Patent ID: 12201266

DETAILED DESCRIPTION OF EMBODIMENTS

Overview

Accurate position tracking and visualization of a medical instrument are particularly important in surgical procedures carried out in small organs, such as in a patient eye.

Embodiments of the present invention that are described hereinbelow provide improved techniques for tracking and visualizing a medical instrument, which is at least partially obstructed or hidden from view to a surgeon during an ophthalmic surgical procedure.

In some embodiments, an ophthalmic surgical system comprises a location pad having a frame made from a flexible substrate, such as a flexible printed circuit board (PCB), which is configured to be attached to facial tissue surrounding at least part of a patient eye. In some embodiments, the location pad comprises multiple field-generators of a position tracking system (PTS), which are coupled to the frame at respective positions surrounding at least a portion of the eye and are configured to generate respective magnetic fields at least in a region-of-interest (ROI) of the patient eye.

In some embodiments, the ophthalmic surgical system comprises a surgical tool having one or more position sensors of the PTS, which is coupled to the surgical tool, for example in an embodiment, the sensor is coupled with the distal end of the surgical tool, and is configured to sense the magnetic fields. In response to sensing the magnetic fields, the position sensor is configured to produce a position signal indicative of the position of the surgical tool, such as the distal end, in the ROI.

In some embodiments, the ophthalmic surgical system comprises a processor, which is configured to receive one or more of (a) a stereoscopic optical image of the patient eye, (b) an anatomical image, such as a computerized tomography image (CTI), of the patient eye, and (c) a position signal of the PTS. The processor is further configured to register the optical image and the anatomical image in a coordinate system of the PTS, and to estimate the position of the medical instrument in at least one of the optical image and the CTI.

In some embodiments, the ophthalmic surgical system comprises a display, which is configured to visualize the medical instrument overlaid on at least one of the optical image and the CTI. In some cases, eye tissue or any other blocking element, may obstruct or conceal (from the surgeon's view) at a portion of the surgical tool, like the distal end of the surgical tool, at for example, the ROI. In some embodiments, the display comprises an augmented reality display, and the processor is configured to display, on the display, the position of the medical instrument unobstructed. For example, the processor is configured to simultaneously display the optical image surrounding the ROI, and the CTI on the ROI, so as to visualize the estimated position of the surgical tool in the ROI.

In some embodiments, the location pad comprises tracking elements, fixed at predefined positions on the frame for registering the location pad with the patient eye. The tracking elements may comprise infrared light emitting diodes (LEDs), each of which having a different flashing rate. In some embodiments, the augmented reality display comprises a head mount display (HMD) having an image sensor, which is configured to acquire infrared images of the tracking elements during the procedure. Based on the infrared images, the processor is configured to improve the registration between the ROI and the coordinate system of the PTS, so as to improve the accuracy and visualization of the estimated position of the surgical tool during the ophthalmic procedure.

The disclosed techniques improve the quality of a medical procedure carried out in an organ, by visualizing a hidden section of a medical instrument operated within a ROI of the organ. Specifically, the disclosed techniques improve the positioning accuracy of a surgical tool in a small organ.

System Description

FIG.1is a schematic pictorial illustration of an ophthalmic surgical system20, in accordance with an embodiment of the present invention. System20is configured to carry out various types of ophthalmic procedures, such as but not limited to a cataract surgery.

In some embodiments, system20comprises a medical instrument, such as but not limited to a phacoemulsification handpiece or any other suitable type of an ophthalmic surgical tool, referred to herein as a tool55, used by a surgeon24to carry out the ophthalmic surgical procedure. Other surgical tools may comprise an irrigation and aspiration (I/A) handpiece, a diathermy handpiece, a vitrectomy handpiece, and similar instruments.

Reference is now made to an inset21showing a sectional view of the surgical procedure carried out in an eye22of a patient23. In some embodiments, surgeon24applies tool55for treating eye22, in the present example, surgeon24inserts a distal end88of tool55into a region-of-interest (ROI)76of eye22. In the example of inset21, during a cataract surgical procedure, surgeon24inserts tool55below iris tissue99so as to apply phacoemulsification to a lens89of eye22.

In some embodiments, tool55comprises one or more position sensor(s)56of a magnetic position tracking system (PTS) described in detail below. At least one position sensor56may comprise a triple-axis sensor (TAS) made from three coils or a single-axis sensor (SAS) implemented on a printed circuit board (PCB) or using any other suitable technique. Magnetic position sensors are described in further detail, for example in U.S. Pat. Nos. 6,498,944 and 6,690,963, and in U.S. patent Publication No. 2018/0228392, whose disclosures are all incorporated herein by reference. The one or more position sensor(s)56may be located anywhere on tool55, for example, anywhere on a shaft of the tool or a portion of the tool located near the treatment site. In the present example, position sensor56is coupled to distal end88of tool55.

Additionally or alternatively, the PTS may comprise any other suitable type of PTS, such as but not limited to an optical-based PTS or an impedance-based PTS. In such embodiments, at least one position sensor56may have a suitable structure other than the one or more coils described above.

Reference is now made back to the general view ofFIG.1. In some embodiments, system20comprises a location pad40having a frame and a plurality of field-generators shown and described in detail inFIG.2below. In some embodiments, location pad40comprises a flexible substrate, which is configured to be attached to facial tissue (e.g., skin) of patient23. In the context of the present disclosure, and in the claims, using the term “attached” means that, when head41of patient23is moved in a given offset, location pad40is moved in the same offset. In other words, location pad40and head41are considered to be a single rigid body.

In an embodiment, system20comprises the aforementioned magnetic position tracking system, which is configured to track the position of one or more position sensors, such as position sensor56located on tool55that is used for treating eye22, and/or other position sensors coupled to tools inserted into head41, eye22, or into any other organ of patient23. In an embodiment, the magnetic position tracking system comprises magnetic field-generators (not shown) fixed at respective positions of the aforementioned frame of location pad40, whose details are shown and described inFIG.2below.

In some embodiments, position sensor56is configured to generate one or more position signals in response to sensing external magnetic fields generated by the field-generators of location pad40. In some embodiments, a processor34(described in detail below) of system20is configured to estimate, based on the position signals, the position of tool55, e.g. distal end88, within ROI76of eye22.

This method of position sensing is implemented in various medical applications, for example, in the CARTO™ system, produced by Biosense Webster Inc. (Irvine, Calif.) and is described in detail in U.S. Pat. Nos. 5,391,199, 6,690,963, 6,484,118, 6,239,724, 6,618,612 and 6,332,089, in PCT Patent Publication WO 96/05768, and in U.S. Patent Publication Nos. 2002/0065455 A1, 2003/0120150 A1 and 2004/0068178 A1, whose disclosures are all incorporated herein by reference.

In some embodiments, system20comprises a console33, which comprises a memory49, and a driver circuit42configured to drive, via a cable37, the field-generators with suitable signals so as to generate magnetic fields in a predefined working volume, such as in ROI76of eye22.

In some embodiments, console33comprises processor34, typically a general-purpose computer, with suitable front end and interface circuits for receiving the position signals from position sensor56coupled to tool55. In the present example, processor34receives the position signals via a cable32; and may use cable32for exchanging any suitable signals with other components of tool55. Other means of transmitting and receiving signals known in the art are also contemplated, e.g. BLUETOOTH or other wireless connection. Console33further comprises input device39and a display36(which may also be, for example, a keyboard, touch screen graphical user interface, or the like).

In some embodiments, system20comprises an ophthalmic surgical microscope11, such as ZEISS OPMI LUMERA series or ZEISS ARTEVO series supplied by Carl Zeiss Meditec AG (Oberkochen, Germany), or any other suitable type of ophthalmic surgical microscope provided by other suppliers. Ophthalmic surgical microscope11is configured to produce stereoscopic optical images and two-dimensional (2D) optical images of eye22. In some embodiments, system20comprises two cameras25coupled, respectively, to two eyepieces26of ophthalmic surgical microscope11, and configured to acquire two respective optical images of eye22.

In some embodiments, the coupling between cameras25and eyepieces26may be carried out using a suitable jig, or any other suitable method and/or apparatus.

In some embodiments, processor34is configured to receive the optical images from cameras25, via a cable28(although other means of transmitting and receiving signals known in the art may be used), and, based on the received optical images, to display an optical image35on display36. Note that processor34is configured to display in image35: (i) a stereoscopic image by using two separate optical paths with two objectives and eyepieces26to provide slightly different viewing angles to two respective cameras25, or (ii) a 2D optical image, e.g., by using an optical image received from one selected camera25of system20. Note that in most cases surgeon24may prefer using the stereoscopic image in such surgical applications.

As shown in the sectional view of inset21, surgeon24inserts distal end88of tool55below iris tissue99. Therefore, iris tissue99constitutes a blocking element for imaging distal end88in optical image35. In other words, by looking at optical image35on display36, surgeon24cannot see the location of distal end88due to the blocking element within ROI76, so as to accurately emulsify lens89of eye22.

In some embodiments, processor34is configured to receive, from an anatomical imaging system, such as a computerized tomography (CT) system (not shown), a three-dimensional (3D) anatomical image acquired prior to the ophthalmic procedure.

In some embodiments, system20comprises an optical head mount display (HMD)66using augmented reality techniques for visualizing distal end88of tool55overlaid on at least one of optical image35and the anatomical image, as described herein.

Reference is now made to an inset27showing a displayed augmented image described herein. In an embodiment, processor34is configured to select, from the 3D anatomical image, a 2D slice of the anatomical image comprising CT imaging of ROI76, referred to herein as a CT image (CTI)77.

As described above, distal end88of tool55may be invisible in optical image35, for being obstructed by a blocking element (e.g., iris tissue99, any other tissue, or a medical apparatus used in the ophthalmic procedure). In some embodiments, based on optical image35, CTI77, and the position signal received from position sensor56, processor34is configured to display the position of distal end88unobstructed. In the example of inset27, the visualization of distal end88is shown as a dashed line.

In some embodiments, HMD66and console33have wireless devices (not shown) configured to exchange wireless signals54for transferring, inter alia, the aforementioned augmented image and/or any suitable combination of image35, CTI77, and the position signals of position sensor56.

In an embodiment, processor34is configured to display, on HMD66, a visualization of distal end88overlaid on CTI77. In the example of inset27, processor34is configured to replace, in ROI76, the section of the optical image with a corresponding CTI77, or with any other suitable section of a slice of the CT image.

In some embodiments, using the augmented reality techniques, processor34is configured to display iris tissue99(or any other blocking element) transparent, so as to display the position of distal end88unobstructed.

In some embodiments, processor34is configured to register optical image35and the anatomical image (e.g., a slice comprising CTI77) in a common coordinate system, such as a coordinate system of the position tracking system. In other words, processor34receives two or more of the following inputs: (a) the optical (2D or stereoscopic) image from ophthalmic surgical microscope11, (b) the anatomical image from the CT system, and (c) the position signal (generated by position sensor56) from the position tracking system. Subsequently, processor34processes at least some of the received three inputs (for example, by producing optical image35, and/or CTI77, and registers the coordinate systems of optical image35, CTI77and the position signals received from position sensor56, in a common coordinate system (e.g., the coordinate system of the position tracking system).

In some embodiments, after performing the registration process described above, processor34is configured to track the position of distal end88, based on position signals received from one or more position sensor(s)56. Moreover, processor34is configured to visualize the position of distal end88overlaid on at least one of the registered CTI77and optical image35. In the example of inset27, processor34is configured to produce the aforementioned augmented image comprising: (a) CTI77displayed on the section of ROI76, (b) optical image35displaying tool55and eye22surrounding the section of ROI76, and (c) a visualization of distal end88, overlaid on CTI77in the section of ROI76. In the context of the present disclosure and in the claims, the terms “produce” and “generate” are used interchangeably, e.g., for signals and images made by one or more position sensor(s)56, processor34and any other component of system20.

In some embodiments, processor34is configured to transmit the augmented image shown in inset27and described above, to HMD66so that surgeon24can see eye22and a visualization of the estimated position of distal end88of tool55.

In some embodiments, the augmented image shown in inset27, provides surgeon24with a complete visualization of tool55, including distal end88. In other embodiments, in order to optimize the visualization of distal end88during the ophthalmic procedure, processor34is configured to dynamically control the size of ROI76, automatically (e.g., based on the position and/or obstruction of distal end88) or in response to an instruction received from surgeon24using input device39.

In alternative embodiments, HMD66may comprise a processor (not shown), which is configured to carry out at least some of the operations carried out by processor34and described above. In such embodiments, at least some of the signals described above (e.g., optical images from ophthalmic surgical microscope11, CTI77from processor34or the CTI from the CT system, the position signals from position sensor(s)56) may be transmitted directly (wirelessly or via cables) to the processor of HMD66, which may generate and display the augmented image on HMD66. In yet other embodiments, the operations described above may be divided, using any suitable definition, between processor34and the processor of HMD66, so that the augmented image is displayed on HMD66as described in detail above.

This particular configuration of system20is shown by way of example, in order to illustrate certain problems that are addressed by embodiments of the present invention and to demonstrate the application of these embodiments in enhancing the performance of such a system. Embodiments of the present invention, however, are by no means limited to this specific sort of example system, and the principles described herein may similarly be applied to other sorts of ophthalmic and other minimally invasive and surgical systems.

Improving Position Tracking Accuracy Using a Location Pad Surrounding Treated Eye

FIG.2is a schematic pictorial illustration of location pad40used for tracking tool55when treating eye22, in accordance with an embodiment of the present invention. In some embodiments, location pad40comprises a frame46made from a flexible substrate, such as a flexible printed circuit board (PCB), and a plurality of field-generators44coupled with frame46.

In some embodiments, frame46is attached to tissue (e.g., cheek and forehead) that is at least partially surrounding eye22and is configured to place a plurality of field-generators44at respective positions surrounding ROI76. In some embodiments, each field-generator44comprises one or more coils arranged in any suitable configuration, e.g., concentric or non-concentric arrangement. Several configurations of field-generators are implemented in various types of location pads, and are described in detail, for example, in U.S. Patent Publication Nos. 2007/0265526, US2017/0007156, and in U.S. Pat. No. 8,180,430, whose disclosures are all incorporated herein by reference.

In the exemplary configuration shown inFIG.1, pad comprises three field-generators44, but may alternatively comprise any other suitable number of field-generators44.

As described inFIG.1above, the magnetic position tracking system comprises magnetic field-generators44fixed at respective positions of frame46of location pad40. Position sensor56is configured to generate one or more position signals in response to sensing external magnetic fields generated by the field-generators44of location pad40, and processor34is configured to estimate, based on the one or more position signals, the position of distal end88within ROI76of eye22.

In principle, it is possible to use any suitable type of location pad having field-generators generating respective magnetic fields at least in ROI76. For example, U.S. Patent Publication No. 2018/0098816, whose disclosure is incorporated herein by reference, describes a location pad surrounding head41used for ear-nose-throat (ENT) applications. Such location pads, however, do not enable positioning accuracy sufficient for performing a cataract surgical procedure, mainly because of insufficient proximity between the field-generators and the ROI in which the surgeon performs the procedure. For example, a cataract surgery procedure requires a sub-millimeter positioning accuracy, which can be obtained when field-generators44are positioned in close proximity to ROI76. Moreover, any movement of head41may spoil the registration between optical image35, CTI77and position signals produced by position sensor56, and therefore may degrade the quality of the cataract surgical procedure.

In some embodiments shown inFIG.2, location pad40is attached to and conforms to the skin surrounding at least part of eye22. Therefore, location pad40moves together with head41, so that any movement of head41may not spoil the registration described inFIG.1above.

In some embodiments, the close proximity between ROI76and the surrounding field-generators44improves the positioning accuracy of the position sensor(s)56in the coordinate system of the position tracking system. The improved positioning accuracy results in improved overlay accuracy of distal end88visualized on the augmented image described inFIG.1above, and/or the overlay accuracy in at least one of optical image35and CTI77.

In some embodiments, location pad40comprises one or more tracking elements45for registering location pad40with eye22. In the example ofFIG.2, tracking elements45comprise optical tracking elements, such as infrared light emitting diodes (LEDs), each of which having a different flashing rate.

In some embodiments, HMD66comprises an image sensor80, which is configured, to acquire images of the LEDs of tracking elements45, and to send the images (e.g., carried on wireless signals54as described inFIG.1above) to processor34, e.g., during the cataract surgical procedure.

In some embodiments, based on the received images of the LEDs of tracking elements45, processor34is configured to dynamically update (e.g., in real-time) the registration between ROI76and the coordinate system of the PTS (or any other common coordinate system). The real-time registration may improve the quality of the cataract surgical procedure, by improving the accuracy and visualization of the estimated position of distal end88in ROI76.

In other embodiments, location pad40may comprise any other suitable type of LEDs or other sorts of tracking elements. Moreover, in the example ofFIG.2, location pad comprises three tracking elements45, but in other embodiments, location pad40may have any other suitable number tracking elements45, typically but not necessarily, arranged around eye22.

This particular configuration of location pad40is shown by way of example, in order to illustrate certain alignment and/or registration problems that are addressed by embodiments of the present invention and to demonstrate the application of these embodiments in enhancing the performance of system20. Embodiments of the present invention, however, are by no means limited to this specific sort of example location pad and/or system, and the principles described herein may similarly be applied to other sorts of location pads and/or medical systems. For example, inFIG.2frame46has a horseshoe shape partially surrounding eye22and open at the side of the patient nose, in other embodiments, frame46may have any other suitable shape, e.g., a bagel-shape fully surrounding eye22, or a goggles-shape or eye-mask shape comprising two bagel-shaped frames fully surrounding both eyes of patient23.

Moreover, in some embodiments, a substantially identical location pad40may be flipped 180° for being used on the second eye of patient23. In other embodiments, a location pad for the second eye may have a horseshoe shape open at the side of the patient nose, e.g., having a symmetric configuration to that of location pad40.

In other embodiments, the location pad frame may have any other suitable shape and may have any suitable number of at least field-generators44at suitable respective positions. In such embodiments, the location pad may have only field-generators44fixed on the frame. In alternative embodiments, the location pad may have both field-generators44and tracking elements fixed on the frame having any suitable shape.

Producing Location Pad Adapted to be Attached to Tissue Surrounding Patient Eye

FIG.3is a flow chart that schematically illustrates a method for producing location pad40, in accordance with an embodiment of the present invention. The method begins at a step100with receiving one or more field-generators44for generating magnetic fields at least in a ROI of eye22.

At a step102, receiving tracking elements45, such as infrared LEDs or any other suitable tracking elements, for registering location pad40with eye22. At a step104, field-generators44and tracking elements45are fixed to frame46.

In some embodiments, frame46comprises a flexible substrate, such as the aforementioned flexible PCB, which is configured to (a) conform to the shape and geometry of facial tissue surrounding at least part of eye22, and (b) be attached to the facial tissue, so that head41and frame46of location pad40are moving together as a single unit. In such embodiments, when head41is moved by a given offset during the ophthalmic procedure, frame46is moved in the same offset, so that location pad40remains at the same position relative to eye22and/or head41and particularly to ROI76, as described inFIG.2above.

In some embodiments, in step102both field-generators and tracking elements45are fixed to frame46at respective positions surrounding at least a portion of ROI76, and in alternative embodiments, field-generators44and tracking elements45surrounding ROI76. Field-generators44are arranged at first respective positions for obtaining the specified magnetic fields, at least within ROI76. Tracking elements45are arranged at second respective positions for obtaining the specified physical registration between location pad40and ROI76within eye22.

In the example ofFIG.2, the first and second positions differ from one another, but in other embodiments, at least one field-generator44and one tracking element45may be fixed at the same position on frame46.

In alternative embodiments, tracking element45may not be fixed on frame46and only field-generators44may be attached to frame46for producing the respective magnetic fields. This configuration may be used, for example, when not using augmented reality techniques, or when accurate registration between the eye and location pad is not required.

Visualizing Ophthalmic Surgical Tool Overlaid on Registered Anatomical and Optical Images

FIG.4is a flow chart that schematically illustrates a method for augmented-reality visualization of tool55overlaid on registered CTI77and optical image35, in accordance with an embodiment of the present invention. In the description below, the method is implemented on processor34, but in other embodiments, the method may be implemented, mutatis mutandis, on any other suitable type of computing device or system.

The method begins at an anatomical image receiving step200, with processor34receiving one or more anatomical images (e.g., CT images) of patient eye22. As described inFIG.1above, processor34produces CTI77, which is a 2D slice of the anatomical image comprising the CT imaging of ROI76.

At a medical instrument moving step202, after inserting tool55into or onto patient eye22, surgeon24moves tool55to ROI76for treating patient eye22, e.g., for removing the cataract using phacoemulsification.

At a position signal receiving step204, processor34receives, e.g., from position sensor56, a position signal indicative of the position of distal end88of tool55within ROI76, as described inFIG.1above. At an optical image receiving step206, processor34receives, e.g., from ophthalmic surgical microscope11, one or more stereoscopic or 2D optical images of eye22and tool55. In some embodiments, based on the received images, processor34produces optical image35of eye22, as described inFIG.1above.

At a registration step208, processor34registers optical image35and CTI77(or any other suitable type of anatomical image), in a common coordinate system. For example, in the coordinate system of the position tracking system, as described inFIG.1above. At a position estimation step210, processor34estimates, based on the one or more position signals received from position sensor55, the position of distal end88in the registered optical image35and CTI77, as described inFIG.1above.

At an augmented imaging step212, processor34produces the augmented image shown in inset27and described in detail inFIG.1above. In some embodiments, the augmented image comprises CTI77in ROI76, optical image35surrounding ROI76, and a visualization of distal end88overlaid on CTI77shown in ROI76.

At a displaying step214, processor34displays the augmented image (e.g., the image shown in inset27) on HMD66or on any other suitable type of augmented reality display. Note that optical image35also displays tool55shown out of ROI76, therefore, surgeon24can see both tool55and distal end88in the augmented image shown, for example, in inset27ofFIG.1above.

In some embodiments, surgeon24may decide to carry out the procedure at more than one location within eye22. In such embodiments, after displaying step214, the method may loop back to moving step202, in which surgeon24moves distal end88to a different location within eye22. In these embodiments, the position of the ROI within eye22, could be updated relative to the original position of ROI76, in response to the updated position, surgeon24moves tool55as described in step202above, and the method is carried out using the same steps, mutatis mutandis, ofFIG.4.

In some embodiments, in the phacoemulsification procedure after breaking up and evacuating a cloudy lens89from eye22, surgeon24may use ophthalmic surgical microscope11, or any other suitable image acquisition sensor, for inspecting eye22and verifying that eye22does not have residues of lens89. After the verification, surgeon24may extract tool55out of patient eye22and start implanting, in eye22, an intraocular lens (IOL) (not shown) in place of the aspirated lens89.

Although the embodiments described herein mainly address ophthalmic procedures, the methods and systems described herein can also be used in other applications.

It will thus be appreciated that the embodiments described above are cited by way of example, and that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and sub-combinations of the various features described hereinabove, as well as variations and modifications thereof which would occur to persons skilled in the art upon reading the foregoing description and which are not disclosed in the prior art. Documents incorporated by reference in the present patent application are to be considered an integral part of the application except that to the extent any terms are defined in these incorporated documents in a manner that conflicts with the definitions made explicitly or implicitly in the present specification, only the definitions in the present specification should be considered.