PATENT DOCUMENT

Publication Number: US-11703698-B1
Application Number: US-201916554136-A
Country: US
Kind Code: B1

Title: Adjustable lens systems

Abstract:
Eyeglasses may include one or more lenses and control circuitry that adjusts an optical power of the lenses. The control circuitry may be configured to determine a user&#39;s prescription and accommodation range during a vision characterization process. The vision characterization process may include adjusting the optical power of the lens until the user indicates that an object viewed through the lens is in focus. A distance sensor may measure the distance to the in-focus object. The control circuitry may calculate the user&#39;s prescription based on the optical power of the lens and the distance to the in-focus object. The control circuitry may adjust the optical power automatically or in response to user input. The object viewed through the lens may be an electronic device. The user may control the optical power of the lens and/or indicate when objects are in focus by providing input to the electronic device.

Claims:
What is claimed is: 
     
       1. Eyeglasses configured to be worn by a user, the eyeglasses comprising:
 a distance sensor that measures a distance to an object; 
 a lens that aligns with a respective one of the user&#39;s eyes; and 
 control circuitry configured to:
 gather user input; 
 adjust an optical power of the lens; and 
 determine the user&#39;s prescription and accommodation range based at least partly on the user input, the optical power, and the distance, wherein the control circuitry cycles through first and second ranges of optical powers, wherein the user input includes a first user input indicating a first optical power in the first range that brings the object into focus for the user and a second user input indicating a second optical power in the second range that brings the object into focus for the user, and wherein the control circuitry determines the accommodation range based on the first and second optical powers. 
 
 
     
     
       2. The eyeglasses defined in  claim 1 , wherein the user input indicates whether the object is in focus for the user. 
     
     
       3. The eyeglasses defined in  claim 2 , wherein the control circuitry is configured to automatically cycle through a range of optical powers until the user input indicates that the object is in focus for the user. 
     
     
       4. The eyeglasses defined in  claim 1 , wherein the control circuitry adjusts the optical power of the lens in response to the user input. 
     
     
       5. The eyeglasses defined in  claim 1 , wherein the object comprises an electronic device that receives the user input from the user, the eyeglasses further comprising:
 wireless communications circuitry that receives signals associated with the user input from the electronic device, wherein the control circuitry is configured to gather the user input from the wireless communications circuitry. 
 
     
     
       6. The eyeglasses defined in  claim 1 , further comprising an input device that receives the user input from the user, wherein the control circuitry is configured to gather the user input from the input device. 
     
     
       7. The eyeglasses defined in  claim 1 , wherein the lens comprises a voltage-modulated optical material. 
     
     
       8. The eyeglasses defined in  claim 7 , wherein the voltage-modulated optical material comprises liquid crystal material. 
     
     
       9. The eyeglasses defined in  claim 1 , further comprising an eye tracking camera that tracks the user&#39;s gaze, wherein control circuitry determines that the object is within the user&#39;s gaze using the eye tracking camera, and wherein the distance sensor measures the distance to the object after the control circuitry determines that the object is within the user&#39;s gaze. 
     
     
       10. An electronic device configured to communicate wirelessly with eyeglasses, wherein the eyeglasses are configured to be worn by a user, wherein the eyeglasses comprise a lens having an adjustable optical power, and wherein the eyeglasses and the electronic device are separated by a distance, the electronic device comprising:
 an input device that receives user input, wherein the input device comprises a rotatable watch crown; 
 wireless communications circuitry that transmits wireless signals associated with the user input to the eyeglasses to adjust the optical power of the lens; and 
 control circuitry that determines a user&#39;s prescription based on the user input, the optical power of the lens, and the distance. 
 
     
     
       11. The electronic device defined in  claim 10 , wherein rotation of the watch crown in a first direction results in an increase in the optical power of the lens and rotation of the watch crown in a second direction results in a decrease in the optical power of the lens. 
     
     
       12. The electronic device defined in  claim 11 , wherein a speed at which the watch crown is rotated controls a speed at which the optical power of the lens is adjusted. 
     
     
       13. An electronic device configured to communicate wirelessly with eyeglasses, wherein the eyeglasses are configured to be worn by a user, wherein the eyeglasses comprise a lens having an adjustable optical power, and wherein the eyeglasses and the electronic device are separated by a distance, the electronic device comprising:
 an input device that receives user input; 
 a display that displays an image that is viewed by the user through the lens, wherein the user input indicates whether the image is in focus for the user; 
 wireless communications circuitry that transmits wireless signals associated with the user input to the eyeglasses to adjust the optical power of the lens; and 
 control circuitry that determines a user&#39;s prescription based on the user input, the optical power of the lens, and the distance, wherein the control circuitry reduces a resolution of the image until the user input indicates that the image is out of focus. 
 
     
     
       14. The electronic device defined in  claim 13 , wherein the display displays user interface face elements, wherein the input device comprises a touch sensor, and wherein the user input comprises touch input that controls the user interface elements to adjust the optical power of the lens. 
     
     
       15. A method for determining a user&#39;s prescription using eyeglasses and an electronic device, wherein the eyeglasses are configured to be worn by a user and wherein the eyeglasses comprise a lens, control circuitry that adjusts an optical power of the lens, and wireless communications circuitry that communicates with the electronic device, the method comprising:
 with the wireless control circuitry, receiving first and second signals associated with first and second user inputs received by the electronic device; 
 with the control circuitry, adjusting the optical power of the lens in response to the first signal associated with the first user input; 
 with a distance sensor, measuring a distance between the electronic device and the eyeglasses in response to the second signal associated with the second user input; and 
 with the control circuitry, determining the user&#39;s prescription based on the optical power of the lens and the distance. 
 
     
     
       16. The method defined in  claim 15  wherein the electronic device comprises a display that displays an image, wherein the user views the image through the lens, and wherein the second user input indicates whether the image is in focus for the user. 
     
     
       17. The method defined in  claim 16  wherein the lens comprises liquid crystal material and wherein the control circuitry adjusts the optical power of the lens by applying an electric field across the liquid crystal material.

Description:
This application claims the benefit of provisional patent application No. 62/725,174, filed Aug. 30, 2018, which is hereby incorporated by reference herein in its entirety. 
    
    
     FIELD 
     This relates generally to optical systems, and, more particularly, to devices with tunable lenses. 
     BACKGROUND 
     Eyewear may include optical systems such as lenses. For example, eyewear such as a pair of glasses may include lenses that allow users to view the surrounding environment. 
     It can be challenging to design lenses that function properly for users having different prescriptions. A user may not know or remember his or her lens prescription, or the user may provide a prescription that is inaccurate. 
     SUMMARY 
     Eyeglasses may be worn by a user and may include one or more adjustable lenses each aligned with a respective one of a user&#39;s eyes. For example, a first adjustable lens may align with the user&#39;s left eye and a second adjustable lens may align with the user&#39;s right eye. Each of the first and second adjustable lenses may include one or more liquid crystal cells or other voltage-modulated optical material. Each liquid crystal cell may include a layer of liquid crystal material interposed between transparent substrates. Control circuitry may adjust the optical power of the lens by applying control signals to an array of electrodes in the liquid crystal cell to adjust a phase profile of the liquid crystal material. 
     The control circuitry may be configured to determine a user&#39;s prescription and accommodation range during a vision characterization process. The vision characterization process may include adjusting the optical power of the lens until the user indicates that an object viewed through the lens is in focus. A distance sensor may measure the distance to the in-focus object. The control circuitry may calculate the user&#39;s prescription based on the optical power of the lens and the distance to the in-focus object. During vision characterization operations, control circuitry may adjust the optical power automatically or in response to user input. 
     The object viewed through the lens may be an electronic device. The user may control the optical power of the lens and/or indicate when objects are in focus by providing input to the electronic device. For example, the electronic device may be an electronic wrist watch having a rotatable watch crown, and the user may control the optical power of the lens and/or indicate whether objects are in focus by rotating the watch crown. In another illustrative example, the electronic device may be having a touch sensor and a display that displays user interface elements, and the user may control the optical power of the lens and/or indicate whether objects are in focus by providing touch input to control the user interface elements. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a diagram of illustrative system that includes eyeglasses with adjustable lenses in accordance with an embodiment. 
         FIG.  2    is a diagram of an illustrative electronic device that may be used in a system of the type described in connection with  FIG.  1    in accordance with an embodiment. 
         FIG.  3    is an equation describing a relationship between the optical power of a lens, the distance to an in-focus object, and a user&#39;s prescription in accordance with an embodiment. 
         FIG.  4    is a diagram of an illustrative system showing how a user may view an object through a lens during a vision characterization process in accordance with an embodiment. 
         FIG.  5    is a perspective view of an illustrative electronic device having input-output devices such as a display and rotatable watch crown that may be used in a vision characterization process in accordance with an embodiment. 
         FIG.  6    is a perspective view of an illustrative electronic device having input-output devices such as a display, a keyboard, and a touch pad that may be used in a vision characterization process in accordance with an embodiment. 
         FIG.  7    is a front view of an illustrative electronic device having input-output devices such as a display and touch sensor that may be used in a vision characterization process in accordance with an embodiment. 
         FIG.  8    is a diagram illustrating how a vision characterization process may be used to determine a user&#39;s accommodation range in accordance with an embodiment. 
         FIG.  9    is a diagram illustrating how eyeglasses may bring an object out of focus to check whether a user&#39;s prescription and accommodation range have been accurately determined in accordance with an embodiment. 
         FIG.  10    is a flow chart of illustrative steps involved in determining a user&#39;s prescription and accommodation range using optical power adjustment in accordance with an embodiment. 
         FIG.  11    is a flow chart of illustrative steps involved in determining a user&#39;s prescription and accommodation range using distance adjustment in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An illustrative system having a device with one or more electrically adjustable optical elements is shown in  FIG.  1   . System  10  may include a head-mounted device such as eyeglasses  14  (sometimes referred to as glasses  14 ). Glasses  14  may include one or more optical systems such as adjustable lens components  22  mounted in a support structure such as support structure  12 . Structure  12  may have the shape of a pair of eyeglasses (e.g., supporting frames), may form a housing having a helmet shape, or may have other configurations to help in mounting and securing the components of glasses  14  on the head of a user. 
     Adjustable lens components  22  may form lenses that allow a viewer (e.g., user  16 ) to view external objects such as object  18  in the surrounding environment. Glasses  14  may include one or more adjustable lens components  22 , each aligned with a respective one of a user&#39;s eyes. As an example, lens components  22  may include a left lens  22  aligned with a viewer&#39;s left eye and may include a right lens  22  aligned with a viewer&#39;s right eye. This is, however, merely illustrative. If desired, glasses  14  may include adjustable lens components  22  for a single eye. 
     Adjustable lenses  22  may be corrective lenses that correct for vision defects. For example, user  16  may have eyes with vision defects such as myopia, hyperopia, presbyopia, astigmatism, and/or other vision defects. Corrective lenses such as lenses  22  may be configured to correct for these vision defects. Lenses  22  may be adjustable to accommodate users with different vision defects and/or to accommodate different focal ranges. For example, lenses  22  may have a first set of optical characteristics for a first user having a first prescription and a second set of optical characteristics for a second user having a second prescription. Glasses  14  may be used purely for vision correction (e.g., glasses  14  may be a pair of spectacles) or glasses  14  may include displays that display virtual reality or augmented reality content (e.g., glasses  14  may be a head-mounted display). In virtual reality or augmented reality systems, adjustable lens components  22  may be used to move content between focal planes. Arrangements in which glasses  14  are spectacles that do not include displays are sometimes described herein as an illustrative example. 
     Glasses  14  may include control circuitry  26 . Control circuitry  26  may include processing circuitry such as microprocessors, digital signal processors, microcontrollers, baseband processors, image processors, application-specific integrated circuits with processing circuitry, and/or other processing circuitry and may include random-access memory, read-only memory, flash storage, hard disk storage, and/or other storage (e.g., a non-transitory storage media for storing computer instructions for software that runs on control circuitry  26 ). 
     Control circuitry  26  may control the operation of optical elements such as adjustable lens components  22 . Adjustable lens components  22 , which may sometimes be referred to as adjustable lenses, adjustable lens systems, adjustable optical systems, adjustable lens devices, tunable lenses, etc., may contain electrically adjustable material such as liquid crystal material, or other electrically modulated material that may be adjusted to produce customized lenses. Each of components  22  may contain an array of electrodes that apply electric fields to portions of a layer of liquid crystal material or other voltage-modulated optical material with an electrically adjustable index of refraction (sometimes referred to as an adjustable lens power or adjustable phase profile). By adjusting the voltages of signals applied to the electrodes, the index of refraction profile of components  22  may be dynamically adjusted. This allows the size, shape, and location of the lenses formed within components  22  to be adjusted. 
     Glasses  14  may include input-output circuitry such as eye state sensors, range finders disposed to measure the distance to external object  18 , touch sensors, buttons, microphones to gather voice input and other input, sensors, and other devices that gather input (e.g., user input from viewer  16 ) and may include light-emitting diodes, displays, speakers, and other devices for providing output (e.g., output for viewer  16 ). If desired, sensors such as an accelerometer, compass, an ambient light sensor or other light detector, a proximity sensor, a scanning laser system, and other sensors may be used in gathering input during use of glasses  14 . 
     Glasses  14  may, if desired, include wireless circuitry and/or other circuitry to support communications with a computer or other external equipment. For example, control circuitry  26  may include wireless communications circuitry (e.g., a radio-frequency transceiver) that exchanges wireless signals with external electronic devices. In some arrangements, object  18  is an electronic device and glasses  14  may send signals to and/or receive signals from the electronic device using wireless communications circuitry. 
     Sensors in glasses  14  may include one or more digital image sensors such as camera  24 . Cameras such as camera  24  may be an inward-facing camera that captures images of the user&#39;s eyes and/or may be an outward-facing camera that captures images of the user&#39;s environment. As an example, camera  24  may be used by control circuitry  26  to gather images of the pupils and other portions of the eyes of the viewer. The locations of the viewer&#39;s pupils and the locations of the viewer&#39;s pupils relative to the rest of the viewer&#39;s eyes may be used to determine the locations of the centers of the viewer&#39;s eyes (i.e., the centers of the user&#39;s pupils) and the direction of view (gaze direction) of the viewer&#39;s eyes. 
     Glasses  14  may include sensors such as depth sensor  20  for measuring the distance d to external objects such as external object  18 . Depth sensor  20  may be a light-based proximity sensor, a time-of-flight camera sensor, a camera-based depth sensor using parallax, a structured light depth sensor (e.g., having an emitter that emits beams of light in a grid, a random dot array, or other pattern, and having an image sensor that generates depth maps based on the resulting spots of light produced on target objects), a sensor that gathers three-dimensional depth information using a pair of stereoscopic image sensors, a lidar (light detection and ranging) sensor, a radar sensor, or other suitable sensor. 
     If desired, control circuitry  26  may operate depth sensor  20  based on information from inward-facing camera  24 . For example, control circuitry  26  may use data from camera  24  to determine which external object  18  the user is looking at and may use depth sensor  20  to measure the distance to that object  18 . Distance information gathered by depth sensor  20  may be used to adjust the optical power of lens components  22 . For example, control circuitry  26  may adjust the focal length of lens components  22  based on the distance d to object  18  so that object  18  is in focus for the user. As the user&#39;s gaze shifts to different objects at different distances, control circuitry  26  may actively adjust the optical power of lens components  22  so that objects at different distances remain in focus. 
     In addition to controlling lenses  22  to focus on objects at different distances, control circuitry  26  may adjust the optical power of lenses  22  to correct for vision defects such as myopia, hyperopia, presbyopia, astigmatism, and/or other vision defects. To correct such vision defects, control circuitry  26  may obtain a user&#39;s prescription and accommodation range. Such information may be provided directly to glasses  14  by a user, may be collected from another electronic device in which a user&#39;s health data is stored, and/or may be determined using glasses  14 . 
     Control circuitry  26  may be configured to determine a user&#39;s prescription and/or accommodation range using a vision characterization process. The vision characterization process may be carried out using glasses  14  and an external object such as object  18 . Vision characterization operations may include, for example, having the user view object  18  through lens  22  and receiving user input indicating when object  18  is in focus. The optical power of lens  22  and the distance to the in-focus object may be used to determine the user&#39;s prescription. Different properties of system  10  may be varied until the user&#39;s prescription and/or accommodation range is determined. For example, the optical power of lenses  22  may be varied, the distance d between glasses  14  and object  18  may be varied, and/or other properties of system  10  may be varied while user input is gathered. The optical power of lens  22  and the distance to the in-focus objects may be used to determine the user&#39;s prescription and accommodation range. Once a user&#39;s prescription and accommodation range are known, control circuitry  26  may operate lenses  22  in accordance with the user&#39;s prescription and accommodation range (e.g., to correct for vision defects and provide an appropriate amount of accommodation for the user). 
     In some arrangements, the vision characterization process may be conducted for both eyes at the same time. In other arrangements, the vision characterization process may be conducted separately for each eye to obtain the prescription and/or accommodation range of each individual eye. This may be achieved by having the user cover the eye that is not being characterized and/or by using glasses  14  to block the eye that is not being characterized. 
     In some arrangements, external object  18  may be an object without electronics. In other arrangements, external object  18  is an electronic device that is used in conjunction with glasses  14  during vision characterization operations. Arrangements in which external object  18  is an electronic device are sometimes described herein as an illustrative example. 
     An illustrative electronic device of the type that may be used in system  10  to facilitate characterizing a user&#39;s vision is shown in  FIG.  2   . As shown in  FIG.  2   , electronic device  18  may have control circuitry  28 . Control circuitry  28  may include storage and processing circuitry for supporting the operation of device  18 . The storage and processing circuitry may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in control circuitry  28  may be used to control the operation of device  18 . The processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio chips, application specific integrated circuits, etc. 
     Device  18  may include input-output circuitry such as cellular telephone transceiver circuitry, wireless local area network transceiver circuitry, and other communications circuitry. Input-output circuitry in device  18  such as input-output devices  30  may be used to allow data to be supplied to device  18  and to allow data to be provided from device  18  to external devices. Input-output devices  30  may include buttons, joysticks, scrolling wheels, touch pads, key pads, keyboards, speakers, tone generators, vibrators (e.g., piezoelectric vibrating components, etc.), light-emitting diodes and other status indicators, data ports, and other circuitry. 
     Input-output devices  30  may include one or more displays such as display  32 . Display  32  may be a touch screen display that includes a touch sensor for gathering touch input from a user or display  32  may be insensitive to touch. A touch sensor for display  32  may be based on an array of capacitive touch sensor electrodes, acoustic touch sensor structures, resistive touch components, force-based touch sensor structures, a light-based touch sensor, or other suitable touch sensor arrangements. If desired, display  32  may include actuators to provide haptic feedback for a user. 
     Input-output devices  30  may include sensors  34 . Sensors  34  may include strain gauge sensors, proximity sensors, ambient light sensors, touch sensors, force sensors, temperature sensors, pressure sensors, magnetic sensors, accelerometers, gyroscopes and other sensors for measuring orientation (e.g., position sensors, orientation sensors), microelectromechanical systems sensors, and other sensors. Sensors  34  may be light-based sensors (e.g., proximity sensors or other sensors that emit and/or detect light), capacitive sensors (e.g., sensors that measure force and/or touch events using capacitance measurements). Strain gauges, piezoelectric elements, capacitive sensors, and other sensors may be used in measuring applied force and can therefore be used to gather input from a user&#39;s fingers or other external source of pressure. Capacitive touch sensors may make capacitance measurements to detect the position of a user&#39;s finger(s). If desired, sensors  34  may include microphones to gather audio signals. Sensors  34  may be incorporated into display  32 . For example, display  32  may have an array of light-emitting diodes and sensors  34  and/or actuator components may be incorporated into the array to provide display  32  with the ability to sense user input and provide haptic feedback in addition to the ability to display images for the user. 
     Sensor(s)  34 , which may sometimes be referred to as sensor circuitry, may include visible light cameras and/or infrared light cameras. To capture depth information, sensors  34  in input-output devices  30  may include one or more depth sensors such as light-based proximity sensors, time-of-flight camera sensors, camera-based depth sensors using parallax, structured light depth sensors (e.g., having an emitter that emits beams of light in a grid, a random dot array, or other pattern, and having an image sensor that generates depth maps based on the resulting spots of light produced on target objects), sensors that gather three-dimensional depth information using a pair of stereoscopic image sensors, lidar (light detection and ranging) sensors, radar sensors, and/or other suitable sensors. 
     Control circuitry  28  may be used to run software on device  18  such as operating system code and applications. During operation of device  18 , the software running on control circuitry  28  may be used in gathering user input and making measurements using sensors  34  and may be used in providing output to a user with display  32  and other output resources in input-output devices  30 . 
     Device  18  may be a cellular telephone, a tablet computer, a laptop computer, a wrist watch device, or other portable electronic device and/or may include or be based on a desktop computer, set-top box, or other electronic equipment. Illustrative configurations in which device  18  is a portable device such as a wrist watch device, a cellular telephone, or laptop computer may sometimes be described herein as an example. 
       FIG.  3    is an equation for determining the diopters needed for a lens to bring an object at a given distance into focus for a user with vision defects. In equation  36  of  FIG.  3   , D LENS  corresponds the focal power of lens  22  in diopters,  DISTANCE  corresponds to the distance in meters to the object that the user is focusing on, and D PRESCRIPTION  corresponds to the user&#39;s prescription in diopters. System  10  of  FIG.  1    may conduct a vision characterization process to determine D PRESCRIPTION  for a user. In the vision characterization process, D LENS  and  DISTANCE  of equation  36  of  FIG.  3    may be known and/or measureable, allowing system  10  (e.g., control circuitry  26  of glasses  14  and/or control circuitry  28  of electronic device  18 ) to solve for D PRESCRIPTION . 
     It should be understood that equation  36  of  FIG.  3    is merely an illustrative example of how system  10  might determine a user&#39;s prescription. If desired, system  10  may use other methods or formulas to determine a user&#39;s prescription based on user input and distance measurements. In some arrangements, system  10  may not explicitly calculate a user&#39;s prescription but may use user input and distance measurements to determine appropriate operating parameters for glasses  14  that account for the user&#39;s prescription (e.g., may determine appropriate settings for glasses  14  that correct for any deficiencies in the user&#39;s vision). 
     Vision characterization operations may be conducted entirely by glasses  14  (e.g., using control circuitry  26  and depth sensor  20 ), may be conducted entirely by electronic device  18  (e.g., using control circuitry  28  and sensors  34 ), or may be conducted by both glasses  14  and electronic device  18 . Glasses  14  and electronic device  18  may include wireless communications circuitry such as radio-frequency transceiver circuitry for handling various radio-frequency communications bands. For example, control circuitry  26  and  28  may be configured to communicate with each other using wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as WiFi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol, cellular telephone protocols, MIMO protocols, antenna diversity protocols, satellite navigation system protocols, millimeter wave communications protocols, IEEE 802.15.4 ultra-wideband communications protocols, etc. 
       FIG.  4    is a diagram illustrating how system  10  may conduct a vision characterization process to solve for D PRESCRIPTION  of equation  36  in  FIG.  3   . As shown in  FIG.  4   , user  16  may view external objects such as object  18  through lens  22 . Object  18  may be an object without electronics or may be an electronic device of the type shown in  FIG.  2   . In arrangements where object  18  is an electronic device, user  16  may provide input to device  18  and/or may receive output from device  18 . If desired, display  32  of device  18  may display an image during vision characterization operations. During vision characterization operations, the lens power of lens  22  and/or distance d between lens  22  and object  18  may be adjusted until object  18  is in focus. Once object  18  is in focus, control circuitry  26  (and/or control circuitry  28 ) may use the optical power of lens  22  (corresponding to D LENS  in equation  36  in  FIG.  3   ) and the distance d (corresponding to  DISTANCE  in equation  36  in  FIG.  3   ) to solve for D PRESCRIPTION  in equation  36  in  FIG.  3   . 
     If desired, the resolution or amount of blurring in images on display  32  of electronic device  18  may be adjusted to determine a user&#39;s prescription. For example, control circuitry  28  may adjust the resolution of an image on display  32  in a controlled fashion until the user provides feedback indicating when the image on display  32  is out of focus. When the resolution of an image on display  32  exceeds the resolution of the human retina, the change in resolution of the image on display  32  will not be noticeable to the user. When the resolution of the image on display  32  falls below the resolution of the human retina, the user will notice blurring and can provide appropriate feedback. This information may in turn be used to determine the user&#39;s prescription. 
     In one illustrative arrangement, control circuitry  26  of glasses  14  may cycle through different lens powers for lens  22  automatically (e.g., without requiring user input) until user  16  provides input indicating that object  18  is in focus. For example, control circuitry  26  may continuously adjust the optical power of lens  22  across a range of optical powers (e.g., between maximum and minimum optical powers such as 5D to −5D, or any other suitable range of optical powers). As the optical power of lens  22  changes, object  18  may come in and out of the user&#39;s focus. Control circuitry  26  may cycle through one or more ranges of lens powers at one or more speeds. In one illustrative example, control circuitry  26  cycles through a first range of lens powers at a first speed until a first user input is received. Control circuitry  26  may then cycle through a second range of lens powers at a second speed until a second user input is received. If desired, the second range may be smaller than the first range and the second speed may be slower than the first speed. 
     When lens  22  reaches an optical power that brings object  18  into focus for the user, the user may provide input to glasses  14  and/or to electronic device  18  to indicate when object  18  is in focus. The user input may be touch input, voice input, motion input, button press input, or any other suitable type of user input. If desired, control circuitry  26  may stop cycling through different lens powers and/or may begin cycling through a different range of lens powers upon receiving user input indicating that object  18  is in focus. When object  18  is in focus, equation  36  of  FIG.  3    may be used to determine the user&#39;s prescription. The distance d to object  18  may be measured using depth sensor  20  of glasses  14  and/or using a depth sensor in sensors  34  of device  18 . The lens power of lens component  22  when object  18  is in focus corresponds to D LENS  in equation  36  of  FIG.  3   , and the distance d to the in-focus object  18  corresponds to  DISTANCE  in equation  36  of  FIG.  3   . Using these two values, control circuitry  26  may solve for D PRESCRIPTION  of equation  36  in  FIG.  3   . 
     In another illustrative arrangement, control circuitry  26  may adjust the lens power of lens component  22  in response to user input. For example, a user may provide input to glasses  14  and/or electronic device  18  to adjust the lens power of lens  22  until object  18  is in focus. A user may provide a first user input to adjust the optical power of lens  22  and may provide a second user input to indicate when object  18  comes into focus. For example, a user may turn a watch crown, move a slider on a touch screen, provide touch input to a touch pad, or provide other suitable input (e.g., touch input, voice input, motion input, button press input, etc.) to adjust the lens power until object  18  is in focus. When an object is in focus, the user may stop adjusting the lens power of lens  22 . If no user input is received for a given period of time, control circuitry  26  may conclude that object  18  is in focus for the user. This is, however, merely illustrative. If desired, user  16  may provide active user input (e.g., touch input, voice input, motion input, button press input, etc.) indicating that object  18  is in focus. Wireless communications circuitry in device  18  may be used to convey the user input (e.g., the first user input that controls the optical power of lens  22  and the second user input that indicates object  18  is in focus) to glasses  14 . When object  18  is in focus, equation  36  of  FIG.  3    may be used to determine the user&#39;s prescription. The distance d to object  18  may be measured using depth sensor  20  of glasses  14  and/or using a depth sensor in sensors  34  of device  18 . The optical power of lens  22  when object  18  is in focus corresponds to D LENS  in equation  36  of  FIG.  3    and the distance d to the in-focus object  18  corresponds to  DISTANCE  in equation  36  of  FIG.  3   . Using these two values, control circuitry  26  may solve for D PRESCRIPTION  of equation  36  in  FIG.  3   . 
     In another illustrative arrangement, the distance d between object  18  and lens  22  may be varied until object  18  comes into focus. For example, user  16  may move object  18  back and forth until object  18  is in focus. As distance d changes, the lens power of lens  22  may remain constant or may be varied. The user may provide input indicating when object  18  is in focus (e.g., by holding object  18  at a given distance for a given period of time or by providing other suitable input to device  18  and/or glasses  14 ). When the user indicates that object  18  is in focus, control circuitry  26  may use the lens power of lens  22  (corresponding to D LENS  in equation  36  of  FIG.  3   ) and distance d to in-focus object  18  (corresponding to  DISTANCE  in equation  36  of  FIG.  3   ) to solve for D PRESCRIPTION  in equation  36  of  FIG.  3   . The distance d to object  18  may be measured using depth sensor  20  of glasses  14  and/or using a depth sensor in sensors  34  of device  18 . 
     In another illustrative arrangement, the user may look around at different objects  18  at different distances d and may provide suitable input when the object is in focus. In other words, instead of changing distance d by moving object  18 , distance d may be changed by the user simply adjusting his or her gaze to an in-focus object in the user&#39;s environment. The user may provide suitable input to indicate when his or her gaze has found an object in focus (e.g., by holding his or her gaze on the object for a given period of time or by providing other suitable input to device  18  and/or glasses  14 ). When the user indicates that object  18  is in focus, control circuitry  26  may use the lens power of lens  22  (corresponding to D LENS  in equation  36  of  FIG.  3   ) and distance d to in-focus object  18  (corresponding to  DISTANCE  in equation  36  of  FIG.  3   ) to solve for D PRESCRIPTION  in equation  36  of  FIG.  3   . The distance d to object  18  may be measured using depth sensor  20  of glasses  14  and/or using a depth sensor in sensors  34  of device  18 . 
       FIGS.  5 ,  6 , and  7    are illustrative types of electronic devices  18  that may be used during vision characterization operations. 
     In the example of  FIG.  5   , electronic device  18  is a wrist watch having a housing  42  and a band  40  that attaches housing  42  to a user&#39;s wrist. Electronic device  18  may have input-output devices such as touch screen display  32  and crown  44 . During vision characterization operations, display  32  may display image  38 . User  16  ( FIG.  4   ) may view image  38  through lens  22  of glasses  14  and may provide input to glasses  14  and/or electronic device  18 . For example, a user may provide input by rotating and/or pressing crown  44 , touching display  32 , and/or providing other suitable input. 
     In one illustrative arrangement, a user may rotate crown  44  to adjust the optical power, cylindrical correction, or higher order corrections of lens  22 . Wireless circuitry in device  18  may send wireless signals to glasses  14  that cause control circuitry  26  to adjust the optical power of lens  22  in accordance with the rotation of crown  44 . Rotation of crown  44  in one direction, for example, may result in an increase in optical power of lens  22 , whereas rotation of crown  44  in the opposite direction may result in a decrease in optical power of lens  22 . For aberrations such as cylindrical, trefoil, coma, and higher order aberrations, crown  44  may be used to adjust the power of lens  22  and/or may be used to adjust the orientation angle of the aberration. Pressing on crown  44  and/or providing other user input may be used to switch the adjustment mode of crown  44  (e.g., to change the effect that rotation of crown  44  has on lens  44 ). For example, the user may press on crown  44  to change between an aberration selection mode, a phase selection mode, an orientation angle adjustment mode, a fine tuning mode, or other adjustment mode. The speed at which control circuitry  26  adjusts the optical power of lens  22  may be based on the speed at which the user rotates crown  44  (e.g., slower rotation of crown  44  may result in slower and/or finer adjustment of lens  22 , and vice versa). 
     As the optical power of lens  22  changes in response to rotation of crown  44 , image  38  may go in and out of focus for the user. When image  38  comes into focus, the user may provide input to device  18  by pressing crown  44  inward (e.g., towards housing  42 ) or providing other suitable input to device  18  and/or glasses  14 . Wireless circuitry in device  18  may send wireless signals to glasses  14  to communicate the user&#39;s input to device  18 . When the user indicates that object  18  is in focus, control circuitry  26  and/or control circuitry  28  may use the lens power of lens  22  (corresponding to D LENS  in equation  36  of  FIG.  3   ) and distance d to in-focus object  18  (corresponding to  DISTANCE  in equation  36  of  FIG.  3   ) to solve for D PRESCRIPTION  in equation  36  of  FIG.  3   . The distance d to object  18  may be measured using depth sensor  20  of glasses  14  and/or using a depth sensor in sensors  34  of device  18 . 
     If desired, other types of input (e.g., touch input, voice input, motion input, button press input, etc.) to electronic device  18  of  FIG.  5    and/or glasses  14  may be used to adjust the optical power of lens  22  and/or to indicate whether an object is in focus. Providing input to watch crown  44  is merely illustrative. 
     In the example of  FIG.  6   , electronic device  18  is a laptop computer having a housing  42  with upper and lower housing portions coupled by a hinge. Electronic device  18  may have input-output devices such as display  32 , keyboard  56 , and touch pad  46 . During vision characterization operations, display  32  may display image  38 . User  16  ( FIG.  4   ) may view image  38  through lens  22  of glasses  14  and may provide input to glasses  14  and/or electronic device  18 . For example, a user may provide input to keyboard  56  and/or touch pad  46 . 
     In one illustrative arrangement, a user may slide one or more fingers on touch pad  56  to adjust the optical power of lens  22 . Wireless circuitry in device  18  may send wireless signals to glasses  14  that cause control circuitry  26  to adjust the optical power of lens  22  in accordance with the touch input on touch pad  46 . Sliding one or more fingers on touch pad  46  in one direction, for example, may result in an increase in optical power of lens  22 , whereas sliding one or more fingers on touch pad  46  in the opposite direction may result in a decrease in optical power of lens  22 . The speed at which control circuitry  26  adjusts the optical power of lens  22  may be based on the speed at which the user slides his or her finger(s) on touch pad  46  (e.g., slower sliding motion on touch pad  46  may result in slower and/or finer adjustment of lens  22 , and vice versa). If desired, other types of touch input (e.g., clicking, pressing, swiping, pinching, etc.) may be provided to touch pad  46 . The use of sliding fingers is merely illustrative. 
     As the optical power of lens  22  changes in response to touch input on touch pad  46 , image  38  may go in and out of focus for the user. When image  38  comes into focus, the user may provide input to device  18  by pressing down (e.g., clicking) on touch pad  46  or providing other suitable input to device  18  and/or glasses  14 . Wireless circuitry in device  18  may send wireless signals to glasses  14  to communicate the user&#39;s input to device  18 . When the user indicates that object  18  is in focus, control circuitry  26  and/or control circuitry  28  may use the lens power of lens  22  (corresponding to D LENS  in equation  36  of  FIG.  3   ) and distance d to in-focus object  18  (corresponding to  DISTANCE  in equation  36  of  FIG.  3   ) to solve for D PRESCRIPTION  in equation  36  of  FIG.  3   . The distance d to object  18  may be measured using depth sensor  20  of glasses  14  and/or using a depth sensor in sensors  34  of device  18 . 
     If desired, other types of input (e.g., touch input, voice input, motion input, button press input, etc.) to electronic device  18  of  FIG.  6    and/or glasses  14  may be used to adjust the optical power of lens  22  and/or to indicate when an object is in focus. Providing input to touch pad  46  is merely illustrative. 
     In the example of  FIG.  7   , electronic device  18  is a cellular telephone or tablet computer having a housing  42 . Electronic device  18  may have input-output devices such as touch screen display  32 . During vision characterization operations, display  32  may display image  38 . User  16  ( FIG.  4   ) may view image  38  through lens  22  of glasses  14  and may provide input to glasses  14  and/or electronic device  18 . For example, a user may provide input to touch screen display  32 . 
     In one illustrative arrangement, display  32  may display images such as user interface elements that allow a user to provide input to device  18  and/or glasses  14 . For example, display  32  may display user interface elements such as slider  50  and bar  48 . A user may move slider  50  along bar  48  to adjust the optical power of lens  22 . Wireless circuitry in device  18  may send wireless signals to glasses  14  that cause control circuitry  26  to adjust the optical power of lens  22  in accordance with movement and position of slider  50  on bar  48 . Moving slider  50  in direction  52 , for example, may result in an increase in optical power of lens  22 , whereas moving slider  50  in direction  54  may result in a decrease in optical power of lens  22 . The speed at which control circuitry  26  adjusts the optical power of lens  22  may be based on the speed at which the user moves slider  50  (e.g., slower movement of slider  50  may result in slower and/or finer adjustment of lens  22 , and vice versa). If desired, other types of user interface elements and/or other types of touch input (e.g., clicking, pressing, swiping, pinching, etc.) may be used during vision characterization operations. The use of slider  50  and bar  48  on display  32  is merely illustrative. 
     As the optical power of lens  22  changes in response to touch input on display  32 , image  38  may go in and out of focus for the user. When image  38  comes into focus, the user may provide input to device  18  by leaving slider  50  in a given position for a period of time and/or by providing other suitable input to device  18  and/or glasses  14 . Wireless circuitry in device  18  may send wireless signals to glasses  14  to communicate the user&#39;s input to device  18 . When the user indicates that object  18  is in focus, control circuitry  26  and/or control circuitry  28  may use the lens power of lens  22  (corresponding to D LENS  in equation  36  of  FIG.  3   ) and distanced to in-focus object  18  (corresponding to  DISTANCE  in equation  36  of  FIG.  3   ) to solve for D PRESCRIPTION  in equation  36  of  FIG.  3   . The distance d to object  18  may be measured using depth sensor  20  of glasses  14  and/or using a depth sensor in sensors  34  of device  18 . 
     If desired, other types of input (e.g., touch input, voice input, motion input, button press input, etc.) to electronic device  18  of  FIG.  7    and/or glasses  14  may be used to adjust the optical power of lens  22  and/or to indicate when an object is in focus. Providing input to display  32  is merely illustrative. 
     In addition to determining a user&#39;s prescription (e.g., D PRESCRIPTION  in equation  36  of  FIG.  3   ), which may include cylindrical, trefoil, coma, higher order aberrations (as examples), system  10  (e.g., control circuitry  26  and/or control circuitry  28 ) may be configured to determine a user&#39;s accommodation range. Accommodation refers to the process by which the eye changes optical power to maintain focus on an object as its distance varies. Accommodation range refers to the range of distances over which an object can be accurately focused on the retina by accommodation of the eye. The accommodation range is characterized by a near point and a far point. The near point is the minimum distance at which the eye can maintain focus on an object, and the far point is the maximum distance at which the eye can maintain focus on an object. Some users may have a full accommodation range, whereas other users may have little or no accommodation range. When a user&#39;s accommodation range is known, control circuitry  26  may operate lens  22  in accordance with the user&#39;s accommodation range. For example, if a user has a 70% of a normal accommodation range, lens  22  may provide the remaining 30% accommodation to keep objects in focus. If a user has no accommodation range, lens  22  may provide 100% of the accommodation. If a user has 100% of a normal accommodation range, lens  22  may provide no accommodation or may provide a small amount of accommodation, if desired. 
       FIG.  8    is a diagram illustrating how an accommodation range may be determined during vision characterization operations. Using a similar setup to the arrangement described in connection with  FIG.  4   , user  16  may view object  18  through lens  22 . Control circuitry  26  may cycle lens  22  through different ranges of optical powers to determine the user&#39;s near point NP and far point FP. For example, to determine a user&#39;s near point NP, control circuitry  26  may cycle through a first range of optical powers corresponding to a first range of focal distances (e.g., between focal distance P 1  and focal distance P 2 ). When the user provides input indicating that object  18  comes into focus or goes out of focus, the optical power of lens  22  at that time may be used to solve for  DISTANCE  in equation  36  of  FIG.  3   , which corresponds to the user&#39;s near point NP. To determine a user&#39;s far point FP, control circuitry  26  may cycle through a second range of optical powers corresponding to a second range of focal distances (e.g., between focal distance P 3  and focal distance P 4 ). When the user provides input indicating that object  18  comes into focus or goes out of focus, the optical power of lens  22  at that time may be used to solve for  DISTANCE  in equation  36  of  FIG.  3   , which corresponds to the user&#39;s far point FP. 
     The optical power adjustment of lens  22  may be performed automatically by control circuitry  26  (e.g., without requiring user input) or may be performed by control circuitry  26  in response to user input to device  18  and/or glasses  14  (e.g., touch input, voice input, motion input, button press input, input of the type described in connection with  FIGS.  5 ,  6 , and  7   , or any other suitable type of user input). 
     The distance between the user&#39;s near point NP and far point FP corresponds to the user&#39;s accommodation range AR. Once control circuitry  26  knows accommodation range AR, control circuitry  26  may control lens  22  based on the user&#39;s accommodation range (e.g., to provide an appropriate amount of accommodation based on the user&#39;s accommodation range). 
     Adjusting the optical power of lens  22  to determine the user&#39;s accommodation range is merely illustrative. If desired, optical power of lens  22  may remain unchanged, and near point NP and far point FP may be determined by measuring the distance to the nearest object in focus for the user and the farthest object in focus for the user. In this type of arrangement, control circuitry  26  may determine the near point NP by receiving user input indicating that the user is looking at the closest object  18  in focus (e.g., whether object  18  is an electronic device or an object without electronics). Control circuitry  26  may determine the far point FP by receiving user input indicating that the user is looking at the farthest object  18  in focus (e.g., whether object  18  is an electronic device or an object without electronics). This may be achieved by the user looking at different objects  18  at different distances, or may be achieved by the user looking at the same object  18  and moving the object to different distances. 
     If desired, control circuitry  26  may perform a check to ensure that the prescription and accommodation range determined for a user are accurate. This type of check is illustrated in  FIG.  9   . 
     After determining a user&#39;s prescription and accommodation range, a user may view object  18  (e.g., an image on display  32  of electronic device  18  or other suitable object) through lens  22 . Initially, control circuitry  26  may set the optical power of lens  22  so that the image on display  32  is in focus for the user, using the prescription and accommodation information gathered during vision characterization operations. As shown in  FIG.  9   , the “normal image” is located at a distance between the near point NP and far point FP of the user&#39;s accommodation range, as determined using a process of the type described in connection with  FIG.  8   . Control circuitry  26  may then adjust the optical power of lens  22  so that the image on display  32  is outside of the user&#39;s accommodation range. As shown in  FIG.  9   , the “blurred image” is located outside of the user&#39;s accommodation range. If the blurred image does not actually appear blurry to the user, the accommodation range determined by control circuitry  26  may not be accurate. If the blurred image does in fact appear blurry to the user, then control circuitry  26  may conclude that the determined accommodation range is accurate. A user may provide input to device  18  and/or glasses  14  to indicate whether the blurred image is in focus or not so that control circuitry  26  can assess the accuracy of the determined accommodation range. If desired, vision characterization operations may be repeated to ensure that the user&#39;s prescription and/or accommodation range are accurately determined. 
     If desired, control circuitry  28  may intentionally blur an image on display  32  of electronic device  18  to check the validity of the prescription. If a user&#39;s prescription has been determined incorrectly, the user may not notice that the resolution of the image has been reduced. On the other hand, if a user&#39;s prescription has been determined correctly, the user may notice that the image is blurry and may provide appropriate input to electronic device  18  or glasses  14 . 
     Instead of or in addition to blurring images on display  32 , control circuitry  28  may display text of varying size on display  32  to measure the user&#39;s visual acuity and determine whether glasses  14  are focusing appropriately for the user. The size of the text on display  32  may be varied based on the distance between the user and display  32 . Control circuitry  28  may use input-output devices  30  to provide the user with instructions during vision characterization operations and to receive input from the user. For example, a speaker in device  18  may instruct the user to read the text on display  32 , and a microphone in device  18  may listen for the user&#39;s response. As the text on display  32  gets smaller, the user may indicate when he or she is unable to focus the text accurately. Based on this user input, the distance between the user and display  32 , and the size of the text on display  32 , control circuitry  28  may be configured to determine whether glasses  14  are appropriately focusing for the user. 
     As discussed in connection with  FIG.  3    and  FIG.  8   , a user&#39;s prescription and accommodation range may be determined by adjusting the optical power of lens  22  (corresponding to D LENS  in equation  36  of  FIG.  3   ) and/or by adjusting the distance to in-focus object  18  (corresponding to  DISTANCE  in equation  36  of  FIG.  3   ).  FIG.  10    is a flow chart of illustrative steps involved in determining a user&#39;s prescription and accommodation range via optical power adjustment of lens  22 .  FIG.  11    is a flow chart of illustrative steps involved in determining a user&#39;s prescription and accommodation range via distance adjustment. In both the process of  FIG.  10    and the process of  FIG.  11   , vision characterization operations may be performed using a setup of the type described in connection with  FIG.  4   . User  16  may view object  18  (sometimes referred to as the target) through lens  22 . Object  18  may be an electronic device of the type described in connection with  FIG.  2    or object  18  may be an object without electronics. 
     At step  100 , control circuitry  26  of glasses  14  and/or control circuitry  28  may determine the distance to object  18  at which the user is looking. This may include, for example, using inward-facing camera  24  to determine which object  18  the user is looking at, and using distance sensor  20  of glasses  14  and/or a distance sensor in sensors  34  of device  18  to determine the distance  18  to that object. Measuring the distance to object  18  at the beginning of the process of  FIG.  10    is merely illustrative. If desired, the distance to object  18  may be measured later in the process (e.g., after step  102 , step  104 , or step  106 ). 
     At step  102 , control circuitry  26  may adjust the optical power of lens  22 . In some arrangements, the optical power adjustment of lens  22  may be done automatically (e.g., without requiring user input). In other arrangements, optical power adjustment of lens  22  may be done in response to user input (e.g., user input to glasses  14  and/or device  18 , such as the user input described in connection with  FIGS.  5 ,  6 , and  7   ). 
     At step  104 , glasses  14  and/or device  18  may receive user input indicating that the target is in focus. The user input may be touch input, voice input, motion input, button press input, or any other suitable type of user input (e.g., input of the type described in connection with  FIGS.  5 ,  6 , and  7   ). The optical power of lens  22  when user  16  indicates that object  18  in focus may correspond to D LENS  in equation  36  of  FIG.  3   , and the distance to the in-focus object  18  corresponds to  DISTANCE  in equation  36  of  FIG.  3   , thus allowing control circuitry  26  to solve for D PRESCRIPTION  in equation  36  of  FIG.  3   . 
     If desired, step  102  and step  104  may be repeated one or more times to fine tune the prescription measurement. For example, step  102  may include a course adjustment of optical power across a first range of values at a first speed until the user provides a first input at step  104 . Processing may then loop back to step  102  to perform a fine adjustment of optical power across a second range of values at a second speed until the user provides a second input at step  104 . The second range may be smaller than the first range, and the second speed may be slower than the first speed, if desired. 
     At step  106 , control circuitry  26  may adjust the optical power of lens  22  over smaller ranges for gathering accommodation range information. For example, control circuitry  26  may cycle through a first range of optical powers corresponding to close focal distances (e.g., P 1  and P 2  of  FIG.  9   ) until user input is received at step  108 . Control circuitry  26  may cycle through a second range of optical powers corresponding to far focal (e.g., P 3  and P 4  of  FIG.  9   ) until user input is received at step  108 . 
     The user input of step  108  may be touch input, voice input, motion input, button press input, or any other suitable type of user input (e.g., input to glasses  14  and/or device  18 , input of the type described in connection with  FIGS.  5 ,  6 , and  7   , etc.). The user input may be used to indicate when object  18  comes into focus or goes out of focus. 
     At step  110 , control circuitry  26  and/or control circuitry  28  may determine the user&#39;s prescription and accommodation range based on the information gathered in step  102 ,  104 ,  106 , and  108 . Using the optical power of lens  22  when user  16  indicates that object  18  in focus (corresponding to D LENS  in equation  36  of  FIG.  3   ) and the distance to the in-focus object  18  (corresponding to  DISTANCE  in equation  36  of  FIG.  3   ), control circuitry  26  may solve for D PRESCRIPTION  in equation  36  of  FIG.  3   . The accommodation range may be determined based on the nearest point in focus for the user and the farthest point in focus for the user. 
       FIG.  11    is a flow chart of illustrative steps involved in determining a user&#39;s prescription and accommodation range via distance adjustment. During the process of  FIG.  11   , control circuitry  26  may, if desired, maintain the optical power of lens  22  at a known value (corresponding to D LENS  in equation  36  of  FIG.  3   ). 
     At step  200 , glasses  14  and/or device  18  may receive user input indicating the object at which the user is looking is in focus. The user input may be touch input, voice input, motion input, button press input, or any other suitable type of user input (e.g., input of the type described in connection with  FIGS.  5 ,  6 , and  7   , etc.). The user may bring object  18  into focus by moving target  18  back and forth until it is in focus for the user, or the user may simply look around at different objects  18  until the user&#39;s gaze finds an object  18  that is in focus. 
     At step  202 , control circuitry  26  of glasses  14  and/or control circuitry  28  may determine the distance to object  18  at which the user is looking. This may include, for example, using inward-facing camera  24  to determine which object  18  the user is looking at, and using distance sensor  20  of glasses  14  and/or a distance sensor in sensors  34  of device  18  to determine the distance to that object. 
     At step  204 , glasses  14  and/or device  18  may receive user input indicating nearest and farthest objects that are in focus for the user. The user input may be touch input, voice input, motion input, button press input, or any other suitable type of user input (e.g., input of the type described in connection with  FIGS.  5 ,  6 , and  7   , etc.). This may be achieved by having the user move object  18  to the closest and furthest points where object  18  is still focus, or this may be achieved by having the user look around until the user&#39;s gaze finds the nearest object in focus and the farthest object in focus. 
     At step  206 , control circuitry  26  of glasses  14  and/or control circuitry  28  may determine the distance to the nearest object  18  in focus and the farthest object  18  in focus. This may include, for example, using inward-facing camera  24  to determine which object  18  the user is looking at, and using distance sensor  20  of glasses  14  and/or a distance sensor in sensors  34  of device  18  to determine the distance to that object. 
     At step  208 , control circuitry  26  and/or control circuitry  28  may determine the user&#39;s prescription and accommodation range based on the information gathered in step  200 ,  202 ,  204 , and  206 . Using the set optical power of lens  22  (corresponding to D LENS  in equation  36  of  FIG.  3   ) and the distance to the in-focus object  18  (corresponding to  DISTANCE  in equation  36  of  FIG.  3   ), control circuitry  26  may solve for D PRESCRIPTION  in equation  36  of  FIG.  3   . The accommodation range may be determined based on the nearest point in focus for the user and the farthest point in focus for the user. 
     As discussed above, aspects of the present technology include the gathering and use of biometric data such as a user&#39;s prescription and accommodation range. The technology also contemplates and/or may be implemented along with technologies that involve gathering personal data that relates to the user&#39;s health, that uniquely identifies a specific person, and/or that can be used to contact or locate a specific person. Such personal data can include demographic data, date of birth, location-based data, telephone numbers, email addresses, home addresses, and data or records relating to a user&#39;s health or level of fitness (e.g., vital signs measurements, medication information, exercise information). 
     The present disclosure recognizes that a user&#39;s personal data, including biometric data, such as data generated and used by the present technology, can be used to the benefit of users. For example, information about a user&#39;s prescription and/or accommodation range may allow glasses  14  to operate effectively for users with different vision capabilities. 
     The present disclosure contemplates that the entities responsible for the collection, analysis, disclosure, transfer, storage, or other use of such personal data will comply with well-established privacy policies and/or privacy practices. In particular, such entities should implement and consistently use privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining personal information data private and secure. Such policies should be easily accessible by users, and should be updated as the collection and/or use of data changes. Personal information from users should be collected for legitimate and reasonable uses of the entity and not shared or sold outside of those legitimate uses. Further, such collection/sharing should require receipt of the informed consent of the users. Additionally, such entities should consider taking any needed steps for safeguarding and securing access to such personal information data and ensuring that others with access to the personal information data adhere to their privacy policies and procedures. Further, such entities can subject themselves to evaluation by third parties to certify their adherence to widely accepted privacy policies and practices. The policies and practices may be adapted depending on the geographic region and/or the particular type and nature of personal data being collected and used. 
     Despite the foregoing, the present disclosure also contemplates embodiments in which users selectively block the collection of, use of, or access to, personal data, including biometric data. For example, a user may be able to disable hardware and/or software elements that collect biometric data. Further, the present disclosure contemplates that hardware and/or software elements can be provided to prevent or block access to personal data that has already been collected. Specifically, users can select to remove, disable, or restrict access to certain health-related applications collecting users&#39; personal health or fitness data. 
     The foregoing is merely illustrative and various modifications can be made to the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20190828
Publication Date: 20230718
Grant Date: 20230718
Priority Date: 20180830
Inventors: KANGAS, Miikka M.
SMITH, ERIC G.
LIU, QING
KOLLER, JEFFREY G.
Assignee: APPLE INC
CPC Classifications: [{"code": "G02F1/0123", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01C3/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02C7/083", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/13306", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/0123", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/13306", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02C7/083", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01C3/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02F1/0123", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02C11/10", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 87163361