Patent Publication Number: US-10775643-B2

Title: Dynamic presbyopia correction in electronic contact lenses

Description:
BACKGROUND 
     1. Technical Field 
     This disclosure relates generally to eye-mounted electronics and, more particularly, to electronic contact lenses that correct presbyopia. 
     2. Description of Related Art 
     Electronic contact lenses can include electronic components to perform a number of functions, for instance using tiny video projectors (or “femtoprojectors”) as described in Deering (U.S. Pat. No. 8,786,675) to implement an AR system. The potential for electronic contact lenses to include specialized electronic components makes them an attractive mechanism to address a variety of eye conditions, such as presbyopia. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the disclosure have other advantages and features which will be more readily apparent from the following detailed description and the appended claims, when taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  ( FIG. 1 ) is an illustration of a user wearing an electronic contact lens system. 
         FIG. 2  is an illustration of a necklace of an electronic contact lens system. 
         FIG. 3  is an illustration of a liquid crystal matrix within an electronic contact lens. 
         FIG. 4  is an illustration of an aperture within a liquid crystal matrix of an electronic contact lens. 
         FIG. 5  is an illustration of a movement of an aperture within a liquid crystal matrix during a calibration of an electronic contact lens. 
         FIG. 6  is a flow chart of a process of calibrating and operating an electronic contact lens in a reading mode. 
     
    
    
     The figures depict various embodiments for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles described herein. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Introduction 
     Presbyopia is an eye condition that affects people over 40. It is a consequence of age-related hardening of the lens of the eye which reduces the ability to change focus. 
     An electronic contact lens can address presbyopia. Whenever the contact lens is configured to operate in a reading mode, a liquid crystal matrix of the contact lens can be configured to include an aperture. The aperture functions as a pinhole, increasing the depth of focus of light passing through the aperture by blocking off-axis light. Such a contact lens can aid a user with presbyopia by enabling the user to focus on close objects. 
     The aperture can be formed by configuring elements within the liquid crystal matrix surrounding the aperture to block light. The aperture can be located at a location within the liquid crystal matrix corresponding to the user&#39;s visual axis. The location within the liquid crystal matrix corresponding to the user&#39;s visual axis can be determined when calibrating the contact lens. A user can configure the contact lens to operate in a calibration mode and can provide input to the contact lens indicating a location corresponding to the user&#39;s visual axis. The user can subsequently configure the contact lens to operate in a reading mode, in response to which the aperture can be located at the indicated location. 
     Electronic Contact Lens Architecture 
     Turning now to the figures,  FIG. 1  is an illustration of a user wearing an electronic contact lens system  100 . The electronic contact lens system  100  includes a wireless power source and an electronic contact lens  120  (“contact lens”). In addition to providing power to the contact lens  120 , the power source can also transmit data to and receive data from the contact lens. In the illustrated example, the power source is a necklace  110 , though in other embodiments, the power source can be embedded within the contact lens, or can be an accessory or device other than a necklace (such as a hat, eyeglasses, earrings or other piece of jewelry, clothing item, or any other suitable wireless power source). The contact lens  120  can include various electronic components that can be, for instance, configured by or operated in response to control signals received from the necklace  110 . Additionally, the contact lens  120  can wirelessly communicate with the necklace  110 , for instance by providing motion and orientation information representative of the contact lens. 
     The contact lens  120  can also include other components such as antennae or optical/infrared photodetectors, data storage and buffering, controls, and a calibration system (including, for instance, a motion detection system). In addition, the contact lens  120  can include positioning components such as accelerometers, magnetometers, and gyroscopes used for motion detection, eye tracking, and head tracking. The contact lens  120  can also include data processing components, such as microprocessors, microcontrollers, and other data processing elements configured to, for instance, implement the functionality described herein. Finally, the contact lens  120  can include a liquid crystal matrix to aid in correcting the effects of presbyopia, as described below. 
     In order to maintain health, the cornea requires oxygen through exposure to air. Accordingly, the contact lens  120  can include various oxygenation structures to allow for sufficient oxygenation of the cornea. For instance, the contact lens  120  can include a dual-gap structure with a set of oxygen channels to allow for the flow of oxygen from outside the contact lens to the cornea. Contact lens oxygenation structures are described in greater detail in U.S. patent application Ser. No. 15/885,079, filed Jan. 31, 2018, the contents of which are incorporated herein by reference. 
     The electronic contact lens system of  FIG. 1  may feel natural to the wearer because the contact lenses  120  and the necklace  110  are similar to normal contacts lenses and necklaces used in everyday life. For example, the contact lenses  120  may also function as regular contact lenses that provide refractive eyesight correction and the necklace  110  may be designed to look like ordinary jewelry. The necklace  110  may include additional hardware elements within its band  130  that can provide added functionality to the electronic contact lens system. For example, the necklace can communicatively couple to a smartphone, can receive configuration/reading mode instructions from an application running on the smartphone, and can provide the instructions to the contact lens. The necklace may also replace the smartphone rather than merely communicate with it. 
     As illustrated in  FIG. 1 , the power source is a necklace  110  that generates a time-varying magnetic field (“TVMF”) and that can inductively couple to the contact lens  120 . In other embodiments the power source may be any other type of device. For example, in some cases, the power source can be integrated into another type of wearable device such as a necktie, a scarf, a belt, the brim of a hat, the collar of a shirt, the hood of a jacket, the sleeve of a sweater, the front of a t-shirt, etc. In other examples, the power source can be an external device or structure. As an example, the power source can be a smart phone, a table-top box, or a power source coupled to the walls of an office. 
       FIG. 2  is an illustration of a necklace  110  of an electronic contact lens system  100 . In the illustrated embodiment, the necklace  110  includes an electronic module  220  and a coil  210  of conductive material. The coil can be connected or disconnected with a plug  240  and a socket  250 , or may be a single band without the plug and socket. 
     The necklace  110  includes various hardware elements, for instance within the electronic module  220 , that enable functionality of the electronic contact lens system  100 . For example, the necklace  110  can include hardware elements that generate a TVMF for transferring power to the contact lens  120 . Additionally, the hardware elements can include one or more of: a power source such as a battery; a modulator to drive a radio-frequency current in the necklace coil that can be used to inductively couple to and communicate with the contact lens  120 ; a data modem to encode data on the radio-frequency signal; sensors such as microphones, cameras, inertial sensors, and GPS receivers; a cellular radio; a Wi-Fi radio; a Bluetooth radio; a graphics processing unit; and a microprocessor and memory. In various configurations, the hardware elements can be included in module  220  and/or may be distributed about the necklace band  130 . Alternatively, when the electronic contact lens system  100  is connected to an external device or structure, any of the sensors, processors and other components mentioned above may be located in the device or structure. 
     It should be noted that in some embodiments, the power source is incorporated into the contact lens. For instance, the contact lens  120  can include an embedded battery that provides power to the electronic components of the contact lens. The battery can be charged by, for instance, a photovoltaic cell within the contact lens or inductively (e.g., while resting in a cleaning case overnight). 
     Presbyopia Correction 
     As noted above, the contact lens can include a liquid crystal matrix. The liquid crystal matrix can be located, for instance, within the contact lens and surrounding a center of the contact lens. When the contact lens is configured to operate in a reading mode, an aperture can be formed within the liquid crystal matrix. For instance, a controller of the contact lens can identify a first portion of the liquid crystal matrix corresponding to a user&#39;s visual axis, and can form an aperture within the liquid crystal matrix by configuring a second portion of the liquid crystal matrix surrounding the first portion to block light from passing through the second portion of the liquid crystal matrix. 
       FIG. 3  is an illustration of a liquid crystal matrix within an electronic contact lens. The contact lens  120  of  FIG. 3  includes a liquid crystal matrix  300 . The size, shape, and location of the liquid crystal matrix  300  within the contact lens  120  can vary, but is generally centered on an area of the contact lens expected to correspond with a user&#39;s visual axis. The liquid crystal matrix  300  includes an array of elements, each of which can be individually configured to enable light to pass through the element or to block light from passing through the element. The elements of the liquid crystal matrix  300  can be square, rectangular, hexagonal, circular, or any other suitable shape. 
     A user can configure the contact lens  120  to include an aperture within the liquid crystal matrix  300 , for instance in response to the contact lens being configured to operate in a reading mode.  FIG. 4  is an illustration of an aperture within a liquid crystal matrix of an electronic contact lens, illustrating the aperture as black pixels and the opaque portions of the liquid crystal matrix as white pixels. The aperture  400  is formed within the liquid crystal matrix  300  by configuring the liquid crystal matrix elements corresponding to the aperture to allow light to pass through the liquid crystal matrix and configuring the liquid crystal matrix elements surrounding and immediately adjacent to the aperture to block light from passing through the liquid crystal matrix. In other words, an aperture is formed by blocking light from passing through the liquid crystal matrix of the contact lens around an area of the liquid crystal matrix through which light passes. 
     The size of the aperture  400  can be predetermined, or can be set by a user. In some embodiments, the size of the aperture  400  can be established during a calibration mode (described below), while in other embodiments, the size of the aperture can dynamically change during use of the contact lens  120  (for instance, in response to user input). As a size of an aperture  400  decreases, the brightness of the light passing through the aperture decreases and the depth of focus of the light passing through the aperture increases. Likewise, as a size of an aperture  400  increases, the brightness of the light passing through the aperture increase and the depth of focus of the light passing through the aperture decreases. Thus, a user can configure the size of the aperture  400  based on a tradeoff between a depth of focus provided by the aperture and a brightness of light passing through the aperture. In some embodiments, the size of the aperture varies between approximately 200 μm to 8 mm. 
     The shape of the aperture  400  may be circular (or may approximate a circle), rectangular, hexagonal, or any other suitable shape. Likewise, the shape of the portion of the liquid crystal matrix  300  surrounding the aperture  400  configured to block light (the “surrounding portion”) may be circular (or approximately circular), ring-shaped, rectangular, hexagonal, and the like. The width of the surrounding portion of the liquid crystal matrix  300  can be predetermined or selected by the user. In some embodiments, an increase in the width of the surrounding portion of the liquid crystal matrix  300  can magnify the pinhole effects of the aperture, but at the cost of blocking additional light from passing through the liquid crystal matrix. In one example, the surrounding portion includes every liquid crystal matrix element bordering the aperture  400 , creating a ring- or “O”-shaped portion within the liquid crystal matrix  300  that blocks light from passing through the liquid crystal matrix. In some embodiments, the aperture  400  is formed by configuring every liquid crystal matrix element outside of the aperture to block light. 
     An aperture  400  can be included within the liquid crystal matrix  300  in response to the contact lens  120  being configured to operate in a reading mode. The contact lens  120  may be configured to operate in a reading mode in response to an input from a user, such as a voice input, a hand gesture input, an eye movement input, or an input from a connected device (such as a smartphone, the necklace  110 , or other devices). The contact lens  120  may also be configured to operate in a reading mode in response to detecting a vergence of both eyes of the user. For instance, contact lenses  120  can determine a gaze direction of each using cameras, accelerometers, or other circuits within the contact lens, and can detect a vergence of the eyes of the user when the gaze directions converge by a threshold amount. Likewise, the contact lens  120  can detect a vergence of the user&#39;s eyes by determining that a distance between fixed points within the contact lens is less than a threshold distance, for instance using circuits embedded within the contact lenses that are configured to determine a proximity to each other. 
     The contact lens  120  may be configured to operate in a reading mode in response to determining that the user is reading or determining that the user is looking at an object close to the user. For instance, a camera can be embedded within the contact lens  120  or an accessory or clothing item worn by the user to detect the presence of an object within a threshold distance of the user&#39;s face, or to detect text on an object within a threshold distance of the user&#39;s face. Further, the contact lens  120  may be configured to operate in a reading mode in response to detecting that the user is looking downward. For example, the user can be determined to be looking downward when a capacitive sensor included within the contact lens  120  detects a bottom eyelid of the user, or in response to a motion sensor within the contact lens (such as an accelerometer) detecting a downward motion or tilt of the eye of the user. 
     The aperture  400  can be included within the liquid crystal matrix  300  at a location determined to correspond to a visual axis of the user. The location within the liquid crystal matrix corresponding to a visual axis of the user can be determined when the contact lens  120  is configured to operate in a calibration mode. The calibration mode can be initiated by a user, for instance in response to a voice or hand gesture of the user, or in response to an input received via a connected device. Likewise, the calibration mode can be initiated upon initialization of the contact lens  120 , upon activation of electronics of the contact lens (e.g., upon startup), or during a calibration procedure, for instance performed by an optometrist or other professional. In some embodiments, the contact lens  120  can be re-calibrated during use, for instance periodically (e.g., after the passage of a threshold interval of time since a previous calibration) or in response to a request from a user. 
     When the contact lens  120  is configured to operate in the calibration mode, the liquid crystal matrix of the contact lens may be configured to include a test aperture within the liquid crystal matrix at a location estimated to correspond to the user&#39;s visual axis. In response to the test aperture, a user can provide an input indicating a location within the contact lens  120  or the liquid crystal matrix  300  corresponding to the user&#39;s visual axis. For instance, a user may provide an input to move the test aperture via a connected device to a location corresponding to the user&#39;s visual axis (e.g., a location overlapping or adjacent to the location within the liquid crystal matrix through which the user&#39;s visual axis passes). Likewise, an eye movement of the user, a blink pattern of the user, a hand gesture of the user, or a voice command from the user may indicate a direction from the location estimated to correspond to the user&#39;s visual axis to the actual location corresponding to the user&#39;s visual axis. 
     In response to the input from the user, the contact lens  120  can move the test aperture, for instance in an indicated direction towards the location corresponding to the user&#39;s visual axis. This process can iterate until the test aperture is located within the liquid crystal matrix  300  at a location corresponding to the user&#39;s visual axis. In addition, the location within the liquid crystal matrix  300  can be indicated by a user via an input provided through an interface of a smartphone or connected device. It should be noted that in other embodiments, the liquid crystal matrix  300  can be configured to include test patterns or images other than a test aperture for use in calibrating the contact lens  120 . The location within a contact lens corresponding to a user&#39;s visual axis may also be determined in other ways, for instance as described in U.S. application Ser. No. 15/977,985, filed on May 11, 2018, the contents of which are incorporated by reference herein in their entirety. 
       FIG. 5  is an illustration of a movement of an aperture within a liquid crystal matrix during a calibration of an electronic contact lens. In the example of  FIG. 5 , a test aperture is initially displayed at a pre-calibration location  500  within the liquid crystal matrix  300 . A user then provides an input to move the aperture to the location  502  within the liquid crystal matrix  300 . For instance, the location  500  of the test aperture may appear off-center to the user, and the user can provide an input via a connected smartphone to center the aperture on the user&#39;s visual axis at the location  502  within the liquid crystal matrix  300  (or simply to move the aperture to a location within the liquid crystal matrix  300  that is acceptable to the user). The contact lens  120 , when subsequently configured to operate in the reading mode, can configure the liquid crystal matrix  300  to include an aperture at the location  502  determined during calibration. 
     In addition to identifying a location within the liquid crystal matrix  300  corresponding to a user&#39;s visual axis, one or more other properties of aperture can be selected during calibration. For example, a size of the aperture can be selected by a user during calibration. A test aperture can be displayed to the user, and the user can increase or decrease a size of the test aperture, for instance using a hand or eye gesture, via an input to a connected device, and the like. If the user provides an input requesting an increase in the size of the aperture, the diameter of the test aperture can be increased and vice versa. In other examples, a shape of the aperture and/or any other suitable property of the contact lens can be selected by a user during calibration. 
     Once the contact lens is calibrated, the contact lens can be configured to operate in a normal operating mode, for instance in response to an input from the user requesting operation in the normal operating mode. When the contact lens is configured to operate in the normal operating mode, the elements of the liquid crystal matrix  300  are configured to allow all light to pass through the liquid crystal matrix. In other words, when the contact lens  120  is configured to operate in the normal operating mode, the contact lens may function without the use of apertures within the liquid crystal matrix  300 . The user can then configure the contact lens to operate in a reading mode (for instance, via an input associated with enabling reading mode), and the contact lens  120  can form an aperture within the liquid crystal matrix  300  at a location determined during calibration to correspond to a user&#39;s visual axis. The user can subsequently configure the contact lens  120  to return to the normal operating mode, and the aperture within the liquid crystal matrix  300  can be removed from the liquid crystal matrix by configuring all of the elements of the liquid crystal matrix to allow light to pass through. 
       FIG. 6  is a flow chart of a process of calibrating and operating an electronic contact lens in a reading mode. A request to operate a contact lens in a calibration mode is received  600 . In response, a liquid crystal matrix of the contact lens is configured to include a test aperture or other test pattern. A calibration input is received  610  from a user in response to the text aperture or test pattern. Based on the received calibration input, a location within the contact lens is determined  620  to correspond to a visual axis of the user. 
     After the contact lens has been calibrated, a request is received  630  to operate the contact lens in a reading mode. In response, the contact lens is configured to configured  640  to operate in the reading mode by centering an aperture within the liquid crystal matrix at the location determined during calibration to corresponding to the visual axis of the user. The aperture increases the depth of focus of light passing through the aperture, enabling a user suffering from presbyopia to focus on objects (such as a book) close to the user&#39;s face. 
     Although the detailed description contains many specifics, these should not be construed as limiting the scope of the invention but merely as illustrating different examples. It should be appreciated that the scope of the disclosure includes other embodiments not discussed in detail above. For example, the technologies described are applicable to eye-mounted displays other than the specific types described above. Various other modifications, changes and variations which will be apparent to those skilled in the art may be made in the arrangement, operation and details of the method and apparatus disclosed herein without departing from the spirit and scope as defined in the appended claims. Therefore, the scope of the invention should be determined by the appended claims and their legal equivalents.