Patent Publication Number: US-10307246-B2

Title: Intraocular lens devices, systems, and related methods

Description:
RELATED METHODS 
     If an Application Data Sheet (ADS) has been filed on the filing date of this application, it is incorporated by reference herein. Any applications claimed on the ADS for priority under 35 U.S.C. §§ 119, 120, 121, or 365(c), and any and all parent, grandparent, great-grandparent, etc. applications of such applications, are also incorporated by reference, including any priority claims made in those applications and any material incorporated by reference, to the extent such subject matter is not inconsistent herewith. 
     CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of the earliest available effective filing date(s) from the following listed application(s) (the “Priority Applications”), if any, listed below (e.g., claims earliest available priority dates for other than provisional patent applications or claims benefits under 35 USC § 119(e) for provisional patent applications, for any and all parent, grandparent, great-grandparent, etc. applications of the Priority Application(s)). 
     PRIORITY APPLICATIONS 
     None. 
     If the listings of applications provided above are inconsistent with the listings provided via an ADS, it is the intent of the Applicant to claim priority to each application that appears in the Domestic Benefit/National Stage Information section of the ADS and to each application that appears in the Priority Applications section of this application. 
     All subject matter of the Priority Applications and of any and all applications related to the Priority Applications by priority claims (directly or indirectly), including any priority claims made and subject matter incorporated by reference therein as of the filing date of the instant application, is incorporated herein by reference to the extent such subject matter is not inconsistent herewith. 
     BACKGROUND 
     Intraocular lenses (IOLs), such as pseudophakic IOLs, aphikic IOLs, or phakic IOLs (PIOLS), can be used to correct the vision of a subject. Typical IOLs can include monofocal, multifocal, or accommodative configurations. IOLs can include an optic element (e.g., lens) and haptic elements (e.g., arms or wings configured to aid in positioning the IOL). 
     Such configurations can be limited to focusing either on near or far vision without selectively modifiable adjustment therebetween. Therefore, manufacturers, users, and designers of IOLs continue to seek improved IOLs. 
     SUMMARY 
     Embodiments disclosed herein are directed to IOL devices, IOL systems, and methods that include determining relative tilt and/or vergence rotation of a subject&#39;s eyes and focusing one or more intraocular lenses responsive to the determined vergence rotation. In an embodiment, an IOL system can include at least one IOL device that can be positioned in an eye of a subject, a sensor that can provide or generate an output related to the vergence rotation of the subject&#39;s eyes, and a controller that can direct the IOL device to change focal length. For example, the IOL system can include a field source that can establish an identifiable field that can be sensed or detected by the sensor. In an embodiment, the sensor and the identifiable field can have relative locations such that change in vergence between the eyes (e.g., vergence rotation of the eyes) of the subject produces a change in relative positions and/or orientations between the sensor and the identifiable field. For example, as the eyes of the subject tilt or pivot, the sensor and the identifiable field can move relative to each other, and the detected changes in the field can be related to a vergence rotation between the eyes of the subject. 
     An embodiment includes an IOL system. The IOL system includes a magnetic field source sized and configured to be placed in a first eye of a subject. The magnetic field source is configured to establish an identifiable magnetic field having a predetermined orientation relative to the first eye. The IOL system also includes an IOL device sized and configured to be placed in a second eye of the subject. The IOL device includes a switchable lens configured to selectively switch between a first focal length and at least a second focal length that is less than the first focal length. The IOL device further includes a sensor configured to detect a change in the established identifiable magnetic field corresponding to a vergence rotation between the first eye and the second eye. The sensor is configured to generate one or more detection outputs at least partially based on the detected change. The IOL device further includes a controller operably coupled to the sensor to receive the one or more detection outputs therefrom. The controller includes control electrical circuitry configured to direct the switchable lens to selectively switch between the first focal length and the at least a second focal length responsive to the one or more detection outputs. 
     An embodiment includes a method of adjusting a focal length of one or more intraocular lens devices. The method includes establishing an identifiable magnetic field with a magnetic field source positioned in a first eye of the subject. The identifiable magnetic field has a predetermined orientation relative to the first eye. The method also includes, at a controller, receiving one or more detection outputs from a sensor. The one or more detection outputs based on a detected change in the established identifiable magnetic field corresponding to a vergence rotation between the first eye and a second eye of the subject. The method further includes, responsive to at least the one or more detection outputs, modifying the focal length of one or more intraocular lens devices positioned in one or more of the first eye or the second eye. 
     An embodiment includes an IOL system. The IOL system includes a magnetic field source configured to be positioned on a subject. The magnetic field source is configured to establish an identifiable magnetic field having a predetermined orientation relative to the first eye. The IOL system also includes a sensor configured to detect a change in the established identifiable magnetic field at least partially corresponding to a vergence rotation between the first eye and a second eye of the subject. The sensor is configured to generate one or more detection outputs on the detected change. The system further includes an IOL device sized and configured to be placed in the second eye of the subject. The IOL device includes a switchable lens configured to selectively switch between a first focal length and at least a second focal length that is less than the first focal length. The IOL device also includes a controller operably coupled to the sensor to receive the one or more detection outputs therefrom. The controller includes control electrical circuitry configured to direct the switchable lens to selectively switch between the first focal length and the second focal length responsive to the one or more detection outputs. 
     Features from any of the disclosed embodiments can be used in combination with one another, without limitation. In addition, other features and advantages of the present disclosure will become apparent to those of ordinary skill in the art through consideration of the following detailed description and the accompanying drawings. 
     The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a schematic top view of a subject&#39;s eyes having a first vergence therebetween and focused on a first object at a first distance from the subject according to an embodiment. 
         FIG. 2  is a schematic top view of the subject&#39;s eyes of  FIG. 1 , with the eyes having a second vergence therebetween and are focused on a second object at a second distance from the subject that is less than the first distance according to an embodiment. 
         FIG. 3  is a schematic, side, cross-sectional view of a subject&#39;s eye and an intraocular lens device located in the eye according to an embodiment. 
         FIG. 4A  is a top view of an IOL device located in the eye according to an embodiment. 
         FIG. 4B  is a side view of the IOL device of  FIG. 4A . 
         FIG. 5A  is a schematic top view of an IOL system that includes two IOL devices oriented by the subject&#39;s eyes at a first vergence therebetween according to an embodiment. 
         FIG. 5B  is a schematic top view of the IOL system of  FIG. 5A  in which the IOL devices are oriented by the subject&#39;s eyes at a second vergence therebetween according to an embodiment. 
         FIG. 5C  is a schematic top view of the IOL system of  FIG. 5A  in which the IOL devices are oriented by the subject&#39;s eyes co-tilted in a first direction according to an embodiment. 
         FIG. 5D  is a schematic top view of the IOL system of  FIG. 5A  in which the IOL devices are oriented by the subject&#39;s eyes co-tilted in a second direction according to an embodiment. 
         FIG. 6A  is a schematic top view of an IOL system that includes two IOL devices oriented by the subject&#39;s eyes at a first vergence therebetween according to another embodiment. 
         FIG. 6B  is a schematic top view of the IOL system of  FIG. 6A  in which the IOL devices are oriented by the subject&#39;s eyes at a second vergence therebetween according to an embodiment. 
         FIG. 7A  is a schematic view of an IOL system that includes two IOL devices oriented by the subject&#39;s eyes at a first vergence therebetween according to yet another embodiment. 
         FIG. 7B  is a schematic view of the IOL system of  FIG. 7A  in which the IOL devices are oriented by the subject&#39;s eyes at a second vergence therebetween. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments disclosed herein are directed to IOL devices, IOL systems, and methods that include determining relative tilt or vergence rotation of a subject&#39;s eyes and focusing one or more intraocular lenses based on the determined vergence rotation. In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments can be utilized, and other changes can be made, without departing from the spirit or scope of the subject matter presented here. 
     In one or more embodiments, the IOL system can include at least one IOL device that can be positioned in an eye of a subject, a sensor that can provide or generate an output related to a vergence rotation of the subject&#39;s eyes, and a controller that can direct the IOL device to change focal length responsive to the output related to the vergence rotation. For example, the IOL system can include a field source that can establish an identifiable field that can be sensed or detected by the sensor. In an embodiment, the sensor and the identifiable field can have relative locations such that a change in vergence between the eyes (e.g., vergence rotation of the eyes) of the subject produces a change in relative positions or orientations between the sensor and the identifiable field. For example, as the eyes of the subject tilt or pivot, the sensor and the identifiable field can move relative to each other, and the detected changes in the field can be related to a vergence rotation between the eyes of the subject. 
     In an embodiment, the field can be an identifiable magnetic field established by a permanent or electromagnet. Furthermore, as discussed below in more detail, the field source (e.g., a magnetic field source) can be positioned in at least one eye of the subject. For example, the field source can be embedded in or mounted to an IOL device that can be located in one of the subject&#39;s eye. Alternatively or additionally, the field source can be positioned near, but externally to one or both of the subject&#39;s eyes. In an embodiment, one or more sensors positioned in one or both eyes of the subject can detect a change in the identifiable field or in a component thereof, during vergence rotation (e.g., as the vergence between the eyes changes), such as when the eyes converge or diverge. Hence, for example, the detected change in an identifiable magnetic field or a component thereof can correspond to a change in the vergence between the eyes. 
     As mentioned above, the IOL system can include a controller. For example, the controller can be operably coupled to the sensor and can receive detection output from the sensor. More specifically, the detection output from the sensor can be based on the detected change in the field or based on the one or more components thereof, which can be related to vergence rotation between the eyes of the subject. In an embodiment, the control can distinguish between vergence rotation of the eyes and co-tilt rotation of the eyes (e.g., when the eyes of the subject tilt in the same direction, such as to view an object located peripherally or to a side of the subject). As a consequence of such distinguishing, in such embodiments each IOL can act independently of the other, reaching an accurate vergence determination (and hence an accurate focal length determination) on its own, without a need for communication between both IOLs so as to compare each IOL&#39;s determined tilt with that of the other IOL in order to decide which portion of each IOL&#39;s tilt represents vergence and which represents co-tilt. 
     In an embodiment, the IOL device can be switchable between two or more focal lengths (e.g., a first focal length for distance vision and a second focal length for close-up vision). For example, the IOL device can include one or more switchable lenses that can be directed or switched between two or more focal lengths by the controller. Moreover, the controller can be operably connected to the sensor(s) and can receive outputs therefrom, which can be related to the detected change in the field and, hence, to vergence rotation between the eyes. In an embodiment, the controller can switch or direct switching of the IOL device at least partially based on the outputs received from the sensor(s). 
     In an embodiments, the IOL systems disclosed herein can include one or more sensors configured to detect one or more physiological indicia of the subject. For example, the IOL system can include one or more sensors configured to detect glucose concentration, such as in the eye of the subject; eye pressure, heart rate, biological proteins present in the eye, or any other biological indicia. The one or more sensors can be operably coupled to the controller. The controller of the IOL system can be configured to transmit the measurements of the physical indicia to a remote source such as a computer, a cellular phone, or other electronic device. In an embodiment, the measured physical indicia may be used to determine the health of a subject or eye thereof, customize the operation of the IOL device to the particular subject, determine if the IOL controller needs to be removed or adjusted, or determine if the focal adjustments of the IOL controller are suitable for the subject. The electronic device may then transmit instructions to the controller to selectively control or otherwise adjust the functioning of the IOL system, such as controllably changing the focal length of the IOL device. 
       FIG. 1  schematically illustrates eyes  20  and  30  of a subject focused on a first object  10  that is positioned at a first distance from the subject. In particular, when the eyes  20 ,  30  are focused on the first object  10 , an angle between respective optical axes thereof can be at a vergence angle ϕ 1 .  FIG. 1  also schematically illustrates an IOL system  100  according to an embodiment. For example, an IOL system  100  can include a first IOL device  110  positioned in a first eye  20  and a second IOL device  110 ′ positioned in a second eye  30  of the subject. 
     Generally, the first IOL device  110  or the second IOL device  110 ′ can be configured to augment or correct visual deficiencies of the subject or to replace the lenses in the respective first eye  20  or second eye  30  of the subject (e.g., in cataract surgeries). It should be appreciated that, in one or more embodiments, the IOL system  100  can include only a single IOL device (e.g., the first IOL device  110  or the second IOL device  110 ′), which can be positioned in the first eye  20  or in the second eye  30 . The IOL devices  110  or  110 ′ can be switched to or set at a first focal length, such that the light entering the eye from the distance of the first object  10  is focused on the retina of the respective eyes  20 ,  30 , thereby focusing the eyes  20 ,  30  on the first object  10 . 
     When the subject focuses on another object, such as an object that is closer to the subject than the first object  10 , the object&#39;s eyes  20 ,  30  can tilt such as to converge, thereby changing the angle between the optical axes thereof.  FIG. 2  schematically shows the subject&#39;s eyes  20 ,  30  focused on a second object  40 , which is positioned at a second distance and closer to the subject than the first object  10  ( FIG. 1 ). For example, when the eyes  20 ,  30  focus on the second object  40 , the angle between the optical axis thereof can change to a second angle ϕ 2 . More specifically, as the eyes  20 ,  30  focus on the closer, second object  40 , the eyes  20 ,  30  converge or in-tilt, such that the second angle ϕ 2  defined by the respective optical axis thereof is greater than the first angle ϕ 1 . 
     In an embodiment, responsive to the changed tilt between the eyes  20 ,  30 , the IOL devices  110  or  110 ′ can be switched to the second focal length, which can be shorter than the first focal length. The IOL devices  110  or  110 ′ can include one or more sensors that can sense or detect a change in an identifiable field (e.g., magnetic field) and can correlate that change to the change vergence rotation between the eyes  20 ,  30  (e.g., convergence to focus on a closer object or divergence to focus on a farther object). Similarly, as the subject attempts to focus eyes  20 ,  30  on an object at a distance that is greater than the distance to the second object  40  (e.g., on the first object  10  ( FIG. 1 )), the IOL devices  110  or  110 ′ can be switched to the first focal length (longer than the second focal length). 
     Moreover, as described below in more detail, the IOL devices  110  or  110 ′ can distinguish between vergence rotation from co-tilt rotation (e.g., when the eyes  20 ,  30  rotate in the same direction, such as to observe an object located peripherally from the user). As such, for example, the IOL device  110  or  110 ′ can switch focal length responsive to detected vergence rotation. In an embodiment, the IOL devices  110  or  110 ′ can maintain a previously set focal length during co-tilt of the eyes  20 ,  30 . 
     As mentioned above, the IOL devices  110  or  110 ′ can be located in the subject&#39;s eyes (e.g., in the eye  20  or in the eye  30 ).  FIG. 3  is a side, cross-sectional view of the eye  20  with the IOL device  110  implanted therein, according to an embodiment. It should be appreciated that, while the description herein is related to the IOL device  110  and to the corresponding eye  20  of the subject, the IOL device  110 ′ or its location in the eye  30  ( FIGS. 1-2 ) can have the same or similar configuration. Generally, the eye  20  includes a cornea  21 , an iris  22 , a natural lens, and a retina  23  therebehind. One or more IOL device  110  can be implanted in the eye  20 . For example, the IOL device  110  can be implanted over the natural lens, in front of (e.g., in the anterior chamber) or behind the iris  22  (e.g., in the posterior chamber), or internal to the natural lens such as in a capsular bag  24  of the natural lens. In an embodiment, the natural lens can be absent from the eye  20  (e.g., the IOL device  110  can replace the natural lens and can be placed in the anterior chamber, the posterior chamber, or internal to the capsular bag that is used to contain the natural lens). 
     Generally, as described below in more detail, the IOL device  110  can include a lens  111  and haptics  112  connected to or integrated with the lens  111 . In an embodiment, the haptics  112  can be positioned on or secured to one or more structures in the eye  20 , thereby positioning or securing the IOL device  110  in the eye  20 . For example, the haptics  112  can be positioned on the ciliary body or muscles or in or on the capsular bag  24  of the natural lens. The lens  111  can be located laterally in the center of the eye  20  with the haptics  112  extending laterally therefrom. As mentioned above, the lens  111  of the IOL device  110  can be switched between two or more focal lengths, to focus light entering the eye from a selected distance on the retina  23  of the eye  20 , thereby providing a focus on an object located at the selected focal length and augmenting or correcting the vision of the subject. 
     In an embodiment, the IOL device  110  can be substantially fixed within the eye  20  (e.g., the IOL device can be substantially immobile relative to the optical axis of the eye  20 ). As such, for example, movement of the eye  20  can result in a corresponding movement of the IOL device  110 . In particular, as the eye  20  tilts or pivots in the eye socket, the IOL device  110  can correspondingly tilt or pivot together with the eye  20 . Furthermore, one, some, or all of the elements or components of the IOL device  110  can have a predetermined orientation relative to the eye  20  or relative to the optical axis thereof, as described below in more detail. 
       FIGS. 4A and 4B  illustrate the IOL device  110  according to an embodiment.  FIG. 4A  is a top view of the IOL device  110  and  FIG. 4B  is a side view of the IOL device  110 . As described above, the IOL device  110  can be configured to fit in or on one or more anatomical structures of the eye and can include the lens  111  and one or more haptics  112 . As shown in  FIG. 4A , in an embodiment, the IOL device  110  includes the lens  111 . For example, the lens  111  can be configured to focus light onto the surface of the retina and can be substantially circular or elliptical. Furthermore, the lens  111  can be switchable between two or more focal lengths and, in an embodiment, three or more focal lengths. 
     In an embodiment, the lens  111  can include or can be configured as a switchable diffractive lens. Additionally or alternatively, the lens  111  can include or can be configured as a refractive lens that can have a selectively modifiable index of refraction and focal length (e.g., a variable focus refractive lens). In any embodiment, the lens  111  can be switched at least between the first focal length and at least a second focal length. 
     In an embodiment, a controller including control electrical circuitry can be operably coupled to the lens  111  and can switch or direct switching of the lens  111  between two or more focal lengths. In an embodiment, the controller can be positioned on or embedded in one or more portions of the IOL device  110 . For example, a controller  130  can be mounted on or embedded in the haptics  112  (as shown in  FIG. 4B ), in the lens  111  of the IOL device  110 , or in another part of the IOL device  110 . Moreover, the controller  130  can receive a detection output from a sensor; the detection output can be related or correspond to the vergence rotation between the subject&#39;s eyes. At least partially based on the received detection output, the controller  130  can switch the lens  111  to a suitable or predetermined focal length. 
     For example, the controller  130  can be operably coupled to and can receive a detection output from a sensor  140  that can be positioned on or embedded in one or more portions of the IOL device  110 . For example, the sensor  140  can be mounted on or embedded in the haptics  112  (as shown in  FIG. 4B ) or in the lens  111  of the IOL device  110 . Generally, the sensor  140  can be any suitable sensor for detecting changes in the identifiable field, which can correspond to vergence rotation of the eyes, as described below in more detail. 
     In an embodiment, the identifiable field can be an identifiable magnetic field. Hence, for example, the sensor  140  can be a magnetic field sensor. Generally, the sensor  140  can be any suitable sensor or multiple sensors, which can be sufficiently miniaturized and can be configured for placement in the subject&#39;s eye (e.g., MEMS-based sensors that can be embedded in or mounted on one or more portions of the IOL device  110 ). Examples of suitable sensors include Hall effect sensors, magnetoresistance sensors (e.g., AMR magnetometer, GMR magnetometer), induction coils, magneto-diodes, Lorentz force based sensors, an electron tunneling based sensor, or a MEMS compass. For example, the sensor  140  can generate a detection output (e.g., a measurable change in voltage or resonant frequency) that can be related to or based on the changes in the position of an identifiable magnetic field, which can be related to the change in vergence between the subject&#39;s eyes. In an embodiment, the sensor  140  can generate a signal that can include detection output of the sensor  140 . 
     In an embodiment, the IOL device  110  can include a field source  150  (e.g., a magnetic field source), which can establish an identifiable magnetic field that can be detectable by an additional sensor that can be operably coupled to an additional controller. The field source  150  can be a dipole magnet (e.g., a permanent magnet, an electromagnet, or combination of the foregoing) and can establish or generate a corresponding identifiable dipole magnetic field. Furthermore, the field source  150  can be mounted on or embedded in the IOL device  110 . For example, the field source  150  can be embedded in the haptics  112  (as shown in  FIG. 4B ) or in the lens  111  of the IOL device  110 . 
     In an embodiment, the field source  150  can be generally fixed in or stationary relative to the eye. Additionally or alternatively, the field source  150  can have a predetermine orientation relative to the eye or to the optical axis thereof. For example, the field source can be embedded within the IOL device  110  at a first predetermined orientation relative to the IOL device  110 , and the IOL device  110  can be implanted within the eye at a second predetermined orientation relative to the eye. As such, for example, the identifiable field, such as an identifiable magnetic field can have a predetermined orientation relative to the eye or relative to the optical axis thereof. 
     Moreover, in an embodiment, the IOL device  110  can be positioned in the eye in a manner that movement of the eye results in a corresponding movement of the IOL device  110 . Hence, for example, movement of the eye can produce a corresponding movement of the field source  150  and of the magnetic field established thereby. As such, a sensor detects the change in the established identifiable magnetic field, which can correspond to the movement of the identifiable magnetic field and of the eye (e.g., the movement of the eye can be tilting or pivoting of the eye that at least partially corresponds to a vergence rotation between the eyes). 
     The IOL device(s) can be located in one or in both eyes of the subject. In an embodiment, an IOL device in the first eye can communicate with another IOL in the second eye, and vice versa (e.g., the IOL devices can be operably coupled together). For example, the IOL device in the second eye can send to the IOL device  110  in the first eye the detection output received from a first sensor in the IOL in the second eye, can send focal length determination, etc. In an embodiment, the IOL device  110  can include a communication device  160  (e.g., the controller  130  can be operably coupled to the communication device  160 ). The communication device  160  can be mounted on or embedded in the IOL device  110 . For example, the communication device  160  can be embedded in the haptics  112  (as shown in  FIG. 4B ) or in the lens  111  of the IOL device  110 . 
     The communication device  160  can be wireless (e.g., the communication device  160  can be a transmitter or a transceiver) or wired. For example, a wireless (e.g., RF-based or US-based) connection can be established between the communication device  160  and another or additional communication device. Alternatively, the communication device  160  and another communication device can have a wired connection therebetween. For example, an electrical conductor connecting the communication device  160  and another communication device can be implanted in or near the eyes of the subject. In any embodiment, the communication device  160  can be operably coupled to the additional communication device, such as to send data therebetween. 
     In an embodiment, the controller  130 , sensor  140 , field source  150 , or communication device  160  can be operably coupled or connected to a power source. For example, the power source can include a rechargeable energy storage device or battery (not shown) that can be mounted on or embedded in the IOL device  110 . The battery can be wirelessly recharged (e.g., a wireless or inductive charger can recharge the battery). In an embodiment, the battery can be operably connected to a photovoltaic cell that can be mounted on or embedded in the IOL device  110 . Alternatively or additionally, the battery can be operably connected or coupled to a charge port that can be configured to accept a charging device. In any event, the power source can power one or more of the controller  130 , sensor  140 , field source  150 , or communication device  160 . 
     In an embodiment, the power source may include a parasitic power device, such as an induction coil, one or more photocells, thermoelectric device, or any other device configured to harvest energy from a subject or the environment. For example, the induction coil can include a channel having a magnet therein, the channel passing the induction coil upon movement of the subject (e.g., eye-movement or blinking) In an embodiment, an induction coil can be disposed in the eye of a subject (e.g., in or adjacent to the IOL) and a corresponding magnet may be positioned on an adjacent part of the subject (e.g., an eyelid or bridge of the nose) whereby movement of the eye or eyelid can cause a current in the induction coil. 
     Again, while the IOL device  110  is described as including the controller  130 , sensor  140 , field source  150 , and communication device  160 , configurations of the IOL device  110  can vary from one embodiment to the next. In particular, for example, the IOL device  110  can include only the controller  130  and sensor  140 , and the sensor  140  can detect a change in the identifiable field (e.g., identifiable magnetic field) established by the field source positioned externally to the IOL device  110  or to the eye in which the IOL device  110  is located (e.g., the field source can be located in another eye, can be implanted near the eyes, such as on a nose, can be wearable, etc.). In an embodiment, the IOL device  110  can include only the field source  150 , and as the eye together with the IOL device  110  tilt or pivot, a sensor in the second eye can detect the change in the identifiable magnetic field that is established by the field source  150  (e.g., another IOL device in the second eye can include a sensor operably coupled to a controller). 
     As described above, the IOL system can include a single IOL device or multiple IOL devices (e.g., an IOL device can be located in one or in both eyes of the subject). Generally, the IOL devices of the IOL system can be similar to or the same as the IOL device  110 . It should be appreciated, however, that any of the IOL devices included in the IOL systems described herein can include or can be operably coupled to any number of controllers, sensors, field sources, communication devices, or combinations thereof, which can be similar to or the same as the controller  130 , sensor  140 , field source  150 , and communication device  160 . 
       FIGS. 5A-5D  schematically illustrate an IOL system  100   a  that includes a first IOL device  110   a  in the first or right eye (not shown), and a second IOL device  110   b  in the second or left eye (not shown), according to an embodiment. It should be appreciated that designations, first eye/right eye and second eye/left eye are used for ease of description only and should not be read as limiting (e.g., the first IOL device  110   a  can be positioned in the second or left eye and the second IOL device  110   b  can be positioned in the first or right eye). Except as otherwise described herein, the first IOL device  110   a , second IOL device  110   b , and their elements and components can be similar to or the same as the IOL device  110  ( FIGS. 3-4B ) and its corresponding elements and components. 
       FIG. 5A  illustrates the first IOL device  110   a  and the second IOL device  110   b , with respective first and second optical axes  60   a  and  60   b  of the first and second eyes oriented to define a first angle ϕ 1  therebetween, at which the eyes are focused on first object at first distance from the subject. In an embodiment, the first IOL device  110   a  includes a sensor  140   a  operably coupled to a controller  130   a  including control electrical circuitry (e.g., the sensor  140   a  or controller  130   a  can be embedded in the first IOL device  110   a , such as in the haptics  112   a  of the first IOL device  110   a ). Moreover, the controller  130   a  can be operably coupled to first lens  111   a  of the first IOL device  110   a , such as to switch or direct switch of the focal length of the first lens  111   a  at least between to different focal lengths. 
     In an embodiment, the second IOL device  110   b  can include a magnetic field source  50   b  mounted thereon or embedded therein. The magnetic field source  150   b  can establish an identifiable magnetic field  50   b  that can be sensed by the sensor  140   a . More specifically, for example, the sensor  140   a  can detect the change in orientation or location of the identifiable magnetic field  50   b . It should be also appreciated that the magnetic field source  50   b  can be positioned or secured in the subject&#39;s second eye without the second IOL device  110   b  (e.g., the magnetic field source  50   b  can be implanted in the eye, such as in the sclera of the eye). In any event, in one or more embodiments, the magnetic field source  150   b  can move and tilt together with the second eye (correspondingly moving the identifiable magnetic field  50   b ), and the sensor  140   a  can detect the change in the orientation or location of the identifiable magnetic field  50   b . It should be also appreciated that any of the elements or components described herein as included in one or more IOL devices can be directly implanted in the eye, without implanting an IOL device in that eye (e.g., a second, a controller, etc., can be implanted in the eye). 
     In an embodiment, the controller  130   a  is configured to correlate the detected change in the identifiable magnetic field  50   b  with the vergence rotation between the eyes. For example, the sensor  140   a  can generate a detection output that can correspond to a change at least partially corresponding to the vergence rotation by detecting a changed component of the identifiable magnetic field, which can be in a direction substantially perpendicular to a direction of a dominant component of the identifiable magnetic field. Furthermore, the detection output can be received by the controller  130   a , and based on the detection output, the controller  130   a  can determine the vergence rotation between the eyes. 
     In an embodiment, at least partially based on or from the vergence rotation, the controller  130   a  can determine an apparent object distance (e.g., the distance from the subject to the object on which the subject&#39;s eyes are attempting to focus). In an embodiment, at least partially based on the determined distance, the controller  130   a  can determine the first or second focal length for the switchable lens (e.g., for the switchable lens  111   a  or for the switchable lens of the second IOL  110   b ) and can switch or direct switch of the switchable lens to the determined focal length. 
     Generally, the magnetic field source  50   b  can be any suitable magnet, which can establish any suitable magnetic field that can vary from one embodiment to the next. In the illustrated embodiment, the magnetic field source  50   b  is a dipole magnet, such as a permanent magnet (e.g., a ferromagnet). In an embodiment, the magnetic field source  50   b  can be a dipole electromagnet. In an embodiment, the magnetic field source  50   b  can generate a magnetic field having both a dipole and a non-dipole contribution. In such an embodiment, the non-dipole contributions generally weaken more with distance from the magnetic field source  50   b  than do the dipole contributions so that at a sufficient distance from the magnetic field source  50   b  (e.g., at the sensor location  140   a ), the dominant contribution is that of a magnetic dipole. In an embodiment, the electromagnet can be operably coupled to the controller  130   a  or to an additional controller (e.g., to a controller in the second IOL device  110   b ), which can turn on or off the electromagnet or can change an intensity of the magnetic field established or generated thereby. For example, the electromagnet can be pulsed in a manner that can distinguish or identify the magnetic field established thereby from other, interfering magnetic fields that can be present in the subject&#39;s environment. Moreover, based on the detection output from the sensor  140   a , the controller  130   a  can distinguish the identifiable pulsed magnetic field from other magnetic fields. 
     Generally, as mentioned above, the sensor  140   a  can be any suitable sensor or multiple sensors, which can be sufficiently miniaturized for placement in the subject&#39;s eye (e.g., MEMS based sensors that can be embedded in or mounted on the first IOL device  110   a ). Examples of suitable sensors include Hall effect sensors, magnetoresistance sensors (e.g., AMR magnetometer, GMR magnetometer), induction coils, magneto-diodes, Lorentz force based sensors, Electron Tunneling based sensor, MEMS compass, etc. In any event, the sensor  140   a  can be or can include any suitable sensor or combination of sensors that can detect the change in the location or orientation of the identifiable magnetic field  50   b.    
     In an embodiment, the first IOL device  110   a  can be positioned at a predetermined location or orientation relative to the first optical axis  60   a  of the first eye, and the second IOL device  110   b  or the identifiable magnetic field  50   b  or pole axis of the magnetic field source  50   b  or the identifiable magnetic field  50   b  can be oriented relative to the second optical axis  60   b  of the second eye at a predetermined pitch angle α. Generally, the predetermined pitch angle can be any suitable angle, which can vary from one embodiment to the next. For example, the pitch angle α can be a non-parallel angle relative to the first or second optical axes  60   a  or  60   b , an obtuse angle, or an acute angle. Moreover, as described below in more detail, the pitch angle can be 0°, such that a magnetic field component of the identifiable magnetic field  50   b  is substantially parallel to the second optical axis  60   b.    
     Furthermore, the identifiable magnetic field  50   b  can be oriented such that the sensor  140   a  or the controller  130   a  can distinguish between in-tilt or convergence of the eyes (e.g., when the subject attempts to change focus on from a first object to a second object that is closer to the subject) from co-tilt of the eyes (e.g., when the subject tilts or pivots eyes to focus on an object located peripherally, such as to the left or to the right of the subject). For example, the identifiable magnetic field  50   b  can be oriented at about 45° relative to the second optical axis  60   b  (e.g., within less than 1° of the 45°, within less than 2° of the 45°, within less than 5° of the 45°). 
     It should be appreciated that the identifiable magnetic field  50   b  can have any suitable orientation relative to the second optical axis  60   b . For example, the identifiable magnetic field  50   b  can be oriented relative to the second optical axis  60   b  such that convergence of the eyes results in an increased magnitude or changed direction of the magnetic field vector (e.g., Lorentz force vector), which can be distinguishable from the direction of the magnetic field vector sensed by the sensor  140   a  when the eyes co-tilt, as discussed below in more detail. In other words, the identifiable magnetic field  50   b  can be oriented such that the detection output received from the sensor  140   a  can be processed by the controller  130   a  to distinguish or identify the change in magnitude or direction of the Lorentz force vector of the identifiable magnetic field  50   b  in a manner that the controller  130   a  can distinguish convergence or in-tilt of the eyes from co-tilt. 
     It should be also appreciated that the sensor  140   a  of the first IOL device  110   a  can be configured to measure the strength and direction of the magnetic field, to measure the component of the magnetic field in a specific sensitivity direction, or to include multiple (collocated or not) magnetic sensors each of which is configured to measure separately directed components of the magnetic field. In an embodiment, the sensor  140   a  includes a sensor configured to measure a magnetic field component oriented at 0° relative to the first optical axis  60   a . In an embodiment, the sensor  140   a  includes a sensor configured to measure a magnetic field component oriented at 90° relative to the first optical axis  60   a  (e.g., in the plane of the first IOL device  110   a ) directed to or away from the second IOL device  110   b . The sensor  140   a  is mounted or embedded within the first IOL device  110   a  so that as the first eye tilts, changing the direction of first optical axis  60   a  and first IOL device  110   a , the sensitivity direction of the sensor  140   a  also changes. Accordingly, the value of a specific directional component of magnetic field measured by the sensor  140   a  will change based on changes in the tilt of the first eye. It should be further appreciated, that the value of a specific directional component of magnetic field measured by the sensor  140   a  will also be changed by changes in the direction the magnetic field source  50   b , and the accompanying changes in the field at the location of the sensor  140   a . Since the magnetic field source  50   b  is implanted in the second eye (either directly, or indirectly via being mounted in the second IOL device  110   b ), then field values measured by the sensor  140   a  will change based on changes in the tilt of the second eye. Accordingly, field values measured by the sensor  140   a  will change based on changes in the tilt of both the first eye and the second eye. 
     It should be also appreciated that the second IOL device  110   b  can include multiple magnets that can establish multiple identifiable magnetic fields. Moreover, a single identifiable magnetic field oriented at an acute or obtuse angle relative to the second optic axis  60   b  can be represented by superpositioning two or more identifiable magnetic fields established by multiple magnets. Conversely, a single tilted identifiable magnetic field source (e.g., magnetic field source oriented at 45° relative to the second optic axis  60   b ) can be represented as two magnetic field sources: e.g., an in-plane field source m ∥  oriented parallel to the plane of the IOL (i.e., orthogonal to the optical axis  60   b ), and an out-of-plane field source m ⊥  oriented perpendicular to the plane of the IOL (i.e., along the optical axis  60   b ). The sensor  140   a  can be configured to measure magnetic field at a specified angle relative to the optical axis  60   a . In an embodiment, one or more sensors  140   a  can measure an in-plane magnetic field component b ∥  and an out-of-plane magnetic field component b ⊥ . For dipole-dominated magnetic fields, the relative magnetic field components measured by sensor  140   a  can be written in matrix form as 
     
       
         
           
             
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     For a magnetic field generated by a dipole source, the dimensionless field b at a given distance depends on the orientation of the source, {circumflex over (m)}, and that of the location {circumflex over (r)} at which the field is being measured:
 
 b= 3( {circumflex over (m)}·{circumflex over (r)} ) {circumflex over (r)}−{circumflex over (m)} 
 
     In this case, the four matrix elements are (using θ 1  as the tilt of the first eye and θ 2  for the second eye):
 
 B   ⊥⊥ =2 sin θ 1  sin θ 2 −cos θ 1  cos θ 2  
 
 B   ⊥∥ =2 sin θ 1  cos θ 2 +cos θ 1  sin θ 2  
 
 B   ∥⊥ =2 cos θ 1  sin θ 2 +sin θ 1  cos θ 2  
 
 B   ∥∥ =2 cos θ 1  cos θ 2 −sin θ 1  sin θ 2  
 
     Since eye rotations are small, we can usefully approximate these relations as:
 
 B   ⊥⊥ =−1
 
 B   ⊥∥ =2θ 1 +θ 2  
 
 B   ∥⊥ =2θ 2 +θ 1  
 
 B   ∥∥ =2
 
     The dominant matrix elements; B ⊥⊥ , the perpendicular field due to a perpendicular source and B ∥∥ , the parallel field due to a parallel source are not sensitive to eye tilts. However, the cross terms, B ⊥∥ , the perpendicular field due to a parallel source and B ∥⊥ , the parallel field due to a perpendicular source are sensitive to eye tilts, depending on both of them. Neither one of these elements, by itself, is capable of distinguishing between vergence and co-tilt, but in combination, they are.
 
Vergence: ϕ=θ 2 −θ 1   =B   ∥⊥   −B   ⊥∥ 
 
Co-Tilt: ψ=½(θ 1 +θ 2 )=⅙( B   ∥⊥   +B   ⊥∥ )
 
     In an embodiment, the magnetic field source  50   b  in the second eye includes two magnetic field sources, one with dipole moment m ⊥  oriented perpendicular to the plane of the second IOL (i.e., along the optical axis  60   b ), and the other with dipole moment m ∥  oriented parallel to the plane of the IOL (i.e., orthogonal to the optical axis  60   b ). In such an embodiment, the sensor  140   a  in the first eye is configured to measure magnetic fields in two orthogonal directions, measuring an in-plane magnetic field component b ∥  and an out-of-plane magnetic field component b ⊥ . As described above, in this embodiment, the cross terms B ⊥∥  and B ∥⊥  can be determined, and used to determine the vergence between the two eyes; if desired, these can also determine the co-tilt. In some situations (e.g., when magnetic dipole moments m ⊥  and m ∥  are produced with permanent magnets), the measured field component b ∥  may include contributions from both m ⊥  and m ∥ , likewise for b ⊥ . In such situations, the controller can separate these contributions (e.g., distinguish B ∥∥  from B ∥⊥ , and distinguish B ⊥∥  from B ⊥⊥ ) by using the fact that B ∥∥  and B ⊥⊥  are insensitive to eye tilts (and hence will remain substantially constant in time); changes in measured b ∥  or b ⊥  values correspond to the B ∥⊥  and B ⊥∥  terms. In other embodiments, such potential ambiguities can be avoided by use of time variable magnetic field sources (e.g., pulsed electromagnets), such that m ⊥  and m ∥  are active at different times. 
     In another embodiment, the magnetic field source  50   b  in the second eye can be tilted at an angle α from the optical axis  60   b . In this embodiment, the sensor  140   a  can be configured to measure the magnetic field component along a direction generally perpendicular to the magnetic field source  60   b , i.e., at an angle)(α-90° from optical axis  60   a , pointing back towards the second eye. In this situation, the proportionality B between the detected field and the dipole source is:
 
 B=− 0.5 sin ϕ−1.5 sin 2α cos ϕ−1.5 cos 2α sin 2ψ
 
     In general, this depends upon both the vergence ϕ and the co-tilt ψ. However, by properly selecting the tilt angle α to be 45 degrees, the detected signal no longer depends on co-tilt, and can be directly used to determine vergence.
 
 B=− 0.5 sin ϕ−1.5 cos ϕ≈−1.5−0.5 ϕ
 
     The controller  130   a  including the control electrical circuitry thereof can distinguish between co-tilt and in-tilt (vergence) using the above methodology and formulas. It is apparent that a similar arrangement of components (i.e., magnetic field source  50   a  in the first eye and sensor  140   b  in the second eye) can be employed to enable a controller  130   b  (located for example in the second eye) to independently determine vergence and/or co-tilt. It is also apparent that, for the above embodiment with field source and sensor oriented at 45° from the optical axes, the magnetic field source  50   a  can be oriented perpendicular to the sensitivity direction of sensor  140   a , while the sensitivity direction of sensor  140   b  can be oriented perpendicular to magnetic field source  50   b ; such alignments may be advantageous for signal to noise purposes. 
     As described above, components of the first IOL device  110   a  can be oriented at a predetermined angle relative to an optical axis  60   a  of the first eye. For example, the sensor  140   a  can be positioned such that when the eyes converge (e.g., in a manner representative of the eyes changing focus to a closer object), the sensor  140   a  pivots with the eye to be more sensitive to the identifiable magnetic field  50   b  (as compared before eye movement); when the eyes co-tilt in a first direction (e.g., in a manner representative of the eyes looking to the left (as shown in  FIG. 5C )), the sensor  140   a  moves together with the eye and can be aligned closer and be more sensitive to the second, south pole of the identifiable magnetic field  50   b  than to the north pole; when the eyes co-tilt in a second direction (e.g., in a manner representative of the eyes looking to the right), the sensor  140   a  can move with the eye and can be aligned closer to and be more sensitive to the north pole of the identifiable magnetic field  50   b  (as compared before eye movement (as shown in  FIG. 5D )). 
     In any event, in an embodiment, when the controller  130   a  receives the detection output generated by the sensor  140   a , the controller  130   a  can identify vergence rotation between the eyes (e.g., convergence) and can distinguish the vergence rotation from co-tilt of the eyes. Moreover, the controller  130   a  can direct the first IOL device  110   a  to change the focal length from the first focal length to the second focal length at least partially based on the detection output(s) of the sensor  140   a , which can correspond to vergence rotation between the eyes. 
     As mentioned above, in the illustrated embodiment, the magnetic field source  150   b  can be included in the second IOL device  110   b  that can be located in the subject&#39;s second eye. For example, the second IOL device  110   b  can include a second lens  111   b  that can be similar to or the same as the first lens  111   a  of the first IOL device  110   a . In an embodiment, the second IOL device  110   b  also can include an additional or second controller (not shown) that can switch or direct switching of the second IOL device  110   b  between two or more focal lengths. Moreover, the controller  130   a  can communicate with the second controller and can send the focal length indication thereto. For example, the controller  130   a  can be operably connected to a first communication device (not shown), and the second controller can be connected to a second communication device (not shown) that can be in communication with or configured to communicate with the first communication device. In other words, the first and second communication devices can be operably coupled. 
     For example, via communication between the first and second communication devices, the controller  130   a  can send to the additional, second controller the controller data. Generally, controller data can include any data or any number of suitable parameters. In an embodiment, the controller data can include information or instructions for switching the first lens  111   a  or the second lens  111   b  to the first focal length or to the second focal length (e.g., the controller data can associated with selected focal length for the first lens  111   a  or for the second lens  111   b ). Additionally or alternatively, the controller data can include or can be associated with the detection output of the sensor  140   a.    
     In an embodiment, the first IOL device  110   a  or the second IOL device  110   b  can include additional or alternative sensors that can detect eye movement in a manner that can aid the controller  130   a  or the additional, second controller to identify or determine vergence rotation between the eyes. For example, the first IOL device  110   a  or second IOL device  110   b  can include one or more accelerometers or gyroscopes. More specifically, outputs generated by the accelerometers or gyroscopes can indicate the direction of rotation or tilting for the first or second eyes. 
     In an embodiment, the direction of tilting or rotation detected or sensed by the accelerometers or gyroscopes in the first eye can be communicated to and compared with the direction of tilting or rotation detected or sensed by the accelerometers or gyroscopes in the second eye. For example, the controller  130   a  can communicate with the additional, second controller (as described above) and can send controller data thereto (e.g., the controller data can include processed or unprocessed output from the accelerometers or from the gyroscopes). The controller  130   a  or the additional, second controller can distinguish co-tilting or the eyes are tilting in the same direction from vergence rotation or the eyes are tilting in different directions (e.g., to focus on an object closer or farther away from previously viewed object). Moreover, based at least partially on the outputs received from the accelerometers or gyroscopes in the first and second eyes, the controller  130   a  or the additional, second controller can determine the focal lengths for the first lens  111   a  or for the second lens  111   b.    
     In an embodiment, the controller  130   a  or the second controller can use the detection outputs from the accelerometers or gyroscopes to cross-check or verify the determination on the change in vergence between the eyes, which can be based on the output from the sensor  140   a . Conversely, the controller  130   a  or the second controller can use the detection outputs from the sensor  140   a  to cross-check or compare the determination or identification of the vergence rotation between the eyes, which can be based on the output from the accelerometers or gyroscopes. Moreover, in an embodiment, the accelerometers or gyroscopes can be initially or periodically calibrated (e.g., based on the detection outputs from the sensor  140   a ) to adjust for noise, drift, other errors, etc. 
       FIG. 5B  shows the first IOL device  110   a  and second IOL device  110   b  and corresponding eyes (not shown) tilted compared with the respective orientations thereof shown in  FIG. 5A  responsive to corresponding convergence of the first and second eyes of the subject. In particular, for example, the first IOL device  110   a  can remain substantially stationary relative to first optical axis  60   a , and the second IOL device  110   b  can remain substantially stationary relative to the second optical axis  60   b . Hence, as the first eye tilts toward or away from the second eye, the first IOL device  110   a  can correspondingly tilt toward the second IOL device  110   b  (e.g., vergence rotation between the first and second eyes can produce a corresponding change in relative orientations or positions of the first IOL device  110   a  and second IOL device  110   b ). In particular, the first and second eyes can converge to form the second angle ϕ 2  between the respective first and second optical axes  60   a ,  60   b  thereof, and the first IOL device  110   a  and second IOL device  110   b  can correspondingly converge together. 
     As described above, for example, when the first IOL device  110   a  and second IOL device  110   b  converge, the sensor  140   a  can be reoriented or repositioned relative to the magnetic field source  150   b  and relative to the identifiable magnetic field  50   b  established thereby. More specifically, for example, the identifiable magnetic field  50   b  and the sensor  140   a  can be reoriented relative to each other such that the sensor  140   a  can generate an output related to a change in the direction of the magnetic field vector or magnitude thereof. Furthermore, at least partially based on the output from the sensor  140   a , the controller  130   a  can distinguish vergence rotation between the eyes (e.g., convergence of the eyes) from co-tilt of the eyes, as described above. 
     Furthermore, as shown in  FIG. 5C , when the eyes tilt in the same direction or co-tilt towards the left, such that the respective first and second optical axes  60   a ,  60   b  thereof are generally parallel to each other, while the first IOL device  110   a  and the second IOL device  110   b  remain generally parallel to one another, the angular position of sensor  140   a  relative to the polar axis of magnetic field source  50   b  changes. The sensor  140   a  and the identifiable magnetic field  50   b  are reoriented, such that the relative position of the sensor  140   a  changes from being closer to the north pole of the identifiable magnetic field  50   b  to being closer to the south pole of the identifiable magnetic field  50   b . Hence, for example, the detection output from the sensor  140   a  can correspond to a detected change in the direction of the magnetic field vector, and the controller  130   a  can correlate the detection output from the sensor  140   a  to the co-tilt of the eyes. 
     Alternatively, as shown in  FIG. 5D , the eyes can co-tilt towards the right, such that while the first IOL device  110   a  and the second IOL device  110   b  remain generally parallel to one another, the angular position of sensor  140   a  relative to the polar axis of magnetic field source  50   b  changes. For example, after repositioning or reorientation of the sensor  140   a  and of the identifiable magnetic field  50   b  (responsive to co-tilt of the eyes to the right), the detection output from the sensor  140   a  can correspond to a detected change in the magnetic field vector, and the controller  130   a  can correlate the detection output from the sensor  140   a  to the co-tilt of the eyes. In any event, the first IOL device  110   a  and second IOL device  110   b  can be positioned or oriented relative to the first optical axis  60   a  and second optical axis  60   b  such that the detection output from the sensor  140   a  can be correlated by the controller  130   a  to distinguish vergence rotation (e.g., convergence or in-tilt of the eyes) from the co-tilt of the eyes. 
     As described above, the IOL system can include multiple identifiable fields and multiple corresponding sensors that can detect relative change in position or orientation therebetween.  FIGS. 6A and 6B  illustrate an IOL system  100   c  that includes a first IOL device  110   c  and a second IOL device  110   d  and establishes multiple identifiable magnetic fields, according to an embodiment. In particular,  FIG. 6A  illustrates the first IOL device  110   c  and the second IOL device  110   d  at first respective locations or orientations relative to each other when the subject&#39;s eyes (not shown) focus or attempt to focus at a first focal length, such that the respective first and second optical axes  60   a ,  60   b  of the first and second eye define the first angle ϕ 1  therebetween. For example, the first IOL device  110   c  and the second IOL device  110   d  can be substantially fixed relative to the first and second optical axes  60   a ,  60   b  of the subject&#39;s eyes.  FIG. 6B  illustrates the first IOL device  110   c  and the second IOL device  110   d  at second respective locations or orientations relative to each other when the subject is attempting to focus or focusing the eyes (not shown) at a second focal length, such that the first optical axis the  60   a  and second optical axis  60   b  define the second angle ϕ 2  therebetween. The following describes the IOL system  100   c  as the subject in-tilts and out-tilts the eyes (e.g., such that vergence rotation between the eyes tilts or pivots the first and second optical axis the  60   a ,  60   b  between defining first angle ϕ 1  and second angle ϕ 2 ). 
     Except as otherwise described herein, the IOL system  100   c  and its elements and components can be similar to or the same as any of the IOL systems  100 ,  100   a  ( FIGS. 1-5D ) and their corresponding elements and components. For example, the first IOL device  110   c  can include a first sensor  140   c  and a first controller (not shown) including control electrical circuitry, which can be similar to or the same as the sensor  140   a  and controller  130   a  of the first IOL device  110   a  ( FIGS. 5A-5D ). Similarly, the second IOL device  110   d  can include a second sensor  140   d  and a second controller (not shown) including control electrical circuitry, which also can be similar to or the same as the sensor  140   a  and controller  130   a  of the first IOL device  110   a  ( FIGS. 5A-5D ). 
     In the illustrated embodiment, the first IOL device  110   c  includes a first field source  150   c  that can establish a first identifiable magnetic field  50   c , and the second IOL device  110   d  includes a second field source  150   d  that can establish a second identifiable magnetic field  50   d . Generally, the first identifiable magnetic field  50   c  and second identifiable magnetic field  50   d  can have any suitable orientation relative to the first optical axis  60   a  or to the second optical axis  60   b  of the first eye and second eye. In an embodiment, the first identifiable magnetic field  50   c  can be oriented at about 90° relative to the first optical axis  60   b , and the second identifiable magnetic field  50   d  can be oriented generally parallel to the second optical axis  60   b , or vice versa. Moreover, the first identifiable magnetic field  50   c  and second identifiable magnetic field  50   d  can have any suitable orientation relative to each other. For example, the first identifiable magnetic field  50   c  and the second identifiable magnetic field  50   d  can be oriented generally perpendicular to each other (e.g., when the first and second optical axes  60   a ,  60   b  are relatively oriented to define the first angle ϕ 1  or the second angle ϕ 2 ). In an embodiment, the first identifiable magnetic field  50   c  or the second identifiable magnetic field  50   d  can be oriented generally parallel to an axis extending between the eyes. 
     As described above, the first sensor  140   c  and second sensor  140   d  can detect change in the position or orientation of the respective second identifiable magnetic field  50   d  and first identifiable magnetic field  50   c  as the eyes together with the first IOL device  110   c  and second IOL device  110   d  converge or diverge. For example, the first sensor  140   c  can sense the first identifiable magnetic field  50   d  and can generate a first detection output as the second identifiable magnetic field  50   d  and the first sensor  140   c  move relative to each other. In an embodiment, the first sensor  140   c  can detect a changed component of the second identifiable magnetic field  50   d  (e.g., in a direction that is substantially perpendicular to the dominant component of the second identifiable magnetic field  50   d ). For example, the first detection output of the first sensor  140   c  can at least partially correspond to the vergence rotation between the eyes. The second sensor  140   d  can detect a changed component of the first identifiable magnetic field  50   c  (e.g., in a direction that is substantially perpendicular to the dominant component of the first identifiable magnetic field  50   c ), which can at least partially correspond to the vergence rotation between the eyes. As such, a second detection output of the second sensor  140   d  also can at least partially correspond to a change in the vergence between the eyes or to vergence rotation. As described below in more detail, the first or second controllers can compare the first and second detection outputs to determine the vergence rotation between the eyes. 
     In one or more embodiments, the first and second controllers can receive the corresponding first and second detection outputs from the respective first and second sensors  140   c ,  140   d  and can process the detection outputs to generate controller data based thereon (e.g., can identify or determine vergence rotation between the eyes or can distinguish vergence rotation from co-tilt of the eyes). In an embodiment, the controller data can include the first and second detection outputs. Moreover, the first controller can send the controller data to the second controller (e.g., via corresponding communication devices), or vice versa. Hence, for example, the first or the second controller can receive first and second detection outputs. Furthermore, in an embodiment, the first or second controller can compare the first and second detection outputs to determine the vergence rotation between the eyes (e.g., to distinguish convergence, divergence, and co-tilt of the eyes). 
     In an embodiment, after determining the vergence rotation between the eyes, the first or second controller can determine the suitable or selectable focal length for the first IOL device  110   c  or for the second IOL device  110   d . For example, as described above, the first IOL device  110   c  or second IOL device  110   d  can include one or more switchable lenses that can be switched between two or more focal lengths (e.g., the first or second controllers can switch or direct switching of the switchable lenses). The first controller can direct the first IOL device  110   c  to switch to a first focal length or to a second focal length based on the determined vergence rotation. Analogously, the second controller can direct the second IOL device  110   d  to switch to a first focal length or to a second focal length based on the determined vergence rotation. In an embodiment, the first controller can send controller data to the second controller (or vice versa), and the controller data can include the determined vergence rotation or change in the vergence between the eyes or the suitable or selected focal length for the first IOL device  110   c  or second IOL device  110   d.    
     As described above, in an embodiment, the IOL system can include a field source positioned externally to the subject&#39;s eyes.  FIGS. 7A and 7B  illustrate an IOL system  100   e  that includes IOL devices  110   e  and  110   f  located in the respective first and second eyes  20 ,  30  of a subject  70  and a magnetic field source  150   e  positioned externally to the first and second eyes  20 ,  30 , according to an embodiment. In particular,  FIG. 7A  illustrates the first and second eyes  20 ,  30  of the subject  70  at first tilt, positioned to focus on first object located at first distance from the subject  70 .  FIG. 7B  illustrates the first and second eyes  20 ,  30  at second tilt, positioned to focus on second object located at second distance from the subject  70 . The following describes the IOL system  100   e  as the subject  70  tilts or pivots the first and second eyes  20 ,  30  between the first and second tilt positions (e.g., the vergence change between the eyes tilts the first and second eyes  20 ,  30  between the first and second tilt positions). 
     In an embodiment, the magnetic field source  150   e  can establish an identifiable magnetic field that can be detected by one or more sensors in the first IOL device  110   e  or in the second IOL device  110   f , as the subject  70  changes tilt of the first and second eyes  20 ,  30  between the first tilt and the second tilt. Generally, the magnetic field source  150   e  can establish the identifiable magnetic field at any suitable angle relative to the first/or second eyes  20 ,  30  or to the optical axes thereof. For example, similar to the IOL system  100   a  ( FIGS. 5A-5D ), the magnetic field source  150   e  can establish the identifiable magnetic field that is oriented at approximately 45° angle relative to the optical axis of the second eye  30  when the first and second eyes  20 ,  30  are at the first tilt therebetween. In contrast to the IOL system  100   a  ( FIGS. 5A-5D ), the magnetic field established by the magnetic field source  150   e  can remain substantially stationary relative to the subject  70  (e.g., relative to the head of the subject  70 ). In an embodiment, movement or tilting of the first eye  20  or the second eye  30  can produce a corresponding relative movement or tilting between the magnetic field source  150   e  and the sensors of the IOL system  100   e  (e.g., the identifiable magnetic field established by the magnetic field source  150   e  can remain stationary relative to the head of the subject, and the sensors of the IOL system  100   e  can move together with the first and second eyes  20 ,  30 , such as during vergence rotation therebetween). 
     In an embodiment, the first IOL device  110   e  can include a first sensor. As the first IOL device  110   e  pivots or tilts together with the first eye  20 , the first sensor can detect a changed component of the identifiable magnetic field in a direction that is substantially perpendicular to the direction of the dominant component of the identifiable magnetic field. Furthermore, the second IOL device  110   f  can include a second sensor. As the second IOL device  110   f  pivots or tilts together with the second eye  30 , the second sensor can detect a changed component of the identifiable magnetic field in a direction that is substantially perpendicular to the direction of the dominant component of the identifiable magnetic field. 
     As described above, the first IOL device  110   e  or the second IOL device  110   f  can include one or more controllers including control electrical circuitry operably coupled to the respective first and second sensors. For example, the first IOL device  110   e  can include a first controller operably coupled to the first sensor and configured to receive a first detection output therefrom (e.g., the first sensor can generate the first detection output based on the detected change in a component of the identifiable magnetic field). Similarly, the second IOL device  110   f  can include a second controller operably coupled to the second sensor and configured to receive a second detection output therefrom (e.g., the second sensor can generate the second detection output based on the detected change in a component of the identifiable magnetic field in a similar manner as described above). 
     In an embodiment, the first controller can be operably coupled to or can be in communication with the second controller. For example, the first controller can be operably coupled to a first communication device and the second controller can be operably coupled to the second communication device, and the first and second communication devices can be configured to transmit data therebetween. Hence, the first controller can send controller data (which can include the detection output from the first sensor or determination of focal length) to the second controller. Additionally or alternatively, the second controller can send controller data (which can include the detection output from the second sensor or determination of focal length) to the first controller. Moreover, the first controller or the second controller is configured to distinguish vergence rotation from co-tilt rotation of the first and second eyes  20 ,  30  based on the first and second detection outputs. 
     As described above, the first or second controller also is adapted to determine a suitable or selectable focal length for one or more switchable lenses. For example, the first IOL device  110   e  can include a first switchable lens that can be switched between two or more focal lengths. Alternatively or additionally, the second IOL device  110   f  can include a second switchable lens that can be switched between two or more focal lengths. Hence, the first controller or second controller can direct or switch the first switchable lens or second switchable lens based on the first and second detection outputs. 
     In an embodiment, the IOL system  100   e  can include multiple magnetic field sources that can generate multiple corresponding identifiable magnetic fields. Generally, each of the multiple magnetic field sources can be oriented relative to the first eye  20  or second eye  30  (e.g., as measured when the first and second eyes  20 ,  30  are at the first tilt therebetween). Likewise, multiple magnetic field sources can be oriented relative to one another at any number of suitable angles. For example, a first identifiable magnetic field can be oriented at a first predetermined angle relative to the optical axis of the first eye  20 , and a second identifiable magnetic field can be oriented at a second predetermined angle relative to the second eye  30  (e.g., when the first and second eyes  20 ,  30  are at the tilt). 
     The magnetic field source  150   e  or additional or alternative magnetic field sources can be generally fixedly positioned relative to the subject  70  with any number of suitable mechanisms or configurations. For example, the magnetic field source  150   e  can be implanted near the first eye  20  or second eye  30  of the subject  70  (e.g., near or on the bridge of the nose of the subject  70 ). Additionally or alternatively, the magnetic field source  150   e  can be removably positioned on or secured to the subject  70  (e.g., with an adhesive, on a wearable object, such as glasses, etc.). In any embodiment, the magnetic field source  150   e  can be generally stationary relative to the head of the subject  70 , such that tilting or pivoting of the first and second eyes  20 ,  30  can result in relative movement between the first eye  20  and the identifiable magnetic field and between the second eye  30  and identifiable magnetic field. 
     In another embodiment, the locations of field sources and field sensors described in conjunction with  FIG. 7 , can be generally reversed. In such an embodiment, the IOL system  110   e  and the IOL system  110   f  can include implanted or embedded magnetic field sources, while one or more magnetic field sensors can be generally fixedly positioned relative to the subject  70  (e.g., in locations discussed above with reference to  150   e ). In this embodiment, the orientations of the magnetic fields change as the eyes tilt, resulting in changed values of magnetic field detected by the fixedly positioned sensor(s). A controller (e.g., a controller external to the IOLs) can receive the signals from the field sensor(s) and determine the tilts of one or both eyes. In particular, the controller can compare tilt values from both eyes to thereby determine vergence, and can distinguish vergence from co-tilt. The controller can then be operatively coupled (e.g., by wireless communication) with controllers in each IOL, which then direct focal length changes of their respective IOL optics. In this embodiment, each IOL only needs a communicative receiver, but does not necessarily require a transmitter. 
     It will be understood that a wide range of hardware, software, firmware, or virtually any combination thereof can be used in the controllers described herein. In one embodiment, several portions of the subject matter described herein can be implemented via Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), digital signal processors (DSPs), or other integrated formats. However, some aspects of the embodiments disclosed herein, in whole or in part, can be equivalently implemented in integrated circuits, as one or more programs running on one or more processors (e.g., as one or more programs running on one or more microprocessors), as firmware, or as virtually any combination thereof. In addition, the reader will appreciate that the mechanisms of the subject matter described herein are capable of being distributed as a program product in a variety of forms, and that an illustrative embodiment of the subject matter described herein applies regardless of the particular type of signal bearing medium used to actually carry out the distribution. 
     In a general sense, the various embodiments described herein can be implemented, individually and/or collectively, by various types of electro-mechanical systems having a wide range of electrical components such as hardware, software, firmware, or virtually any combination thereof; and a wide range of components that can impart mechanical force or motion such as rigid bodies, spring or torsional bodies, hydraulics, and electro-magnetically actuated devices, or virtually any combination thereof. Consequently, as used herein “electro-mechanical system” includes, but is not limited to, electrical circuitry operably coupled with a transducer (e.g., an actuator, a motor, a piezoelectric crystal, etc.), electrical circuitry having at least one discrete electrical circuit, electrical circuitry having at least one integrated circuit, electrical circuitry having at least one application specific integrated circuit, or a microprocessor configured by a computer program which at least partially carries out processes and/or devices described herein), electrical circuitry forming a memory device (e.g., forms of random access memory), electrical circuitry forming a communications device (e.g., a modem, communications switch, or optical-electrical equipment), and any non-electrical analog thereto, such as optical or other analogs. 
     In a general sense, the various aspects described herein which can be implemented, individually and/or collectively, by a wide range of hardware, software, firmware, or any combination thereof can be viewed as being composed of various types of “electrical circuitry.” Consequently, as used herein “electrical circuitry” includes, but is not limited to, electrical circuitry having at least one discrete electrical circuit, electrical circuitry having at least one integrated circuit, electrical circuitry having at least one application specific integrated circuit, or a microprocessor configured by a computer program which at least partially carries out processes and/or devices described herein), electrical circuitry forming a memory device (e.g., forms of random access memory), and/or electrical circuitry forming a communications device (e.g., a modem, communications switch, or optical-electrical equipment). The subject matter described herein can be implemented in an analog or digital fashion or some combination thereof. 
     The herein described components (e.g., steps), devices, and objects and the discussion accompanying them are used as examples for the sake of conceptual clarity. Consequently, as used herein, the specific exemplars set forth and the accompanying discussion are intended to be representative of their more general classes. In general, use of any specific exemplar herein is also intended to be representative of its class, and the non-inclusion of such specific components (e.g., steps), devices, and objects herein should not be taken as indicating that limitation is desired. 
     With respect to the use of substantially any plural and/or singular terms herein, the reader can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations are not expressly set forth herein for sake of clarity. 
     The herein described subject matter sometimes illustrates different components contained within, or connected with, different other components. It is to be understood that such depicted architectures are merely exemplary, and that in fact many other architectures can be implemented which achieve the same functionality. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively “associated” such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as “associated with” each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. Likewise, any two components so associated can also be viewed as being “operably connected,” or “operably coupled,” to each other to achieve the desired functionality, and any two components capable of being so associated can also be viewed as being “operably couplable,” to each other to achieve the desired functionality. Specific examples of operably couplable include but are not limited to physically mateable and/or physically interacting components and/or wirelessly interactable and/or wirelessly interacting components and/or logically interacting and/or logically interactable components. 
     In some instances, one or more components can be referred to herein as “configured to.” The reader will recognize that “configured to” or “adapted to” are synonymous and can generally encompass active-state components and/or inactive-state components and/or standby-state components, unless context requires otherwise. 
     While particular aspects of the present subject matter described herein have been shown and described, it will be apparent that, based upon the teachings herein, changes and modifications can be made without departing from the subject matter described herein and its broader aspects and, therefore, the appended claims are to encompass within their scope all such changes and modifications as are within the true spirit and scope of the subject matter described herein. Furthermore, it is to be understood that the invention is defined by the appended claims. In general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims can contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). Virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.” 
     With respect to the appended claims, any recited operations therein can generally be performed in any order. Examples of such alternate orderings can include overlapping, interleaved, interrupted, reordered, incremental, preparatory, supplemental, simultaneous, reverse, or other variant orderings, unless context dictates otherwise. With respect to context, even terms like “responsive to,” “related to,” or other past-tense adjectives are generally not intended to exclude such variants, unless context dictates otherwise. 
     While various aspects and embodiments have been disclosed herein, the various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.