Device, system and method for detecting a direction of gaze based on a magnetic field interaction

Techniques and mechanisms for determining a direction of gaze by a user of an ophthalmic device. In an embodiment, at least a portion of a magnetic field is generated by one of the ophthalmic device and an auxiliary reference device while the ophthalmic device is disposed in or on an eye of the user, and while the auxiliary reference device is adhered on the user's skin or under a surface of the skin. The ophthalmic device and the auxiliary reference device interact with each other via a magnetic field, and the interaction is detected with one or more sensors of the ophthalmic device. In another embodiment, the ophthalmic device stores predetermined reference information which corresponds various magnetic field signal characteristics each with a different respective direction of gaze. Based on the sensor information and the reference information, a controller of the ophthalmic device determines a direction in which the eye of the user is gazing.

BACKGROUND

1. Technical Field

This disclosure relates generally to the field of optics, and in particular but not exclusively, relates to contact lenses.

2. Background Art

Accommodation is a process by which the eye adjusts its focal distance to maintain focus on objects of varying distance. Accommodation is a reflex action, but can be consciously manipulated. Accommodation is controlled by contractions of the ciliary muscle. The ciliary muscle encircles the eye's elastic lens and applies a force on the elastic lens during muscle contractions that change the focal point of the elastic lens.

As an individual ages, the effectiveness of the ciliary muscle degrades. Presbyopia is a progressive age-related loss of accommodative or focusing strength of the eye, which results in increased blur at near distances. This loss of accommodative strength with age has been well studied and is relatively consistent and predictable. Presbyopia affects nearly 1.7 billion people worldwide today (110 million in the United States alone) and that number is expected to substantially rise as the world's population ages.

Recent technologies have begun to provide for various devices that operate in or on a human eye to aid the visual focus of a user. For some types of these devices, an accommodating lens includes one or more elements and circuitry to apply an electrical signal to change a focusing power of the one or more elements. Determining when to change such focusing power is often based on a direction of a gaze by a user of the optical device. As the capabilities of accommodation-capable optical devices continue to increase, there is expected to be an increased demand for such optical devices to provide accurate tracking of direction of gaze by a user.

DETAILED DESCRIPTION

Embodiments described herein variously provide an apparatus, system and/or method for determining a direction of gaze by a user of an ophthalmic device. In the following description numerous specific details are set forth to provide a thorough understanding of the embodiments. One skilled in the relevant art will recognize, however, that the techniques described herein may be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring certain aspects.

Certain features of various embodiments are described herein with reference to mechanisms and techniques for determining a direction of gaze by a user of an eye-mountable device (EMD) that is mountable as a contact lens and that provides functionality to automatically provide any of various levels of accommodation. However, such discussion may be extended to additionally or alternatively apply to any of a various other types of ophthalmic device. For example, an ophthalmic device according to some embodiments may include an intraocular lens (IOL) that is implantable in an eye and/or may support other functionality in addition to (or instead of) automatic accommodation.

An accommodation-capable ophthalmic device may assist viewing by a user with a condition such as presbyopia or a cataract. An amount of accommodation to be provided by such an ophthalmic device may be determined based at least in part on a direction of gaze by the user of the ophthalmic device. For example, a higher level of accommodation may be needed when the direction of gaze (corresponding to the eye's orientation in the user's skull) is relatively high in the user's field of view. By contrast, a relatively low level of accommodation may be needed when the direction of gaze is lower in the user's field of view and/or is oriented more toward the nose bone of the skull.

In some embodiments, the direction of gaze is determined based on an interaction between the ophthalmic device and another device (referred to herein as an “auxiliary reference device”) that is adhered on or implanted in the user. Such an auxiliary reference device may be fixed relative to the user's skull, and may move relative to the user's eye and relative to the ophthalmic device disposed in or on the eye. An auxiliary reference device according to one embodiment includes a mechanism, such as a magnet or a coil, that can generate, or otherwise affect the generation of, a magnetic field that is sensed by one or more magnetic sensors of the ophthalmic device. Interaction with the auxiliary reference device via the magnetic field may enable the ophthalmic device to detect a position and/or an orientation of the ophthalmic device relative to the auxiliary reference device (and thus, relative to the user's skull).

For example, the ophthalmic device may include or otherwise have access to pre-determined reference information that corresponds various characteristics of magnetic field signals (for brevity, ‘magnetic field signal characteristics’ herein) each with a respective state of the ophthalmic device and/or the auxiliary reference device. Such magnetic field signal characteristics may include characteristics of one or more signal to generate the magnetic field and/or characteristics of one or more signal generated based on the magnetic field. The ophthalmic device may access the reference information, based on output from a magnetic sensor of the ophthalmic device, to identify a position and/or orientation of the ophthalmic device relative to the auxiliary reference device. Based on the identified position and/or orientation, the ophthalmic device may control operation of an accommodation actuator and/or other mechanism.

FIG. 1illustrates features of a system100to detect a direction of gaze according to an embodiment. System100includes devices that are each to be variously disposed in or on the body of a user, where interaction between such devices via one or more magnetic fields is to facilitate detection of a direction of gaze by that user. Unless otherwise indicated, “auxiliary reference device,” “reference device,” “reference unit” and similar terms refer to a mechanism, such as that of an auxiliary reference device120of system100, that operates to interact with an ophthalmic device via a magnetic field, wherein a direction of gaze is determined based on such interaction. An auxiliary reference device external to the ophthalmic device, or a component thereof, may serve as a reference for detecting a direction of gaze—e.g., relative to some baseline gaze direction. An auxiliary reference device may comprise a magnetic source configured to be positioned on or under the user's skin—e.g., peripherally to an eye of the user. The auxiliary reference device may thus have a fixed position, relative to the skull of the user, at least during a period of time during which the user's eye moves (along with an ophthalmic device disposed therein or thereon) within an orbital socket of the skull. The position of the ophthalmic device relative to the auxiliary reference device may thus correspond to an orientation of the user's eye within the skull. This relative position (and/or a change in such a relative position) may provide a basis for determining a direction of gaze by the user.

In the illustrative embodiment shown, system100includes an ophthalmic device110that is (or is configured to be) disposed in or on a user's eye (not shown). For example, an enclosure116of device110may form a biocompatible exterior to accommodate such disposition in or on the eye. System100may further comprise one or more other devices—e.g., including the illustrative auxiliary reference device120—each of which is (or is configured to be) disposed on or under the user's skin. Ophthalmic device110may include a contact lens, or an intraocular device, comprising integrated circuitry, encapsulated by enclosure116, to facilitate detection of a direction of gaze. Such integrated circuitry may include one or more magnetic sensors (such as the illustrative sensor112shown) and a controller114. Sensor112may operate to detect one or more characteristics of a magnetic field130between ophthalmic device110and auxiliary reference device120(e.g., where magnetic field130is concurrent with and overlaps one or more other magnetic fields). Alternatively or in addition, sensor112may sense one or more characteristics of signaling to generate at least a portion of magnetic field130. Based on sensor information output by sensor112, controller114may determine a direction of gaze by an eye in which or on which is disposed ophthalmic device110.

For example, controller114may comprise logic (e.g., application-specific integrated circuitry, executable instructions and/or the like) that, when executed, causes the controller114to measure, with one or more magnetic sensors such as sensor112, a magnetic field interaction between the ophthalmic device110and auxiliary reference device120. Such measuring may include generating magnetic field130with an electromagnet circuit of ophthalmic device110—e.g., wherein the magnetic field interaction is measured as a load on the electromagnet circuit. The one or more magnetic sensors may be operated by controller114to generate one or more magnetic field signals in response to such measuring of the magnetic field interaction. In some embodiments, controller114operates to monitor the one or more magnetic field signals and to correlate the one or more magnetic field signals to a gazing direction of ophthalmic device110.

For example, controller114may include or otherwise have access to pre-determined reference information (not shown) that corresponds various sets of sensor information each with a different respective configuration of ophthalmic device110and auxiliary reference device120relative to each other. Some or all configurations may each include, for example, a respective distance between ophthalmic device110and auxiliary reference device120and/or a respective angular offset between ophthalmic device110and auxiliary reference device120.

Controller114may include logic operable to output one or more signals—based, for example, on information from sensor112and predetermined reference information—identifying or otherwise indicating an angular offset of the gaze direction from some reference direction. Such one or more signals may indicate the direction of gaze by identifying a distance and/or an angular offset between respective components of ophthalmic device110and auxiliary reference device120—e.g., with respect to the illustrative x, y, z coordinate system shown. In an embodiment, signaling output by controller114is used to control an automatic accommodation and/or some other functionality that is provided by ophthalmic device110.

Auxiliary reference device120is one example of an embodiment that may be disposed on or under the skin of a user of ophthalmic device110(or of some other user of an ophthalmic device). By way of illustration and not limitation, auxiliary reference device120may include a capsule or an adhesive bandage. Interaction with ophthalmic device110via magnetic field130may occur while auxiliary reference device120is within 1 cm of a surface of the user's skin—e.g., while auxiliary reference device120is also in a fixed position relative to the user's skull. Auxiliary reference device120may be small enough and/or light enough to be imperceptible by the user of ophthalmic device100. An overall weight of auxiliary reference device120may be equal to or less than 1 ounce, for example. Alternatively or in addition, a total volume of auxiliary reference device120may be equal to or less than 1 cm3—e.g., where such a volume is equal to or less than 500 mm3and, in some embodiments, equal to or less than 250 mm3. In some embodiments, auxiliary reference device120has a maximum width (e.g., a diameter) that is equal to or less than 2.5 cm—e.g., where the maximum width is equal to or less than 2.0 cm and, in some embodiments, equal to or less than 1 cm. Alternatively or in addition, a smallest side of auxiliary reference device120may have a length that is equal to or less than 5 mm—e.g., where the smallest side is equal to or less than 2 mm. In some embodiments, the smallest side is equal to or less than 1 mm (e.g., equal to or less than 500 um). Alternatively or in addition, a maximum cross-sectional area of auxiliary reference device120may be equal to or less than 4 cm2, for example. Such a maximum cross-sectional area may be equal to or less than 3 cm2and, in some embodiments, equal to or less than 2 cm2. However, such weights and dimensions of auxiliary reference device120are merely illustrative, and not limiting on other embodiments.

Auxiliary reference device120may omit some functionality that is provided by one or more other devices that are included in, or are to operate with, system100. For example, in one embodiment, any user interface mechanism (e.g., including any display, any microphone and/or any speaker) of system100is provided by one or more devices other than auxiliary reference device120. Alternatively or in addition, any optics of system100may be provide by one or more devices other than auxiliary reference device120. In one embodiment, any communication between auxiliary reference device120and ophthalmic device110(or between auxiliary reference device120and any other device, for example) is only via wireless signaling.

The illustrated embodiment of auxiliary reference device120includes an enclosure122(or other housing structure) having disposed therein a mechanism, illustrated as reference unit124, that is to serve as a reference for determining a relative position and/or a relative orientation of ophthalmic device110. Enclosure122may be at least partially transparent to electromagnetic energy, thus allowing one or more components of reference unit124to generate or interact with at least some component of the magnetic field130that extends between ophthalmic device110and auxiliary reference device120.

In one embodiment, enclosure122includes any of a variety of biocompatible materials that facilitate implantation (e.g., subcutaneous injection) of auxiliary reference device120within the body of a user of ophthalmic device110. By way of illustration and not limitation, enclosure122may include any of various polyimide, parylene, silicone, ceramic and/or other materials adapted from conventional implantable medical device technologies. In another illustrative embodiment, auxiliary reference device120is to be disposed on a surface of the user's skin. For example, enclosure122may include a flexible material—such as a woven fabric, a plastic (such as polyethylene or polyurethane), latex or other such material—and a coating comprising an acrylate, resin or other such adhesive for applying auxiliary reference device120onto an exterior surface of the user's skin.

Reference unit124illustrates any of a variety of mechanisms to generate or to interact with at least a portion of magnetic field130. For example, reference unit124may include a permanent magnet and/or an electromagnet circuit (e.g., including a solenoid) to generate at least a portion of magnetic field130. In such an embodiment, sensor112may operate to detect a strength and/or a direction of such a portion of magnetic field130. A permanent magnet of reference unit124may include, for example, Neodymium (Nd), samarium-cobalt (SmCo) and/or any of a variety of other materials adapted from conventional techniques for generating a magnetic field.

Alternatively or in addition, one or more components (not shown) of ophthalmic device110may instead, or also, generate at least part of magnetic field130. For example, ophthalmic device110may itself include a permanent magnet and/or an electromagnet circuit. In such an embodiment, reference unit124may include a circuit structure (e.g., including an antenna) that interacts with one or more components of magnetic field130that are generated by ophthalmic device110. Such interaction may include coupling whereby the circuit structure of reference unit124functions as a load on the generation of magnetic field components by ophthalmic device110. By way of illustration and not limitation, reference unit124may include an antenna to couple with at least a portion of magnetic field130, the antenna including a conductor forming a coil, helix, logarithmic spiral and/or any of various other shapes. Such a conductor may include a non-ferromagnetic metal forming a microcoil, or other such structure.

In some embodiments, such an antenna includes any of various short dipole antenna structures, near field antenna structures and/or the like. As used herein, “antenna” refers to any structure that can operate to perform one or both of radiating an electromagnetic field and coupling to an electromagnetic field. This includes, for example, any of a variety of structures that facilitate a reactive exchange of energy—e.g., in addition to, any exchange of energy by electromagnetic radiation.

Reference unit124may interact with magnetic field130using only one or more passive circuit structures. For example, circuit structures of reference unit124may omit any transistors or other active circuit elements. Such one or more passive circuit structures may be energized using only a power source that is external to auxiliary reference device120(e.g., where such a power source is a component of ophthalmic device110). In other embodiments, reference unit124(or some other component of auxiliary reference device120) includes integrated circuitry to facilitate interaction with ophthalmic device110via magnetic field130. By way of illustration, such integrated circuitry may modulate the generation of, or an interaction with, some component of magnetic field130. Alternatively or in addition, such integrated circuitry may facilitate wireless communication between auxiliary reference device120and ophthalmic device110(and/or some other device, not shown).

FIG. 2illustrates elements of a method200, according to an embodiment, to detect a direction of gaze by a user of an ophthalmic device. Method200may include operations performed with some or all components of system100, for example. In one embodiment, method200is performed by a device having some or all of the features of ophthalmic device110. To illustrate certain features of various embodiments, method200is described herein with reference to a system300that is shown inFIG. 3. However, such discussion may be extended to additionally or alternatively apply to any of a variety of other devices and/or systems of devices, according to different embodiments. Some or all of system300may, in various embodiments, provide functionality that is alternative to and/or in addition to that provided according to method200.

In an embodiment, method200includes, at210, measuring a magnetic field interaction between an ophthalmic device and an auxiliary reference device (e.g., between ophthalmic device110and auxiliary reference device120). The magnetic field interaction may take place via a magnetic field, such as field130, which extends outside of the ophthalmic device in a region between the ophthalmic device and the auxiliary reference device. The magnetic field interaction (and the measuring thereof at210) may occur while the auxiliary reference device is adhered onto, or disposed under a surface of, the skin of a user—e.g., while the ophthalmic device is disposed in or on an eye of that user.

Method200may further comprise, at220, generating one or more magnetic field signals in response to the measuring at210. As used herein, ‘magnetic field signal’ refers to a signal—e.g., including a voltage signal or a current signal—which is generated based on a sensing of a magnetic field, wherein the signal specifies or otherwise indicates a characteristic of the magnetic field. One or more magnetic field signals may, for example, indicate any of a variety of combinations of one or more static conditions and/or one or more dynamic conditions including, but not limited to, a magnitude, direction, rate of change, modulation, etc. of a magnetic field.

In the illustrative embodiment ofFIG. 3, system300includes an ophthalmic device OD314disposed in or on an eye of a user310using system100. The other eye of user310may also have another ophthalmic device (not shown) disposed therein or thereon. OD314may provide functionality such as that of ophthalmic device110or any of various other ophthalmic devices described herein. For example, system300may further comprise an auxiliary reference device RD312that is configured to remain in a fixed orientation relative to the head of user310—e.g., at least while user310is variously viewing in different directions with OD314at different times. During such viewing, one of RD312and OD314may generate at least part of a magnetic field that extends into some region including the other of RD312and OD314. One or more magnetic sensors (not shown) of OD314may determine, based the magnetic field and/or signaling to create the magnetic field, a direction of gaze by the eye of user310. For example, a magnet or a circuit structure of RD312may interact with ophthalmic device312via such a magnetic field while ophthalmic device312is disposed in or on the eye of user310, and also while RD312is adhered onto, or disposed under a surface of, the skin of user310. In one embodiment, RD312is configured to interact with ophthalmic device312while within 2 cm of the eye in which (or on which) is disposed ophthalmic device312. For example, RD312may be within 1 cm of the eye during interaction of RD312with OD314.

In one embodiment shown by the detail view in inset320, an eye-mountable device EMD340(e.g., OD314) is disposed on an eye330. EMD340may be configured to interact with an auxiliary reference device (not shown) via a magnetic field B that is generated at least in part by the auxiliary reference device or by a component of EMD340. In an example embodiment, an enclosure material of EMD340has formed therein a signal line342in which other circuitry (not shown) of ophthalmic device342is to drive a current. EMD340may further comprise one or more sensors to measure a current, voltage and/or other signal characteristic based on signal line342conducting the current within magnetic field B.

By way of illustration and not limitation, a current in signal line342, in combination with magnetic field B, may results in a Hall effect sensor344of EMD340exhibiting a voltage difference—e.g., along a line of a direction that is orthogonal to a direction of the current in signal line342. Sensor information generated with Hall effect sensor344—such as the one or more magnetic field signals generated at220—may indicate a direction, strength and/or any of various other characteristics of magnetic field B (e.g., including a change, rate of change, etc. of a characteristic). In some embodiments, the EMD340includes an accommodation actuator (not shown)—e.g., wherein signal line342, an electromagnet circuit and/or other such magnetic sensor circuit structure forms one or more loop structures which extend around some or all of a periphery of the accommodation actuator.

Method200may further comprise, at230, correlating the one or more magnetic field signals generated at220to a gazing direction. For example, the correlating at230may include accessing or otherwise determining reference information which corresponds various magnetic field signal characteristics each with a different respective direction of gaze. The reference information may be provided, for example, as an a priori input to the ophthalmic device prior to a sensing of a gaze direction with the ophthalmic device. In some embodiments, the determining at210includes performing a configuration operation to calibrate a gaze detection functionality.

The correlating at230may include generating, based on a characteristic of the one or more magnetic field signals and further based on predefined reference information, one or more signals describing a direction of gaze by a user of the ophthalmic device. For example, the correlating at230may include performing a search of the reference information to identify, from among different magnetic field signal characteristics (e.g., different sets of magnetic field signal characteristics), those one or more magnetic field signal characteristics that most closely match the one or more magnetic field signals generated at220. The correlating at230may further comprise selecting the direction of gaze which is identified by the reference information as corresponding to the most closely matching one or more magnetic field signal characteristics. In the illustrative embodiment shown in inset320, reference information (not shown) stored at EMD340may be searched or otherwise processed by evaluation logic a controller of EMD340to select, calculate or otherwise determine a direction of gaze that most closely corresponds to the or more characteristics of magnetic field B that are detected with Hall effect sensor344.

In an embodiment, method200further comprises, at240, detecting, in real-time, changes in the gazing direction based upon changes in the one or more magnetic field signals. For example, controller logic of the ophthalmic device may operate to monitor the one or more magnetic field signals over time. Such monitoring may include or otherwise be based on a measuring the magnetic field interaction as a load on an electromagnet circuit of the ophthalmic device. In such an embodiment, method200may comprise modulating the magnetic field to induce the load. For example, the ophthalmic device may deliver energy via the magnetic field to power a modulation of the magnetic field by circuitry of the auxiliary reference device.

Although some embodiments are not limited in this regard, method200may further comprise operations (not shown) to provide an accommodation level with the ophthalmic device based on the gazing direction. For example, such operations may include electrically manipulating an accommodation lens of the ophthalmic device to automatically change an optical power of the ophthalmic device in response to the detecting at240. Such electrical manipulating may include one or more processes that, for example, are adapted from conventional techniques and/or mechanisms which identify one of a plurality of gazing directions as corresponding to a particular optical power to be provided with an accommodation lens. The particular details of such conventional techniques and mechanisms are not detailed herein to avoid obscuring features of various embodiments.

The correlating at230may include, or otherwise be based on, a calibration, training or other initial configuration process—e.g., to determine magnetic field signal characteristics that are to be variously associated each with one of a baseline (or reference) direction of gaze and various degrees and/or types of deviation from that baseline direction of gaze. Such a configuration process may further determine, for each of various gaze directions other than the baseline, a respective one or more magnetic field signal characteristics that are indicative of that corresponding gaze direction.

By way of example and not limitation, such a configuration process may include configuration hardware, software and/or other such logic—e.g., included in a laptop, mobile device, or other external hardware (not shown) that communicates wirelessly with OD314—operating to display some sequence of visual targets to user310while OD314and RD312interact via a magnetic field. The configuration logic may prompt user310—e.g., through visual and/or audio output—to variously view such targets at different times, where the targets each have a known position, distance (depth) from user310and/or the like. In response, user310may provide to the calibration logic input (e.g., via a microphone, handheld device or the like) variously indicating when such targets are being viewed. The calibration target may continuously move to different positions, where user310indicates by a button press, verbal and/or other means when they are or are not visually tracking the moving target.

In some embodiments, two (or more) auxiliary reference devices may be arranged in a configuration that is fixed, relative to the skull of a user, and that enables such auxiliary reference devices to participate in different respective magnetic interactions with the same ophthalmic device. One or more magnetic sensors of the ophthalmic device may variously detect signal characteristics that are variously based each on a respective one of such interactions. A controller of the ophthalmic device may process the output of the one or more magnetic sensors, wherein the two or more auxiliary reference devices are used as multiple references for detecting a relative position of the ophthalmic device (and a corresponding direction of gaze by a user of the ophthalmic device).

For example, method200may further comprise the ophthalmic device measuring, with one or more magnetic sensors, a second magnetic field interaction between the ophthalmic device and a second auxiliary reference device which is also external to the ophthalmic device. The one or more magnetic sensors may further generate a second one or more magnetic field signals based on the second magnetic field interaction. In such an embodiment, the correlating at230may include correlating a combination of both the one or more magnetic field signals (generated at220) and the second one or more magnetic field signals to the gazing direction.

By way of illustration and not limitation, as shown in inset360ofFIG. 3, one embodiment may include an ophthalmic device380configured to be disposed in or on an eye372—e.g., where ophthalmic device380is a contact lens to cover some or all of an iris374of eye372and that may be partially overlapped by an eyelid370. Inset360illustrates some examples of locations390(on or under a surface of the user's skin) where such one or more auxiliary reference devices—e.g., including RD312—might be variously located. However, the one or more auxiliary reference devices may be located in more, fewer and/or different locations near (e.g., within 2 cm) of eye372. A range of possible locations of ophthalmic device380during movement of eye372may allow for interaction between ophthalmic device380and one or more auxiliary reference devices that are each disposed on or under a surface of the skin of the user. In an embodiment, ophthalmic device380includes one or more magnetic sensors—e.g., including the illustrative magnetic sensor382—to detect interactions between ophthalmic device380and multiple auxiliary reference devices variously disposed each at a different respective one of the locations390.

In one embodiment, ophthalmic device380includes circuitry that operates to determine a correspondence of auxiliary reference devices each with a different respective magnetic field or magnetic field response. By way of illustration and not limitation, a memory (not shown) of ophthalmic device380may store additional reference information that defines resonant frequencies and/or other signal characteristics that are to variously serve as signatures each of a different respective auxiliary reference device. Such signatures may be used by a controller of the ophthalmic device to distinguish a magnetic field interaction involving one auxiliary reference device from another magnetic field interaction involving a different auxiliary reference device. In distinguishing such interactions from one another, ophthalmic device380may determine a direction of gaze by eye372by performing calculations to triangulate a position and/or an orientation of ophthalmic device380relative to multiple auxiliary reference devices.

FIG. 4Aillustrates features of a system400to determine a direction of gaze according to an embodiment. System400may include features of system100and/or system300, for example. In an embodiment, operation of system400is performed according to method200. System400includes an ophthalmic device410and an auxiliary reference device420that are to interact with one another via a magnetic field402. Based on such interaction, ophthalmic device410may determine a direction of gaze by a user of ophthalmic device410.

In the illustrative embodiment of system400, auxiliary reference device420generates some or all of magnetic field402. For example, magnetic field402may include at least some non-varying component that is provide by a permanent magnet of auxiliary reference device420. Alternatively or in addition, auxiliary reference device420may include an electromagnet circuit (e.g., comprising a solenoid) that operates to provide some or all of magnetic field402. Such an electromagnet circuit may modulate one or more components of magnetic field402—e.g., where such modulation is to serve as a signature for distinguishing auxiliary reference device420from one or both of a background magnetism of the surrounding environment and any magnetic field signature of some other device (not shown). Although some embodiments are not limited in this regard, operation of such an electromagnetic circuit may be powered by an energy harvesting antenna (not shown) of auxiliary reference device420. Such an energy harvesting antenna may be powered, for example, by signals from ophthalmic device410or from some other device (not shown) that is included in or operates with system400.

A magnetic sensor412of ophthalmic device410may provide to a controller (not shown) of ophthalmic device410sensor information indicating a direction, strength and/or other characteristic of field402. For example, magnetic sensor412may include one or more Hall effect sensors, a magnetic coupling detector, a giant magnetoresistance (GMR) sensor and/or any of a variety of other mechanisms adapted from conventional techniques for detecting a characteristic of a magnetic field and/or characteristics of signaling to generate a magnetic field. The details of such conventional techniques are not limiting on some embodiments, and are not detailed herein to avoid obscuring features of various embodiments.

FIG. 4Billustrates another system430to determine a direction of gaze according to a different embodiment—e.g., where system430is an alternative embodiment to that of system410. System430includes an ophthalmic device440and an auxiliary reference device450that are to interact with one another via a magnetic field432. Based on such interaction, ophthalmic device440may determine a direction of gaze by a user of ophthalmic device440. In the illustrative embodiment of system430, a magnetic field generator442of ophthalmic device440provides some or all of magnetic field402. For example, magnetic field generator442may include an electromagnet circuit. A passive circuit structure452of auxiliary reference device450may couple with magnetic field402—e.g., the passive circuit structure452including an antenna structure such as a micro-coil. For example, auxiliary reference device450may interact with magnetic field432only via passive circuit elements, conductors and/or the like. Such coupling may serve as a load on an electromagnet circuit of magnetic field generator442. The load may be detected with a magnetic sensor444of ophthalmic device410, where such detection aids in determining a position of auxiliary reference device450relative to ophthalmic device410.

FIG. 4Cillustrates a system460to determine a direction of gaze according to another embodiment—e.g., where system460is an alternative embodiment to one of systems410,430. System460includes an ophthalmic device470and an auxiliary reference device480that are to interact with one another via a magnetic field462. Based on such interaction, ophthalmic device470may determine a direction of gaze by a user of ophthalmic device470. In system460, a magnetic field generator472of ophthalmic device470provides some or all of magnetic field402. An antenna482of auxiliary reference device480may couple with magnetic field402. Such coupling may be varied over time by a control circuit480of auxiliary reference device480. For example, control circuit480may include integrated circuitry comprising active circuit elements that are powered by magnetic field432(and/or some other remote source of electromagnetic energy) to modulate coupling of antenna482with magnetic field432. Such coupling may serve as a time-varying load on an electromagnet circuit of magnetic field generator472, which may be detected with a magnetic sensor474of ophthalmic device410. Such detection may in turn aid in a controller (not shown) of EMD410determining a position of auxiliary reference device480relative to EMD410.

FIG. 5is a functional block diagram of an accommodation-capable eye-mountable device500to be accessed via an auxiliary device505, in accordance with an embodiment. EMD500may include some or all features of one of ophthalmic devices110,314,410,430,460, for example. An exposed portion of EMD500may include an enclosure material510formed to be contact-mounted to a corneal surface of an eye. A substrate515may be embedded within or surrounded by enclosure material510to provide a mounting surface for a power supply520, a controller525, an accommodation actuator530, a sensor system535, an antenna540, and various interconnects545and550. The illustrated embodiment of power supply520includes an energy harvesting antenna555, charging circuitry560, and a battery565. The illustrated embodiment of controller525includes control logic570, accommodation logic575, and communication logic580. The illustrated embodiment of auxiliary device505includes a processor582, an antenna584, and memory586. The illustrated embodiment of memory586includes data storage588and program instructions590.

Controller525may be coupled to receive feedback control signals from sensor system535and further coupled to operate accommodation actuator530. Sensor system535may provide functionality such as that of one of sensors112,382,412,444,474, for example. Power supply520supplies operating voltages to the controller525and/or the accommodation actuator530. Antenna540may be operated by the controller525to communicate information to and/or from eye-mountable device500. In one embodiment, antenna540, controller525, power supply520, and sensor system535are all situated on the embedded substrate515. In one embodiment, accommodation actuator530may be embedded within enclosure material510, but is not disposed on substrate515. Because eye-mountable device500includes electronics and is configured to be contact-mounted to an eye, it is also referred to herein as an ophthalmic electronics platform, contact lens, or smart contact lens.

To facilitate contact-mounting, the enclosure material510may have a concave surface configured to adhere (“mount”) to a moistened corneal surface (e.g., by capillary forces with a tear film coating the corneal surface). Additionally or alternatively, the eye-mountable device500may be adhered by a vacuum force between the corneal surface and enclosure material510due to the concave curvature. While mounted with the concave surface against the eye, the outward-facing surface of the enclosure material510may have a convex curvature that is formed to not interfere with eye-lid motion while the eye-mountable device500is mounted to the eye. For example, the enclosure material510may be a substantially transparent curved disk shaped similarly to a contact lens.

Enclosure material510may include one or more biocompatible materials, such as those employed for use in contact lenses or other ophthalmic applications involving direct contact with the corneal surface. Enclosure material510may optionally be formed in part from such biocompatible materials or may include an outer coating with such biocompatible materials. Enclosure material510may include materials configured to moisturize the corneal surface, such as hydrogels and the like. In some instances, enclosure material510may be a deformable (“non-rigid”) material to enhance wearer comfort. In some instances, enclosure material510may be shaped to provide a predetermined, vision-correcting optical power, such as can be provided by a contact lens. Enclosure material may be fabricated of various materials including a polymeric material, a hydrogel, PMMA, silicone based polymers (e.g., fluoro-silicon acrylate), or otherwise.

Substrate515includes one or more surfaces suitable for mounting the sensor system535, controller525, power supply520, and antenna540. Substrate515may be employed both as a mounting platform for chip-based circuitry (e.g., by flip-chip mounting) and/or as a platform for patterning conductive materials (e.g., gold, platinum, palladium, titanium, copper, aluminum, silver, metals, other conductive materials, combinations of these, etc.) to create electrodes, interconnects, antennae, etc. In some embodiments, substantially transparent conductive materials (e.g., indium tin oxide) may be patterned on substrate515to form circuitry, electrodes, etc. For example, antenna540may be formed by depositing a pattern of gold or another conductive material on substrate515. Similarly, interconnects545and550may be formed by depositing suitable patterns of conductive materials on substrate515. A combination of resists, masks, and deposition techniques may be employed to pattern materials on substrate515. Substrate515may be a relatively rigid material, such as polyethylene terephthalate (“PET”) or another material sufficient to structurally support the circuitry and/or electronics within enclosure material510. Eye-mountable device500may alternatively be arranged with a group of unconnected substrates rather than a single substrate. For example, controller525and power supply520may be mounted to one substrate, while antenna540and sensor system535are mounted to another substrate and the two may be electrically connected via interconnects.

In some embodiments, power supply520and controller525(and the substrate515) may be positioned away from the center of eye-mountable device500and thereby avoid interference with light transmission to the eye through the center of eye-mountable device510. In contrast, accommodation actuator530may be centrally positioned to apply optical accommodation to the light transmitted to the eye through the center of eye-mountable device510. For example, where eye-mountable device500is shaped as a concave-curved disk, substrate515may be embedded around the periphery (e.g., near the outer circumference) of the disk. In some embodiments, sensor system535includes one or more discrete voltage and/or current sensors that are configured to detect one or more characteristics of a magnetic field (not shown) extending at least in part between EMD500and an auxiliary reference device590(e.g., one of devices120,312,420,450,480). For example, sensor system535and auxiliary reference device590may include some or all of the respective features of sensor112and auxiliary reference device120. Sensor system535and/or substrate515may be substantially transparent to incoming visible light to mitigate interference with light transmission to the eye.

Substrate515may be shaped as a flattened ring with a radial width dimension sufficient to provide a mounting platform for the embedded electronics components. Substrate515may have a thickness sufficiently small to allow the substrate to be embedded in enclosure material510without adversely influencing the profile of eye-mountable device500. Substrate515may have a thickness sufficiently large to provide structural stability suitable for supporting the electronics mounted thereon. For example, substrate515may be shaped as a ring with a diameter of about 10 millimeters, a radial width of about 1 millimeter (e.g., an outer radius 1 millimeter larger than an inner radius), and a thickness of about 50 micrometers. Substrate515may optionally be aligned with the curvature of the eye-mounting surface of eye-mountable device500(e.g., convex surface). For example, substrate515may be shaped along the surface of an imaginary cone between two circular segments that define an inner radius and an outer radius. In such an example, the surface of substrate515along the surface of the imaginary cone defines an inclined surface that is approximately aligned with the curvature of the eye mounting surface at that radius.

In the illustrated embodiment, power supply520includes a battery565to power the various embedded electronics, including controller525. Battery565may be inductively charged by charging circuitry560and energy harvesting antenna555. In one embodiment, antenna540and energy harvesting antenna555are independent antennae, which serve their respective functions of energy harvesting and communications. In another embodiment, energy harvesting antenna555and antenna540are the same physical antenna that are time shared for their respective functions of inductive charging and wireless communications with auxiliary device505. Additionally or alternatively, power supply520may include a solar cell (“photovoltaic cell”) to capture energy from incoming ultraviolet, visible, and/or infrared radiation. Furthermore, an inertial power scavenging system may be included to capture energy from ambient vibrations.

Charging circuitry560may include a rectifier/regulator to condition the captured energy for charging battery565or directly power controller525without battery565. Charging circuitry560may also include one or more energy storage devices to mitigate high frequency variations in energy harvesting antenna555. For example, one or more energy storage devices (e.g., a capacitor, an inductor, etc.) may be connected to function as a low-pass filter.

Controller525contains logic to choreograph the operation of the other embedded components. Control logic570controls the general operation of eye-mountable device500, including providing a logical user interface, power control functionality, etc. Accommodation logic575includes logic for monitoring feedback signals from sensor system535, determining the current gaze direction or gaze distance of the user, and manipulating accommodation actuator530in response to provide the appropriate accommodation. The auto-accommodation may be implemented in real-time based upon feedback from the gaze tracking, or permit user control to select specific accommodation regimes (e.g., near-field accommodation for reading, far-field accommodation for regular activities, etc.). Circuitry of controller525may include or couple to a repository on substrate515—as represented by the illustrative memory585(e.g., including volatile memory cells)—that, for example, is to store data written by such circuitry, data to determine operation of such circuitry and/or data received by (or to be sent from) EMD500. Such a repository may store log information that describes performance of accommodation logic575and/or other components of controller525.

Communication logic580provides communication protocols for wireless communication with auxiliary device505via antenna540. In one embodiment, communication logic580provides backscatter communication via antenna540when in the presence of an electromagnetic field571output from auxiliary device505. In one embodiment, communication logic580operates as a smart wireless radio-frequency identification (“RFID”) tag that modulates the impedance of antenna540for backscatter wireless communications. The various logic modules of controller525may be implemented in software/firmware executed on a general purpose microprocessor, in hardware (e.g., application specific integrated circuit), or a combination of both.

Eye-mountable device500may include various other embedded electronics and logic modules. For example, a light source or pixel array may be included to provide visible feedback to the user. An accelerometer or gyroscope may be included to provide positional, rotational, directional or acceleration feedback information to controller525.

It is noted that the block diagram shown inFIG. 5is described in connection with functional modules for convenience in description, but does not necessarily connote physical organization. Rather, embodiments of eye-mountable device500may be arranged with one or more of the functional modules (“sub-systems”) implemented in a single chip, multiple chips, in one or more integrated circuits, or otherwise.

Auxiliary device505includes an antenna584(or group of more than one antennae) to send and receive wireless signals571to and from eye-mountable device500. Auxiliary device505also includes a computing system with a processor582in communication with a memory586. Memory586may be a non-transitory computer-readable medium that may include, without limitation, magnetic disks, optical disks, organic memory, and/or any other volatile (e.g. RAM) or non-volatile (e.g. ROM) storage system readable by the processor582. Memory586may include a data storage588to store indications of data, such as data logs (e.g., user logs), program settings (e.g., to adjust behavior of eye-mountable device500and/or auxiliary device505), etc. Memory586may also include program instructions590for execution by processor582to cause the auxiliary device505to perform processes specified by the instructions590. For example, program instructions590may cause auxiliary device505to provide a user interface that allows for retrieving information communicated from eye-mountable device500or allows transmitting information to eye-mountable device500to program or otherwise select operational modes of eye-mountable device500. Auxiliary device505may also include one or more hardware components for operating antenna584to send and receive wireless signals571to and from one or both of eye-mountable device500and auxiliary reference device590.

Auxiliary device505may be a smart phone, digital assistant, or other portable computing device with wireless connectivity sufficient to provide the wireless communication link571. Auxiliary device505may also be implemented as an antenna module that may be plugged in to a portable computing device, such as in an example where the communication link571operates at carrier frequencies not commonly employed in portable computing devices. In some instances, auxiliary device505is a special-purpose device configured to be worn relatively near a wearer's eye to allow the wireless communication link571to operate with a low power budget. For example, the auxiliary device505may be integrated in a piece of jewelry such as a necklace, earing, etc. or integrated in an article of clothing worn near the head, such as a hat, headband, etc. In other embodiments, auxiliary device505is a personal computer or game console.

FIGS. 6A and 6Billustrate two views of an eye-mountable device600, in accordance with an embodiment of the disclosure.FIG. 6Ais a top view of EMD600whileFIG. 6Bis a perspective view of the same. Eye-mountable device600is one possible implementation of eye-mountable device500illustrated inFIG. 5. The illustrated embodiment of eye-mountable device600includes an enclosure material610, a substrate615, a power supply620, a controller625, an accommodation actuator630, a sensor system635, and an antenna640. It should be appreciated thatFIGS. 6A and 6Bare not necessarily drawn to scale, but have been illustrated for purposes of explanation only in describing the arrangement of the example eye-mountable device600.

Enclosure material610of eye-mountable device600may be shaped as a curved disk. Enclosure material610is a substantially transparent material to allow incident light to be transmitted to the eye while eye-mountable device600is mounted to the eye. Enclosure material610may be a biocompatible material similar to those employed to form vision correction and/or cosmetic contact lenses in optometry, such as a polymeric material, polyethylene terephthalate (“PET”), polymethyl methacrylate (“PMMA”), polyhydroxyethylmethacrylate (“polyHEMA”), a hydrogel, silicon based polymers (e.g., fluoro-silicon acrylate) combinations of these, or otherwise. Enclosure material610may be formed with one side having a concave surface611suitable to fit over a corneal surface of an eye. The opposite side of the disk may have a convex surface612that does not interfere with eyelid motion while eye-mountable device600is mounted to the eye. In the illustrated embodiment, a circular or oval outer side edge613connects the concave surface611and convex surface612.

Eye-mountable device600may have dimensions similar to a vision correction and/or cosmetic contact lenses, such as a diameter of approximately 1 centimeter, and a thickness of about 0.1 to about 0.5 millimeters. However, the diameter and thickness values are provided for explanatory purposes only. In some embodiments, the dimensions of eye-mountable device600may be selected according to the size and/or shape of the corneal surface of the wearer's eye. Enclosure material610may be formed with a curved shape in a variety of ways. For example, techniques similar to those employed to form vision-correction contact lenses, such as heat molding, injection molding, spin casting, etc. may be employed to form enclosure material610.

Substrate615may be embedded within enclosure material610. Substrate615may be embedded to be situated along the outer periphery of enclosure material610, away from the central region where accommodation actuator630is positioned. In the illustrated embodiment, substrate615encircles accommodation actuator630. Substrate615may not interfere with vision because it is too close to the eye to be in focus and is positioned away from the central region where incident light is transmitted to the light-sensing portions of the eye. In some embodiments, substrate615may optionally be formed of a transparent material to further mitigate effects on visual perception. Substrate615may be shaped as a flat, circular ring (e.g., a disk with a centered hole). The flat surface of substrate615(e.g., along the radial width) may be a platform for mounting electronics and for patterning conductive materials to form electrodes, antenna(e), and/or interconnections.

Sensor system635may be distributed about eye-mountable device600to sense one or more characteristics of a magnetic field between EMD600and an auxiliary reference device (not shown) that is remote from EMD600. Such sensing may be used to determine a distance of the remote device from EMD600and/or a difference between respective orientations of EMD600and the remote device. By monitoring such magnetic field characteristics, feedback signals from sensor system635may be measured by controller625to determine the approximate gaze direction and/or focal distance. Sensor system635may be disposed within enclosure material610on substrate615. In the illustrated embodiment, sensor system635is distributed peripherally around accommodation actuator630along the inner edge of substrate615between antenna640and accommodation actuator630. In other embodiments, sensor system635may be alternatively distributed in or on eye-mountable device600.

Accommodation actuator630may be centrally positioned within enclosure material610to affect the optical power of eye-mountable device600in the user's center of vision. In various embodiments, accommodation actuator630operates by changing its index of refraction under the influence of controller625. By changing its refractive index, the net optical power of the curved surfaces of eye-mountable device600may be altered, thereby applying controllable accommodation. Accommodation actuator630may be implemented using a variety of different electro-active optical devices. For example, accommodation actuator630may be implemented using a layer of liquid crystal (e.g., a liquid crystal cell) disposed in the center of enclosure material610. In other embodiments, accommodation actuator630may be implemented using other types of electro-active optical materials such as electro-optic materials that vary refractive index in the presence of an applied electric field. Accommodation actuator630may be a distinct device embedded within enclosure material610(e.g., liquid crystal cell), or a bulk material having a controllable refractive index. In yet another embodiment, accommodation actuator630may be implemented using a deformable lens structure that changes shape under the influence of an electrical signal. Accordingly, the optical power of eye-mountable device600may be controlled by controller625with the application of electric signals via one or more electrodes extending from controller625to accommodation actuator630.

Accommodation actuator630may be implemented using a variety of different liquid crystal structures including nematic liquid crystal, nematic twisted liquid crystal, cholesteric liquid crystal, or blue phase liquid crystal. Since a low switching voltage is desirable for low power chip design, nematic liquid crystals with switching voltages less than 5 V are suitable. With the application of a 5V control signal, refractive index switching ranging from approximately 1.74 in an off-mode to 1.52 in an on-mode is achievable. A refractive index shift of 0.2 should be sufficient to provide near-field accommodation for reading.

Returning toFIG. 6A, loop antenna640is a layer of conductive material patterned along the flat surface of the substrate to form a flat conductive ring. In some examples, to allow additional flexibility along the curvature of the enclosure material, loop antenna640may include multiple substantially concentric sections electrically joined together. Each section may then flex independently along the concave/convex curvature of eye-mountable device600. In some examples, loop antenna640may be formed without making a complete loop. For instances, antenna640may have a cutout to allow room for controller625and power supply620, as illustrated inFIG. 6A. However, loop antenna640may also be arranged as a continuous strip of conductive material that wraps entirely around the flat surface of substrate615one or more times. For example, a strip of conductive material with multiple windings may be patterned on the backside of substrate615opposite controller625, power supply620, and sensor system635. Interconnects between the ends of such a wound antenna (e.g., the antenna leads) may then be passed through substrate615to controller625.

FIG. 7is a cross-sectional illustration of an eye715having implanted therein an intraocular device700that, according to an embodiment, determines a direction of gaze based on an interaction, via a magnetic field, with an auxiliary reference device (not shown). Intraocular device700may include features of EMD100and/or features of one of ophthalmic devices314,410,430,460,500,600, for example.

The illustrated embodiment of intraocular device700includes a housing750and circuitry disposed therein. An exterior of intraocular device700may include a surface of housing750that is biocompatible to accommodate direct contact with an interior of a human (or other) eye. Such a surface of housing750may be formed by one or more materials that are both electromagnetically transparent (at least partially) and biocompatible to accommodate implantation of intraocular device700. Examples of such materials include, but are not limited to, any of various biocompatible hydrogels, silicones, hydrophobic acrylics, fluorinated polymethacrylates and/or the like. In an embodiment, housing750includes a coating of biocompatible material that, for example, is formed by atomic layer deposition. Such materials may be adapted from those used in existing intraocular devices, for example.

Intraocular device700may be implanted into the anterior chamber, the posterior chamber, or other locations of a user's eye. Intraocular device700is illustrated as being implanted within the posterior chamber705behind an iris710of eye715. However, intraocular device700may be implanted into other locations, as well, such as anterior chamber720disposed between iris710and cornea725. In an embodiment, intraocular device700includes a housing750and circuitry760disposed in or on housing750. Circuitry760may enable device700to interact via a magnetic field with an auxiliary reference device (not shown) that is in or on the body of the user of intraocular device700. For example, circuitry760may be disposed at a side752of housing750that faces toward cornea725—e.g., to sense a magnetic field (not shown) extending in posterior chamber705. In an embodiment, circuitry760includes one or more magnetic sensors to detect one or more characteristics of such a magnetic field. Alternatively or in addition, such one or more magnetic sensors may detect a voltage and/or a current that is based on operation of other circuitry (included in or coupled to circuitry760) that, for example, may generate at least part of such a magnetic field.