WO2024011141A2

WO2024011141A2 - Ultrasonic implant and system for measurement of intraocular pressure

Info

Publication number: WO2024011141A2
Application number: PCT/US2023/069658
Authority: WO
Inventors: Aubrey SHAPERO; Pujitha WEERAKOON; Yasha KARIMI; Dwight David Griffin
Original assignee: Iota Biosciences, Inc.
Priority date: 2022-07-06
Filing date: 2023-07-05
Publication date: 2024-01-11
Also published as: WO2024011141A3

Abstract

An implantable device for measuring an intraocular pressure, and methods of using such a device, are described herein. Also described is a system that includes the implantable device and an external device that wirelessly communicates with the implantable device. To power the implantable device, the external device contacts a surface on or near the eye. By contacting the surface on or near the eye, the external device can artificially alter the intraocular pressure. To avoid this artificial pressure skew, the implantable device is configured to measure the intraocular pressure within the eye after the external device has been removed and store the pressure data in a memory for later transmittal to the external device.

Description

ULTRASONIC IMPLANT AND SYSTEM FOR MEASUREMENT OF

INTRAOCULAR PRESSURE

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the priority benefit of U.S. Patent Application Serial No. 63/358,798, filed July 6, 2022, the entire contents of which are incorporated herein by reference for all purposes

FIELD

[0002] The present disclosure relates to devices for sensing and reporting eye conditions, such as intraocular pressure.

BACKGROUND

[0003] Intraocular pressure (IOP) of a patient is typically monitored by an eye care professional to assess whether the patient has or is at risk for developing glaucoma. Glaucoma is an eye disease known to cause damage to the optic nerve, resulting in vision loss. The optic nerve can be affected by high IOP and thus early detection of high IOP is typically used to provide early treatment options for minimizing vision loss associated with high IOP. In general, regular monitoring of IOP can help identify abnormal IOP readings based on IOP trends of a patient. A widely accepted method for accurately measuring IOP requires assistance of an eye care professional to administer anesthetic eye drops, fluorescent dye, and measure intraocular pressure using specialized tonometry equipment. The specialized tonometry equipment includes a tip that is used to flatten the cornea of an eye by applying a calibrated amount of force. The reliance on an eye care professional for IOP monitoring limits the frequency of IOP monitoring to the number of patient visits to an eye care professional.

SUMMARY

[0004] Described herein are devices, systems, and methods that allow for on-demand collection of intraocular pressure (IOP) measurements while reducing measurement error imparted by external pressures on a patient’s eye.

[0005] In some embodiments, an implantable device for measuring an intraocular pressure of an eye, the device comprises a pressure sensor configured to measure intraocular pressure, a wireless communication system, and an integrated circuit electrically coupled to the pressure sensor and the wireless communication system, wherein the implantable device is configured to be implanted within an eye of the patient and wherein the implantable device is configured to: receive power from an external device for a first period of time; measure an intraocular pressure within the eye after the first period of time; store data associated with the intraocular pressure in a memory of the implantable device; and wirelessly transmit the data associated with the intraocular pressure to the external device.

[0006] In some embodiments, the integrated circuit is configured to operate a timer preset with a predetermined time period and wherein said timer is configured to start after the first period of time.

[0007] In some embodiments, the integrated circuit is configured to operate the pressure sensor measure the intraocular pressure when the predetermined time period has ended.

[0008] In some embodiments, the predetermined time period is a maximum relaxation time of compression of the eye.

[0009] In some embodiments, the implantable device is configured to measure the intraocular pressure in the absence of an external pressure on the eye.

[0010] In some embodiments, the integrated circuit is configured to receive power when the external device is positioned at a location proximal to the eye.

[0011] In some embodiments, the integrated circuit is configured to wirelessly transmit the data associated with the intraocular pressure when the external device is repositioned a location proximal to the eye.

[0012] In some embodiments, the memory of the implantable device is a volatile memory.

[0013] In some embodiments, the memory of the implantable device is a non-volatile memory.

[0014] In some embodiments, the implantable device comprises an ultrasonic transducer.

[0015] In some embodiments, the power is transmitted to the implantable device using ultrasonic waves.

[0016] In some embodiments, the integrated circuit is configured to operate the wireless communication system to wirelessly transmit the data associated with the intraocular pressure using ultrasonic backscatter.

[0017] In some embodiments, the integrated circuit is configured to operate the wireless communication system to wirelessly transmit the data associated with the intraocular pressure using actively generated ultrasonic waves.

[0018] In some embodiments, the implantable device comprises a radio frequency antenna. [0019] In some embodiments, the power is transmitted to the implantable device using radio waves.

[0020] In some embodiments, the integrated circuit is configured to control the wireless communication system to wirelessly transmit the data associated with the intraocular pressure using radio wave backscatter.

[0021] In some embodiments, the integrated circuit is configured to control the wireless communication system to wirelessly transmit the data associated with the intraocular pressure using actively generated radio waves.

[0022] In some embodiments, the implantable device further comprises a thermometer configured to measure an internal temperature of the eye, wherein the thermometer is electrically coupled to the integrated circuit and wherein the integrated circuit is configured to: operate the thermometer to measure the internal temperature; store data associated with the internal temperature in the memory of the implantable device; and wirelessly transmit the data associated with the internal temperature to the external device.

[0023] In some embodiments, a system for measuring an intraocular pressure comprises the implantable device and the external device, wherein the external device is configured to transmit power to the implantable device and receive the data associated with the intraocular pressure

[0024] In some embodiments, the external device is a hand-held device.

[0025] In some embodiments, a first method for measuring an intraocular pressure of an eye comprises: receiving, at a device implanted in the eye, power from an external device for a first period of time; measuring, using the device implanted in the eye, an intraocular pressure within the eye after the first period of time; storing data associated with the intraocular pressure in the device implanted in the eye; and wirelessly transmitting the data associated with the intraocular pressure from the device implanted in the eye to the external device.

[0026] In some embodiments, the first method further comprising determining, using the device implanted in the eye, that a predetermined time period has ended prior to measuring the intraocular pressure.

[0027] In some embodiments of the first method, the predetermined time period is based on a maximum relaxation time of compression of the eye.

[0028] In some embodiments of the first method, determining that the predetermined time period has ended comprises starting a timer preset with the predetermined time period.

[0029] In some embodiments of the first method, the intraocular pressure is measured in the absence of an external pressure on the eye. [0030] In some embodiments of the first method, power is received when the external device is placed at a location proximal to the eye.

[0031] In some embodiments of the first method, the data associated with the intraocular pressure is wirelessly transmitted to the external device when the external device is repositioned at a location proximal to the eye.

[0032] In some embodiments of the first method, the power is transmitted from the external device using ultrasonic waves.

[0033] In some embodiments of the first method, the power transmitted from the external device using radio waves.

[0034] In some embodiments of the first method, the data associated with the intraocular pressure is stored in a volatile memory of the device implanted in the eye.

[0035] In some embodiments of the first method, the data associated with the intraocular pressure is stored in a non-volatile memory of the device implanted in the eye.

[0036] In some embodiments of the first method, the data associated with the intraocular pressure is wirelessly transmitted using ultrasonic backscatter.

[0037] In some embodiments of the first method, the data associated with the intraocular pressure is wirelessly transmitted using actively generated ultrasonic waves.

[0038] In some embodiments of the first method, the data associated with the intraocular pressure is wirelessly transmitted using radio wave backscatter.

[0039] In some embodiments of the first method, the data associated with the intraocular pressure is wirelessly transmitted using actively generated radio waves.

[0040] In some embodiments, a method for measuring an intraocular pressure of an eye comprises: positioning an external device at a location proximal to the eye; receiving, at a device implanted in the eye, ultrasonic waves transmitted by the external device; removing the external device from the location proximal to the eye; detecting, at the device implanted in the eye, a termination of the ultrasonic waves received by the device implanted in the eye, wherein the termination indicates the removing of the external device from the location proximal to the eye; determining, using the device implanted in the eye, that a predetermined time period has ended; measuring, using the device implanted in the eye, the intraocular pressure of the eye after the predetermined time period has ended; storing data associated with the intraocular pressure of the eye in a memory in the device implanted in the eye; repositioning the external device at the location proximal to the eye; wirelessly transmitting, using ultrasonic backscatter, the data associated with the intraocular pressure of the eye from the device implanted in the eye to the external device. [0041] In some embodiments of the second method, the device implanted in the eye comprises an ultrasonic detector to detect ultrasonic waves transmitted by the external device. [0042] In some embodiments of the second method, the device implanted in the eye is configured to operate a timer preset to the predetermined time period and wherein the timer is configured to start after the device detects the termination of the ultrasonic waves.

[0043] In some embodiments of the second method, the external device comprises one or more ultrasonic transducers configured to transmit the ultrasonic waves to the device implanted in the eye and receive the ultrasonic backscatter from the device implanted in the eye.

[0044] In some embodiments of the second method, the predetermined time period is based on a maximum relaxation time of compression of the eye.

BRIEF DESCRIPTION OF THE FIGURES

[0045] Various aspects of the disclosed methods and systems are set forth with particularity in the appended claims. A better understanding of the features and advantages of the disclosed methods and systems will be obtained by reference to the detailed description of illustrative embodiments and the accompanying drawings.

[0046] FIG. 1 A shows an exemplary system for measuring intraocular pressure, according to some embodiments.

[0047] FIG. IB shows an exemplary schematic of an exemplary system for measuring intraocular pressure.

[0048] FIG. 2A shows a schematic of an exemplary device, according to some embodiments. [0049] FIG. 2B shows a schematic of an exemplary device, according to some embodiments. [0050] FIG. 2C illustrates an exploded view of the device of FIG. 2B. The exploded view shows the housing of the device detached from the substrate of the device, according to some embodiments.

[0051] FIG. 3A shows an exemplary device having a substrate that includes lateral fasteners, the lateral fasteners are configured in an open position.

[0052] FIG. 3B shows an exemplary device having a substrate that includes lateral fasteners, the lateral fasteners are configured in a closed position.

[0053] FIG. 4A shows a perspective view of an exemplary device having a substrate that includes vertical fasteners.

[0054] FIG. 4B shows a side view of the exemplary device of FIG. 4A. [0055] FIG. 5 A shows an exemplary schematic of an exemplary device implanted within an eye.

[0056] FIG. 5B shows an exemplary cross-sectional schematic of an exemplary device implanted within an eye at an exemplary location.

[0057] FIG. 6A shows an exemplary board assembly for a device, which may be enclosed in a housing.

[0058] FIG. 6B shows an exemplary board assembly for a device, which may be enclosed in a housing.

[0059] FIG. 7 shows a board assembly for a body of a device that includes two orthogonally positioned ultrasonic transducers.

[0060] FIG. 8 shows an interrogator in communication with a device. The interrogator can transmit ultrasonic waves. The device emits an ultrasonic backscatter, which can be modulated by the device to encode information.

[0061] FIG. 9A shows an exemplary housing having an acoustic window that may be attached to the top of the housing, and a port that may be used to fill the housing with an acoustically conductive material.

[0062] FIG. 9B shows an exploded view of a housing may be configured to house a circuit board.

[0063] FIG. 10A shows an exemplary interrogator that can be used with a device.

[0064] FIG. 10B shows an exemplary schematic of an exemplary interrogator.

[0065] FIG. 11 shows a method for measuring intraocular pressure, according to some embodiments.

[0066] FIG. 12 shows a method for measuring intraocular pressure using an ultrasonic implant, according to some embodiments.

[0067] FIG. 13 shows a circuit for an ultrasonic implant, according to some embodiments.

DETAILED DESCRIPTION

[0068] The devices disclosed herein are configured for measuring and communicating IOP data. Implantable systems and devices configured to measure IOP allow a patient to measure eye pressures outside of a clinical setting. However, due to their small size, such devices may need to be charged before measuring the intraocular pressure. Charging or extracting pressure data from the implanted device generally involves placing an external device at a location near the patient’s eye. This can impart an external pressure on the patient’s eye and skew the IOP measurement. As further described herein, to minimize the impact of external pressure placed on or near the eye, a delay may be set between the application of the external device on or near they and the IOP measurement. For example, the implantable device may be configured to receive power from the external device for a first period of time. After the first period of time, the external device may be removed from the location non or near eye, the device is configured to measure the intraocular pressure, and store data associated with measured intraocular pressure (e.g., the pressure data) in a memory of the implantable device. The device may then wirelessly transmit the data to the external device, for example after the external deice has again be placed on or near the eye to allow for the wireless communication. By configuring the device in this manner, there is a dissociation between placement of the external device on or near the eye and the measurement of the intraocular pressure, thereby minimizing the impact of the pressure due to the external device on the intraocular pressure measurement.

[0069] The devices include a pressure sensor configured to measure the intraocular pressure and a wireless communication system, which can communicate to an external device. Further, the device include an integrated circuit coupled to the pressure sensor and the wireless communication system. In some embodiments, the device further includes a substrate, which is configured as a platform for mounting the device within the eye.

[0070] The systems disclosed herein include an implantable device and an external device for measuring and communicating IOP data. The implantable device is configured to be implanted within an eye. From its implanted location, the implantable device is configured to measure IOP data using one or more sensors onboard the implantable device, and communicate the measured IOP data to the external device using the wireless communication system, which may rely on, for example, radiofrequency and/or ultrasonic backscatter communication. The external device is configured to receive the measured IOP data. Optionally, the external device may be configured to measure environmental conditions, determine a final IOP measurement by adjusting the measured IOP data using the measured environmental conditions, and/or communicate the final IOP measurement to a recipient external to both the external device and the implantable device. The implantable device, the external device, and the ultrasonic communication between the device and the interrogator are described further below according to some embodiments.

[0071] The implantable devices, systems, and methods disclosed herein enable quick and efficient monitoring of IOP outside a clinical setting, allowing a patient to measure eye pressure frequently and as desired. The capability of measuring eye pressure frequently and as desired enable an on-demand IOP measurement collection towards the prevention and management of glaucoma, ocular hypertension, and/or vision loss associated with abnormal eye pressures. Regular use of on-demand IOP sensing can be used to identify trends in IOP data for early detection of abnormal (high or low) IOP measurements. Furthermore, the dimensions of the device are configured to enable the device to be implanted within an eye via minimally invasive surgery requiring no sutures or mounted on the eye.

[0072] As used herein, the singular forms “a,” “an,” and “the” include the plural reference unless the context clearly dictates otherwise.

[0073] Reference to “about” a value or parameter herein includes (and describes) variations that are directed to that value or parameter per se. For example, description referring to “about X” includes description of “X”.

[0074] The terms “individual,” “patient,” and “subject” are used synonymously, and refer to a mammal.

[0075] It is understood that aspects and variations of the invention described herein include “consisting” and/or “consisting essentially of’ aspects and variations.

[0076] When a range of values is provided, it is to be understood that each intervening value between the upper and lower limit of that range, and any other stated or intervening value in that states range, is encompassed within the scope of the present disclosure. Where the stated range includes upper or lower limits, ranges excluding either of those included limits are also included in the present disclosure.

[0077] The section headings used herein are for organization purposes only and are not to be construed as limiting the subject matter described. The description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements. Various modifications to the described embodiments will be readily apparent to those persons skilled in the art and the generic principles herein may be applied to other embodiments. Thus, the present invention is not intended to be limited to the embodiment shown but is to be accorded the widest scope consistent with the principles and features described herein.

[0078] The figures illustrate processes according to various embodiments. In the exemplary processes, some blocks are, optionally, combined, the order of some blocks is, optionally, changed, and some blocks are, optionally, omitted. In some examples, additional steps may be performed in combination with the exemplary processes. Accordingly, the operations as illustrated (and described in greater detail below) are exemplary by nature and, as such, should not be viewed as limiting. [0079] In the following description of the disclosure and embodiments, reference is made to the accompanying drawings in which are shown, by way of illustration, specific embodiments that can be practiced. It is to be understood that other embodiments and examples can be practiced, and changes can be made, without departing from the scope of the disclosure.

[0080] Reference will now be made in detail to various embodiments, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

Device for Measuring Intraocular Pressure

[0081] FIG. 1A shows a system 100 for measuring intraocular pressure. The system 100 may be configured to monitor IOP in at least two types of patients: those with early -to-late openangle glaucoma who require regular IOP monitoring and, patients with normal-tension glaucoma with visual field loss who require frequent IOP monitoring. Users of the system may include surgeons implanting or mounting the device, clinicians training and assisting patients in taking IOP measurements, and the patients. In some embodiments, the system 100 may be used in a controlled clinical environment where the clinician can supervise the patient using the system 100. In some embodiments, the system 100 may be used outside a clinical environment, for example in a patient’s home.

[0082] System 100 may comprise an implantable device 104 and an external device 112. As shown, implantable device 104 may be implanted in a patient’s eye 102 and may comprise a integrated circuit 106 (e.g., a digital circuit) that is electrically coupled to a wireless communication device 108 and a pressure sensor 110.

[0083] Optionally, integrated circuit 106 may be configured to receive power from external device 112. In some embodiments, integrated circuit 106 may receive power from external device 112 whenever external device 112 is placed at a location proximal to patient’s eye 102.

[0084] In some embodiments, power may be received by integrated circuit 106 in many different ways. In some embodiments, for instance, integrated circuit 106 may be powered by ultrasonic waves received from external device 112. In such a case, wireless communication device 108 may comprise an ultrasonic transducer which may be controlled by integrated circuit 106. External device 112 may comprise one or more ultrasonic transducers configured to transmit the ultrasonic waves to integrated circuit 106. In some embodiments, integrated circuit 106 may be powered by radio waves received from external device 112. In these cases, wireless communication device 108 may comprise a RF antenna configured to be controlled by integrated circuit 106. External device 112 may comprise an RF antenna configured to transmit the radio waves to integrated circuit 106.

[0085] In some embodiments, after integrated circuit 106 stops receiving power from external device 112, integrated circuit 106 may be configured to control pressure sensor 106 to measure an intraocular pressure of patient’s eye 102. Integrated circuit 106 may be configured to measure the intraocular pressure in the absence of any external pressure on patient’s eye 102. For example, integrated circuit 106 may measure the intraocular pressure after external device 112 has been removed from a location proximal to patient’s eye 102. [0086] In some embodiments, integrated circuit 106 may comprise a timer. Optionally, the timer may be preset with a predetermined time duration. In some embodiments, the timer may be triggered to count down from the predetermined time duration after integrated circuit 106 stops receiving power from external device 112. Integrated circuit 106 may be configured to control pressure sensor 106 to measure an intraocular pressure of patient’s eye 102 after the timer indicates that the predetermined time duration has passed. In some embodiments, the predetermined amount of time may be based on a maximum relaxation time of compression of patient’s eye 102.

[0087] In some embodiments, integrated circuit 106 may store data associated with the intraocular pressure measurement in a memory of implantable device 104. Optionally, implantable device 104 may comprise volatile memory or non-volatile memory. In some embodiments, if implantable device 104 comprises volatile memory, integrated circuit 106 may be required to receive additional power from external device 112 in order to store data associated with the intraocular pressure measurement. After storing the data, integrated circuit 106 may be configured to wirelessly transmit the data associated with the intraocular pressure measurement to external device 112. In some embodiments, integrated circuit 106 may wirelessly transmit the data through ultrasonic backscatter or RF waves.

[0088] In some embodiments, implantable device 104 may comprise one or more additional sensors for measuring properties of patient’s eye 102. The one or more additional sensors may be electrically coupled to integrated circuit 106. For example, implantable device 104 may comprise a thermometer configured to measure an intraocular temperature of patient’s eye 102. In some embodiments, integrated circuit 106 may be configured to control the one or more additional sensors after receiving power from external device 112. In some embodiments, integrated circuit 106 may store data associated with measurements made by the one or more additional sensors in a memory of implantable device 104. [0089] FIG. IB shows another exemplary schematic of an exemplary system 100 for measuring IOP, according to some embodiments. In some embodiments, the system 100 may include an implantable device 104 and an external device 112. The external device 112 may include a computer or graphical display 112a configured to process and display IOP data and a head 112b configured to couple (for example, via ultrasound or radiofrequency) to the implantable device 104. In FIG. IB, the implantable device 104 is implanted inside the lens capsule (i.e., capsular bag) of the patient. The implantable device 104 may measure intraocular pressure data and communicate the measured data to the external device 112. The external device 112 may process the received measured data before communicating a final IOP measurement to a user.

[0090] Optionally, the external device 112 can include an application configured to receive processed data from a cloud backend application 114, supply information to a graphical user interface 112a, and/or enable limited interactions with the ultrasonic external device 112. The cloud backend application 114 may be used for data aggregation and analytics.

[0091] The device can include a substrate configured to interface a surface on or within the eye. The surface of an eye may include a natural surface of the eye or an engineered surface implanted within or mounted on an eye (such as an intraocular lens implanted within an eye, a phakic intraocular lens implanted within an eye, or a contact lens mounted on an eye). In some embodiments, the substrate can include a flexible material configured to interface with the surface of an eye. In some embodiments, the device can include a housing configured to mount onto the substrate of the device and to house a pressure sensor of the device.

[0092] In some embodiments, for example in some embodiments where the wireless communication system is configured to communicate using ultrasonic waves (e.g., ultrasonic backscatter), the housing can include an acoustic window that allows ultrasonic waves to penetrate and equilibrate pressure external and internal to the housing. The equilibration of pressure enables accurate IOP measurements while protecting the sensor within the housing. The device may include an ultrasonic transducer for receiving the ultrasonic waves penetrating the acoustic window and emitting ultrasonic waves through the acoustic window. In some embodiments, the emitted ultrasonic waves include ultrasonic backscatter received at an external device.

[0093] FIG. 2 A shows an exemplary schematic of an exemplary implantable device 104, according to some embodiments. The implantable device 104may be part of an IOP measuring system as shown in system 100. In some embodiments, the implantable device 104 may include a housing 214 that encloses internal components and the housing 214 may be hermetically sealed. In some embodiments, the device 212 may include a substrate 216 configured to attach to and support the housing 214. In some embodiments, the substrate 216 may be an annular member 216 made of a flexible material. In some embodiments, the substrate 216 may be an annular member 216 configured as a tension ring. The annular member 216 may be configured to exert a radially outward force applied to the interfacing surface. For example, the annular member 216 may be compressed during implantation, generating an outward spring force when relaxed after implantation. The resulting outward force exerted by the annular member 216 can help stabilize the device in position after implantation. In some embodiments, the annular member 216 can be made of polymethylmethacrylate (PMMA). In some embodiments, the annular member 216 may have a full or partial ring structure. In some embodiments, annular member 216 can form at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, or at least 95% of a circle, or a complete circle.

[0094] In some embodiments, the ring structure may include a mount (e.g., an inwardly extending portion) 218 configured to mount the housing 214. The mount 218 on the exemplary device sown in FIG. 2A extends inwardly, although in other configurations the mount may extend outwardly or may be positioned on top of the annular member 216. In some embodiments, the size of the annular member 216 may be configured for a particular range of patient eye size. The annular member 216 may include a plurality of apertures 219 that can be used to guide positioning of the device 212 during implantation or mounting. In some embodiments, for an annular member having a partial ring structure, each aperture 219 may be located at an end of the partial ring structure. In some embodiments, one or more of the apertures 19 may be spaced away from an end of the partial ring structure. The apertures 219 may be engaged by an external medical tool (such as a hook, forceps, etc.) for placing the device 212 properly within the eye. In some embodiments, the implantable device 104 may include atop surface 213a, a bottom surface 213b, and a side surface 213c.

[0095] FIG. 2B shows a schematic of an exemplary implantable device 204, according to some embodiments. Implantable device 204 may be part of an IOP measuring system such as system 100. Similar to device 104, device 204 may include a housing 222, a substrate 224, an inwardly extending portion 226, and a plurality of apertures 228. FIG. 2B shows the implantable device 204 interfaced with (e.g., may be mounted about) an intraocular lens 230. When implanted within an eye, the intraocular lens 230 may be the surface within the eye referenced herein. [0096] In some embodiments, the implantable device 204 may be implanted in one of the patient’s eyes during the same surgery for intraocular lens placement. In some embodiments, the implantable device 204 may allow co-placement with an intraocular lens. An example of co-placement of implantable device 204 and an intraocular lens 230 is shown in FIG. 2B. In some embodiments, the device 204 may be co-placed with an intraocular lens (e.g., a commercially available intraocular lens) such that the substrate of the device 204 interfaces the arms (e.g., haptics 232) of the intraocular lens 230. The annular member 224 can exert a radial outward force against the haptics 232 of the intraocular lens 230, which stabilizes the device 204 in position. When the annular member 224 is co-placed with an intraocular lens, the placement of the annular member 224 does not interfere with the line of sight of the eye or the functioning of the intraocular lens. In some embodiments, the housing 222, the substrate 224, and the plurality of apertures 228 may be configured to not interfere with the haptics 232 of the intraocular lens 230.

[0097] In some embodiments, the implantable device 204 or 104 may be co-placed with an intraocular lens such that the top surface 213a of the implantable device 104 or 204 interfaces the intraocular lens 230. In some embodiments, the implantable device 104 or 204 may be coplaced with an intraocular lens such that the bottom surface 213b of the implantable device 104 or 204 interfaces the intraocular lens 230. In some embodiments, the implantable device 104 or 204 may be co-placed with an intraocular lens such that the side surface 213c of the implantable device 104 or 204 interfaces the intraocular lens 230. In some embodiments, the implantable device 104 or 204 may be co-placed with an intraocular lens such that the device interfaces with the haptics of the intraocular lens without interfering with the function of the haptics. In other embodiments, the implantable device 104 or 204 may be implanted within other areas of the eye such the posterior chamber and anterior chamber of the eye. The implantable device 104 or 204 may be configured to maintain functional integrity as an implanted device for at least about 3 years, 4 years, 5 years, 6 years, 7 years, or more.

[0098] FIG. 2C illustrates an exploded view of implantable device 104, according to some embodiments. The exploded view shows the housing 214 detached from the substrate 216, according to some embodiments. As shown in FIG. 2C, the housing 214 may include one or more mounting features 240 (e.g., snaps, clips, outwardly projecting members, etc.) to secure the housing 214 to a mount 218 positioned on the substrate 216 via corresponding features 242 (e.g., receiving snaps, inwardly projecting members, etc.). In some embodiments, the corresponding features 242 may be part of a radially extending portion configured to mount the housing. In some embodiments, the radially extending portion may include sidewalls 244 configured to at least partially cover sidewalls 246 of the housing 214. In some embodiments, a bottom surface 248 of the housing 214 may be configured to interface a surface of the eye when the housing 214 is mounted on the substrate 216 that interfaces with (e.g., is mounted on) the surface on or within the eye, such as an intraocular lens.

[0099] In some embodiments, the substrate 216 may be an annular member. In some embodiments, the substrate 216 may be an annular member that is a tension ring. In some embodiments, when the device 104 is implanted within the capsular bag of an eye, the annular member may be configured to apply a supporting force (i. e. , a tension) to the capsular bag. In some embodiments, the supporting force may be enough to hold the tension ring in place within the eye. In some embodiments, the annular member may be held in place within the eye and retain its shape based on its size and position within the eye within the capsular bag of the eye. In some embodiments, the annular member may interface a perimeter of the capsular bag.

[0100] In some embodiments, the substrate may include fasteners to mount the substrate to the surface within the eye. In some embodiments, the fasteners may include a plurality of lateral clamps. FIGS. 3A and 3B show exemplary devices 300, 400, having a respective housing 310, 410 mounted onto a substrate 320, 420, according to some embodiments. The substrate may have a first side for mounting the substrate to a surface within or an eye. For example, FIG. 3A shows substrate 320 having a first side 322 for mounting within or an eye. The surface within the eye may be, for example, an iris, a lens capsule, an episclera, an intraocular lens implanted within an eye, or a phakic intraocular lens implanted within an eye. The substrate 320, 420 can include lateral clamps. A first lateral clamp 330, 430 can be positioned at one end of the substrate 320, 420 and a second lateral clamp 340, 440 can be positioned at an opposite end of the substrate 320, 420. Each lateral clamp may be shaped by a slit in the substrate and may include an open position in which eye tissue of the surface (such as iris 130) within the eye is positioned within the slit and a closed position in which the eye tissue positioned between the slit is clamped to mount the substrate to the surface within the eye. In some embodiments, the slit may be at least about 0.1, 0.2 mm, or 0.4 mm. In some embodiments, the slit may be at most about 1 mm, 0.8 mm, or 0.6 mm. In some embodiments, the slit may be about 0.1-1 mm, 0.2-0.8, or 0.4-0.6 mm.

[0101] FIG. 3A shows an example of the lateral clamps 330, 340 in an open position in which eye tissue (such as iris tissue 130) or outermost part of a surface may be positioned within slit 342 in the substrate 320, according to some embodiments. In some embodiments, the device 300 may be configured such that during placement of the device 300, a surgeon may move slit walls 344 to clamp onto eye tissue (such as iris tissue 130) within the slit 342. FIG. 3B shows an example of the lateral clamps 430, 440 in a position in which eye tissue or outermost part of a surface may be clamped within a thinner slit 442 (thinner compared, for example, to the slit 342), according to some embodiments. In some embodiments, the device 400 may be configured such that during placement of the device 400, a surgeon may pinch eye tissue (such as iris tissue 130) to feed the pinched eye tissue through the thinner slit 342. In some embodiments, the lateral clamps may be made from polymer. In some embodiments, the positioning slits of slits 342, 442 may be configured to follow the radial grain of the iris fibers 130

[0102] In some embodiments, each slit includes slit walls that are spaced from each other in the open position and the slit walls are movable towards each other for clamping eye tissue in a closed position. For example, slit wall 344 of slit 342 may be configured to clamp onto eye tissue. In some embodiments, the lateral clamps are configured to move from the open position (such as the open position of FIG. 3 A) to a closed position by a force applied during a surgical implantation or procedure. The lateral clamps may remain in the closed position until purposefully moved to an open position by a force applied during a surgical procedure. In some embodiments, each slit may extend into a circular aperture (such as aperture 346) of the substrate.

[0103] In some embodiments, the substrate may be flexible and may be bonded to the rigid housing. In some embodiments, the housing may attach to the substrate by being fixed on an outer surface of the substrate. In some embodiments, the housing may attach to the substrate by extending through substrate. In some embodiments, the substrate may have a second side for attaching a mountable side of the housing to the substrate. For example, FIG. 3 A shows the substrate having a second side 324 on which the housing 310 is mounted.

[0104] In some embodiments, the fasteners may include a plurality of vertical hooks. FIGS. 4A and 4B show an example of an exemplary device 500 mounted onto a substrate 550 having vertical hooks, according to some embodiments. In some embodiments, the vertical hooks may be insert molded. A first vertical hook 552 may be positioned at the one end of the substrate 550 and a second vertical hook 554 may be positioned at the opposite end of the substrate 550. Each vertical hook may be configured to extend from an interior channel 510 of the substrate 550 that holds a first portion of the vertical hook within the substrate 550. A second portion of each vertical hook may extend in a first direction passed the first side 556 of the substrate and away from the first side 556 of the substrate 550. The second portion of each hook may include an end that extends in a second direction, different from the first direction to form a hook shape. For example, hook 554 can include an end 558 configured to catch eye tissue. Each vertical hook having a hook shape may be configured to enter eye tissue for mounting the substrate to the surface within the eye. For example, the hooks 552, 554 are configured to pass through the tissue of an eye surface (such as iris surface 130) to mount the device 500 on the eye surface. When the hooks 552, 554 pass through eye tissue or outermost part of the eye surface, the hooks 552, 554 are configured to prevent the device 500 from being unmounted from the eye surface. In some embodiments, the vertical hooks 552, 554 may be pushed towards the surface within the eye to insert the vertical hooks 552, 554 within the eye tissue. In some embodiments, the vertical hooks may be made from polymer.

[0105] FIG. 5A and FIG. 5B show a schematic of an exemplary device 350 (such as devices 300, 400) having an exemplary substrate 352 (such as 320, 420) for mounting the device 350 within an eye 360 and an exemplary housing 354 (such as 310, 410) for housing internal components of the device, according to some embodiments. FIG. 5A shows an exemplary top-view of the device 350 mounted within the eye 360, according to some embodiments. In other embodiments, the device 350 may be configured to be mounted on an eye. The device 350 may be configured to maintain functional integrity as a mounted or implanted device for at least about 3 years, 4 years, 5 years, 6 years, 7 years, or more.

[0106] FIG. 5A shows possible exemplary locations for minimally invasive incision sites 370 for mounting the device 350 within the eye 360 such that mounted device does not interfere with the line of sight of the eye 360. FIG. 5B shows an exemplary cross-sectional schematic displaying the exemplary device 350 mounted to a surface 380 within the eye 360, according to some embodiments. As shown in FIG. 5B, the surface 380 within the eye 360 may be a top surface of the iris located in anterior chamber of an eye. Mounting the device on the top surface of the iris located in the anterior chamber as shown in FIG. 5B, rather than mounting on a bottom surface of the iris located in the posterior chamber of the eye, is advantageous because there is less risk of damaging the iris during implantation compared to mounting on the bottom surface of the iris. In some embodiments, the surface within the eye may be on or near a pars plana 382 of the ciliary body of the eye.

[0107] In other embodiments, the device may be implanted within the capsular bag. For example, the device may be co-placed with an intraocular lens.

[0108] The device is configured to measure IOP data and encode IOP data via ultrasonic backscatter using internal components of the device, such as one or more sensors, one or more transducers, and an integrated circuit. Exemplary implantable devices that are powered by ultrasonic waves and can emit an ultrasonic backscatter encoding a detected physiological condition are described in WO 2018/009905 Al; WO 2018/009911A1; and WO 2022/035889A1; the contents of each of which are incorporated herein by reference for all purposes.

[0109] An integrated circuit of the device can electrically connect and communicate with the one or more sensors of the device and the wireless communication system (which may include, for example, one or more ultrasonic transducers or radiofrequency antennas). The integrated circuit can include or operate a modulation circuit within the wireless communication system, which modulates an electrical current flowing through the wireless communication system (e.g., one or more ultrasonic transducers) to encode information in the electrical current. The modulated electrical current affects backscatter waves (e.g., ultrasonic backscatter waves) emitted by the wireless communication system, and the backscatter waves encode the information.

[0110] FIG. 6 A shows a side view of an exemplary board assembly of an exemplary device, which may be surrounded by a housing and include an integrated circuit, according to some embodiments. The device includes a wireless communication system (e.g., one or more ultrasonic transducers) 602 and an integrated circuit 604. In the illustrated embodiment, the integrated circuit 604 includes a power circuit that includes a capacitor 606. In the illustrated embodiment, the capacitor is an “off chip” capacitor (in that it is not on the integrated circuit chip), but is still electrically integrated into the circuit. The capacitor can temporarily store electrical energy converted from energy (e.g., ultrasonic waves) received by the wireless communication system, and can be operated by the integrated circuit 604 to store or release energy. The device further includes one or more sensors 608. The one or more sensors can include a pressure sensor. Since ultrasound waves transmitted to and from the device may affect sensor measurements, the one or more sensors of the device may be configured to measure IOP data when ultrasound waves are not being transmitted. The one or more ultrasonic transducers 602, integrated circuit 604, the capacitor 606, and the one or more sensors 608 are mounted on a circuit board 610, which may be a printed circuit board. In some embodiments, the one or more ultrasonic transducers 602, integrated circuit 604, the capacitor 606, and the one or more sensors 608 are adhered on the circuit board 610. In some embodiments, the circuit board 610 may include ports 612a-d. Similar to FIG. 6 A, FIG. 6B shows a side view of an exemplary board assembly that may be enclosed in a housing, according to some embodiments. The board assembly of FIG. 6B includes a piezoelectric transducer 602b and one or more sensors 608b adhered on the circuit board 610b, according to some embodiments.

[OHl] FIG. 13 shows an eye implant circuit 1300 configured to measure an intraocular pressure. In some embodiments, circuit 1300 may be housed in an implantable device such as implantable device described herein. As shown in FIG. 13, circuit 1300 may comprise a transducer 1314, an AC/DC rectifier 1318, a capacitor 1322, a power management unit 1324, an ultrasound detector 1326, a digital circuit 1306, an analog-digital converter 1332, and a pressure sensor 1310. Optionally, circuit 1300 may comprise temperature or other sensors 1334 in addition to pressure sensor 1310.

[0112] In some embodiments, circuit 1300 may receive ultrasonic waves 1312 from an external device. Transducer 1314 may be configured to convert the energy carried by ultrasonic waves 1312 into an electrical signal to power circuit 1300. Optionally, transducer 1314 may be a crystal oscillator (e.g., a piezoelectric transducer). In some embodiments, transducer 1314 may be a crystal oscillator with a frequency greater than or equal to 20, 40, 60, 80, 100, 1000, 10,000, or 100,000 kHz. In some embodiments, transducer 1314 may be a crystal oscillator with a frequency between 20-40, 20-60, 20-80, 20-100, 20-1000, 20-10,000, or 20-100,000 kHz. In some embodiments, an electrical signal generated by transducer 1314 may be transmitted to AC/DC rectifier 1318, where it may be converted from an alternating current (AC) signal to a direct current (DC) signal.

[0113] Optionally, circuit 1300 may comprise a switch 1320 between AC/DC rectifier 1318 and power management unit 1324. In some embodiments, if switch 1320 is open, a DC output from AC/DC rectifier 1318 may be transmitted to capacitor 1322 in order to charge capacitor 1322. In some embodiments, a capacitance of capacitor 1322 may be less than or equal to 0.001, 0.01, 0.1, 1.0, 10, 100, 1000, or 10,000 pF. In some embodiments, a capacitance of capacitor 1322 may be greater than or equal to 0.001, 0.01, 0.1, 1.0, 10, 100, 1000, or 10,000 pF. In some embodiments, a capacitance of capacitor 1322 may be 0-0.001, 0-0.01, 0-0.1, 0-1.0, 0-10, 1.0-10, 10-100, 100-1000, or 1000-10,000 pF.

[0114] In some embodiments, if switch 3120 is closed, a DC signal may be transmitted to power management unit 1324. Power management unit 1324 may be configured to control the flow of electrical energy to analog-digital converter 1332, pressure sensor 1310, and/or temperature or other sensors 1334.

[0115] In some embodiments, analog-digital converter may be configured to convert an electrical signal received from power management unit 1324 to a digital signal to power digital circuit 1306. Optionally, digital circuit may comprise a timer 1328. Timer 1328 may be preset to a time period and may be configured to communicate with ultrasound detector 1326. In some embodiments, ultrasound detector 1326 may be configured transmit a signal to timer 3128 upon detecting a termination of a transmission of ultrasonic waves 1312. Upon receiving a signal from ultrasound detector 1326, timer 3128 may initiate a countdown of the preset time period. Optionally, if ultrasonic detector 1326 detects ultrasonic waves 1312 after timer 1328 has already initiated a countdown, timer 1328 may be configured to reset to the preset time period and begin the countdown again. This may prevent circuit 1300 from measuring an intraocular pressure when an external device is applying external pressure to the patient’s eye.

[0116] In some embodiments, integrated circuit 1306 may be configured to transmit a command 1330 to pressure sensor 1310 to initiate a pressure measurement. Optionally, integrated circuit 1306 may be configured to transmit command 1330 when timer 1328 has concluded a countdown of a preset time period. In some embodiments, upon receiving command 1330, pressure sensor 1310 may be configured to measure an intraocular pressure of the patient’s eye. Optionally, integrated circuit 1306 may be configured to transmit additional commands to additional temperature or other sensor sensors 1334; upon receiving such commands, additional temperature or other sensors 1334 may be configured to collect data such an intraocular temperature.

[0117] In some embodiments, pressure sensor 1310 and additional temperature or other sensors 1334 may be configured to transmit signals comprising data associated with an intraocular pressure measurement and/or other intraocular measurements to analog-digital converter 1332. Analog-digital converter 1332 may convert signals from pressure sensor 1310 and additional temperature or other sensors 1334 to analog signals.

[0118] In some embodiments, AC/DC rectifier 1318 may be configured to convert signals comprising intraocular measurement data to AC signals. Optionally, circuit 1300 may comprise a backscatter switch 1316. In some embodiments, when backscatter switch 1316 is closed, AC signals comprising intraocular measurement data may be transmitted to an external device using ultrasonic backscatter.

[0119] The wireless communication system of the device can be configured to receive instructions for operating the device. The instructions may be transmitted, for example, by a separate device, such as the external device described herein. By way of example, ultrasonic waves received by the implantable device (for example, those transmitted by the external device) can encode instructions for operating the implantable device. The instructions may include, for example, a trigger signal that instructs the device to operate the pressure sensor to detect the intraocular pressure. As further described herein, detection of the intraocular pressure may occur after a period of time (e.g., a predetermined period of time).

[0120] The external device can transmit energy waves (e.g., ultrasonic waves or radiofrequency waves), which are received by the wireless communication system of the implantable device to generate an electrical current flowing through the wireless communication system (e.g., to generate an electrical current flowing through the ultrasonic transducer). The flowing current can then generate backscatter waves that are emitted by the wireless communication system. The modulation circuit can be configured to modulate the current flowing through the wireless communication system to encode the information. For example, the modulation circuit may be electrically connected to an ultrasonic transducer, which received ultrasonic waves from an interrogator. The current generated by the received ultrasonic waves can be modulated using the modulation circuit to encode the information, which results in ultrasonic backscatter waves emitted by the ultrasonic transducer to encode the information. The modulation circuit includes one or more switches, such as an on/off switch or a field-effect transistor (FET). An exemplary FET that can be used with some embodiments of the implantable device is a metal-oxide-semiconductor field-effect transistor (MOSFET). The modulation circuit can alter the impedance of a current flowing through the wireless communication system, and variation in current flowing through the wireless communication system encodes the information. In some embodiments, information encoded in the backscatter waves includes information related to an electrical pulse emitted by the device, or a physiological condition detected by the one or more sensors of the device. In some embodiments, information encoded in the backscatter waves includes a unique identifier for the device. This can be useful, for example, to ensure the interrogator is in communication with the correct implantable device when a plurality of implantable devices is implanted in the subject. In some embodiments, the information encoded in the backscatter waves includes a verification signal that verifies an electrical pulse was emitted by the device. In some embodiments, the information encoded in the backscatter waves includes an amount of energy stored or a voltage in the energy storage circuit (or one or more capacitors in the energy storage circuit). In some embodiments, the information encoded in the backscatter waves includes a detected impedance. Changes in the impedance measurement can identify scarring tissue or degradation of the electrodes over time.

[0121] In some embodiments, the modulation circuit is operated using a digital circuit or a mixed-signal integrated circuit (which may be part of the integrated circuit), which can actively encode the information in a digitized or analog signal. The digital circuit or mixed- signal integrated circuit may include a memory and one or more circuit blocks, systems, or processors for operating the implantable device. These systems can include, for example, an onboard microcontroller or processor, a finite state machine implementation, or digital circuits capable of executing one or more programs stored on the implant or provided via ultrasonic communication between interrogator and implantable device. In some embodiments, the digital circuit or a mixed-signal integrated circuit includes an analog-to- digital converter (ADC), which can convert analog signal encoded in the ultrasonic waves emitted from the interrogator so that the signal can be processed by the digital circuit or the mixed-signal integrated circuit. The digital circuit or mixed-signal integrated circuit can also operate the power circuit, for example to generate the electrical pulse to operate the pressure sensor to detect IOP. In some embodiments, the digital circuit or the mixed signal integrated circuit receives the trigger signal encoded in the ultrasonic waves transmitted by the interrogator, and operates the power circuit to discharge the electrical pulse in response to the trigger signal.

[0122] In some embodiments, the one or more sensors 608 may a pressure sensor configured to measure IOP. The pressure sensor may implement capacitive or resistive pressure sensing. The measurement accuracy of the pressure sensor may be at least 0. 1 mmHg, 0.2 mmHg, 0.3 mmHg, 0.4 mmHg, or 0.5 mmHg. The measurement accuracy of the pressure sensor may be at most 1.0 mmHg, 0.9 mmHg, 0.8 mmHg, 0.6 mmHg, or 0.7 mmHg. The measurement accuracy of the pressure sensor may be 0.1-1.0mm Hg, 0.2-0.9 mm Hg, 0.3-0.8 mm Hg, 0.4- 0.7 mm Hg, or 0.5-0.6 mmHg. In some embodiments, the measurement accuracy of the pressure sensor may be over a range of 1 mmHg to 70 mmHg, 3 mmHg to 60 mmHg, or 5 mmHg to 50 mmHg. In some embodiments, the pressure sensor may have a sensitivity of about 10 pV/V/mmHg, 20 pV/V/mmHg, or 30 pV/V/mmHg. In some embodiments, the pressure sensor may have a sensitivity requirement dependent on the sensitivity of the readout electronics. In some embodiments, the pressure sensor may have a measurement accuracy and sensitivity range dependent on the sensitivity of the readout electronics.

[0123] In some embodiments, the pressure sensor may be temperature sensitive. The pressure sensor may be calibrated based on a temperature response of the temperature sensor. The calibration may be configured to ensure that a difference in pressure output of the pressure sensor is an actual different in pressure and not an artifact of a change in temperature.

[0124] In some embodiments, the one or more sensors may include a temperature sensor configured to measure an anterior chamber temperature of an eye. In some embodiments, the temperature sensor may have an accuracy of about 0.1-1 °C, 0.2-0.8 °C, or 0.3-0.6 °C. In some embodiments, the temperature sensor may monitor a range of temperature inside the eye from about 28 °C to 46 °C, 30 °C to 44 °C, or 32 °C to 40 °C. In some embodiments, the temperature sensor data may be used for compensation purposes to increase accuracy of the final pressure measurement.

[0125] Both the pressure data from the pressure sensor and temperature data from the temperature sensor may be reported to the external device. The reported pressure data and the reported temperature data may be an averaged or processed result taken from multiple discrete measurements from the corresponding sensor. The data (e.g., pressure data and/or temperature data) may be stored in a memory, and can be wirelessly communicated to the external device after communication is re-established with the external device.

[0126] In some embodiments, the wireless communication system includes one ultrasonic transducer that is an ultrasonic transceiver configured to convert mechanical energy from ultrasound waves to electrical current and vice versa. The ultrasonic transducer may be capable of harvesting energy originating from an external ultrasonic interrogator and capable of producing a modulation depth detectable by an external interrogator.

[0127] In some embodiments, the wireless communication system includes one or more ultrasonic transducers, such as one, two, or three or more ultrasonic transducers. In some embodiments, the wireless communication system includes a first ultrasonic transducer having a first polarization axis and a second ultrasonic transducer having a second polarization axis, wherein the second ultrasonic transducer is positioned so that the second polarization axis is orthogonal to the first polarization axis, and wherein the first ultrasonic transducer and the second ultrasonic transducer are configured to receive ultrasonic waves that power the device and emit an ultrasonic backscatter. In some embodiments, the wireless communication system includes a first ultrasonic transducer having a first polarization axis, a second ultrasonic transducer having a second polarization axis, and a third ultrasonic transducer having a third polarization axis, wherein the second ultrasonic transducer is positioned so that the second polarization axis is orthogonal to the first polarization axis and the third polarization axis, wherein the third ultrasonic transducer is positioned so that the third polarization axis is orthogonal to the first polarization and the second polarization axis, and wherein the first ultrasonic transducer and the second ultrasonic transducer are configured to receive ultrasonic waves that power the device and emit an ultrasonic backscatter. FIG. 7 shows a board assembly of a device that includes two orthogonally positioned ultrasonic transducers. The device includes a circuit board 702, such as a printed circuit board, and an integrated circuit 704, which a power circuit that includes a capacitor 706. The device further includes a first ultrasonic transducer 708 electrically connected to the integrated circuit 704, and a second ultrasonic transducer 710 electrically connected to the integrated circuit 704. The first ultrasonic transducer 708 includes a first polarization axis 712, and the second ultrasonic transducer 710 includes a second polarization axis 714. The first ultrasonic transducer 708 and the second ultrasonic transducer are positioned such that the first polarization axis 712 is orthogonal to the second polarization axis 714.

[0128] The one or more ultrasonic transducers, if included in the wireless communication system, can be a micro-machined ultrasonic transducer, such as a capacitive micro-machined ultrasonic transducer (CMUT) or a piezoelectric micro-machined ultrasonic transducer (PMUT), or can be a bulk piezoelectric transducer. Bulk piezoelectric transducers can be any natural or synthetic material, such as a crystal, ceramic, or polymer. Exemplary bulk piezoelectric transducer materials include barium titanate (BaTiOs), lead zirconate titanate (PZT), zinc oxide (ZO), aluminum nitride (AIN), quartz, berlinite (AIPO4), topaz, langasite (LasGasSiOir), gallium orthophosphate (GaPOr). lithium niobate (LiNbOs), lithium tantalite (LiTaOs), potassium niobate (KNbOs), sodium tungstate (Na2WOs), bismuth ferrite (BiFeOs), poly vinylidene (di)fluoride (PVDF), and lead magnesium niobate-lead titanate (PMN-PT).

[0129] In some embodiments, the bulk piezoelectric transducer is approximately cubic (i.e. , an aspect ratio of about 1:1:1 (length: width:height). In some embodiments, the piezoelectric transducer is plate-like, with an aspect ratio of about 5:5:1 or greater in either the length or width aspect, such as about 7:5:1 or greater, or about 10: 10:1 or greater. In some embodiments, the bulk piezoelectric transducer is long and narrow, with an aspect ratio of about 3:1:1 or greater, and where the longest dimension is aligned to the direction of the ultrasonic backscatter waves (i.e., the polarization axis).

[0130] In some embodiments, one dimension of the bulk piezoelectric transducer is equal to one half of the wavelength (Z) corresponding to the drive frequency or resonant frequency of the transducer. At the resonant frequency, the ultrasound wave impinging on either the face of the transducer will undergo a 180° phase shift to reach the opposite phase, causing the largest displacement between the two faces. In some embodiments, the piezoelectric crystal may be assembled into the housing such that its poled direction is perpendicular to an acoustic window.

[0131] In some embodiments, the height of the piezoelectric transducer is about 10 pm to about 1000 pm (such as about 40 pm to about 400 pm, about 100 pm to about 250 pm, about 250 pm to about 500 pm, or about 500 m to about 1000 pm). In some embodiments, the height of the piezoelectric transducer is about 5 mm or less (such as about 4 mm or less, about 3 mm or less, about 2 mm or less, about 1 mm or less, about 500 pm or less, about 400 pm or less, 250 pm or less, about 100 pm or less, or about 40 pm or less). In some embodiments, the height of the piezoelectric transducer is about 20 pm or more (such as about 40 pm or more, about 100 pm or more, about 250 pm or more, about 400 pm or more, about 500 pm or more, about 1 mm or more, about 2 mm or more, about 3 mm or more, or about 4 mm or more) in length. In some embodiments, the ultrasonic transducer has a length of about 5 mm or less such as about 4 mm or less, about 3 mm or less, about 2 mm or less, about 1 mm or less, about 500 pm or less, about 400 pm or less, 250 pm or less, about 100 pm or less, or about 40 pm or less) in the longest dimension. In some embodiments, the ultrasonic transducer has a length of about 20 pm or more (such as about 40 pm or more, about 100 pm or more, about 250 pm or more, about 400 pm or more, about 500 pm or more, about 1 mm or more, about 2 mm or more, about 3 mm or more, or about 4 mm or more) in the longest dimension.

[0132] In some embodiments the micro-machined piezoelectric crystal can have dimensions of about at least 0.3 micrometer x 0.3 micrometer x 0.1 micrometer. In some embodiments, the piezoelectric crystal can have dimensions of about at most 1.2 micrometer x 1.2 micrometer x 0.6 micrometer. In some embodiments, the piezoelectric crystal can have dimensions of about 0.3-1.2 micrometer x 0.3-1.2 micrometer x 0.1-0.6 micrometer.

[0133] The one or more ultrasonic transducers, if included in the wireless communication system, can be connected to two electrodes to allow electrical communication with the integrated circuit. The first electrode is attached to a first face of the transducer and the second electrode is attached to a second face of the transducer, wherein the first face and the second face are opposite sides of the transducer along one dimension. In some embodiments, the electrodes comprise silver, gold, platinum, platinum-black, poly (3 ,4- ethylenedioxythiophene (PEDOT), a conductive polymer (such as conductive PDMS or polyimide), or nickel. In some embodiments, the axis between the electrodes of the transducer is orthogonal to the motion of the transducer.

[0134] The wireless communication system may be used to wireless receive the energy, or a separate system may be configured to receive the energy. For example, an ultrasonic transducer (which may be an ultrasonic transducer contained within the wireless communication system or a different ultrasonic transducer) can be configured to receive ultrasonic waves and convert energy from the ultrasonic waves into an electrical energy. The electrical energy is transmitted to the integrated circuit to power the device. The electrical energy may power the device directly, or the integrated circuit may operate a power circuit to store the energy for later use.

[0135] In some embodiments, the integrated circuit may be configured to control the harvesting of energy from the received ultrasonic waves, power the one or more sensors, and encode the eye-related data collected by the one or more sensors using backscatter modulation. The encoding of the eye-related data includes digitizing the eye-related data collected by the one or more sensors and modulating the characteristics of electrical current within the device for digital backscatter communication with the external interrogator. In some embodiments, the integrated circuit (such as integrated circuit 604, 704) is an application specific integrated circuit (ASIC). In some embodiments, the ASIC operation may be passive. The ASIC may power up and transmit messages only when commanded by the external interrogator. In some embodiments, there is no OFF command for the ASIC since the ASIC may be powered off by stopping ultrasound communication between the device and the external interrogator. The stopping of the ultrasound communication may quickly deplete the energy store of the device. When powered, the ASIC may transmit data bits or acknowledgments to the interrogator to allow for status evaluation of the ultrasound communication link. When a measurement command is received the ASIC may perform the command if it can complete the command with the available power.

[0136] In some embodiments, power may be harvested from the received ultrasonic waves using the piezoelectric crystal of the ultrasonic transducer and the ASIC of the device. The ASIC may convert AC ultrasonic power to DC power, may be able to sustain operation of the device with a minimum average power, and may generate an IOP measurement within a predetermined amount of time. In some embodiments, the minimum average power may be about 10 * 10'⁶ W, 20 * 10'⁶ W, or 30 x 10'⁶ W average power. In some embodiments, the pre-determined amount of time may be about less than 1 second, 3 seconds, or 5 second. [0137] In some embodiments, the integrated circuit includes a power circuit, which can include an energy storage circuit. The energy storage circuit may include a battery, or an alternative energy storage device such as one or more capacitors. The device may be batteryless, and may rely on one or more capacitors. By way of example, energy from ultrasonic waves received by the device (for example, through the wireless communication system) is converted into a current, and can be stored in the energy storage circuit. The energy can be used to operate the device, such as providing power to the integrated circuit, the modulation circuit, or one or more amplifiers, or can be used to generate an electrical pulse. In some embodiments, the power circuit further includes, for example, a rectifier and/or a charge pump.

[0138] In some embodiments, the piezoelectric crystal may be electrically and mechanically connected to the ASIC and substrate such that the Curie temperature, the resonant frequency, and resistance range at resonance are maintained within pre-determined ranges. In some embodiments, the Curie temperature may be at least about 180 °C, 200 °C, or 220 °C. In some embodiments, the Curie temperature may be at most about 260 °C, 250 °C, or 240 °C. In some embodiments, the Curie temperature may be about 180 to 60 °C, 200 to 250 °C, or 220 to 240 °C. In some embodiments, the resonant frequency may be at least about 1.2 MHz, 1.4 MHz, 1.6 MHz, or 1.8 MHz. In some embodiments, the resonant frequency may be at most about 2.8 MHz, 2.6 MHz, 2.4 MHz, or 2.2 MHz. In some embodiments, the resonant frequency may be about 1.2 to 2.8 MHz, 1.4 to 2.6 MHz, 1.6 to 2.4 MHz, or 1.8 to 2.2 MHz. In some embodiments, the resistance range at resonance may be at least about 0.1 kQ. 0.2 kQ, or 0.3 k . In some embodiments, the resistance range at resonance may be at most about 1.7 kQ , 1.5 kQ , 1.3 kQ , or 1.1 kQ. In some embodiments, the resistance range at resonance may be about 0.1 to 1.7 kQ , 0.2 to 1.5 kQ , 0.3 to 1.3 kQ , or 0.3 to 1.1 kQ.

[0139] FIG. 8 shows a schematic of an exemplary device 700 having one or more sensors 810 and a wireless communication system 820. The sensors or electrodes 810 may be configured to electrically communicate with the wireless communication system 820. Additionally, the wireless communication system 820 may be configured to communicate with an external device having a communication system. For example, the external device may be an interrogator 830 having a communication system that includes one or more ultrasonic transducers.

[0140] In some embodiments, the housing may house the wireless communication system, the one or more sensors, and the integrated circuit. The housing of the device can include a base, one or more sidewalls, and a top for enclosing the internal components of the device. In some embodiments, the housing may be at most about 0.25 mm high, 0.5 mm high, 1 mm high, or 2 mm high. In some embodiments, the housing may be at most 1 mm wide, 2 mm wide, or 3 mm wide. In some embodiments, the housing may be at most 1 mm long, 2 mm long, 3 mm long, 4 mm long, or 5 mm long. FIG. 9A shows an exploded view of an exemplary housing 940, according to some embodiments. The housing is made from a bioinert material, such as a bioinert metal (e.g., steel or titanium) or a bioinert ceramic (e.g., titania or alumina). In some embodiments, the housing may have no sharp comers or edges that could cause excessive reaction or inflammation beyond that caused by an implanting procedure. The housing is preferably hermetically sealed, which prevents body fluids from entering the body. In some embodiments, the hermetic seal may meet or exceed an equivalent leak rate of at least 2 x 10'⁸ atm-cc/sec Air, 5 x 10'⁸ atm-cc/sec Air, or 8 x 10'⁸ atm-cc/sec Air. The hermetically sealed housing may withstand shock, thermal cycling, and pressure change specifications identified by standards such as ISO 14708-1.

[0141] In some embodiments, the housing can include an acoustic window that serves at least one or both of the following: 1) it allows ultrasonic waves to penetrate the window and power the piezoelectric crystal of the device, and 2) it provides a compliant membrane that allows changes in intraocular pressure to transfer to the MEMS pressure sensor. In this way, the acoustic window allows ultrasonic waves to penetrate and equilibrate pressure external and internal to the housing. In some embodiments, the acoustic window may have a compliance that is at least about 400 times, 600 times, or 800 times larger than the compliance of a pressure sensor membrane of the pressure sensor. In some embodiments, the acoustic window may have a compliance that is at most about 1600 times, 1400 times, or 1,200 times larger than the compliance of a pressure sensor membrane of the pressure sensor. In some embodiments, the acoustic window may have a compliance that is at most about 400 to 1600 times, 600 to 1400 times, or 800 to 1,200 times larger than the compliance of a pressure sensor membrane of the pressure sensor. In some embodiments, the acoustic window may be oriented anterior to the Coronal Plane. The equilibration of pressure enables accurate IOP measurements while protecting the sensor within the housing. For example, the top 944 of the housing 940 can include an acoustic window. An acoustic window is a thinner material (such as a foil) that allows acoustic waves to penetrate the housing 940 so that they may be received by one or more ultrasonic transducers within the body of the device. In some embodiments, the housing (or the acoustic window of the housing) may be thin to allow ultrasonic waves to penetrate through the housing. In some embodiments, the thickness of the housing (or the acoustic window of the housing) is about 100 micrometers (pm) or less in thickness, such as about 75 pm or less, about 50 pm or less, about 25 pm or less, about 15 pm or less, or about 10 pm or less. In some embodiments, the thickness of the housing (or the acoustic window of the housing) is about 5 pm to about 10 pm, about 10 pm to about 15 pm, about 15 pm to about 25 pm, about 25 pm to about 50 pm, about 50 pm to about 75 pm, or about 75 pm to about 100 pm in thickness. In some embodiments, the acoustic window can be made from a metallic film. [0142] The housing of the device is relatively small, which allows for comfortable and longterm implantation while limiting tissue inflammation that is often associated with implanting devices. In some embodiments, the longest dimension of the housing of the device is about 8 mm or less, about 7 mm or less, about 6 m or less, about 5 mm or less, about 4 mm or less, about 3 mm or less, about 2 mm or less, about 1 mm or less, about 0.5 mm or less, about 0.3 mm or less, about 0.1 mm or less in length. In some embodiments, the longest dimension of the housing of the device is about 0.05 mm or longer, about 0.1 mm or longer, about 0.3 mm or longer, about 0.5 mm or longer, about 1 mm or longer, about 2 mm or longer, about 3 mm or longer, about 4 mm or longer, about 5 mm or longer, about 6 mm or longer, or about 7 mm or longer in the longest dimension of the device. In some embodiments, the longest dimension of the housing of the device is about 0.3 mm to about 8 mm in length, about 1 mm to about 7 mm in length, about 2 mm to about 6 mm in length, or about 3 mm to about 5 mm in length. In some embodiments, the housing of the implantable device has a volume of about 10 mm³ or less (such as about 8 mm³ or less, 6 mm³ or less, 4 mm³ or less, or 3 mm³ or less). In some embodiments, the housing of the implantable device has a volume of about 0.5 mm³ to about 8 mm³, about 1 mm³ to about 7 mm³, about 2 mm³ to about 6 mm³, or about 3 mm³ to about 5 mm³.

[0143] The housing may be filled with an acoustic medium and void of water, moisture, or air bubbles. The acoustic medium may have a density that avoids an impedance mismatch with surrounding tissue. The acoustic medium may be electrically non-conductive. For example, the housing 940 may be filled with a polymer or oil (such as a silicone oil). The material can fill empty space within the housing to reduce acoustic impedance mismatch between the tissue outside of the housing and within the housing. Accordingly, an interior of the device is preferably void of air or vacuum. A port can be included on the housing, for example one of the sidewalls 942 of housing 940, there may be a port 946 to allow the housing to be filled with the acoustic medium. Once the housing 940 is filled with the material, the port 946 can be sealed to avoid leakage of the material after implantation.

[0144] FIG. 9B shows an exploded view of exemplary housing 950 that shows the housing is configured to house the circuit board 610b, according to some embodiments. Similar to housing 940, the housing 950 includes sidewalls 952, port 956, and a top 954.

[0145] In some embodiments, the housing 940, 950 may include externally attached features that allow placement and fixation of the device within or on an eye. The externally attached features do not interfere with ultrasound transmission, pressure transmission, or mounting of the device within or on the eye. For example, the housing may have externally attached features which allow placement and fixation into the lens capsule of the eye without interfering with the patient’s line of sight or intraocular lens placement (if applicable). In some embodiments, the externally attached features may be free of sharp comers or edges that could cause excessive reaction or inflammation beyond that caused by the mounting procedure, or rough surfaces which are not required for the correct functioning of the device. In some embodiments, any externally attached features may not increase the rigid dimensions of the implant by more than 0.50 mm in height, 1.00 mm in width, or 1.50 mm in length.

External Device

[0146] In some embodiments, the device may be configured to wirelessly communicate with components external to the device for IOP measuring operations. For example, the implantable device may be configured to wirelessly communicate with an external device. Through the wireless communication, the implantable device may be configured to instruct the device to collect a plurality of IOP measurements. The external device may include one or more transducers, one or more sensors, and one or more force gauges.

[0147] An exemplary external device 1000 is shown in FIG. 10A, according to some embodiments. An exemplary schematic of the exemplary external device 1000 is shown in FIG. 10B, according to some embodiments. The interrogator of FIGS. 10A-10B may be configured to wirelessly communicate with implantable devices such as implantable devices 300, 400, and 500. The external device 1000 may include one or more transducers 1010 for wireless communication. In some embodiments, the one or more transducers 1010 may include an ultrasonic transducer. The ultrasonic transducer may be configured to ultrasonically couple to skin of an eyelid, skin over a brow bone, skin over a nasal bone, or skin over an eye socket to facilitate ultrasonic communication between the external device and the implantable device mounted on or within an eye. In some embodiments, an ultrasound coupling gel or an alternative couplant may be used to ultrasonically couple the external device to the skin.

[0148] In some embodiments, the external device 1000 may include ultrasound receive and transmit circuitry 1020, a data interface 1030, an embedded controller 1040, and a power source 1050. In some embodiments, the device may be configured to rely on power transmission from the external device. The power transmission from the external device may be used to power the device to initiate IOP measurements collected by the one or more sensors of the implantable device. In some embodiments, the ultrasonic transducer of the external device may be configured to transmit instructions to the implantable device. The instructions from the external device may instruct the device to reset itself, enter a specific mode, set device parameters, or begin a transmission sequence.

[0149] Physical contact between the eye/eyelid of a patient and the external device enables the external device to receive measurements from the implanted/mounted device.

[0150] Optionally, the external device is controlled using a separate computer system, such as a mobile device (e.g., a smartphone or a table). The computer system can wirelessly communicate to the interrogator, for example through a network connection, a radiofrequency (RF) connection, or Bluetooth. The computer system may, for example, turn on or off the interrogator or analyze information encoded in ultrasonic waves received by the interrogator.

[0151] The implantable device and the external device wirelessly communicate with each other, for example using ultrasonic waves or radiofrequency. The communication may be a one-way communication (for example, the interrogator transmitting information to the device, or the device transmitting information to the interrogator), or a two-way communication (for example, the interrogator transmitting information to the device, or the device transmitting information to the interrogator). Information transmitted from the device to the interrogator may rely on, for example, a backscatter communication protocol. For example, the interrogator may transmit ultrasonic waves to the device, which emits backscatter waves that encode the information. The interrogator can receive the backscatter waves and decipher the information encoded in the received backscatter waves.

[0152] In some embodiments, the one or more ultrasonic transducers of the device may include a piezoelectric crystal configured to receive commands from ultrasonic energy transmitted from the external interrogator. The device may decode pulse interval encoded commands transmitted from the external interrogator and may passively transmit data to the external device via amplitude-modulated, backscatter communication. In some embodiments, the implanted device receives ultrasonic waves from the external device through one or more ultrasonic transducers on the implantable device, and the received waves can encode instructions for operating the implantable device. For example, vibrations of the ultrasonic transducer(s) on the device generate a voltage across the electric terminals of the transducer, and current flows through the device, including the integrated circuit. The current (which may be generated, for example, using one or more ultrasonic transducers) can be used to charge an energy storage circuit.

[0153] In some embodiments, ultrasonic backscatter is emitted from the device, which can encode information relating to the device. In some embodiments, a device is configured to detect a physiological condition describing IOP, and information regarding the detected physiological condition can be transmitted to the external device by the ultrasonic backscatter. To encode physiological condition in the backscatter, current flowing through the ultrasonic transducer(s) of the device is modulated as a function of the encoded information, such as a measured physiological condition. In some embodiments, modulation of the current can be an analog signal, which may be, for example, directly modulated by the detected physiological condition. In some embodiments, modulation of the current encodes a digitized signal, which may be controlled by a digital circuit in the integrated circuit. The backscatter is received by an external device (which may be the same or different from the external device that transmitted the initial ultrasonic waves). The information can thus be encoded by changes in amplitude, frequency, or phase of the backscattered ultrasound waves. [0154] In some embodiments, the ultrasound communication does not raise the temperature of any part of the eye more than about 1.5 °C at any time, in accordance with ISO 14708- 01:2014 clause 17 which stipulates any surface of the implant shall not exceed a temperature increase of 2 °C.

[0155] In some embodiments, the ultrasound communication may be established when the piezoelectric crystal of the device is about 5mm +/- 20% distance from the external device. In some embodiments, the ultrasound communication may be established when a surface of the piezoelectric crystal is at most about a 3 mm, 5mm, 7 mm, or 9 mm distance from a surface of the external device configured to touch skin of an eyelid, skin over a brow bone, skin over a nasal bone, or skin over an eye socket. In some embodiments, the ultrasound communication may be established when a surface of the piezoelectric crystal is at least about 1 mm, 2mm, or 3 mm distance from the interrogator configured to touch skin of an eyelid, skin over a brow bone, skin over a nasal bone, or skin over an eye socket . In some embodiments, the ultrasound communication may be established when a surface of the piezoelectric crystal is about 1-9 mm, 2-7 mm, or 3-5 mm distance from the external device configured to touch skin of an eyelid, skin over a brow bone, skin over a nasal bone, or skin over an eye socket. Once established, the ultrasound communication may tolerate typical involuntary eye movement for the brief duration of the IOP measurement.

[0156] FIG. 8 shows an interrogator in communication with an implantable device. The external ultrasonic transceiver emits ultrasonic waves (“carrier waves”), which can pass through tissue. The carrier waves cause mechanical vibrations on the ultrasonic transducer (e.g., a bulk piezoelectric transducer, a PUMT, or a CMUT). A voltage across the ultrasonic transducer is generated, which imparts a current flowing through an integrated circuit on the implantable device. The current flowing through to the ultrasonic transducer causes the transducer on the implantable device to emit backscatter ultrasonic waves. In some embodiments, the integrated circuit modulates the current flowing through the ultrasonic transducer to encode information, and the resulting ultrasonic backscatter waves encode the information. The backscatter waves can be detected by the external device, and can be analyzed to interpret information encoded in the ultrasonic backscatter.

[0157] The instructions from the external device to the device can be carried by the ultrasonic carrier. Specifically, the ultrasonic carrier generated by the ultrasonic transducer of the external device may include a series of ultrasonic pulses that have a varying number of carrier periods. The number of carrier periods encode information specific to the device. For example, based on the number of carrier periods, the information may include instructions for the device to begin a data transmission sequence. The transmission sequence can include steps for measuring IOP data and encoding the IOP data as ultrasonic backscatter. The encoding includes backscattering the IOP data on the ultrasonic carrier to modulate the electrical current and converting the modulated current to ultrasonic backscatter for transmission to the external device. The number of carrier periods may encode other information related to the device. For example, the information may include instructions for the device to reset itself, enter a specific mode, or set device parameters.

[0158] Communication between the external device and the implantable device can use a pulse-echo method of transmitting and receiving ultrasonic waves. In the pulse-echo method, the interrogator transmits a series of interrogation pulses at a predetermined frequency, and then receives backscatter echoes from the implanted device. In some embodiments, the pulses are square, rectangular, triangular, sawtooth, or sinusoidal. In some embodiments, the pulses output can be two-level (GND and POS), three-level (GND, NEG, POS), 5-level, or any other multiplelevel (for example, if using 24-bit DAC). In some embodiments, the pulses are continuously transmitted by the external device during operation. In some embodiments, when the pulses are continuously transmitted by the interrogator a portion of the transducers on the interrogator are configured to receive ultrasonic waves and a portion of the transducers on the interrogator are configured to transmit ultrasonic waves. Transducers configured to receive ultrasonic waves and transducers configured to transmit ultrasonic waves can be on the same transducer array or on different transducer arrays of the external device. In some embodiments, a transducer on the external device can be configured to alternatively transmit or receive the ultrasonic waves. For example, a transducer can cycle between transmitting one or more pulses and a pause period. The transducer is configured to transmit the ultrasonic waves when transmitting the one or more pulses, and can then switch to a receiving mode during the pause period.

[0159] In some embodiments, the backscattered waves are digitized by the implantable device. For example, the implantable device can include an oscilloscope or analog-to-digital converter (ADC) and/or a memory, which can digitally encode information in current (or impedance) fluctuations. The digitized current fluctuations, which can encode information, are received by wireless communication system, which then transmits digitized ultrasonic waves. The digitized data can compress the analog data, for example by using singular value decomposition (SVD) and least squares-based compression. In some embodiments, the compression is performed by a correlator or pattern detection algorithm. The backscatter signal may go through a series of non-linear transformation, such as 4th order Butterworth bandpass filter rectification integration of backscatter regions to generate a reconstruction data point at a single time instance. Such transformations can be done either in hardware (i.e., hard-coded) or in software.

[0160] In some embodiments, the digitized signal compresses the size of the analog signal. The decreased size of the digitized signal can allow for more efficient reporting of information encoded in the backscatter. By compressing the size of the transmitted information through digitization, potentially overlapping signals can be accurately transmitted.

[0161] The wireless communication system, which can communicate with a separate device (such as an external interrogator or another device). For example, the wireless communication may be configured to receive instructions for emitting ultrasonic backscatter associated with measured IOP data from the one or more sensors. The wireless communication system can include, for example one or more ultrasonic transducers. The wireless communication system may also be configured to receive energy (for example, through ultrasonic waves) from another device, which can be used to power the implantable device.

[0162] In addition to providing the device with instructions, in some embodiments, the ultrasonic carrier from the interrogator may transmit vibrational energy configured to power the device. That is, the ultrasonic pulses of the ultrasonic carrier is delivered to the device at a frequency suitable for imparting energy to power the ASIC.

[0163] In some embodiments, the implantable device can also be operated to transmit information (i.e., uplink communication), which can be received by the interrogator, through the wireless communication system. In some embodiments, the wireless communication system is configured to actively generate a communication signal (e.g., ultrasonic waves) that encode the information. In some embodiments, the wireless communication system is configured to transmit information encoded on backscatter waves (e.g., ultrasonic backscatter waves). Backscatter communication provides a lower power method of transmitting information, which is particularly beneficial for small devices to minimize energy uses. By way of example, the wireless communication system may include one or more ultrasonic transducers configured to receive ultrasonic waves and emit an ultrasonic backscatter, which can encode information transmitted by the implantable device. Current flows through the ultrasonic transducer, which can be modulated to encode the information. The current may be modulated directly, for example by passing the current through a sensor that modulates the current, or indirectly, for example by modulating the current using a modulation circuit based on a detected physiological condition such as IOP.

[0164] The information wirelessly transmitted using the wireless communication system can be received by an interrogator. In some embodiments, the information is transmitted by being encoded in backscatter waves (e.g., ultrasonic backscatter). The backscatter can be received by the interrogator, for example, and deciphered to determine the encoded information. Additional details about backscatter communication are provided herein, and additional examples are provided in WO 2018/009905; WO 2018/009908; WO 2018/0091010; WO 2018/009911; WO 2018/009912; International Patent Application No. PCT/US2019/028381; International Patent Application No. PCT/US2019/028385; and International Patent Application No. PCT/2019/048647; each of which is incorporated herein by reference for all purposes. The information can be encoded by the integrated circuit using a modulation circuit. The modulation circuit is part of the wireless communication system, and can be operated by or contained within the integrated circuit.

Methods for Detecting Intraocular Pressure

[0165] FIG. 11 shows a method 1100 for measuring an intraocular pressure of a patient’s eye. Method 1100 may be executed by an implantable device configured to be implanted in the patient’s eye, for example has described herein. In some embodiments, the implantable device may include features of the implantable device shown in FIGS. 1A-1B, 2A-2C, 3A- 3B, or 4A-4B, e.g., it may comprise an integrated circuit that is electrically coupled to a wireless communication device and a pressure sensor configured to measure the intraocular pressure. [0166] Optionally, in a first step 1102, power may be received from an external device. In some embodiments, power may be received as ultrasonic waves or as RF waves. The external device may include features of external device as described herein. In some embodiments, power may be received when the external device is placed at a location proximal to an eye that contains an implantable device.

[0167] In some embodiments, in a second step 1104, an intraocular pressure of the patient’s eye may be measured. As described above, the transmission of power from the external device may, in some embodiments, involve the external device being placed at a location proximal to the patient’s eye. In other words, the transmission of power from external device may cause an external pressure to be exerted on patient’s eye. The presence of external pressure may skew measurements of the intraocular pressure. As such, the intraocular pressure may be measured after power is no longer being received from the external device - i.e., after a source of external pressure has been removed. In some embodiments, a predetermined time period must be determined to have passed before the intraocular pressure of the patient’s eye may be measured. Optionally, this predetermined time period may be chosen to allow the patient’s eye to relax to an equilibrium state following the removal of the external pressure source.

[0168] After the intraocular pressure has been measured, method 1100 may optionally proceed to a third step 1106, wherein data associated with the intraocular pressure may be stored. In some embodiments, the data associated with the intraocular pressure may be stored in a volatile memory or in a non-volatile memory. Finally, in a fourth step 1108, the data associated with the intraocular pressure may be wirelessly transmitted to an external device. In some embodiments, this external device may be the same external device that provides power in step 1102. Wireless transmission may involve transmitting the data using ultrasonic backscatter or RF waves.

[0169] As mentioned above, the intraocular pressure may be measured with an implantable device comprising an ultrasonic transducer. FIG. 12 shows a method 1200 for measuring an intraocular pressure of a patient’s eye with an ultrasonic implantable device. The ultrasonic implantable device may comprise a digital circuit that is electrically coupled to a wireless communication system and a pressure sensor. The wireless communication system may comprise an ultrasonic transducer configured to receive ultrasonic waves from an external device. The external device may comprise one or more ultrasonic transducers configured to transmit ultrasonic waves to the wireless communication system and receive data from the wireless communication system in the form of ultrasonic backscatter. [0170] In some embodiments, at a first step 1202, an external interrogator may be positioned at a location proximal to an eye that contains an ultrasonic implantable device. In some embodiments, after the eternal device has been appropriately positioned, it may be configured to query the implantable device for a power level status. Optionally, the implantable device may be configured to transmit its current power level to the external device in response to the power level status query.

[0171] In some embodiments, in step 204, the implantable device may receive ultrasonic waves from the external device. The implantable device may comprise an ultrasonic transducer configured to convert the ultrasonic energy received from the external device to electrical energy for powering the device. In some embodiments, the amount of energy transmitted by the external device may be based on a current power level of the implantable device. In some embodiments, after transmitting the ultrasonic waves, the external device may be configured to query the implantable device for a power level status. Optionally, the implantable device may be configured to transmit its current power level to the external device in response to the power level status query.

[0172] Positioning the external device at a location proximal to the patient’s eye may apply an external pressure to said eye. Optionally, in step 1206, the interrogator may be removed from said location. In some embodiments, at step 1208, the implantable device may identify the removal of the interrogator by detecting a termination of the transmission of ultrasonic waves. Removing the interrogator necessarily removes any external pressure from the interrogator on the patient’s eye and, as a result, reduces error in intraocular pressure measurements.

[0173] After the implantable device has detected the termination of the ultrasonic waves from the external device, method 1200 may optionally proceed to step 1210, wherein the implantable device detects that a predetermined time period has ended. In some embodiments, the predetermined time period may be selected to allow the eye to return to an equilibrium state after the external device has been removed. In some embodiments, the implantable device may comprise a timer that has been preset with the predetermined time period. The removal of the external device may trigger the timer to begin counting down the predetermined time period. In some embodiments, if the implantable device identifies a transmission of ultrasonic waves while the timer is running, the timer will be caused to restart until a termination of the transmission of ultrasonic waves has been detected.

[0174] In some embodiments, at step 1212, the implantable device may measure an intraocular pressure of the eye. The implantable device may measure the intraocular pressure using a pressure sensor. The pressure sensor may be controlled by a digital circuit. In some embodiments, the implantable device may measure additional properties of the eye (e.g., the intraocular temperature) using additional sensors (e.g., a thermometer).

[0175] At step 1214, data associated with the intraocular pressure measurement may be stored in a memory of the implantable device. In some embodiments, the memory may be a volatile memory or a non-volatile memory. In some embodiments, at step 1216, the external device may be repositioned at the location proximal to the eye that contains the implantable device. Optionally, if the memory of the implantable device is a volatile memory, the external device may query the implantable device for a power level status; if necessary, the external device may transmit ultrasonic waves to the implantable device to ensure that the device does not lose power completely.

[0176] Finally, in some embodiments, at step 1218, the implantable device may wirelessly transmit the data associated with the intraocular pressure measurement to the external device. In some embodiments, the external device may receive the data as ultrasonic backscatter from a wireless communication system of the implantable device.

[0177] While method 1200, as shown, is intended for execution by an implantable device powered by ultrasonic waves, it can be adapted for implantable devices powered by other forms of energy. In some embodiments, method 1200 can be adapted for execution by an implantable device powered by radio waves. In such embodiments, the implantable device may comprise an RF antenna configured to receive radio waves from an external interrogator. The implantable device may transmit data associated with an intraocular pressure measurement to the interrogator using radio waves.

[0178] The foregoing description, for the purpose of explanation, has been described with reference to specific embodiments. However, the illustrative discussions above are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. The embodiments were chosen and described in order to best explain the principles of the techniques and their practical applications. Others skilled in the art are thereby enabled to best utilize the techniques and various embodiments with various modifications as are suited to the particular use contemplated.

[0179] Although the disclosure and examples have been fully described with reference to the accompanying figures, it is to be noted that various changes and modifications will become apparent to those skilled in the art. Such changes and modifications are to be understood as being included within the scope of the disclosure and examples as defined by the claims. Finally, the disclosures of all publications, patents, and patent applications referred to herein are each hereby incorporated by reference in their entireties. To the extent that any reference incorporated by reference conflicts with the instant disclosure, the instant disclosure shall control.

[0180] Any of the systems, methods, techniques, and/or features disclosed herein may be combined, in whole or in part, with any other systems, methods, techniques, and/or features disclosed herein.

Claims

CLAIMS What is claimed is:

1. An implantable device for measuring an intraocular pressure of an eye, the device comprising: a pressure sensor configured to measure intraocular pressure; a wireless communication system; and an integrated circuit electrically coupled to the pressure sensor and the wireless communication system; wherein the implantable device is configured to be implanted within an eye of the patient and wherein the implantable device is configured to: receive power from an external device for a first period of time; measure an intraocular pressure within the eye after the first period of time; store data associated with the intraocular pressure in a memory of the implantable device; and wirelessly transmit the data associated with the intraocular pressure to the external device.

2. The implantable device of claim 1, wherein the integrated circuit is configured to operate a timer preset with a predetermined time period and wherein said timer is configured to start after the first period of time.

3. The implantable device of claim 2, wherein the integrated circuit is configured to operate the pressure sensor measure the intraocular pressure when the predetermined time period has ended.

4. The implantable device of claims 2 or 3, wherein the predetermined time period is a maximum relaxation time of compression of the eye.

5. The implantable device of any one of claims 1-4, wherein the implantable device is configured to measure the intraocular pressure in the absence of an external pressure on the eye.

6. The implantable device of any one of claims 1-5, wherein the integrated circuit is configured to receive power when the external device is positioned at a location proximal to the eye.

7. The implantable device of any one of claims 1-6, wherein the integrated circuit is configured to wirelessly transmit the data associated with the intraocular pressure when the external device is repositioned a location proximal to the eye.

8. The implantable device of any one of claims 1-7, wherein the memory of the implantable device is a volatile memory.

9. The implantable device of any one of claims 1-7, wherein the memory of the implantable device is a non-volatile memory.

10. The implantable device of any one of claims 1-9, wherein the implantable device comprises an ultrasonic transducer.

11. The implantable device of claim 10, wherein the power is transmitted to the implantable device using ultrasonic waves.

12. The implantable device of claim 10 or 11, wherein the integrated circuit is configured to operate the wireless communication system to wirelessly transmit the data associated with the intraocular pressure using ultrasonic backscatter.

13. The implantable device of claim 10 or 11, wherein the integrated circuit is configured to operate the wireless communication system to wirelessly transmit the data associated with the intraocular pressure using actively generated ultrasonic waves.

14. The implantable device of any one of claims 1-9, wherein the implantable device comprises a radio frequency antenna.

15. The implantable device of claim 14, wherein the power is transmitted to the implantable device using radio waves.

16. The implantable device of claim 14 or 15, wherein the integrated circuit is configured to control the wireless communication system to wirelessly transmit the data associated with the intraocular pressure using radio wave backscatter.

17. The implantable device of claim 14 or 15, wherein the integrated circuit is configured to control the wireless communication system to wirelessly transmit the data associated with the intraocular pressure using actively generated radio waves.

18. The implantable device of any one of claims 1-17, further comprising a thermometer configured to measure an internal temperature of the eye, wherein the thermometer is electrically coupled to the integrated circuit and wherein the integrated circuit is configured to: operate the thermometer to measure the internal temperature; store data associated with the internal temperature in the memory of the implantable device; and wirelessly transmit the data associated with the internal temperature to the external device.

19. A system comprising the implantable device of any one claim 1-18, and the external device, wherein the external device is configured to transmit power to the implantable device and receive the data associated with the intraocular pressure

20. The system of claim 19, wherein the external device is a hand-held device.

21. A method for measuring an intraocular pressure of an eye, the method comprising: receiving, at a device implanted in the eye, power from an external device for a first period of time; measuring, using the device implanted in the eye, an intraocular pressure within the eye after the first period of time; storing data associated with the intraocular pressure in the device implanted in the eye; and wirelessly transmitting the data associated with the intraocular pressure from the device implanted in the eye to the external device.

22. The method of claim 21, further comprising determining, using the device implanted in the eye, that a predetermined time period has ended prior to measuring the intraocular pressure.

23. The method of claim 22, wherein the predetermined time period is based on a maximum relaxation time of compression of the eye.

24. The method of claims 22 or 23, wherein determining that the predetermined time period has ended comprises starting a timer preset with the predetermined time period.

25. The method of any one of claims 21-24, wherein the intraocular pressure is measured in the absence of an external pressure on the eye.

26. The method of any one of claims 21-25, wherein power is received when the external device is placed at a location proximal to the eye.

27. The method of any one of claims 21-26, wherein the data associated with the intraocular pressure is wirelessly transmitted to the external device when the external device is repositioned at a location proximal to the eye.

28. The method of any one of claims 21-27, wherein the power is transmitted from the external device using ultrasonic waves.

29. The method of any one of claims 21-27, wherein the power transmitted from the external device using radio waves.

30. The method of any one of claims 21-29, wherein the data associated with the intraocular pressure is stored in a volatile memory of the device implanted in the eye.

31. The method of any one of claims 21-29, wherein the data associated with the intraocular pressure is stored in a non-volatile memory of the device implanted in the eye.

32. The method of any one of claims 21-31, wherein the data associated with the intraocular pressure is wirelessly transmitted using ultrasonic backscatter.

33. The method of any one of claims 21-31, wherein the data associated with the intraocular pressure is wirelessly transmitted using actively generated ultrasonic waves.

34. The method of any one of claims 21-27 and 29-31, wherein the data associated with the intraocular pressure is wirelessly transmitted using radio wave backscatter.

35. The method of any one of claims 21-27 and 29-31, wherein the data associated with the intraocular pressure is wirelessly transmitted using actively generated radio waves.

36. A method for measuring an intraocular pressure of an eye, the method comprising: positioning an external device at a location proximal to the eye; receiving, at a device implanted in the eye, ultrasonic waves transmitted by the external device; removing the external device from the location proximal to the eye; detecting, at the device implanted in the eye, a termination of the ultrasonic waves received by the device implanted in the eye, wherein the termination indicates the removing of the external device from the location proximal to the eye; determining, using the device implanted in the eye, that a predetermined time period has ended; measuring, using the device implanted in the eye, the intraocular pressure of the eye after the predetermined time period has ended; storing data associated with the intraocular pressure of the eye in a memory in the device implanted in the eye; repositioning the external device at the location proximal to the eye; and wirelessly transmitting, using ultrasonic backscatter, the data associated with the intraocular pressure of the eye from the device implanted in the eye to the external device.

37. The method of claim 36, wherein the device implanted in the eye comprises an ultrasonic detector to detect ultrasonic waves transmitted by the external device.

38. The method of claims 36 or 37, wherein the device implanted in the eye is configured to operate a timer preset to the predetermined time period and wherein the timer is configured to start after the device detects the termination of the ultrasonic waves.

39. The method of any one of claims 36-38, wherein the external device comprises one or more ultrasonic transducers configured to transmit the ultrasonic waves to the device implanted in the eye and receive the ultrasonic backscatter from the device implanted in the eye.

40. The method of any one of claims 36-39, wherein the predetermined time period is based on a maximum relaxation time of compression of the eye.