Control of height adjustable patient interface for ophthalmic imaging device

Abstract

The invention relates to control of a height adjustable patient interface for an ophthalmic imaging device. A control system comprises at least one camera arranged to acquire one or more images of at least a portion of a subject's head, and a processor arranged 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 is located, a value of the first indicator is mapped to a value of a second indicator indicative of a target height using at least one mapping, and a control signal is generated for adjusting a height at which a height-adjustable contact surface of the ophthalmic imaging device is placed to the target height, during imaging of the eye of the subject by the ophthalmic imaging device. The contact surface will contact the subject's head at the target height.

Description

field

[0001] Example aspects herein relate generally to the field of ophthalmic imaging equipment, and in particular, to mechanisms for adjusting the height of a patient interface (such as a chin rest, head rest, eye shield, etc.) of an ophthalmic imaging device, with the patient's head contacting the patient interface to stabilize the head during imaging. background

[0002] Ophthalmic imaging devices employ various imaging techniques to image different parts of the eye and are used by clinicians to diagnose and manage various eye conditions. Ophthalmic imaging devices include, but are not limited to, scanning laser ophthalmoscopy (SLO), optical coherence tomography (OCT) imaging devices, fundus cameras, microperimetry devices, and corneal topography devices (among other devices), or a combination of two or more such devices. Ophthalmic imaging devices typically include a highly adjustable patient interface (also called a facial interface), such as a chin rest, head rest, or eye shield, having a contact surface against which the patient's head contacts during imaging of the patient's eye. Such a contact surface allows the position of the eye to be set to an approximately correct position relative to the ophthalmic imaging device and helps to keep the subject's head steady during imaging, thereby reducing artifacts in the acquired images caused by movement of the patient's head relative to the device.

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

[0004] Adjustment of the height of the patient interface of an ophthalmic imaging device (so-called "macro alignment") is typically performed manually by an operator monitoring the subject's line of sight while adjusting the height of the patient interface to approximate the height of the line of sight using a mechanical or electromechanical mechanism. This is a time-consuming process and typically needs to be repeated for each subject that requires an operator to perform. Correctly performing this adjustment can be particularly time-consuming and challenging for an operator with limited skills and / or experience. Once macro alignment has been completed and the subject has been engaged with the patient interface, the ophthalmic imaging device can perform an automated micro-alignment process to align its scanning head with the subject's eye. Overview

[0005] According to a first exemplary aspect of the present disclosure, a control system is provided, the control system being configured to generate a control signal for adjusting the height at which a height-adjustable contact surface of an ophthalmic imaging device is positioned to a target height at which the contact surface will contact a subject's head during imaging of the subject's eye by the ophthalmic imaging device. The control system includes at least one camera and a processor, the at least one camera being configured to capture one or more images of at least a portion of the subject's head, the subject being positioned next to the ophthalmic imaging device so as 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, the value of the first indicator indicating the height at which at least a portion of the head was positioned when the one or more images were captured; map the value of the first indicator to a value of a second indicator using at least one mapping, the value of the second indicator indicating the target height at which the contact surface will contact the head during imaging; 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 example 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 to adjust the height of the contact surface. For example, the user interface may comprise at least one of a display for providing visual instructions to the user to adjust the height of the contact surface, and a speaker for providing audio instructions to the user to adjust the height of the contact surface. In an example embodiment, the processor is configured to control the user interface using the generated control signal to provide instructions to the user to adjust the height of the contact surface to a target height.

[0007] In another example 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 arranged to cause the height adjustment mechanism to automatically adjust the height of the contact surface to a target height.

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

[0009] In an example embodiment, wherein the value of a first indicator indicates a height at which the subject's eyes are positioned when acquiring one or more images, and at least one mapping maps each value of the first indicator to a corresponding value of a second indicator such that when the contact surface is set at a target height indicated by the value of the second indicator, the height of the imaging axis of the ophthalmic imaging device is less than the height indicated by the value of the first indicator, at least one camera may be arranged to acquire one or more images while the subject is seated in a seated position on a chair next to the ophthalmic imaging device, at least one mapping may depend on the height of the chair such that for each value of the first indicator, the corresponding target height indicated by the corresponding value of the second indicator increases as the height of the chair increases, and the processor may also be arranged 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 the first example aspect set forth above in any of its example embodiments or variations thereof, the contact surface can be moved in a lateral direction toward the subject's head, the control system can be further arranged to generate a second control signal for moving the contact surface along the lateral axis to a target lateral position at which the contact surface will contact the subject's head during imaging of the subject's eye by the ophthalmic imaging device, and the processor can be further arranged to: process one or more images to generate a value of a third indicator, the value of the third indicator indicating a spacing along the lateral axis between the contact surface and the first lateral position at which at least a portion of the head is placed when the subject is sitting in a seated position on a chair next to the ophthalmic imaging device; map the value of the third indicator to a value of a fourth indicator using at least one second mapping, the value of the fourth indicator indicating the target lateral position at which the contact surface will contact the subject's head during imaging of the subject'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 moved in a lateral direction toward the subject's head, and the control system may be further arranged to generate a second control signal for moving the contact surface along the lateral axis to a target lateral position at which the contact surface will contact the subject's head during imaging of the subject's eye by the ophthalmic imaging device, the control system may further include a distance sensor arranged to generate a value of a third indicator indicating a spacing along the lateral axis between the contact surface and a first lateral position at which at least a portion of the subject's head is placed when the subject is sitting in a seated position on a chair next to the ophthalmic imaging device, and the processor may be further arranged to: use at least one second mapping to map the value of the third indicator to a value of a fourth indicator indicating the target lateral position at which the contact surface will contact the subject's head during imaging of the subject's eye by the ophthalmic imaging device; and 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, at least one second mapping may map the value of the third indicator to a corresponding value of a fourth indicator, at least one second mapping may depend on the age of the subject such that for each value of the third indicator, the corresponding target lateral position indicated by the corresponding value of the fourth indicator is closer to the first lateral position as age increases, and the processor may also be arranged to receive an indication of the age of the subject and use the received indication of the age of the subject and the at least one second mapping to map the value of the third indicator to the value of the fourth indicator.

[0011] According to a second example aspect of this document, a system for imaging an eye of a subject is provided. The system includes an ophthalmic imaging device arranged to image the eye of the subject, the ophthalmic imaging device including a height-adjustable contact surface arranged to contact the subject's head during imaging of the eye. The system also includes a moving mechanism arranged to adjust the height at which the height-adjustable contact surface is placed to a target height, at which the contact surface will contact the subject's head during imaging of the eye. The system also includes a control system according to the first example aspect of this document, the control system being arranged to generate a control signal for controlling the moving mechanism to adjust the height to the target height. The moving mechanism may include a height-adjustable table arranged 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 and a proximity sensor, the distance sensor being arranged to measure the distance to the object, the proximity sensor being arranged to detect the object when the object is within a detection range of the proximity sensor, wherein the at least one sensor and the control system are arranged to determine whether at least one of the height-adjustable worktable or the ophthalmic imaging device has moved within a predetermined distance of the object, and in response to determining that at least one of the height-adjustable worktable or the ophthalmic imaging device has moved within the predetermined distance of the object, generate an instruction to stop the adjustment of the height by the moving mechanism to the target height. Alternatively, the system may further include at least one distance sensor being arranged to measure the distance to the object, wherein the at least one distance sensor and the control system are arranged to determine whether at least one of the height-adjustable worktable or the ophthalmic imaging device will be moved within the predetermined distance of the object during height adjustment by the moving mechanism to the target height, and in response to determining that at least one of the height-adjustable worktable or the ophthalmic imaging device will be moved within the predetermined distance of the object during adjustment, generate a warning for the user.

[0013] Additionally or alternatively, the system may further comprise at least one sensor of the object, each sensor being one of a distance sensor and a proximity sensor, the distance sensor being arranged to measure a distance to the object, the proximity sensor being arranged to detect the object when the object is within a detection range of the proximity sensor, wherein the at least one sensor and the control system are arranged to determine whether the subject is within a predetermined distance of the ophthalmic imaging device, and in response to determining that the subject is within the predetermined distance of the ophthalmic imaging device, controlling at least one camera of the control system to acquire one or more images. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Example embodiments will now be explained in detail, by way of non-limiting example only, with reference to the accompanying drawings described below.Unless otherwise indicated, like reference numerals appearing in different figures of the drawings may represent the same element or a functionally similar element.

[0015] Figure 1 is a schematic diagram of a system for imaging an eye of a subject according to example embodiments herein.

[0016] Figure 2 is a schematic diagram of a control system according to an example embodiment herein.

[0017] Figure 3A is a schematic illustration of a subject seated next to a system for imaging an eye of the subject before the chin rest of the ophthalmic imaging device has been moved to a target position for the subject according to an example embodiment herein.

[0018] Figure 3B is a schematic illustration of a subject seated next to the system of this example embodiment after the chin rest has been moved to a target position.

[0019] Figure 3C is in Figure 3B Schematic diagram of a system of an example embodiment in the same state, and a subject before and after being moved to engage the chin rest.

[0020] Figure 4 is a schematic diagram of programmable signal processing hardware that can be configured to perform the functions of the processor described herein.

[0021] Figure 5 is a flow chart illustrating a process in an example embodiment herein by which a processor of a control system generates a first control signal.

[0022] Figure 6 is a schematic diagram of the first mapping described herein in example table form.

[0023] Figure 7 is a flow chart illustrating a process in an example embodiment herein by which a processor of a control system generates a second control signal.

[0024] Figure 8 is a schematic diagram of the second mapping described herein in example table form.

[0025] Detailed Description of Example Embodiments

[0026] To address the aforementioned issues, the inventors have devised a control system according to an exemplary embodiment, the control system being configured to generate a control signal for adjusting the height at which a height-adjustable contact surface of an ophthalmic imaging device is positioned to a target height at which the contact surface will contact a subject's head during imaging of the subject's eye by the ophthalmic imaging device. The control system includes at least one camera configured to capture one or more images of at least a portion of the subject's head, wherein the subject is positioned adjacent to the ophthalmic imaging device so as to contact 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 for a first indicator, the value of the first indicator indicating the height at which at least a portion of the subject's head was positioned when the one or more images were captured. Instead of automating conventional methods of performing patient interface height adjustment, in which the height difference between the patient interface and the head is determined by an operator and minimized by the operator iteratively adjusting the height of the patient interface and evaluating the height difference resulting from the previous adjustments, the processor of an example embodiment may obtain the target height at which the contact surface will contact the head during imaging in a faster, non-iterative manner by mapping the value of a first indicator to the value of a second indicator indicating a target height for the contact surface using a mapping M, and generating 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. The mapping M may be provided, for example, in the form of a lookup table (LUT) that associates the value of the first indicator with the corresponding value 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 indicating the target height for the contact surface in the LUT.

[0027] In some example embodiments, the mapping may depend on how far (which may be measured, estimated, or assumed) the subject is seated or standing relative to the ophthalmic imaging device, such that adjusting the height of the contact surface to a target height indicated by the value of the second indicator allows the subject to lean forward and engage with the contact surface while remaining comfortable, which may help the subject maintain a more stable eye position during imaging of the eye by the ophthalmic imaging device, thereby reducing motion artifacts in acquired images. The mapping may additionally or alternatively depend on the age of the subject and reflect the observation that older subjects have lower mobility than younger subjects and, in particular, tend to have a more limited ability to adjust the height of their eyes once stabilized in a particular seated posture when engaging with the contact surface of the ophthalmic imaging device compared to younger subjects. Thus, using such a mapping to set the height of the contact surface of the ophthalmic imaging device may allow subjects, particularly older subjects, to maintain a more stable eye position during imaging, thereby reducing motion artifacts in acquired images.

[0028] Figure 1is a schematic diagram of a system 100 for imaging an eye 101 of a (human) subject 102. The system 100 includes an ophthalmic imaging device 110, a movement mechanism 120, and a control system (also referred to as a guidance system) 130.

[0029] The ophthalmic imaging device 110 is arranged to image the eye 101 of the subject 102. As in the present example embodiment, 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. However, the ophthalmic imaging device 110 may be another Fourier domain OCT (FD-OCT) imaging device, such as a spectral domain OCT (SD-OCT) imaging device, or may alternatively be a time domain OCT (TD-OCT) imaging device. However, the ophthalmic imaging device 110 is not limited thereto and may 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 and may alternatively or additionally be arranged to image the anterior segment of the eye 101.

[0030] The OCT imaging device 110 may include well-known components, such as a beam generator, a scanning system, an interferometer, a photodetector, OCT data processing hardware, and a scan head (not shown). The scanning system may be arranged to perform one-dimensional and / or two-dimensional point scanning of a beam on the retina of the eye 101 and collect light that has been scattered by the retina during the point scanning. Thus, the OCT imaging device 110 can acquire A-scans distributed over the surface of the retina at corresponding scanning positions by sequentially illuminating the scanning positions with the beam (one scanning position at a time) and collecting at least some of the light scattered by the retina at each scanning position. The OCT imaging system 110 may be arranged to acquire OCT images in the form of B-scans by performing point scanning, for example, to acquire continuous A-scans along a straight line. Alternatively, however, the OCT imaging system 110 may be arranged to acquire B-scans by performing a scanning system that performs line scanning using hardware well known to those skilled in the art. More generally, the OCT imaging system 110 may be arranged to acquire OCT images in the form of B-scans or C-scans by performing point scanning or line scanning using a predetermined scanning pattern well known to those skilled in the art (e.g., spiral scanning), or by employing a full field of view setting.

[0031] Ophthalmic imaging device 110 includes a height-adjustable patient interface 111 having a contact surface 112 arranged to contact and help hold head 103 of subject 102 steady during imaging of eye 101. Patient interface 111 for this purpose may take one of many different forms.

[0032] For example, as in the present example embodiment, the patient interface 111 may be provided in the form of a chin rest having an upward facing contact surface 112 upon which the chin of the subject 102 rests during imaging of the eye 101 by the ophthalmic imaging device 110 .

[0033] As another example, 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 example embodiments, the forehead rest may be arranged to contact only the forehead of subject 102 when subject 102 is engaged with the forehead rest. In other example embodiments, the forehead rest may be shaped to contact not only the forehead of the subject but also a portion of the subject's face surrounding the eye sockets when subject 102 is engaged with the forehead rest, thereby helping to inhibit lateral movement of head 103 and forward and backward movement of head 103 when subject's head 103 is engaged with the forehead rest. In such other example embodiments, the forehead rest may be shaped to fit around the subject's eye sockets and over the bridge of the nose so as to provide a contact surface on the subject's head 103 that is similar in shape to the contact surface of, for example, a ski mask or a snorkeling mask.

[0034] 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 eye shields (among other possibilities).

[0035] The height h of the contact surface 112 may be adjustable relative to some of the remaining components of the ophthalmic imaging apparatus 110. However, in this example embodiment, the height h of the contact surface 112 is fixed relative to the rest of the ophthalmic imaging apparatus 110 and is adjustable by vertical movement of the ophthalmic imaging apparatus 110 as a whole, specifically by adjusting the height of the top surface of the height-adjustable table (along the Figure 1 The contact surface 112 can be adjusted by upward and downward movement (along the z-axis) of the height adjustable table on which the ophthalmic imaging device 110 rests. The height h is measured relative to a reference height (such as ground plane 200), which can be the floor of the room containing the ophthalmic imaging device 110. As in the present example embodiment, the contact surface 112 can also be (along the Figure 1 1 and 2. The contact surface 112 may be moved horizontally about the x-axis in FIG. 1 (in FIG. 1 ) toward and away from the subject 102 to change its lateral position, as described in detail below, although such horizontal adjustability of the contact surface 112 may not be available in some example embodiments.

[0036] Movement mechanism 120 is arranged to adjust the height h at which height-adjustable contact surface 112 is positioned to a target height at which contact surface 112 will contact head 103 of subject 102 during imaging of eye 101 of subject 102. As in the present example embodiment, movement mechanism 120 may also be arranged to move contact surface 112 horizontally to a target lateral position at which contact surface 112 will contact head 103 of subject 102 during imaging.

[0037] As in the present example embodiment, the moving mechanism 120 may include a height-adjustable table that is arranged to support the ophthalmic imaging device 110 on a top surface of the table. Thus, the ophthalmic imaging device 110 rests on the height-adjustable table. Thus, the height of the top surface of the height-adjustable table is adjustable and, as in the present example embodiment, can also be moved horizontally toward and away from the head 103 of the subject 102. Thus in an example embodiment similar to the present embodiment, in which the contact surface 112 is fixed relative to the rest of the ophthalmic imaging device 110, vertical adjustment of changing the height of the top surface of the table and horizontal adjustment of changing the lateral position of the top surface result in corresponding adjustments of the height of the contact surface 112 and the lateral position of the contact surface 112, respectively. Any suitable height-adjustable table may be used to support the ophthalmic imaging device 110 and, optionally, allow the ophthalmic imaging device 110 to be moved horizontally toward and away from the subject 102 (e.g., A height-adjustable workbench may have a motorized movement mechanism that is controllable by an operator (e.g., via operator-depressible buttons on the workbench or a handheld device) to adjust the height, and optionally also the lateral position, of the top surface of the workbench.

[0038] However, the movement mechanism 120 can be provided in other forms, such as a height-adjustable wall mount (e.g., a height-adjustable wall-mounted arm) that is attached to a wall of a room and arranged to support the ophthalmic imaging device 110 on a height-adjustable top surface of the wall mount. The top surface of the height-adjustable wall mount that supports the ophthalmic imaging device 110 can also be moved horizontally toward and away from the head 103 of the subject 102. Thus, with the contact surface 112 fixed relative to the rest of the ophthalmic imaging device 110, vertical adjustment to change the height of the top surface of the wall mount and horizontal adjustment to change the lateral position of the top surface result in corresponding adjustments to the height and lateral position of the contact surface 112, respectively. The height-adjustable wall mount can include a motorized movement mechanism that can be controlled by an operator (e.g., via a button on the wall mount or a handheld device that can be pressed by the operator) to adjust the height and, optionally, also the lateral position of the top surface of the wall mount.

[0039] Although adjustment of the height and optionally the lateral position of the contact surface 112 is described above as being achieved by moving the ophthalmic imaging device 110 as a whole by a movement mechanism 120 supporting 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 includes the scan head and scanning system, and that portion may be arranged 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 by optically coupling the scanning system to the interferometer, for example, using optical fibers, and providing a mechanism that employs a stepper motor or the like to move the scanning system, scan head, and patient interface 111 including the contact surface 112 relative to the remaining components of the ophthalmic imaging device 110.

[0040] The control system 130 is arranged to generate a first control signal S1 for adjusting the height h to a target height. As in the present example embodiment, the control system 130 may also be arranged to generate a second control signal S2 for horizontally moving the contact surface 112 to change the lateral position of the contact surface 112 to a target lateral position at which the contact surface 112 will contact the head 103 of the subject 102 during imaging of the eye 101 by the ophthalmic imaging device 110. However, the generation of the second control signal S2 by the control system 130 is optional and may be omitted in some example embodiments.

[0041] Figure 2is a schematic diagram showing details of the control system 130. The control system 130 includes at least one camera 132, at least one processor 134, and may also include one or more sensors 136, which are described in more detail below.

[0042] In this example embodiment, the control system 130 includes a single camera 132 arranged to acquire an image 138 of at least a portion 104 of a head 103 of a subject 102, wherein the subject 102 is in a body position next to the ophthalmic imaging device 110 suitable for bringing the head 103 into contact with the contact surface 112 when the contact surface 112 is at a target height, e.g., by the subject 102 leaning forward to engage the patient interface 111. The camera 132 may be a camera of the ophthalmic imaging device 110 having an automatic pupil alignment module (also referred to as a patient alignment module, PAM) for automatically aligning an imaging beam of the imaging device 110 with the pupil during micro-alignment, or the camera 132 may be a dedicated digital camera for use with the control system 130. For example, the subject 102 may be in a seated position on a chair beside the ophthalmic imaging device 110, and after the contact surface 112 has moved to the target height, the subject 102 may contact the contact surface 112 with their head 103 by leaning toward the ophthalmic imaging device 110 to move their head 103 forward from the seated position. Alternatively, and typically where the subject 102 is a child, the subject 102 may be standing beside the ophthalmic imaging device 110 (i.e., in a standing position), and after the contact surface 112 has moved to the target height, the subject 102 may contact the contact surface 112 with their head 103 by leaning toward the ophthalmic imaging device 110 to move their head 103 forward from the standing position. When the subject 102 is in a body position next to the ophthalmic imaging device 110 so that their head 103 is in contact with the contact surface 112 once the contact surface 112 has been set at the target height, the imaged portion 104 of the head 103 can be the portion of the head 103 that is within the field of view (FoV) of the camera 132 (or in example embodiments where there is more than one camera 132, within the combined FoV of two or more cameras).

[0043] Figures 3A to 3C 1 is a schematic diagram of a subject 102 in a seated position next to an ophthalmic imaging device 110 of the system 100 at various stages of a macro alignment process, which will now be described. As described above, in this exemplary embodiment, the movement mechanism 120 of the system 100 is provided in the exemplary form of a height-adjustable table. Figures 3A to 3C It is shown as 300 in FIG. Figures 3A to 3CAlso shown are components of a control system 130, including a camera 132, a processor 134, and sensors 136-1, 136-2, and 136-3 (as Figure 2 ). These figures also schematically illustrate a user interface 113, which the processor 134 is arranged to control in order 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.

[0044] like Figure 3A As shown, the subject 102 is initially seated in a seated position (posture) on a chair 400 next to the ophthalmic imaging device 110, ready to have their eyes 101 imaged while remaining seated on the chair 400. Although in the present example embodiment, the chair 400 is provided in the form of a chair, in other example embodiments, the chair 400 may be, for example, a wheelchair for the subject. With the subject 102 thus seated, the camera 132 acquires an image 138 of the head 103 of the subject 102, for example in response to a start command input to the control system 130 by an operator, or automatically in response to detecting the presence of the subject 102, as described below. The camera 132 is arranged so that its field of view captures the head 103 of the subject 102, while preferably avoiding any portion of the ophthalmic imaging device 110, such as the patient interface 111.

[0045] The processor 134 is arranged to generate a first control signal S1 and optionally a second control signal S2 based on the acquired image 138. The processes by which the processor 134 generates the first control signal S1 and the second control signal S2 are respectively referred to below. Figure 5 and Figure 7 Provide a detailed description.

[0046] As in the present example embodiment, the height h of the contact surface 112 and its lateral position can be adjusted by the operator using any known type of mechanical or operator-controlled electric drive mechanism to move 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 subject 102. In either case, the user interface 113 (which may include a screen viewable by the operator) is controlled by the processor 134 using a first control signal S1 and a second control signal S2 to provide the operator with instructions, such as in the form of "up," "down," "forward," and "backward" direction indicators (e.g., in the form of arrows or triangles), to set the height and lateral position of the contact surface 112 to a target height and target lateral position, respectively. In some example embodiments, the user interface 113 may include a display of the ophthalmic imaging device 110 for controlling the ophthalmic imaging device 110 and viewing acquired images. The user interface 113 may additionally or alternatively include a speaker to provide audio instructions to the user for adjusting the height h and lateral position d of the contact surface 112.

[0047] Alternatively, the control system 130 may use the first control signal S1 and the second control signal S2 to automatically control one or more electric actuators (e.g., motors) that may be included in the height-adjustable workbench 300 to adjust the height h at which the height-adjustable contact surface 112 is located from the initial height h0 to the target height h T (During imaging of the eye 101, the contact surface 112 will be at the target height h T The lateral position of the contact surface 112 (which can be expressed as the distance d from a point on the contact surface 112 to a fixed reference point on the height-adjustable table 300 in the direction along the x-axis toward the subject 102) is adjusted from the initial position at distance d0 to a distance d T Thus, control system 130 can guide patient interface 111 to a position suitable for subject 102 to comfortably engage patient interface 111 .

[0048] Figure 3B The operator is shown adjusting the height and lateral position of the top of the height-adjustable workbench 300 according to instructions provided by the control system 130 via the display and / or speaker of the user interface 113 to correspondingly adjust the height and lateral position of the contact surface 112 to the target height h, respectively. T and distance d TThe user interface 113 may indicate to the operator when the target height and target lateral position of the contact surface 112 have been reached based on the vertical and horizontal movement of the top of the height-adjustable worktable 300, which may be monitored by the control system 130. The subject 102 may be guided to remain seated while the height-adjustable worktable 300 is moved to reduce the risk of the height-adjustable worktable 300 or the ophthalmic imaging device 110 thereon colliding with the subject 102 during macro alignment.

[0049] When the contact surface 112 has been moved to the target height and target lateral position during macro alignment, then, as Figure 3C As shown, the subject 102 aligns with the patient interface 111 by leaning forward to engage the patient interface 111 (in this example embodiment, a chin rest) so that their chin contacts the contact surface 112 on the chin rest. The subject 102 maintains the resulting seated position until imaging of the eye 101 by the ophthalmic imaging device 110 (as well as any prior micro-alignment that may be performed by the ophthalmic imaging device 110 to more closely align the eye 101 (e.g., the center of the pupil) with the imaging axis 114) has been completed. During imaging of the eye 101 by the ophthalmic imaging device 110, there is no further movement of the height-adjustable table 300, and the subject 102 remains as still as possible. As the subject 102 leans forward, the subject's 102 hips generally remain in substantially the same position, with the seat 400 also remaining stationary. Alternatively, the seat 400 may be moved forward by the subject 102, as further described below.

[0050] While the subject 102 adopts a seated position next to the ophthalmic imaging device 110, once the contact surface 112 has been adjusted to be at the target height h T , the head 103 of the subject 102 can then make contact with the contact surface 112 from the seated position by the subject 102 leaning forward to engage the patient interface 111, but the subject 102 need not be seated and may 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, where the ophthalmic imaging device 110 is being used to image the eye of a child, the ophthalmic imaging device 110 may be used with the subject 102 assuming a standing position beside the ophthalmic imaging device 110, the standing position being suitable for bringing the head 103 into contact with the contact surface 112 when the contact surface 112 is at the target height. Accordingly, when the contact surface 112 has been set at the target height, the standing subject 102 can lean forward and make contact with the contact surface 112 during imaging of the eye 101 by the ophthalmic imaging device 110.

[0051] Reference again Figure 2, as in this example embodiment, the processor 134 may also be arranged to receive an indication of the age of the subject 102. age , its use is as follows. For example, the indicator I age The data may be input to processor 134 by an operator, or may be received from an external computer (eg, a PC or server) as part of the subject's patient record.

[0052] As in the present example embodiment, the processor 134 may also be arranged to obtain an indication of the distance of the subject 102 from the contact surface 112 when the subject 102 is in the aforementioned position beside the ophthalmic imaging device 110. dist For example, the processor 134 may be arranged to obtain an indication of distance by processing at least some of the one or more images acquired by the at least one camera 134. dist Where control system 130 includes a single camera 132, processor 134 may use known object detection techniques based on machine learning, such as a Haar cascade classifier, to identify the pupil of the subject's eye in an image acquired by camera 132, use the identified pupil location to determine the interpupillary distance (in pixels) in the image, and then convert the determined interpupillary distance in pixels to an estimate of the distance of the subject's eye from contact surface 112. This conversion may be performed using a mapping in the form of a conversion function or lookup table, for example, obtained by measuring the respective distances (in pixels) of a calibration plate showing two marks spaced approximately 63 mm (the average interpupillary distance for an adult) in each image of a set of images captured by camera 132, where the calibration plate is positioned at different known distances from contact surface 112. If a measured interpupillary distance for subject 102 is input by an operator or otherwise available to processor 134 (e.g., from a patient record for subject 102 retrieved from a remote data storage device), the measured interpupillary distance for subject 102 may be used to refine the estimate. In other example embodiments, where control system 130 includes a stereoscopic vision system having two cameras spaced apart from each other, the two cameras having parallel optical axes, the stereoscopic vision system being arranged to acquire stereoscopic images of subject 102's head 103, processor 134 may estimate the distance of subject 102 from the cameras (and therefore from contact surface 112) by processing the images using well-known techniques for distance estimation from stereoscopic vision.

[0053] As another alternative, as in the present example embodiment, the control system 130 may further include a distance sensor as one of the sensors 136, the distance sensor being arranged to measure the distance of the head 103 or torso of the subject 102 from the contact surface 112 (e.g., a reference point on the contact surface, such as the point on the contact surface closest to the subject 102) when the subject 102 is in the aforementioned position next to the ophthalmic imaging device 110. The processor 134 may be arranged to receive the data from the distance sensor (e.g., at the contact surface) and to receive the data from the ophthalmic imaging device 110. Figures 3A to 3C 136-1 in the figure) receives the measured distance to obtain the indication I dist , which will be described in more detail below. For example, distance sensor 136-1 can be of any known type, such as an ultrasonic sensor, an infrared (IR) distance sensor, or a light detection and ranging (LIDAR) sensor. As in the present example embodiment, distance sensor 136-1 can be located next to patient interface 111 so as to measure the distance d between distance sensor 136-1 (and therefore, equivalently, contact surface 112 of patient interface 111) and head 103 or torso of subject 102. DS In this case, the processor 134 may be arranged to obtain the distance d by receiving the measured distance from the distance sensor 136-1. DS Instructions I dist However, the distance sensor 136-1 may be located elsewhere on the ophthalmic imaging device 110, and the processor 134 may be arranged to correct the distance measured by the distance sensor 136-1 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) to determine the distance d DS .

[0054] Reference again Figure 2 In this example embodiment, the processor 134 may also be arranged to obtain an indication of the height of the seat 400. seat_h , its use will be described below. This instruction I seat_h This may be input to the processor 134 by an operator, or may be obtained from a seat height sensor (not shown) of the control system 130 , which is arranged to measure the height of the seat 400 from the ground 200 and transmit this height to the processor 134 .

[0055] As in this example embodiment, Figure 2The one or more sensors 136 of the control system 130 shown in can include at least one sensor of an object, each sensor being a distance sensor arranged to measure the distance to an object, or a proximity sensor arranged to detect an object when the object is within a detection range of the proximity sensor. For example, the distance sensor can be of any known type, such as an ultrasonic sensor, an infrared (IR) distance sensor, or a light detection and ranging (LIDAR) sensor. Alternatively, the distance sensor can include a digital camera and a processor, the digital camera being arranged to capture an image including the object and another object, the processor being arranged to process the image using any known technique to estimate the distance between the objects. For example, the proximity sensor can be of any known type, such as a contact switch or a contactless proximity sensor (such as an IR or ultrasonic proximity sensor).

[0056] In this exemplary embodiment, three such object sensors are provided, namely the above-mentioned distance sensor 136-1 and Figures 3A to 3C As in this example embodiment, each object sensor and processor 134 of control system 130 may be arranged to determine whether one or both of height-adjustable work table 300 or ophthalmic imaging device 110 has moved within a predetermined distance of an object (e.g., a portion of subject 102 (e.g., a leg), or a portion of seat 400 (e.g., an armrest) when subject 102 is seated on seat 400). Processor 134 uses distance sensor 136-1 to determine whether the portion of ophthalmic imaging device 110 closest to subject 102 (e.g., patient interface 112) has moved within a first predetermined distance of subject 102 (by comparing the distance value measured by distance sensor 136-1 to a first predetermined threshold), proximity sensor 136-2 is arranged to sense whether height-adjustable work surface 300 has moved within a second predetermined distance of subject 102 or chair 400, and proximity sensor 136-3 is arranged to sense whether height-adjustable work surface 300 has moved within a third predetermined distance of subject 102 or chair 400. The first predetermined distance, the second predetermined distance, and the third predetermined distance may be different from one another, but two or more of these predetermined distances may be the same. Each of the proximity sensors 136-2 and 136-3 is also arranged to transmit a corresponding signal to the processor 134 in response to sensing that the height-adjustable workbench 300 or the ophthalmic imaging device 110 (as the case may be) has moved within a corresponding predetermined distance of the subject 102 or the chair 400 (as the case may be).

[0057] Similarly, the processor 134 compares the distance value reported by the distance sensor 136 - 1 with a first predetermined threshold and generates an instruction to stop adjusting the height of the height-adjustable workbench 300 when the reported distance becomes smaller than the first threshold.

[0058] In response to determining that at least one of the height-adjustable worktable 300 and the ophthalmic imaging device 110 (as the case may be) has moved to within a predetermined distance of the object based on a signal received from the object sensor, the processor 134 may generate an instruction to stop the height adjustment to the target height by the movement mechanism 120. For example, the processor 134 may compare the distance value reported by the distance sensor 136-1 with a first predetermined threshold value and generate an instruction when the reported distance becomes less than the first threshold value. The instruction may be displayed on the user interface 113, where the operator adjusts the height of the height-adjustable worktable 300 by operating a mechanical drive mechanism or controlling an electromechanical drive mechanism. Alternatively, the control system 130 may use the instruction to automatically control one or more electrical actuators (e.g., motors) that may be included in the height-adjustable worktable 300.

[0059] In addition to or as an alternative to its use in collision avoidance as described above, the distance sensor 136-1 may be used to initiate imaging of the subject's head 103 by the camera 132. More particularly, the processor 134 of the control system 130 may be arranged to determine whether the subject 102 is within a predetermined distance of the ophthalmic imaging device 110 and, in response to determining that the subject 102 is within the predetermined distance of the ophthalmic imaging device 110, control the camera 132 to acquire the image 138. Imaging of the subject's head 103 by the camera 132 may alternatively be initiated by a proximity sensor arranged to trigger imaging upon detecting the subject 102 within its detection range.

[0060] As an alternative to a reactive approach for avoiding a collision between at least one of the height-adjustable workbench 300 and the ophthalmic imaging device 110 and an object (e.g., a portion of the subject 102 or a portion of the chair 400), a predictive approach for collision avoidance may be employed instead. In this case, at least one distance sensor, such as the distance sensor 136-1, may be provided that is arranged to measure a distance to an object, such as the subject 102, wherein the distance sensor and the control system 130 are arranged to adjust the height h of the contact surface 112 to the target height h by the movement mechanism 120. TDuring the adjustment, it is determined whether at least one of the height-adjustable work table 300 or the ophthalmic imaging device 110 will be moved within a predetermined distance of the object, and a warning is generated for the operator in response to determining that at least one of the height-adjustable work table 300 or the ophthalmic imaging device 110 will be moved within the predetermined distance of the object during the adjustment. For example, the warning may be communicated to the operator via one or both of the display and the speaker of the user interface 113 described above.

[0061] although Figure 2 One or more sensors 136 have been Figures 3A to 3C The sensors 136-1, 136-2, and 136-2 shown in FIG are illustrative, but the present disclosure is not limited to these examples, and any number of sensors of any type 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.

[0062] The data processor 134 may be provided in any suitable form, for example Figure 4 1. The programmable signal processing device 500 includes a processor 520 of the type schematically shown in FIG. Components of the programmable signal processing hardware 500 may be included within the control system 130. The programmable signal processing device 500 includes a communication interface (I / F) 510 for receiving the image 138 from the camera 132 (or, in other example embodiments, multiple images from multiple cameras), and optionally receiving the above-mentioned indication I age , I dist and I seat_h At least one of the above, and a second control signal S2 (if provided) received by the user interface 113 or to the movement mechanism 120, for automatically adjusting the height and lateral position of the contact surface 112, as described above. The signal processing hardware 500 also includes 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 storage device 540 storing a computer program 545, which includes computer-readable instructions that, when executed by the processor 520, cause the processor 520 to perform the various functions of the processor 134 described herein.

[0063] 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 indicating 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 indicating a target height h for the contact surface 112. TThe working memory 530 may also store another mapping, described below, for converting the y-axis component of the pixel position of a pixel in the image 138 to the height of the anatomical feature represented by the pixel. The working memory 530 may alternatively store a mapping in place of the aforementioned mapping that can be used to directly map the y-axis component of the pixel position of a pixel in the image 138 representing an anatomical feature such as the eye 101 to a target height h indicative of the contact surface 112. T The corresponding value of the second indicator.

[0064] The instruction storage device 540 may include a ROM (e.g., in the form of an electrically erasable programmable read-only memory (EEPROM) or flash memory) preloaded with computer-readable instructions. Alternatively, the instruction storage device 540 may include a RAM or similar type of memory, and the computer-readable instructions of the computer program 545 may be input to the instruction storage device 540 from a computer program product (e.g., a non-transitory computer-readable storage medium 550 in the form of a CD-ROM, DVDROM, etc.) or a computer-readable signal 560 carrying the computer-readable instructions. In any 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 this example embodiment may include a computer processor 520 and a memory 540 storing computer-readable instructions that, when executed by the computer processor 520, causes the computer processor 520 to perform the functions of the processor 134 described herein.

[0065] However, it should be noted that the processor 134 may alternatively be implemented in non-programmable hardware (such as an ASIC, FPGA, or other integrated circuit dedicated to performing the functions of the processor 134 described herein), or in such non-programmable hardware and as described above with reference to FIG. Figure 4 Furthermore, in some example embodiments, the programmable signal processing hardware 500 may also perform at least one of the functions of the OCT data processing hardware, or the functions of the controller of the movement mechanism 120 (if provided), if the ophthalmic imaging device 110 is an OCT imaging device.

[0066] Figure 5 is a flow chart illustrating a process by which the processor 134 generates a first control signal S1 for adjusting the height h at which the contact surface 112 is placed to a target height h. T Note that processor 134 may first receive image 138 of head 103 (or portion thereof) and any additional images from camera 132 via, for example, I / F 510 .

[0067] exist Figure 5In process S10, processor 134 processes one or more images acquired by a camera of control system 130 to generate a value of a first indicator that indicates the height at which head 103 (or a portion thereof) in the image was positioned when the one or more images were acquired. As in this example embodiment, processor 134 may generate the value of the first indicator by first identifying eye 101 of subject 102, although in other example embodiments, another anatomical feature of head 103 may be identified, such as an eyebrow, mouth, ear, or chin of subject 102. This may be achieved by using an object detection algorithm well known to those skilled in the art. For example, processor 134 may use a known object detection technique based on machine learning (such as a Haar cascade classifier) ​​to identify the eye in image 138 acquired by camera 132, thereby generating pixel coordinates of eye 101 in image 138.

[0068] 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 the ground plane 200) using a mapping that can be obtained by acquiring a calibration image of a calibration plate with a series of vertically spaced marks (e.g., at regular intervals of, for example, 1 cm) using the camera 132, wherein the plate is located at a distance from the camera 132 that is equal to the typical distance at which the head 103 of the subject 102 will be positioned when the subject 102 is in position to prepare for their eye 101 to be imaged. The y-axis component of each pixel position in the calibration image corresponding to a corresponding one of the marks on the calibration plate can then be correlated to the height of the corresponding mark on the calibration plate (e.g., relative to the (typically horizontal) optical axis of the camera 132 or the ground plane 200). In this example embodiment, the control system 130 includes a distance sensor 136-1 for measuring the distance d between it and the head 103 or torso of the subject 102 (and therefore, equivalently, between the contact surface 112 and the head 103 or torso). DS A set of such calibration images of the calibration plate at different distances along the x-axis from the sensor / patient interface 111 may be captured by the camera 132 to obtain a set of mappings of the type described above, and may be based on the distance d measured by the distance sensor 136-1 during the macro alignment process described above. DS To select the most appropriate mapping from those mappings, the most appropriate mapping will be used to convert the y-axis component of the pixel position of a pixel in image 138 to the relative height of the part of the subject's face represented by the pixel.

[0069] Note that the value of the first indicator can 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) within image 138. In addition, the height of an anatomical feature of head 103 determined as described above (which can be used to provide a measure of the height of head 103) can be used to estimate the height of another anatomical feature on the subject's face using the average height difference between the features that can be derived from a sample of the population. This estimation can be useful in situations where the height of the anatomical feature of interest (e.g., chin) is more difficult to determine from image 138 than another feature (e.g., eye 101, which may have greater contrast in image 138).

[0070] exist Figure 5 In the process S20, the processor 134 uses at least one mapping M to map the value of the first indicator to an indicator target height h T The contact surface 112 will be at the target height h during imaging of the eye 101. T The contact head 103 is located at the bottom. Figure 6 is a diagram of an example mapping M in the form of a table 600. The table 600 includes values ​​X1, X2, ... X with a first indicator. N The first column 601 and the corresponding values ​​Y1, Y2, ... Y with the second indicator N The second column 602 of . However, the form of the mapping M is not limited thereto, and it may instead be provided as a function of multiple variables or a multi-dimensional lookup table, for example, as described in more detail below.

[0071] As in this example embodiment, the mapping M can be each value X of the first indicator i Mapped to the corresponding value Y of the second indicator i , so that when the contact surface 112 is set at the target height h indicated by the value of the second indicator T , 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, each value X of the second indicator corresponding to the first indicator i The corresponding value Y i Can indicate the target height h of the chin rest of the ophthalmic imaging device T , the target height h T This is so that when the subject has leaned forward and placed their chin at the target height h T The chin rest at the top, and thus relative to the value of the first indicator X iWhen the height of their eyes is lowered to the indicated height, the subject's eyes are approximately aligned with the imaging axis 114 (in other words, at a height suitable for acquiring an image of the eye 101 by the ophthalmic imaging device 110, or at a height suitable for performing a micro-alignment of the ophthalmic imaging device 110 with the eye 101, after which the eye 101 can be imaged). This mapping can be based on, for example, an average height difference between the eye and the chin derived from a sample of the population. For example, the height of the imaging axis 114 above the contact surface 112 can similarly be set to correspond to this average height difference. The value of the first indicator X is represented by i The indicated height is aligned with the subject's eyes (or imaging axis 114) when the subject's chin rests at the target height h T The difference between the heights at which the subject's chin is resting on the chin and the height at which the subject's head is resting on the chin can be set to a predetermined value, which can be in the range of 2 cm-10 cm, preferably 3 cm-8 cm, and more preferably 5 cm, to reflect the height at which the subject's head is positioned when the subject (in this case, assuming average height and mobility) leans forward in a manner and to an extent that is comfortable for them (i.e., without effort) to place their head in a position that is different from the position that would follow a relaxed forward lean movement to a posture that the subject can comfortably maintain for the duration of the imaging session. Figure 3C The natural downward movement of the head 103 is shown in FIG.

[0072] The degree to which a subject can lean forward in order to adopt a posture that they can comfortably maintain for the duration of the imaging session can depend on the subject's age, as older subjects (e.g., subjects over 50 years of age) tend to have more limited mobility than younger subjects and are therefore generally able to lean forward less while remaining comfortable. More specifically, the degree of flexion at the hips tends to decrease with increasing age after middle age, and this can reduce the degree to which a person can lean forward and comfortably maintain the resulting position for the duration of imaging of the person's eye, and therefore can also reduce the amount that head height is lowered as the subject leans forward.

[0073] To consider the ideal target height h of the contact surface 112 T In order to determine the corresponding variability among subjects of the same or similar height but different ages, as in the present example embodiment, the map M may depend on the age of the subject 102, such that for each value of the first indicator, the corresponding target height h indicated by the corresponding value of the second indicator is T, increases with increasing age of the subject 102, at least if the age falls within a predetermined range (e.g., 50 years and older). Thus, this dependence of the mapping M on the age of the subject 102 may allow the patient interface 111 to be set to a height that allows the subject to adopt a tilted position that more closely suits their needs and may be more comfortable, and thus further reduces the prevalence of motion artifacts within the image of the eye 101 acquired by the ophthalmic imaging device 110. For example, for a subject between the ages of 50 and 60, the value of the first indicator X may be i The indicated height is the same as the target height h where the subject's chin rests T The difference between the heights at which the subject's eyes (or imaging axis 114) are located when the chin is resting on the chin at the left and right sides of the eye sockets may be 75% of the difference for subjects under 50 years old, and for subjects between 60 and 70 years old, the difference is 75% of the difference for subjects between 60 and 70 years old, as indicated by the value of the first indicator X. i The indicated height is the same as the target height h where the subject's chin rests T The difference between the heights at which the subject's eyes (or imaging axis 114) are located when the chin is resting on the chin at the left and right sides of the eye sockets may be 50% of the difference for subjects under 50 years old, and for subjects older than 70 years old, the difference is determined by the value of the first indicator X. i The indicated height is the same as the target height h where the subject's chin rests T The difference between the heights at which the subject's eyes (or imaging axis 114) are located when the chin is resting at 40°C may be 30% of the difference for subjects under 50 years old.

[0074] As in this example embodiment, the map M may also depend on the distance d of the subject 102 from the contact surface 112 when the subject 102 is in position next to the ophthalmic imaging device 110. DS , so that for each value of the first indicator, the corresponding target height h indicated by the corresponding value of the second indicator T With the distance d DS As the distance d between the subject 102 and the contact surface 112 increases, DS As the height h increases, the amount that the subject 102 must lean forward to contact the contact surface 112 increases, so when the subject 102 leans forward, the target height h of the contact surface 112 increases. T should be reduced to account for the arcuate trajectory of the head 103 (e.g. Figure 3C This allows the target height h of the contact surface 112 to be TConsider different starting positions of the subject 102, as indicated by the position of the chair 400. This is particularly useful if the chair 400 is a wheelchair, as attempting to place the wheelchair in a predetermined position relative to the ophthalmic imaging device 110 each time the ophthalmic imaging device 110 is to be used can be time consuming and inaccurate. As described above, as in this example embodiment, the distance sensor 136-1 can be located next to the patient interface 111 to measure the distance d between the distance sensor 136-1 (and therefore, equivalently, the contact surface 112 of the patient interface 111) and the head 103 or torso of the subject 102. DS .

[0075] In the case where the camera 132 is arranged to acquire the image 138 when the subject is seated at 102 on the chair 400 next to the ophthalmic imaging device 110, as in the present example embodiment, the mapping M may depend on the height of the chair 400, such that for each value of the first indicator, the corresponding target height h indicated by the corresponding value of the second indicator is T As the height of the seat 400 increases. For a given value of the first indicator, the taller the seat 400, the shorter the spine of the subject 102 is likely to be. Since the subject 102 pivots about their hips when leaning forward from a seated position, a shorter spine will provide a higher hip pivot point than a longer spine. Therefore, the target height h indicated by the value of the second indicator is T Increases as the height of the chair 400 increases to reflect the smaller drop in head height for subjects with shorter spines (compared to subjects with longer spines) when the subject leans forward. This may allow the processor 134 to determine a target height h for the contact surface 112 T , does not require a subject with a relatively short spine to lean forward unnecessarily far, and thus may help establish a comfortable position for the subject 102 during imaging of the eye 101 by the ophthalmic imaging device 110. This may further reduce the prevalence of motion artifacts within images of the eye 101 acquired by the ophthalmic imaging device 110.

[0076] Thus, in process S20, as in this example embodiment, processor 134 may use the received indication of age of subject 102 to age , the distance d obtained DS Instructions I dist , and the obtained indication of the height of the seat 400 seat_h (Each as above reference Figure 2), and at least one mapping M to map the value of the first indicator to the value of the second indicator. However, each of the above dependencies of mapping M is an optional improvement to mapping M, and one or more of these dependencies may be omitted. For example, mapping M may depend on the height of chair 400 rather than the distance d from subject 102 to contact surface 112. DS and the age of the subject 102, therefore, the processor 134 may use only the acquired indication of the height of the seat 400. seat_h In this case, processor 134 may not receive an indication of the age of subject 102. age and can be no such as about Figure 2 The distance d is obtained as described DS Instructions I dist .

[0077] exist Figure 5 In the process S30, the processor 220 generates a first control signal S1 for adjusting the height h at which the contact surface 112 is located to a target height h indicated by the value of the second indicator. T The first control signal S1 can be used to adjust the height h at which the contact surface 112 is located to the target height h T , as mentioned above about Figure 2 As stated.

[0078] Figure 7 is a flow chart illustrating a process by which the processor 134 may (as in this example embodiment) generate a second control signal S2 for moving the contact surface 112 along the transverse axis (x-axis) to a target transverse position d T , during imaging of the eye 101 of the subject 102 by the ophthalmic imaging device 110, the contact surface 112 will be at the target lateral position d T The head 103 of the subject 102 is contacted at a certain position. Figure 7 The process shown in Figure 5 The process shown in is performed in parallel, although it can alternatively be Figure 5 Executed after the process in has completed.

[0079] exist Figure 7 In process S100, the processor 134 receives a value of a third indicator from the distance sensor 136-1, which indicates the distance along the horizontal axis (x-axis) between the contact surface 112 and the first lateral position where the head 103 is located when the subject 102 is sitting in a seated position on the chair 400 next to the ophthalmic imaging device 110.

[0080] exist Figure 7In an alternative to process S100, which may be performed in an example embodiment in which the control system 130 includes a stereoscopic vision system having two cameras separated from each other, the two cameras having parallel optical axes, wherein the stereoscopic vision system is arranged to acquire stereoscopic images of the head 103 of the subject 102, the processor 134 may process the images to generate a value of a third indicator that indicates a separation along the transverse axis (x-axis) between the contact surface 112 and a first lateral position at which the imaged portion 104 of the head 103 is positioned when the subject 102 is seated in a seated position on the chair 400 adjacent to the ophthalmic imaging device 110. The processor 134 may estimate the distance of the subject 102 from the cameras (and therefore from the contact surface 112) by processing the images using known techniques for distance estimation from stereoscopic vision.

[0081] exist Figure 7 In the process S200, the processor 134 uses one or more second mappings to map the value of the third indicator to an indicator of the target lateral position d. T , the contact surface 112 will be at the target lateral position d during imaging of the eye 101 of the subject 102 by the ophthalmic imaging device 110. T The first indicator contacts the head 103 of the subject 102. The one or more second mappings map the value of the third indicator to a corresponding value of the fourth indicator. Figure 8 is a diagram of an example second mapping in the form of a table 800. Table 800 includes values ​​A1, A2, ..., A with a third indicator. N The first column 801 and the corresponding values ​​B1, B2, ... B with the fourth indicator N However, the form of the second mapping is not limited thereto, and it may instead be provided as a function of a plurality of variables or a multi-dimensional lookup table, for example.

[0082] It should be noted that the first mapping and the second mapping may form part of a common mapping. That is, in some example embodiments, one or more mappings may receive as input the value of the first indicator and the value of the third indicator, and output the value of the second indicator and the value of the fourth indicator. In this case, the mapping of the value of the first indicator to the value of the second indicator may be a function of the value of the third indicator. Additionally or alternatively, the mapping of the value of the third indicator to the value of the fourth indicator may be a function of the value of the first indicator.

[0083] The at least one second mapping may similarly depend on the age of the subject 102 such that for each value of the third indicator, the corresponding target lateral position d indicated by the corresponding value of the fourth indicator is TAs age increases, the processor 134 moves closer to the first lateral position. age (As reference Figure 2 described) and at least one second mapping mapping the value of the third indicator to the value of the fourth indicator.

[0084] 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 corresponding target lateral position d indicated by the corresponding value of the fourth indicator is T As the height of the seat 400 increases, the seat 400 approaches the first lateral position. seat_h (As reference Figure 2 described) and at least one second mapping mapping the value of the third indicator to the value of the fourth indicator.

[0085] exist Figure 7 In the process S300, the processor 134 generates a second control signal S2 for moving the contact surface 112 to the 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 Figure 2 As stated.

[0086] In the foregoing description, example aspects have been described with reference to several example embodiments. Therefore, the description should be regarded as illustrative rather than restrictive. Similarly, the figures shown in the accompanying drawings, which highlight the features and advantages of the example embodiments, are presented for illustrative purposes only. The architecture of the example embodiments is sufficiently flexible and configurable that it can be utilized in ways other than those shown in the accompanying drawings.

[0087] In one example embodiment, some aspects of the examples given herein (such as the functionality of processor 134) may be provided as a computer program or software, such as one or more programs having instructions or sequences of instructions, included or stored in an article of manufacture, such as a machine-accessible or machine-readable medium, an instruction storage device, or a computer-readable storage device, each of which may be non-transitory. The program or instructions on a non-transitory machine-accessible medium, machine-readable medium, instruction storage device, or computer-readable storage device may be used to program a computer system or other electronic device. The machine-readable medium or computer-readable medium, instruction storage device, and storage device may include, but is not limited to, floppy disks, optical disks, and magneto-optical disks or other types of media / machine-readable media / instruction storage devices / storage devices suitable for storing or transmitting electronic instructions. The techniques described herein are not limited to any particular software configuration. They may find application in any computing or processing environment. As used herein, the terms "computer-readable," "machine-accessible medium," "machine-readable medium," "instruction storage," and "computer-readable storage device" shall include any medium that is capable of storing, encoding, or transmitting instructions or sequences of instructions for execution by a machine, computer, or computer processor and causing the machine / computer / computer processor to perform any of the methods described herein. Furthermore, it is common in the art to refer to software in one form or another (e.g., program, procedure, process, application, module, unit, logic, etc.) as taking an action or causing a result. Such expressions are simply a shorthand way of stating that execution of the software by a processing system causes the processor to perform an action to produce a result.

[0088] Some or all of the functionality of processor 134 may also be implemented by the preparation of application specific integrated circuits, field programmable gate arrays, or by interconnecting an appropriate network of conventional component circuits.

[0089] The computer program product may be provided in the form of one or more storage media, instruction storage means, or storage devices having stored thereon or therein instructions that can be used to control or cause a computer or computer processor to perform any of the processes of the example embodiments described herein. The storage media / instruction storage means / storage devices may include, by way of example and without limitation, optical disks, ROM, RAM, EPROM, EEPROM, DRAM, VRAM, flash memory, flash memory cards, magnetic cards, optical cards, nanosystems, molecular memory integrated circuits, RAID, remote data storage / archiving / warehousing devices, and / or any other type of device suitable for storing instructions and / or data.

[0090] With respect to storage on any one of one or more computer-readable media, instruction storage devices, or storage devices, some embodiments include hardware for controlling the system and software for enabling the system or microprocessor to utilize the results of the example embodiments described herein to interact with a human user or other mechanism. Such software may include, without limitation, device drivers, operating systems, and user applications. Ultimately, as described above, such computer-readable media or storage devices also include software for performing example aspects of the present invention.

[0091] Software modules for implementing the processes described herein are included in the system's programming and / or software. In some example embodiments herein, the modules include software, but in other example embodiments herein, the modules include hardware or a combination of hardware and software.

[0092] Although various exemplary embodiments of the present invention have been described above, it should be understood that they are presented by way of example and not limitation. It will be apparent to those skilled in the relevant art that various changes in form and detail may be made. Therefore, the present invention should not be limited by any of the above exemplary embodiments, but should be defined solely in accordance with the appended claims and their equivalents. It should be understood that any process recited in the claims need not be performed in the order presented.

[0093] Although this specification contains many specific embodiment details, these should not be understood as limitations on the scope of any invention or what may be claimed, but rather as descriptions of features specific to the particular embodiments described herein. Certain features described in this specification 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 individually or in any suitable subcombination. Furthermore, although features may be described above as acting in a particular combination and even initially claimed as such, one or more features from the claimed combination may in some cases be deleted from the combination, and the claimed combination may be directed to subcombinations or variations of subcombinations.

[0094] In some cases, multitasking and parallel processing may be advantageous. In addition, the separation of the various components in the above embodiments should not be understood as requiring such separation in all embodiments, and the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.

[0095] Although many examples presented herein involve specific combinations of devices or software elements, these elements can be combined in other ways to achieve the same purpose. Actions, elements, and features discussed in conjunction with only one embodiment are not intended to be excluded from similar roles in the embodiment or other embodiments.

Claims

1. A control system (130) arranged 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 (h T ), during imaging of the eye (101) of the subject (102) by the ophthalmic imaging device (110), the contact surface (112) will be at the target height (h T ) contacts the head (103) of the subject (102), the control system (130) comprising: At least one camera (132) arranged to acquire one or more images (138) of at least a portion (104) of a head (103) of a subject (102), wherein the subject is positioned beside the ophthalmic imaging device (110) to allow the contact surface to be at the target height (h T ), bringing the head (103) into contact with the contact surface (112); and A processor (134), the processor (134) being arranged to: processing the one or more images (138) to generate a value for a first indicator, the value of the first indicator indicating an altitude at which the at least a portion of the head (103) was positioned when the one or more images (138) were acquired; The first indicator value is mapped to a second indicator value using at least one mapping (M), the second indicator value indicating the target height (h) at which the contact surface (112) is to contact the head (103) during the imaging. T );as well as generating a control signal for adjusting the height (h) at which the contact surface (112) is positioned to the target height (h) indicated by the value of the second indicator; T ).

2. The control system (130) of claim 1, wherein 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 a user for adjusting the height (h) of the contact surface (112), and The processor (134) is arranged to control the user interface (113) using the generated control signal (S1) to provide the user with an option for adjusting the height (h) of the contact surface (112) to the target height (h T ) instruction.

3. The control system (130) of claim 1, wherein: The height (h) of the contact surface (112) of the ophthalmic imaging device (110) can be automatically adjusted by a height adjustment mechanism, and the generated control signal (S1) is arranged to cause the height adjustment mechanism to automatically adjust the height (h) of the contact surface (112) to the target height (h T ).

4. The control system (130) according to any one of the preceding claims, wherein The value of the first indicator indicates the height at which the subject's (102) eyes (101) were positioned when the one or more images (138) were acquired, and The at least one mapping (M) maps each value of the first indicator to a corresponding value of the second indicator such that when the contact surface (112) is positioned at the target height (h T ), the height of the imaging axis (114) of the ophthalmic imaging device (110) is less than the height indicated by the value of the first indicator.

5. The control system (130) of claim 4, wherein The at least one mapping (M) depends on the age of the subject (102), such that for each value of the first indicator, the corresponding target height (h T ) increases as the age of the subject (102) increases, and The processor (134) is further arranged to receive an indication of the age of the subject (102) (I age ), and using the received indication of age (I age ) and the at least one mapping maps the value of the first indicator to the value of the second indicator.

6. A control system (130) according to claim 4 or claim 5, wherein The at least one mapping (M) is dependent on the distance (d DS ), wherein the subject (102) is positioned beside the ophthalmic imaging device (110) such that for each value of the first indicator, the corresponding target height (h T )With the distance (d DS ) increases and decreases, and The processor (134) is further arranged to obtain the distance (d DS ) instructions (I dist ), and using the distance (d DS ) instructions (I dist ) and the at least one mapping (M) maps the value of the first indicator to the value of the second indicator.

7. The control system (130) of claim 6, wherein: The processor (134) is arranged to obtain the distance (d) by processing at least some of the one or more images (138) acquired by the at least one camera (132). DS ) of the instruction (I dist ).

8. The control system (130) of claim 6, further comprising: A distance sensor (136-1) arranged to measure the distance (d) of the subject (102) from the contact surface (112) DS ), wherein the subject (102) is positioned next to the ophthalmic imaging device (110), The processor (134) is arranged to obtain the distance (d) by receiving the measured distance from the distance sensor (136-1). DS ) of the instruction (I dist ).

9. The control system (130) according to any one of claims 4 to 8, wherein The at least one camera (132) is arranged to acquire the one or more images (138) when the subject (102) is seated in a seated position on a chair (400) next to the ophthalmic imaging device (110), The at least one mapping (M) depends on the height of the seat (400), such that for each value of the first indicator, a corresponding target height (h T ) increases as the height of the seat increases, and The processor (134) is further arranged to obtain an indication of the height of the seat (400) (I seat_h ), and using the obtained indication of the height of the seat (400) (I seat_h ) and the at least one mapping (M) maps the value of the first indicator to the value of the second indicator.

10. The control system (130) according to any one of the preceding claims, wherein The contact surface (112) is movable in a transverse direction (x) toward the head (103) of the subject (102), The control system (130) is further arranged to generate a second control signal (S2) for moving the contact surface (112) along the transverse axis (x) to a target transverse position (d T ), during imaging of the eye (101) of the subject (102) by the ophthalmic imaging device (110), the contact surface (112) will be at the target lateral position (d T ) contacts the head (103) of the subject (102), and The processor (134) is further arranged to: processing the one or more images (138) to generate a value of a third indicator indicating a spacing along the transverse axis (x) between the contact surface (112) and a first transverse position at which the at least a portion of the head (103) is positioned when the subject (102) is seated in a seated position on a chair (400) adjacent to the ophthalmic imaging device (110); The value of the third indicator is mapped using at least one second mapping (M) to a value indicating the target lateral position (d T ), the contact surface (112) will be at the target lateral position (d T ) contacts the head (103) of the subject (102); and A second control signal (S2) is generated for moving the contact surface (112) to the target lateral position (d) indicated by the value of the fourth indicator. T ).

11. The control system (130) according to any one of claims 1 to 9, wherein The contact surface (112) is movable in a transverse direction (x) toward the head (103) of the subject (102), The control system (130) is further arranged to generate a second control signal (S2) for moving the contact surface (112) along the transverse axis (x) to a target transverse position (d T ), during imaging of the eye (101) of the subject (102) by the ophthalmic imaging device (110), the contact surface (112) will be at the target lateral position (d T ) contacts the head (103) of the subject (102), The control system (130) further comprises a distance sensor (136-1) arranged to generate a value of a third indicator indicating a spacing along the transverse axis (x) between the contact surface (112) and a first transverse position in which the at least a portion (104) of the head (103) is positioned when the subject (102) is seated in a seated position on a chair (400) next to the ophthalmic imaging device (110), and The processor (130) is further arranged to: The value of the third indicator is mapped to an indicator target lateral position (d) using at least one second mapping (M) T ), the contact surface (112) will be at the target lateral position (d T ) contacts the head (103) of the subject (102); and A second control signal (S2) is generated for moving the contact surface (112) along the transverse axis (x) to the target transverse position (d) indicated by the value of the fourth indicator. T ).

12. A control system (130) according to claim 10 or claim 11, wherein said at least one second mapping (M) mapping a value of said third indicator to a corresponding value of said fourth indicator, The at least one second mapping (M) is dependent on the age of the subject (102) such that for each value of the third indicator, the corresponding target lateral position (d T ) becomes closer to the first transverse position with increasing age, and The processor (134) is further arranged to receive an indication of the age of the subject (102) (I age ), and using the received indication of the age of the subject (102) (I age ) and the at least one second mapping (M) maps the value of the third indicator to the value of the fourth indicator.

13. A system (100) for imaging an eye (101) of a subject (102), comprising: an ophthalmic imaging device (110) arranged to image an eye (101) of a subject (102), the ophthalmic imaging device (110) comprising a height-adjustable contact surface (112) arranged to contact a head (103) of the subject (102) during imaging of the eye (101); A moving mechanism (120) is arranged to adjust the height (h) at which the height-adjustable contact surface (112) is positioned to a target height (h T ), during imaging of the eye (101), the contact surface (112) will be at the target height (h T ) contacts the head (103) of the subject (102); and The control system (130) according to any one of the preceding claims, the control system (130) being arranged to generate a control signal (S1) for controlling the moving mechanism (120) to adjust the height (h) to the target height (h T ).

14. The system (100) of claim 13, wherein: The moving mechanism (120) includes a height-adjustable table (300) arranged to support the ophthalmic imaging device (110).

15. The system (100) of claim 14, further comprising at least one sensor (136-1, 136-2, 136-3) of the object, each sensor being one of a distance sensor and a proximity sensor, the distance sensor being arranged to measure a distance to the object (102; 400), and the proximity sensor being arranged to detect the object (102; 400) 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 arranged to determine whether at least one of the height-adjustable worktable (300) or the ophthalmic imaging device (110) has moved within a predetermined distance of the object, and in response to determining that at least one of the height-adjustable worktable (300) or the ophthalmic imaging device (110) has moved within the predetermined distance of the object, generate an instruction to stop the movement of the moving mechanism (120) to bring the height (h) to the target height (h) T ) adjustments.

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