (130) is further configured to generate a second control signal (S2) for moving the contact surface (112) along the lateral axis (x) to a target lateral position (dT) at which the contact surface (112) should contact the head (103) of the patient (102) during the imaging of the eye (101) of the patient (102) by the ophthalmic imaging device (110); The processor (134): processing the one or more images (138) to generate a value of a third indicator indicative of a separation along the lateral axis (x) between the contact surface (112) and a first lateral position at which the at least a portion of the head (103) is located when the patient (102) is seated in a seated position in a seat (400) next to the ophthalmic imaging device (110); using at least one second mapping (M) to map the value of the third indicator to a value of a fourth indicator indicative of the target lateral position (dT) at which the contact surface (112) should contact the head (103) of the patient (102) during the imaging of the eye (101) of the patient (102) by the ophthalmic imaging device (110); and generating a second control signal (S2) for moving the contact surface (112) to the target lateral position (dT) indicated by the value of the fourth indicator. A control system (130) according to any one of claims 1 to 3.

11. the contact surface (112) is movable along a horizontal axis (x) toward the head (103) of the patient (102); the control system (130) is further configured to generate a second control signal (S2) for moving the contact surface (112) along the lateral axis (x) to a target lateral position (dT) at which the contact surface (112) should contact the head (103) of the patient (102) during the imaging of the eye (101) of the patient (102) by the ophthalmic imaging device (110); the control system (130) further comprises a distance sensor (136-1) configured to generate a value of a third indicator indicative of a separation along the lateral axis (x) between the contact surface (112) and a first lateral position at which the at least a portion (104) of the head (103) is located when the patient (102) is seated in a seated position in a seat (400) beside the ophthalmic imaging device (110); The processor (134): using at least one second mapping (M) to map the value of the third indicator to a value of a fourth indicator indicating a target lateral position (dT) at which the contact surface (112) should contact the head (103) of the patient (102) during the imaging of the eye (101) of the patient (102) by the ophthalmic imaging device (110); and generating a second control signal (S2) for moving the contact surface (112) along the lateral axis (x) to the target lateral position (dT) indicated by the value of the fourth indicator. A control system (130) according to any one of claims 1 to 3.

12. said at least one second mapping (M) maps values ​​of said third indicator to corresponding values ​​of said fourth indicator; the at least one second mapping (M) is dependent on the age of the patient (102) such that, for each value of the first indicator, the individual target lateral position (dT) indicated by the corresponding value of the fourth indicator approaches the first lateral position with increasing age; the processor (134) is further configured to receive an indication of the age (Iage) of the patient (102) and map the value of the third indicator to the value of the fourth indicator using the received indication of the age (Iage) of the patient (102) and the at least one second mapping. The control system (130) of claim 10.

13. A system (100) for imaging an eye (101) of a patient (102), comprising: an ophthalmic imaging device (110) configured to image the eye (101) of the patient (102), the ophthalmic imaging device (110) comprising a height-adjustable contact surface (112) configured to contact the head (103) of the patient (102) during the imaging of the eye (101); a moving mechanism (120) configured to adjust a height (h) at which the height-adjustable contact surface (112) is positioned to a target height (hT) at which the contact surface (112) should contact the head (103) of the patient (102) during the imaging of the eye (101); and a control system (130) according to any one of claims 1 to 3, configured to generate a control signal (S1) for controlling the moving mechanism (120) to adjust the height (h) to the target height (hT).

14. 14. The system (100) of claim 13, wherein the movement mechanism (120) comprises a height-adjustable table (300) configured to support the ophthalmic imaging device (110).

15. The system of claim 14, further comprising at least one sensor (136-1, 136-2, 136-3), each sensor being one of a distance sensor configured to measure a distance to an object to be sensed and a proximity sensor configured to detect the object when the object is within a detection range of the proximity sensor, wherein the at least one sensor (136-1, 136-2, 136-3) and the control system (130) are configured to determine whether at least one of the height-adjustable table (300) or the ophthalmic imaging device (110) has moved within a predetermined distance from the object, and in response to determining that the at least one of the height-adjustable table (300) or the ophthalmic imaging device (110) has moved within the predetermined distance from the object, generate a command to stop adjustment of the height (h) to the target height (hT) being made by the movement mechanism (120).

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