The present invention relates to a powered or electronic ophthalmic lens, and more particularly, to a powered or electronic ophthalmic lens having an ultrasound module for imaging a wearer's eye including a ciliary muscle and/or a lens to determine a level of lens accommodation and/or to collect data.
As electronic devices continue to be miniaturized, it is becoming increasingly more likely to create wearable or embeddable microelectronic devices for a variety of uses. Such uses may include monitoring aspects of body chemistry, administering controlled dosages of medications or therapeutic agents via various mechanisms, including automatically, in response to measurements, or in response to external control signals, and augmenting the performance of organs or tissues. Examples of such devices include glucose infusion pumps, pacemakers, defibrillators, ventricular assist devices and neurostimulators. A new, particularly useful field of application is in ophthalmic wearable lenses and contact lenses. For example, a wearable lens may incorporate a lens assembly having an electronically adjustable focus to augment or enhance performance of the eye. In another example, either with or without adjustable focus, a wearable contact lens may incorporate electronic sensors to detect concentrations of particular chemicals in the precorneal (tear) film. The use of embedded electronics in a lens assembly introduces a potential requirement for communication with the electronics, for a method of powering and/or re-energizing the electronics, for interconnecting the electronics, for internal and external sensing and/or monitoring, and for control of the electronics and the overall function of the lens.
The human eye has the ability to discern millions of colors, adjust easily to shifting light conditions, and transmit signals or information to the brain at a rate exceeding that of a high-speed internet connection. Contact lenses currently are utilized to correct vision defects such as myopia (nearsightedness), hyperopia (farsightedness), presbyopia and astigmatism. However, properly designed lenses incorporating additional components may be utilized to enhance vision as well as to correct vision defects.
Conventional contact lenses are polymeric structures with specific shapes to correct various vision problems as briefly set forth above. To achieve enhanced functionality, various circuits and components have to be integrated into these polymeric structures. For example, control circuits, microprocessors, communication devices, power supplies, sensors, actuators, light-emitting diodes, and miniature antennas may be integrated into contact lenses via custom-built optoelectronic components to not only correct vision, but to enhance vision as well as provide additional functionality as is explained herein. Electronic and/or powered ophthalmic lenses may be designed to provide enhanced vision via zoom-in and zoom-out capabilities, or just simply modifying the refractive capabilities of the lenses. Electronic and/or powered contact lenses may be designed to enhance color and resolution.
The proper combination of devices could yield potentially unlimited functionality; however, there are a number of difficulties associated with the incorporation of extra components on a piece of optical-grade polymer. In general, it is difficult to manufacture such components directly on the lens for a number of reasons, as well as mounting and interconnecting planar devices on a non-planar surface. It is also difficult to manufacture to scale. The components to be placed on or in the lens need to be miniaturized and integrated onto just 1.5 square centimeters of a transparent polymer while protecting the components from the liquid environment on the eye. It is also difficult to make a contact lens comfortable and safe for the wearer with the added thickness of additional components.
In addition, because of the complexity of the functionality associated with a powered lens and the high level of interaction between all of the components comprising a powered lens, there is a need to coordinate and control the overall operation of the electronics and optics comprising a powered contact lens. Accordingly, there is a need for a system to control the operation of all of the other components based on physiological changes representing attempts to accommodate that is safe, low-cost, and reliable, has a low rate of power consumption and is scalable for incorporation into a contact lens. Accordingly, there exists a need for a means and method for detecting physiological changes representing attempts to accommodate.
There are several scenarios where there is a need for powered contact lenses to communicate during normal operation. Methods of detecting and changing lens state for presbyopia, commonly referred to as accommodation, may require the state of the left and right eye to be shared to determine if the lens focus should be changed. In each case, the independent state of each eye must be communicated so that the system controller can determine the required state of the variable lens actuator. There are other cases where it may enhance the user experience if the lens state (e.g., focus state) is changed in a coordinated fashion.
In the human eye, the lens focuses the image projected from the cornea. The lens has the capability to change shape, and accordingly its degree of refraction, with the aid of the ciliary muscle. The ciliary muscle encircles the lens of the eye and is connected to the lens by ligaments called zonules. The most widely accepted theory of lens accommodation, the active altering of the lens to bring close objects into focus, is that the ciliary muscle either contracts or relaxes to change the shape of the lens. Thus, the ciliary muscle changes the focal point of the eye: when in its relaxed state the eye is focused on objects greater than 6 meters away and conversely, the ciliary muscle contracts or closes when the eye focuses on an object closer than 6 meters away. Accordingly, lens accommodation can be determined by measuring the change in relative position of either the ciliary muscle in its relaxed and contracted states, or the lens when the ciliary muscle is in its relaxed and contracted states, and comparing the displacement during accommodation to known anatomical thresholds.
Ultrasound diagnostic systems utilize the interaction of sound waves with biological tissue to produce cross-sectional images. For purposes of this disclosure, a high frequency sound pressure wave is directed through the iris toward the ciliary muscle. This wave undergoes partial reflection at the front and back boundary of the iris and the boundary of the ciliary muscle. In at least one embodiment, the time based amplitude of the of the sound pressure wave(s), based on the time lapse between when the sound pressure wave is propagated and when the partially reflected sound pressure wave is detected, is recorded. The position of the ciliary muscle relative to the transducer and iris are computed using the time of flight between various amplitude and sound velocity characteristics through the travelling media, e.g. aqueous humour, lens, and eye tissues generally. A high frequency sound pressure wave can also be directed to the lens of the eye. This wave undergoes partial reflection at the anterior boundary of the lens. The time of flight of the sound pressure wave, based on the time that the ‘reflection’ is detected, is recorded and the positions of the lens boundaries are computed using sound velocities through the travelling media, e.g. aqueous humour, lens, and eye tissues generally, and time taken to receive the echoes. A similar approach can be used in an intraocular lens where the boundaries may be the intraocular lens, the iris, and/or the ciliary
In at least one embodiment, an ophthalmic lens is configured for imaging of a wearer's eye including an iris, a ciliary muscle and/or a lens and includes: at least one ultrasound module including at least two transducers orientated such that when a sound pressure wave is propagated, the sound pressure wave travels towards the wearer's ciliary muscle and/or the lens and oriented to receive sound pressure waves reflected from the ciliary muscle and/or the lens; a system controller in electrical communication with the at least one ultrasound module, the system controller configured to provide at least one control signal to the at least one ultrasound module and receive at least one corresponding data signal from the at least one ultrasound module, and the controller configured to determine a relative position, shape, and/or state of the wearer's ciliary muscle and/or lens based on data signals produced by the at least one ultrasound module in response to at least one received sound pressure wave; an actuator in electrical communication with the system controller configured to perform a function in response to at least one control signal from the system controller; and a timing circuit in electrical communication with the system controller. In a further embodiment, the ophthalmic lens includes a memory in communication with the system controller and/or the actuator; wherein the actuator is configured to store data based on each sample taken in the memory. In a further embodiment to any of the above embodiments, the ophthalmic lens includes a communications module in electrical communication with the system controller. In a further embodiment to any of the above embodiments, the ophthalmic lens includes a power source in electrical communication with the system controller and the timing circuit. In a further embodiment to any of the above embodiments, the ophthalmic lens includes a data storage in electrical communication with the system controller, the data storage storing preset values.
In a further embodiment to the any of the above embodiments, the at least one ultrasound module includes a plurality of ultrasound modules distributed around the ophthalmic lens. In a further embodiment to any of the embodiments of the previous paragraph, the at least two transducers are four transducers and includes a first transmit transducer, a second transmit transducer, a first receive transducer, and a second receive transducer.
In a further embodiment to any of the above embodiments, each ultrasound module includes a processor in electrical communication with the system controller; a first transceiver and a second transceiver, each transceiver having a switch in electrical communication with the processor; at least one transmit path having an oscillator in electrical communication with the processor, a burst generator in electrical communication with the oscillator and the processor, a transmit driver in electrical communication with the burst generator configured to receive a burst signal from the burst generator, the transmit driver drives one of the two transducers when connected through the switch; and at least one receive path having a receive amplifier in electrical communication with the one of at least two transducers through the switch and configured to amplify an output of the one of the two transducers, an analog signal processor in communication with the receive amplifier and the processor; and wherein the processor configured to control the switch and an operation mode of the ultrasound module between transmit and receive. In a further embodiment to the previous embodiment, each transceiver is tuned to different frequencies.
In a further embodiment to any of the above embodiments, one of the at least two transducers in the at least one ultrasound module is configured to transmit and receive the sound pressure wave at a frequency in a range of 5 to 20 MHz. or one of the at least two transducers in the at least one ultrasound module is configured to transmit and receive the sound pressure wave at a frequency above 20 MHz.
In at least one embodiment, a method of imaging an eye to detect lens accommodation using an ophthalmic lens having at least one ultrasound module having at least one transducer and a processor configured to perform a clock function, a system controller in electrical communication with the at least one ultrasound module, and a memory in electrical communication with the system controller, the method including: propagating into the eye a first sound pressure wave at a predetermined frequency by one of the at least one transducer of the ultrasound module; transmitting a first data signal to the system controller representing a time, an amplitude, and/or a frequency of at least one first received sound pressure wave detected by at least one of the at least one transducer of the ultrasound module; recording the first data signal in the memory by the system controller; propagating into the eye a second sound pressure wave at a predetermined frequency by one of the at least one transducer of the ultrasound module; transmitting a second data signal to the system controller a time, an amplitude, and/or a frequency of at least one second received sound pressure wave detected by at least one of the at least one transducer of the ultrasound module; setting a position distance based on the relationship of the difference between the first data signal and the second data signal; storing the second data signal by the system controller in memory; comparing the position distance to a distance threshold by the system controller. In a further embodiment to the previous embodiment, the method further including driving an actuator when the position distance reaches the distance threshold correlating to distance displaced by a ciliary muscle during accommodation and/or driving an actuator when the position distance reaches the distance threshold correlating to distance displaced by a lens during accommodation. In a further embodiment to the previous embodiments of this paragraph, the method further including propagating the first sound pressure wave and the second sound pressure wave at a predetermined sampling interval. In a further embodiment to the previous embodiments of this paragraph, the method further including analyzing a series of times of flight in the data signals with time-frequency analysis.
In at least one embodiment, a method of imaging an eye to detect accommodation using an ophthalmic lens system including a first ophthalmic lens and a second ophthalmic lens, each ophthalmic lens having at least one ultrasound module having two transducers tuned to different frequencies and a processor configured to perform a clock function, a system controller in electrical communication with the communications module and the at least one ultrasound module, and a data storage in electrical communication with the system controller, the method including: propagating into the eye a first sound pressure wave at a predetermined frequency by each of the two transducers of the ultrasound module; transmitting a first data signal to the system controller representing a time, an amplitude, and/or a frequency of at least one first received sound pressure wave detected by each of the two transducers of the ultrasound module based in part on a signal from the timing circuit; setting a first position from the relationship of the first data signal using a predefined constant; recording the first position in the data storage; propagating into the eye a second sound pressure wave at a predetermined frequency by each of the two transducers of the ultrasound module; transmitting a second data signal to the system controller representing a time, an amplitude, and/or a frequency of at least one received sound pressure wave detected by each of the two transducers of the ultrasound module by the timing circuit; setting a second position from the relationship of the second data signal using the predefined constant; recording the second position in the data storage; determining a displacement based on the difference between the first position and the second position; and driving the actuator when the displacement reaches a predetermined threshold. In a further embodiment to the previous embodiment, the predetermined threshold correlates to an eye having presbyopia. In a further embodiment to the previous embodiments of this paragraph, the first ophthalmic lens is a master and the second ophthalmic lens is a subordinate, each ophthalmic lens includes a communications module, the method further including: setting a binary accommodation indicator in the data storage on the first lens where 1 corresponds to accommodation; establishing a communications link between the communications modules on the ophthalmic lenses; transmitting a message encoding the binary accommodation indicator by the communications module on the first ophthalmic lens; decoding the received message by the communications module on the second ophthalmic lens; and driving the actuator on the second ophthalmic lens when the received binary accommodation indicator equals 1.
In a further embodiment to any of the above embodiments, the ophthalmic lens is a contact lens. In a further embodiment to any of the embodiments in the previous paragraphs of this section, the ophthalmic lens is an intraocular lens.
In at least one embodiment, a method of imaging an eye to detect accommodation using an ophthalmic lens having at least one ultrasound module having at least two transducers tuned to a first and a second frequency and a processor, a system controller in electrical communication with the at least one ultrasound module, and a memory in electrical communication with the system controller having preset values, the method including: propagating into the eye a first sound pressure wave by each of the at least two transducers; detecting a partially reflected sound pressure wave by each of the at least two transducers; storing a first time of flight corresponding to time lapsed from propagating the first sound pressure wave to detecting the partially reflected sound pressure wave by each of the at least two transducers to memory; propagating into the eye a second sound pressure wave by each of the at least two transducers; detecting a partially reflected sound pressure wave by each of the at least two transducers; storing a second time of flight corresponding to time lapsed from propagating the first sound pressure wave to detecting the partially reflected sound pressure wave by each of the at least two transducers to memory; determining at least a first and a second absolute position by the system controller from the relationship of the first time of flight and the second time of flight for each of the at least two transducers to a predefined constant representative of a speed of sound; driving the actuator when both the first absolute position and the second absolute position reach predetermined thresholds.
The foregoing and other features and advantages of the invention will be apparent from the following, more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings.
Conventional contact lenses are polymeric structures with specific shapes to correct various vision problems as briefly set forth above. To achieve enhanced functionality, various circuits and components may be integrated into these polymeric structures. For example, control circuits, microprocessors, communication devices, power supplies, sensors, ultrasound modules, and miniature antennas may be integrated into contact lenses via custom-built optoelectronic components to not only correct vision, but to enhance vision as well as provide additional functionality as is explained herein. Electronic and/or powered contact lenses may be designed to provide enhanced vision via zoom-in and zoom-out capabilities, or just simply modifying the refractive capabilities of the lenses. Electronic and/or powered contact lenses may be designed to enhance color and resolution.
The powered or electronic ophthalmic lens in at least one embodiment includes the necessary elements to monitor the wearer with or without elements to correct and/or enhance the vision of the wearer with one or more of the above described vision defects or otherwise perform a useful ophthalmic function. The electronic ophthalmic lens may have a variable-focus optic lens, an assembled front optic embedded into an ophthalmic lens or just simply embedding electronics without a lens for any suitable functionality. The electronic lens of the present invention may be incorporated into any number of contact lenses as described above or intraocular lenses. Intraocular lenses may also incorporate the various components and functionality described herein. However, for ease of explanation, the disclosure will focus on an electronic contact lens intended for single-use daily disposability.
The present invention may be employed in a powered contact lens having an electronic system, which actuates a variable-focus optic or any other device or devices configured to implement any number of numerous functions that may be performed including data collection. The electronic system includes one or more batteries or other power sources, power management circuitry, one or more sensors, clock generation circuitry, control algorithms and circuitry, and lens driver circuitry. The complexity of these components may vary depending on the required or desired functionality of the lens.
In at least one embodiment, supplemental control of an electronic or a powered contact lens may be accomplished through a manually operated external device that communicates with the lens through radio frequency (RF) or ultrasonic communication, such as a hand-held remote unit, a phone, a storage container, spectacles, glasses, or a cleaning box. For example, an external device may wirelessly communicate using RF or ultrasound with the powered lens based upon manual input from the wearer. Alternatively, control of the powered contact lens may be accomplished via feedback or control signals directly from the wearer. For example, ultrasound modules built into the lens may include a transmit ultrasound transducer and at least one receive ultrasound transducer, a combination transmit/receive ultrasound transducer, or a combination passive transmit/receive backscatter ultrasound transducer. In at least one embodiment, the powered contact lens may change operation state such as change focus of the contact lens. A further alternative is that the wearer has no control over operation of the powered contact lens.
Because of the complexity of the functionality associated with a powered lens and the high level of interaction between all of the components comprising a powered lens, there is a need to coordinate and control the overall operation of the electronics and optics comprising a powered contact lens. Accordingly, there is a need for a system to control the operation of all of the other components and provide communication between a pair of contact lenses that is low-cost and reliable, has a low rate of power consumption, and is scalable for incorporation into a contact lens.
The distance traveled by the sound pressure wave and the time of flight are related by a constant specific to the media through which the sound pressure wave travels. In at least one embodiment, the constant corresponds to the speed of sound in the aqueous and vitreous humour. The distance to the ciliary muscle can be measured based on the relationship of the time of flight to the speed of sound in eye tissue (typically around 1540 meters/second) divided by two since the ultrasound pulse travels from the eye surface to the ciliary muscle and back. In a normal eye a sound pressure wave would traverse the distance from its surface through the iris to the ciliary muscle and back in roughly 1.3 to 2.6 microseconds. The displacement of the ciliary muscle during accommodation is in the range of 140 micrometers and the imaging frequency required to resolve this change is variable from approximately 5 to 20 MHz where approximately allows for additional variance in manufacturing tolerances along with general variances from these frequencies. In an alternative embodiment, at least one transducer is configured to transmit and/or receive a sound pressure wave at a frequency above approximately 20 MHz. In an alternative embodiment, the full time of flight is used to provide a larger differential when comparing distances and/or time.
In at least one alternative embodiment, the relative position of the lens is used to determine accommodation. When the lens is relaxed, the distance from the surface of the eye to the lens is greater than when the lens is accommodated. The speed of sound in the lens is approximately 9% higher than in the aqueous humour thus providing a reflective boundary to measure lens position. The distance from the surface of the eye to the lens can be sampled to determine displacement. The optic lens in a normal eye is displaced around 200 micrometers in its accommodated state. Lens displacement in an eye having presbyopia, characterized by a thickening of the optical lens, is significantly smaller than in a normal lens, around 50 micrometers. The imaging frequency required to resolve displacement of the presbyopic lens during accommodation is on the order of 40 MHz.
In at least one further alternative embodiment the contact lens is configured to image both the lens and the ciliary muscle to determine accommodation such as a combination of
The system controller 130 in at least one embodiment uses at least one predetermined threshold for interpreting the output of the ultrasound module 110. In another embodiment, the system controller 130 makes use of at least one template (or pattern) to which a series of outputs of the ultrasound module 110 are compared against to determine whether the threshold is being met, exceeded or less than resulting in the threshold being satisfied. In at least one embodiment as illustrated in
The actuator 150 may include any suitable device for implementing a specific function based upon a received command signal from the system controller 130. For example, the system controller 130 may enable the actuator 150 to change focus of the contact lens, provide an alert to the wearer such as a light (or light array) to pulse a light into the wearer's retina (or alternatively across the lens), or to log data regarding the state of the wearer. Further examples of the actuator 150 acting as an alert mechanism include an electrical device; a mechanical device including, for example, chemical release devices with examples including the release of chemicals to cause an itching, irritation or burning sensation, and acoustic devices; a transducer providing optic zone modification of an optic zone of the contact lens such as modifying the focus and/or percentage of light transmission through the lens; a magnetic device; an electromagnetic device; a thermal device; an optical coloration mechanism with or without liquid crystal, prisms, fiber optics, and/or light tubes to, for example, provide an optic modification and/or direct light towards the retina; an electrical device such as an electrical stimulator to provide a mild retinal stimulation or to stimulate at least one of a corneal surface and one or more sensory nerves of the cornea; or any combination thereof. In an alternative embodiment, the actuator 150 sends an alert to an external device using, for example a forward-facing ultrasound module 110. The actuator 150 receives a signal from the system controller 130 in addition to power from the power source 180 and produces some action based on the signal from the system controller 130. For example, if the output signal from the system controller 130 occurs during one operation state, then the actuator 150 may alert the wearer that a medical condition has arisen or the contact lens is ending/nearing its useful life and/defective. In an alternative embodiment, the actuator 150 delivers a pharmaceutical product to the wearer in response to an instruction from the system controller 130. In an alternative embodiment, the signal outputted by the system controller 130 during another operation state, then the actuator 150 will record the information in memory for later retrieval. In a still further alternative embodiment, the signal will cause the actuator to alarm and store information. In an alternative embodiment, the system controller 130 stores the data in the memory (e.g., data storage 132 in other embodiments) associated with the system controller 130 and does not use the actuator 150 for data storage and in at least one embodiment, the actuator 150 is omitted. As set forth above, the powered lens of the present invention may provide various functionality; accordingly, one or more actuators may be variously configured to implement the functionality.
The timing circuit 140 provides a clock function for operation of the contact lens 100A. As illustrated the timing circuit 140 is connected to the system controller 130. In at least one embodiment, the timing circuit 140 drives the system controller 130 to send a signal to the ultrasound module 110 to perform a function based on a sampling time interval, which in at least one embodiment is variable based on the output from the ultrasound module 110 to the system controller 130. In an alternative embodiment, the timing circuit 140 is part of the system controller 130.
Based on this disclosure, it should be appreciated that in addition to the presence of the ultrasound module 110 on the contact lens 100 that additional sensors may be included as part of the contact lens to monitor characteristics of the eye and/or the lens. In at least one embodiment, at least a portion of the actuator 150 is consolidated with the system controller 130.
A communications module 160 on each contact lens being worn by a user permits two-way communication to take place between the contact lenses. In a further or alternative embodiment, the contact lens(es) communicate with an external device. The communications module 160 may include transmitters, receivers, radio frequency (RF) transceivers, antennas, interface circuitry for photosensors, and associated or similar electronic components. A communication channel (or link) between the contact lenses may include RF transmissions at the appropriate frequency and power with an appropriate data protocol to permit effective communication between the contact lenses. The communications module 160 may be configured for two-way communication with the system controller 130. The communications module 160 may contain filtering, amplification, detection, and processing circuitry as is common for establishing a communications link. In an embodiment involving RF, the communications module 160 would be tailored for an electronic or powered contact lens, for example the communication may be at the appropriate frequency, amplitude, and format for reliable communication between eyes, low power consumption, and to meet regulatory requirements. The communications module 160 may work in the RF bands, for example 2.4 GHz, or may use light for communication. Information received by the communications module 160 is an input to the system controller 130. The system controller 130 may also transmit data from, for example, the ultrasound module 110 to the communications module 160, which then transmits data over the communication link to the other contact lens or possibly an external device. In an alternative embodiment, the contact lenses use an ultrasound module to establish the communication link between the contact lenses.
Considerations for the choice of wireless communication protocol include size and power consumption. In embodiments the communications module 160 is configured for communicating using encoded ultrasound pressure waves, the communications module 160 may be the ultrasound modules 100 discussed in this disclosure. In these embodiments, it is understood that the communications module 160 and ultrasound module(s) 110 may be tuned to different frequencies to avoid interference. In at least one embodiment the communications module 160 transmits information concerning the accommodation state of the contact lens. In other embodiments the communications module 160 may transmit other information including sensor data, a request for sensor data, a request for confirmation of data interpretation (e.g., direction of focus and/or contact lens orientation), data interpretation, an instruction to perform a function such as with the actuator and/or a predefined function, etc.
In at least one embodiment as illustrated in
The digital signal processor 111 receives a control signal from the system controller 130. In at least one embodiment, the digital signal processor 111 includes a resettable counter and a time-to-digital convertor and transmit/receive sequencing controls. The oscillator 112 in at least one embodiment is a switched oscillator. In at least one embodiment, the frequency of the oscillator 112 is programmable through a preset oscillator value, the system controller or external interface. The frequency can be tuned using a reference oscillator and an external interface. In at least one further embodiment, the frequency is set or tuned to a value that minimizes transmit and receive electrical power and allows the transmit ultrasound transducer 116 to produce a pressure sound wave that will have maximum amplitude at the receiver input. In a more particular embodiment, the oscillator 112 is a programmable frequency oscillator such as a current starved ring oscillator where the current and the capacitance control the oscillation frequency where the frequency can be altered by changing the current supplied to the oscillator. In at least one embodiment, the wavelength of the sound pressure wave is tuned based on the dimensions of the transducer used. In a further embodiment, the oscillator 112 varies over time for optimal transmission characteristics. In a still further embodiment, the frequency is calibrated using a reference frequency provided through an external interface and an automatic frequency control (AFC) circuit. The frequency is preset with the AFC tuning it. The frequency can be directly set through the serial interface, which can be accessed through the external communications link.
In an embodiment where the time of flight is used, the counter in the digital signal processor 111 begins to count pulses output from the oscillator 112. The burst generator 113 gates the oscillator signal for a fixed amount of time defined as the burst length. In at least one embodiment, the burst length is programmable or determined by static timing relationships within the burst generator 113.
The output voltage of the burst generator 113 may be level shifted to the appropriate value for the transmit driver 115 and the transmit ultrasound transducer 116. An example of the transmit ultrasound transducer 116 is a piezoelectric device which converts applied burst voltage to a sound pressure wave. In at least one embodiment, the sound pressure wave includes a burst or multiple sound pressure waves. In a further embodiment, the transmit ultrasound transducer 116 is made of any piezoelectric material that is compatible with the power source and the physical properties of the contact lens. Another example of a transducer is a polyvinylidene fluoride or polyvinylidene difluoride (PVDF) film. The sound pressure wave produced by the transmit ultrasound transducer 116 propagates from the contact lens 100D into the eye. The distance to the ciliary muscle and/or the lens can be measured by dividing the travel time between the propagation of the sound pressure wave and receipt of the reflected sound pressure wave by the receive ultrasound transducer 121 multiplied by the speed of sound in the eye as discussed previously.
The receive amplifier 120 and the analog signal processor 118 in at least one embodiment are turned on with the oscillator 112 or turned on after a predetermined delay after the oscillator 112 is started. When there is a predetermined delay, power for contact lens 100D operation may be lowered during the period of delay. In an embodiment where the receive amplifier 120 and the analog signal processor 118 are started with the oscillator 112, the receive amplifier 120 will receive an output from the receive ultrasound transducer 121 proximate to when the sound pressure wave is output by the transmit ultrasound transducer 116. This output from the receive ultrasound transducer 121 can be used to reset the counter in the digital signal processor 111. In a further embodiment, the detection of the transmit sound pressure wave can be used as an indicator that a true transmit signal has been generated.
A sound pressure wave received by the receive ultrasound transducer 121 will produce a voltage signal with a frequency, amplitude, and burst length properties related to the transmitted sound pressure wave. The voltage signal is amplified by the receive amplifier 120 before being sent to the analog signal processor 118, which in an alternative embodiment to embodiments having the receive amplifier 120 and the signal processor 118 are combined into a signal processor. The analog signal processor 118 may include, but is not limited to, frequency selective filtering, envelope detection, integration, level comparison and/or analog-to-digital conversion. Based on this disclosure, it should be appreciated that these functions may be separated into individual blocks with some examples being illustrated in later figures. The analog signal processor 118 produces a received signal that represents the received sound pressure wave at the receive ultrasound transducer 121, which in implementation will have a slight delay. The received signal is passed from the analog signal processor 118 to the digital signal processor 111. When transmission time is used, the digital signal processor 111 will stop the counter that is counting pulses from the oscillator 112 when the received signal is received. In such an embodiment, the measured time can be compared to a predetermined value to determine whether a change in focus should occur. In other embodiments, the digital signal processor 111 interprets the received signal for a message from, for example, the other contact lens or an external device. The resulting output from the digital signal processor 111 is provided to the system controller 130. In an alternative embodiment, the counter does not stop so that a series of received sound pressure waves may be detected to develop a representation of an amplitude versus time set of data for analysis by, for example, the system controller 130. This alternative embodiment may also be used in connection to other embodiments in this disclosure.
The charge pump 114 is also electrically connected to the processor 111G, which controls operation of the charge pump 114 in at least one embodiment to minimize power consumption by the system by, for example turning off the oscillator 112, the pulse generator 113, and/or the charge pump 114 at times when the ultrasound module 110G does not need to propagate a sound pressure wave. The envelope detector 119 turns the high-frequency output of the receive ultrasound transducer 121 into a new signal that provides an envelope signal representative of the original output signal to be provided to the comparator 117. This illustrated embodiment has the advantage of simplifying the analysis of the output of the receive ultrasound transducer 121 to determine if a particular threshold has been met for the contact lens 100G to perform a function. The comparator 117 provides an output to the processor 111G, which is in electrical communication with the system controller 130.
Based on the disclosure connected to
In at least one embodiment, a transmit ultrasound transducer 1212 and a receive ultrasound transducer 1213 are present in the ultrasound module. In at least one embodiment, the integrated circuit 1208 includes a transmit ultrasound transducer 1212 and a receive ultrasound transducer 1213 with the associated signal path circuits. The transducers 1212, 1213 face inward through the lens insert and toward the eye (i.e., inward-facing or ciliary muscle-facing), and is thus able to send sound pressure waves toward the wearer's ciliary muscle and/or lens and detect at least the partially reflected waves. In at least one embodiment, the transducers 1212, 1213 are fabricated separately from the other circuit components in the electronic insert 1204 including the integrated circuit 1208. In this embodiment, the transducers 1212, 1213 may also be implemented as separate devices mounted on the electronic insert 1204 and connected with wiring traces 1214. Alternatively, the transducers 1212, 1213 may be implemented as part of the integrated circuit 1208 (not shown). Based on this disclosure one of ordinary skill in the art should appreciate that transducers 1212, 1213 may be augmented by the other sensors.
In a further embodiment to the embodiments illustrated in
In at least one embodiment as illustrated in
In at least one embodiment, the system controller deactivates the transmission components of the ultrasound module when the respective contact lens is not transmitting. In a further embodiment, the illustrated ultrasound modules are replaced by transducers that are multiplexed together as illustrated in
In an alternative embodiment illustrated in
The ultrasound module propagates a first sound pressure wave at a predetermined frequency towards the ciliary muscle and/or the lens, 1610. The ultrasound module transmits at least one detection of a reflected sound pressure wave to the first sound pressure wave by the transducer, 1620. The reflected sound pressure wave time, amplitude, and/or frequency (or detected reflected data) is recorded in memory (or data storage) by the system controller, 1630. The ultrasound module propagates a second sound pressure wave at a predetermined frequency towards the ciliary muscle and/or the lens, 1640. In at least one embodiment, the frequency is used for the second sound pressure wave is different than the frequency used for the first sound pressure wave. The ultrasound module transmits at least one second detection of a reflected sound pressure wave to the second sound pressure wave by the transducer, 1650.
The processor determines a relative position of the wearer's ciliary muscle and/or lens based on the relationship between at least part of the at least one detected reflected data for the first and the second sound pressure waves, 1660. An alternative embodiment uses the relationship of the first time of flight and the second time of flight to a constant, e.g. speed of sound in the eye, 1660. The system controller overwrites the first detected reflected data in the memory with the second detected reflected data, or alternatively stores the second detected reflected data, 1670. The relationship is compared to a threshold (e.g., a distance threshold if a position is being used) and the system controller drives the actuator when the position reaches a predetermined threshold, 1680. In at least one embodiment, the predetermined threshold corresponds to distance displaced by a ciliary muscle during accommodation. In at least one further embodiment, the predetermined threshold corresponds to distance displaced by a lens during accommodation. In at least one further embodiment, the predetermined threshold corresponds to a distance displaced by a lens having presbyopia. In an alternative embodiment, the system controller stores the shortest and/or longest times of flight or a representation of these to measure the differential from and to compare to the predetermined threshold. In another alternative embodiment, the system controller stores the shortest and/or longest detected reflected data based on the time between the first and the last relevant reflection detected by the ultrasound module where in at least one embodiment the last relevant reflection is for the target of the sound pressure wave.
In other embodiments, the ultrasound module includes at least two transmit/receive paths and the method steps are performed simultaneously or contemporaneously to image at least two distinct points, a first point along the boundary of the ciliary muscle and a second point on the boundary of the lens. It should be understood by one skilled in the art that increasing the number of data points imaged enhances overall resolution, and additional ultrasound transducers and/or transceivers may be included to achieve this result.
In an alternative embodiment to the method illustrated in
In a further alternative embodiment, the system controller determines a relative position, shape, and/or state of the target (e.g., P1, P2, P3, and P4) at which the sound pressure waves are being aimed.
In at least one embodiment, the system analysis a series of times of flight (or detected reflected data) with a time-frequency analysis to detect patterns that may be present. In a further embodiment, the system will record the series of times of flight (or detected reflected data series) for later downloading and/or analysis external to the contact lens.
In at least one embodiment, the system will send a series of chirps across a frequency range to create a data set to subject to time-frequency analysis looking for patterns and/or selecting a frequency that provides the strongest data response. In a further embodiment, the frequency sweep will occur at predetermined intervals to allow for the selected frequency to be adjusted akin to frequency hopping and/or to provide additional data sets for time-frequency analysis. In a further embodiment to either of these two embodiments, the detected pattern from the time-frequency analysis is compared to a template representing accommodation and/or non-accommodation. When the detected pattern matches a template and it indicates a change in accommodation, then adjusting the level of accommodation for the contact lens.
One approach to facilitate communication between a first and a second contact lens is to implement automatic frequency control for the communication channel. In at least one embodiment, the timing circuit on one contact lens would be the master. The clock synchronization in at least one embodiment will lead the electronics to be biased towards a lens pair to have one be a master. In a further embodiment, the selection of the master contact lens is made after manufacturing via a software and/or identification tag download to the lenses and/or settings change. This approach also could be used to facilitate the dual frequency approach discussed in this disclosure.
In an alternative embodiment to the methods illustrated in
In a further embodiment, the communications module is tuned to a different frequency than any frequency used by the at least one ultrasound module. An advantage of this is that it improves each receiver's capability of correctly detecting the desired signal. By using separate frequencies, frequency selective techniques (such as mixing and envelope detection) can reject noise or undesired transmit signals that could be produced by the physical geometry and properties of the communication channel through scattering on the nose.
Although shown and described in what is believed to be the most practical embodiments, it is apparent that departures from specific designs and methods described and shown will suggest themselves to those skilled in the art and may be used without departing from the spirit and scope of the invention. The present invention is not restricted to the particular constructions described and illustrated, but should be constructed to cohere with all modifications that may fall within the scope of the appended claims.