Patent Publication Number: US-11045089-B2

Title: Automatic lens to cornea standoff control for non-contact visualization

Description:
BACKGROUND 
     Field of the Disclosure 
     The present disclosure relates to ophthalmic surgery, and more specifically, to an automatic lens standoff system for use during ophthalmic surgery. 
     Description of Related Art 
     Ophthalmic surgery is commonly performed using an operating microscope to visualize various structures in the eye. For example, during cataract surgery, the microscope if used to visualize the anterior segment of the eye such as the cornea, lens, etc. However, a standard operating microscope does not adequately view an entire posterior segment (e.g. the retina) of the eye because the natural optics of the eye (e.g. the cornea and the lens) prevent the operating microscope from focusing on features of the posterior of the eye. 
     To achieve superior posterior viewing during retinal surgery, an operating microscope can be used in conjunction with an additional optical system that is capable of resolving an image of the retina of the eye. For example, an ophthalmoscopic contact lens can contain an optical system for wide-angle viewing of the retina and can be placed over a patient&#39;s eye. The operating microscope can then be focused to view an image created by the contact lens. However, a contact lens system can interfere with a surgeon&#39;s ability to manipulate surgical instruments. Also, the ophthalmoscopic contact lens can become misaligned as a result of movements by the patient. 
     A front lens assembly can also be used in conjunction with an operating microscope to achieve wide angle viewing of the retina or viewing of the macula. A front lens assembly can include a supportive member that can hold a contact-less front lens above the eye of the patient. However, during the course of ophthalmic surgery, liquids from the eye and/or liquids used to wet the cornea can obscure a front lens when it inadvertently contacts the cornea, requiring the surgeon to clean the lens or to replace the lens. 
     Cleaning an ophthalmoscopic contact lens and/or a front lens can be troublesome for a number of reasons. The process of cleaning the lenses can take time away from performing the surgery and cause less desirable outcomes. Also, the ophthalmoscopic contact lens and/or a front lens can have surface features (e.g. diffractive surface features) that make effective cleaning very difficult. As an alternative to cleaning a front lens, a retinal surgeon oftentimes elects to replace the front lens with a lens from a reserve of replacement lenses to ensure continuity during surgery. However, typical lens used for wide angle retinal viewing are diamond turned glass and are very expensive. 
     SUMMARY 
     The disclosed embodiments of the present technology relate to systems, methods, and computer-readable media for automatically controlling a lens to cornea standoff. A system for automatic lens to cornea standoff control can include an ophthalmic microscope with a lens arrangement configured for viewing images of an eye and a front lens assembly with a high diopter lens for resolving an image of a posterior portion of the eye. The front lens assembly can adjustably position the high diopter lens at various positions between the lens arrangement of the ophthalmic microscope and the eye. In some cases, the front lens assembly includes a multi-sectional articulating arm for adjustably positioning the high diopter lens. The front lens assembly can also be a screw drive system for to adjustably positioning the high diopter lens. 
     The system can also include a sensor that can monitor a distance between the high diopter lens and a surface of the eye. The sensor can be an ultrasonic sensor, a laser triangulation sensor, an infrared sensor, etc. In some cases, the sensor is coupled with the lens holder of the front lens assembly. 
     The sensor is communicatively coupled with a control system for receiving information from the sensor describing the distance between the high diopter lens and a surface of the eye. In some cases, the sensor is wirelessly coupled with the control system. The control system is further configured to receive the detected distance from the sensor and determine when the detected distance is less than a predetermined threshold standoff distance. 
     When the detected distance is less than a predetermined threshold standoff distance, the control system can cause an actuator coupled with the front lens assembly to move the front lens assembly back to the threshold standoff distance, past the threshold standoff distance, etc. In some cases, when the controller can also enforce a second predetermined threshold standoff distance to keep the high diopter lens within a range (e.g. 5-10 millimeters) of distances away from an eye surface. 
     The system can also include an auto-focus system coupled with the controller. The auto-focus system can automatically focus the lens arrangement of the ophthalmic microscope to resolve an image of the eye that was being resolved before a position of the high diopter lens was moved by the movement of the front lens assembly. 
     The system can also include a user interface for receiving a user-defined standoff preference, surgical data, or an over-ride signal that can prevent or throttle a control signal for moving the front lens assembly. 
     Methods of maintaining a lens to cornea standoff can involve a sensor monitoring a distance between a corneal surface of an eye and a high diopter lens in a front lens assembly and a control system receiving, from the sensor, the distance measurement. Some methods also include the control system comparing the distance measurement to a predetermined threshold standoff distance and transmitting a control signal to an actuator when the distance measurement is less and the predetermined threshold standoff distance. 
     In some cases, method of maintaining a lens to cornea standoff can involve the actuator receiving a control signal and moving the front lens assembly to position the high diopter lens at the threshold distance, past the threshold distance, etc. Some methods also involve the control system transmitting an instruction to an autofocus system to focus the lens arrangement in order to resolve an image of the eye that was being resolved before a position of the high diopter lens was moved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present technology, its features, and its advantages, reference is made to the following description, taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  illustrates a system for high resolution, wide field of view viewing of the retina of an eye; 
         FIG. 2  illustrates an automatic lens to cornea standoff system; 
         FIG. 3  illustrates the automatic lens to cornea standoff system after the high diopter lens is moved away from the corneal surface; 
         FIG. 4  illustrates an automatic lens to cornea standoff system with a screw drive front lens assembly; 
         FIG. 5A  illustrates a method for preventing a lens from getting too close to a cornea; 
         FIG. 5B  illustrates a method of adjusting a front lens assembly to position a high diopter lens at the predetermined threshold distance away from a corneal surface of an eye; 
         FIG. 5C  illustrates a method for maintaining a target standoff distance between a high diopter lens and a cornea in an ophthalmic microscope and front lens assembly system. 
         FIG. 6  illustrates a block diagram of a system used in an automatic lens to cornea standoff control system for maintaining a lens to cornea standoff; 
         FIG. 7  illustrates a method for preventing contact between a lens and cornea in an ophthalmic microscope and front lens assembly system; and 
         FIG. 8A  and  FIG. 8B  illustrate exemplary possible system embodiments. 
     
    
    
     DESCRIPTION 
     As explained above, a front lens assembly can be used in conjunction with an operating microscope to achieve wide angle viewing of the retina or viewing of the macula. In general, the closer the front lens is to the eye the greater the field of view for clear visualization of the peripheral retina and to repair retinal tears and retinal detachments. The disclosed technology involves encouraging high field of view by maintaining a close distance between a front lens and a patient&#39;s cornea while preventing corneal-front lens contact resulting in view morphing viscoelastic material on the lens surface and corneal epithelial damage. 
     Systems and methods are disclosed for providing automatic lens to cornea standoff in an ophthalmic surgery system.  FIG. 1  illustrates a system  100  for high resolution, wide field of view viewing of the retina  142  of an eye  140 . The system  100  can include a high diopter lens  120  used in conjunction with an ophthalmic microscope  110 . The ophthalmic microscope  110  can include a housing  115  containing a lens arrangement including an objective lens  112 . The ophthalmic microscope  110  also includes a binocular eyepiece arrangement  113  for viewing images formed from a beam of light reflected from the eye  140 . The system  100  can also include a beamsplitter  118  to redirect a portion of the beam of light. 
     The system  100  can also include a front lens assembly  114  coupled with the ophthalmic microscope  110 . The front lens assembly can include a lens holder  116  for supporting the high diopter lens  120 . In some cases, the front lens assembly  114  can be jointed and can articulate in order to alternatively raise and lower the lens holder  116  and high diopter lens  120  and/or position the lens holder  116  and the high diopter lens into and out of the beam of light. In some cases, the front lens assembly  114  is configured as a screw drive that can move the lens holder  116  up and down and the lens holder  116  and that can rotate lens holder  116  into and out of the beam of light. Also, although jointed and screw drive configurations are explicitly mentioned herein, those with ordinary skill in the art having the benefit of the present disclosure will readily appreciate that a wide variety of positioning systems can be used in a front lens assembly to achieve the benefits of the disclosed technology. 
     In some cases, the lens arrangement of the ophthalmic microscope  110  is generally selected to resolve an image of the anterior (e.g. a cornea  144 ) of an eye. Similarly, the prescription of the high diopter lens  120  can selected to resolve an image of the retina  142  of the eye  140  when used in combination with the lens arrangement of the ophthalmic microscope  110 . In these cases, an ophthalmic professional can alternatively view the anterior and retina  142  of the eye  140  by articulating the lens holder  116  and the high diopter lens into and out of the beam of light. 
     As explained above, during the course of ophthalmic surgery, fluids from the eye and/or fluids used to wet the cornea can obscure a front lens when the front lens makes contact with the cornea, requiring the surgeon to clean the lens or to replace the lens. Therefore, to avoid the patient&#39;s eye becoming too close or even contacting the high diopter lens  120 , surgeons routinely position the front lens assembly  114  to place the high diopter lens  120  at a standoff distance away from the patient&#39;s eye. However, the position of patient&#39;s eye may move during the course of a surgery. For example, during an ophthalmic surgery, patients oftentimes move their heads up and down with respiratory movements. With these movements, the standoff distance can be impinged and fluids can come in contact with the high diopter lens  120 . 
     Accordingly, a system  100  for high resolution, wide field of view viewing of the retina  142  of an eye  140  can include one or more sensor for sensing the distance from the high diopter lens  120  and the cornea  144  of the eye  140 . 
       FIG. 2  illustrates an automatic lens to cornea standoff system  230  according to some embodiments of the present technology. The automatic lens to cornea standoff system  230  can include a front lens assembly  214  coupled to an ophthalmic microscope  210 . The front lens assembly  214  includes a lens holder  216  supporting a high diopter lens  220  between a lens arrangement (not shown) of the ophthalmic microscope  210  and an eye  240 . Also, the front lens assembly  214  is configured to adjustably position the high diopter lens  220  at a plurality of positions between the lens assembly and the eye  240 . As shown in  FIG. 2 , the front lens assembly  214  is a multi-sectional articulating arm assembly with a first articulating section  222  that can rotate in the X-Y plane about a first joint  221  coupled with the ophthalmic microscope  210 . The multi-sectional front lens assembly  214  also includes a second articulating section  224  and a third articulating section  226  which are able to rotate in the X-Y plane about the second joint  223  and the third joint  225 , respectively. The multi-sectional front lens assembly  214  shown in  FIG. 2  allows the high diopter lens  120  to be adjustably positioned in a variety of positions between the lens arrangement and the eye  240  while still remaining co-axial with a beampath  205  of the lens arrangement. 
     The automatic lens to cornea standoff system  230  also includes a sensor  236  coupled with the lens holder  216 . The sensor  236  can detect a distance between the sensor  236  and a surface (i.e. a corneal surface  244 ) of the eye  240 . The bottom surface of the sensor  236  can substantially aligned with the bottom of the high diopter lens  220  and/or a difference between the bottom surface of the sensor  236  and bottom of the high diopter lens  220  is known to a controller. Accordingly, the sensor  236  (along with the controller) can also determine a distance  238  between the high diopter lens  220  and the surface of the eye  240 . 
     The sensor  236  is communicatively coupled with a controller  232 , as explained in greater detail below. Also, the controller  232  can include memory for storing threshold standoff distances, e.g. default values, user-defined standoff value preferences, etc. Furthermore, the controller  232  can receive a detected distance  238  from the sensor  232  and determine that the detected distance  238  is greater or less than the predetermined threshold standoff distance, e.g. when a patient moves his head during surgery. 
     The automatic lens to cornea standoff system  230  also includes an actuator  234  coupled with the controller  232  and the front lens assembly  214 . In some cases, the first joint  221 , the second joint  223 , and the third joint  225  also include actuators for causing the articulating sections  222 ,  224 ,  226  to rotate. For ease of explanation, the disclosure refers to the actuator  234  controlling the articulating sections; however, any of the actuators in the joints or actuators located elsewhere in the automatic lens to cornea standoff system  230  can receive control instructions and cause the front lens assembly to articulate. 
     After the controller  232  determines that the detected distance  238  is less than a first predetermined threshold standoff distance, the controller  232  can send a control signal to the actuator  234 . The control signal can cause the actuator  234  to move the front lens assembly  214  and can cause the high diopter lens  220  to move a distance away from the corneal surface  244 , i.e. past the threshold standoff distance. For example, the actuator  234  can cause the first articulating section  222  to rotate up (i.e. in the +y direction) about the first joint  223 , can cause the second articulating section  224  to rotate towards the beampath  205  (i.e. in the −x direction) and can cause the third articulating section  226  to rotate up (i.e. in the +y direction) about the third joint  225 , thereby keeping the high diopter lens  220  co-axial with the beampath  205 . In some cases, the actuator  234  can further cause that lens holder  216  to rotate to further keep the high diopter lens  220  co-axial with the beampath  205 . 
     In some cases, when the controller  232  determines that the detected distance  238  is greater than a second predetermined threshold standoff distance, the controller  232  can send a control signal to the actuator  234 , causing the actuator  234  to move the front lens assembly  214  and can cause the high diopter lens  220  toward the corneal surface  244 . 
     The standoff distance thresholds can cause the controller to keep the high diopter lens within a range of distances away from an eye surface. For example, the standoff distance thresholds can maintain a 5-10 millimeter distance between the high diopter lens and the eye. 
       FIG. 3  illustrates the automatic lens to cornea standoff system  230  after the actuator  234  moves the front lens assembly  214  and causes the high diopter lens  220  to move a distance away from the corneal surface  244 . As shown, the detected distance  238  of  FIG. 3  is larger than the detected distance  238  of  FIG. 2  after the actuator  234  moved the high diopter lens  220 . Further, the high diopter lens  220  remains co-axial with the beampath  205 , thereby still allowing surgical staff to view an image of a posterior portion of the eye  240  (e.g. a retina  242 ). In some cases, the actuator  234  can further cause that lens holder  216  to rotate to further co-axially align the high diopter lens  220 . 
     While a standoff distance between the high diopter lens  220  and a surface of the eye is maintained by the actuator  234  moving the front lens assembly  214 , a distance between an objective lens (not shown) of the lens arrangement of the ophthalmic microscope  210  is changed. Therefore, in some cases, the controller  232  includes and/or is coupled to an autofocus system (explained in greater detail below) for automatically adjusting the lens arrangement for resolving a target image, e.g. the retina  242 . 
       FIG. 4  illustrates an automatic lens to cornea standoff system  230 ′ with a screw drive front lens assembly  214 ′ according to some embodiments of the present technology. The screw drive a front lens assembly  214 ′ is coupled to an ophthalmic microscope  210 ′ and includes a lens holder  216 ′ supporting a high diopter lens  220 ′ between a lens arrangement (not shown) of the ophthalmic microscope  210 ′ and an eye  240 ′. The screw drive front lens assembly  214 ′ contains a motor (not shown) configured to adjustably position the high diopter lens  220 ′ at a plurality of positions between the lens assembly and the eye  240 ′. 
     The automatic lens to cornea standoff system  230 ′ also includes a sensor  236 ′ coupled with the lens holder  216 ′. The sensor  236 ′ can detect a distance between the sensor  236 ′ and a surface (i.e. a corneal surface  244 ′) of the eye  240 ′. Accordingly, the sensor  236 ′ (along with the controller) can also determine a distance  238 ′ between the high diopter lens  220 ′ and the surface of the eye  240 ′. 
     The motor in the screw drive front lens assembly  214 ′ of the automatic lens to cornea standoff system  230 ′ can be connected to a control system  250 ′, e.g. via a wired connection  256 ′. The control system  250 ′ can include a controller  232 ′ communicatively coupled with the sensor  236 ′. In some cases, the controller  232 ′ is coupled with a wireless interface which can wirelessly communicate with a wireless interface  254 ′ in the sensor  236 ′. 
     Also, the controller  232 ′ can include memory for storing a threshold standoff distance, e.g. a default value, a user-defined standoff value preference, etc. Furthermore, the controller  232 ′ can receive a detected distance  238 ′ from the sensor  236 ′ and determine that the detected distance  238 ′ is less than the predetermined threshold standoff distance, e.g. when a patient moves his head during surgery. 
     The control system  250 ′ can also include an actuator  234 ′ coupled with the motor in the screw drive front lens assembly  214 ′. After the controller  232 ′ determines that the detected distance  238 ′ is less than the predetermined threshold standoff distance, the controller  232 ′ can send a control signal to the actuator  234 ′. The control signal can cause the actuator  234 ′ to drive the motor in the screw drive front lens assembly  214 ′ and can cause the high diopter lens  220 ′ to move a distance away from the corneal surface  244 ′, i.e. past the threshold standoff distance. 
       FIG. 5A  illustrates a method  300  for preventing a lens from getting too close to a cornea in an ophthalmic microscope and front lens assembly system. The method  300  involves (at  305 ) establishing a connection between a sensor coupled with the front lens assembly and a controller for maintaining a lens to cornea standoff. As explained above, a sensor can be configured to detect the distance between a corneal surface of an eye and a high diopter lens in a front lens assembly and to transmit the detected distance to a controller. In some cases, establishing a connection between the sensor and the controller involves a wired connection in which distance detection information is transmitted from the sensor to the controller via the wired connection. In some cases, a wireless connection (e.g. a Bluetooth connection) is established between the sensor and the controller and the sensor is configured to wirelessly send distance detection information to the controller. 
     Next, the method  300  involves (at  310 ) receiving an instruction to monitor a distance between a corneal surface of an eye and a high diopter lens in a front lens assembly. In some cases, the ophthalmic microscope and front lens assembly system can include a user interface that is used to enter instructions. After surgical staff prepare the ophthalmic microscope and front lens assembly system and positions the high diopter lens under the lens arrangement and above a patient&#39;s eye, the user interface can be used to enter an instruction to begin monitoring the distance between a corneal surface of an eye and a high diopter lens. 
     After monitoring begins, the method  300  involves (at  315 ) receiving, from a sensor, distance measurements describing the distance between the corneal surface of the eye and the high diopter lens. Next, the method  300  involves at  320 ) comparing the distance measurement to a predetermined threshold standoff distance and (at  325 ) determining whether the distance measurement is greater than, equal to, or less than the predetermined threshold standoff distance. 
     When the distance measurement is greater than or equal to the predetermined threshold standoff distance, the method  300  involves (at  315 ) continuing to monitor the distance and receiving distance measurements describing the distance between the corneal surface of the eye and the high diopter lens. When the distance measurement is less than the predetermined threshold standoff distance, the method  300  involves (at  330 ) transmitting a control signal to an actuator; the control signal describes how to adjust the front lens assembly to position the high diopter lens at the predetermined threshold distance. 
     While the disclosure describes adjusting the front lens assembly in response to determining that the distance between the high diopter lens and a surface of the eye is less than a threshold, those with ordinary skill in the art having the benefit of the present disclosure will readily appreciate that some other embodiments can involve distances greater than the same threshold, a separate threshold causing the actuator to re-position the front lens assembly, or a predetermined target standoff distance, as explained in greater detail in  FIG. 5C  below. 
     Also, the method  300  involves (at  315 ) continuing to monitor the distance and receiving distance measurements describing the distance between the corneal surface of the eye and the high diopter lens  315 . 
       FIG. 5B  illustrates a method  335  of adjusting a front lens assembly to position a high diopter lens at the predetermined threshold distance away from a corneal surface of an eye. The method  335  involves (at  340 ) receiving, by an actuator, a control signal describing how to adjust the front lens assembly to position the high diopter lens at the predetermined threshold distance away from a corneal surface of an eye. Next, the method involves (at  345 ) moving, by the actuator, the front lens assembly according to the control signal to position the high diopter lens predetermined threshold distance away from a corneal surface of an eye. 
       FIG. 5C  illustrates a method  350  for maintaining a target standoff distance between a high diopter lens and a cornea in an ophthalmic microscope and front lens assembly system. The method  350  involves (at  355 ) establishing a connection between a sensor coupled with the front lens assembly and a controller for maintaining a lens to cornea standoff and (at  360 ) receiving an instruction to monitor a distance between a corneal surface of an eye and a high diopter lens in a front lens assembly. Next, the method  350  involves (at  365 ) receiving, from a sensor, distance measurements describing the distance between the corneal surface of the eye and the high diopter lens and (at  370 ) comparing the distance measurement to a predetermined target standoff distance. Based on the distance measurement and the predetermined target standoff distance, the method  350  involves (at  375 ) determining a direction and distance required to move the high diopter lens to the determined target standoff distance and (at  380 ) transmitting a control signal to an actuator  380  describing how to adjust the front lens assembly to position the high diopter lens at the predetermined target standoff distance. 
     As explained above, a controller used in an automatic lens to cornea standoff system can receive sensor data describing a distance between a high diopter lens and a surface of the eye and compare the distance to one or more predetermined threshold distances.  FIG. 6  illustrates a block diagram of a system  400  used in an automatic lens to cornea standoff control system for maintaining a lens to cornea standoff. 
     The system  400  includes a controller  432  with a processor  450  and memory  452 . The memory  452  can contain instructions which, when executed by the processor  450 , cause the controller to perform the functions described in the present disclosure. The controller  432  can further include a wireless interface  454  for communicating with other components of the system  400 . For example, in some cases, the controller  432  is wirelessly connected with a wireless interface  456  in a sensor  436  that detects the distance between a high diopter lens and a surface of an eye. 
     As explained above, the controller  432  can receive a distance measurement of the distance between a surface of the eye and the high diopter lens and the controller can compare the distance measurement to one or more predetermined threshold standoff distances. In some cases, the predetermined threshold standoff distances are pre-programmed default values stored in the memory  452 . Also, the predetermined threshold standoff distances can be user-defined and can be entered via a user interface  460  coupled with the controller  432 . The user-interface  460  can be a stand-alone user interface. Also, the controller  432  can cause another device to display the user interface  460 . For example, the controller  432  can be communicatively coupled with a surgical console specially designed for performing ophthalmic surgery and/or communicatively coupled with an ophthalmic microscope. In these cases, the user interface  460  can be a user interface native to the surgical console and/or ophthalmic microscope. 
     Whichever way the threshold standoff distances are defined, the controller  432  can compare the received distance measurement of the distance between a surface of the eye and the high diopter lens from the sensor  436  and compare the measurement with the threshold standoff distance. When a threshold is exceeded, the controller  432  can transmit, to an actuator  434 , a control signal describing how to adjust a front lens assembly  414 . 
     As explained above, adjustments made to a front lens assembly and, therefore, a position of a high diopter lens can affect an image being viewed through an ophthalmic microscope focused on the high diopter lens. So, the control system  400  can further include an auto-focus system  462  which can interpret the control signal sent to the actuator, determine how to re-focus a lens arrangement to maintain focus, and transmit an additional control signal to the lens arrangement  412  of the ophthalmic microscope. In some cases, the controller  432  and auto-focus system  462  are integral in a single module. 
     In some cases, a situation can dictate that adjusting the front lens assembly is not desirable. For example, during a critical point in a retinal surgery, a surgeon may not want to be distracted by a change in the position of the high diopter lens. Accordingly, the control system  400  can also include an over-ride system  464  which can prevent the controller from transmitting the control signal. In some cases, the over-ride system can include a manual over-ride switch (e.g. a foot brake). In some cases, the controller is configured to receive (e.g. from the user interface  460 ) surgical data such as surgical plan data, real-time surgical process data, etc. Based on the surgical data, the over-ride system  464  can determine points during the surgery where adjustments to the front lens assembly  414  and the high diopter lens would not be appropriate and the over-ride system  460  can prevent transmission of the control signal at those points. 
       FIG. 7  illustrates a method for preventing contact between a lens and cornea in an ophthalmic microscope and front lens assembly system. The method involves (at  505 ) establishing a connection between a sensor coupled with the front lens assembly and a standoff controller for maintaining a lens to cornea standoff. In some cases, the standoff controller is communicatively connected to a surgical console configured to process pre-op surgical data and/or surgery plans and monitor planned surgical progress as well as actual real-time surgical progress. So, after a connection is made between the sensor and the controller, the method involves (at  510 ) the standoff controller receiving surgical data relating to overriding automatic lens standoff adjustment. Similarly, the method involves fat  515 ) receiving (e.g. via a user interface on the surgical console) user-defined standoff threshold preference. 
     Once surgical staff is ready to begin using the high diopter lens, the method  500  can involve (at  520 ) receiving an instruction to monitor a distance between a corneal surface of an eye and a high diopter lens in a front lens assembly. After monitoring begins, the method  500  involves (at  525 ) receiving, from a sensor, distance measurements describing the distance between the corneal surface of the eye and the high diopter lens. Next, the method  500  involves (at  530 ) comparing the distance measurement to a predetermined threshold standoff distance and (at  535 ) determining whether the distance measurement is greater than, equal to, or less than the predetermined threshold standoff distance. 
     When the distance measurement is greater than or equal to the predetermined threshold standoff distance, the method  500  involves (at  525 ) continuing to monitor the distance and receiving distance measurements describing the distance between the corneal surface of the eye and the high diopter lens. 
     When the distance measurement is less and the predetermined threshold standoff distance, the method  500  involves (at  540 ) determining when a manual override command has been received from the surgical staff. When a manual override command has been received from the surgical staff, the method involves (at  525 ) continuing to monitor the distance and receiving distance measurements describing the distance between the corneal surface of the eye and the high diopter lens. 
     When a manual override command has not been received, the method  500  involves (at  545 ) determining when to override adjustment of the high diopter lens based on surgical data. 
     When surgical data dictates overriding high diopter lens adjustment, the method involves (at  525 ) continuing to monitor the distance and receiving distance measurements describing the distance between the corneal surface of the eye and the high diopter lens  515 . Alternatively, when an override based on surgical data has not been received, the method  500  involves (at  550 ) transmitting a control signal to an actuator; the control signal describing how to adjust the front lens assembly to position the high diopter lens at the predetermined threshold distance. 
       FIG. 8A  and  FIG. 8B  illustrate exemplary possible system embodiments. The more appropriate embodiment will be apparent to those of ordinary skill in the art when practicing the present technology. Persons of ordinary skill in the art will also readily appreciate that other system embodiments are possible. 
       FIG. 8A  illustrates a conventional system bus computing system architecture  800  wherein the components of the system are in electrical communication with each other using a bus  805 . Exemplary system  800  includes a processing unit (CPU or processor)  810  and a system bus  805  that couples various system components including the system memory  815 , such as read only memory (ROM)  820  and random access memory (RAM)  825 , to the processor  810 . The system  800  can include a cache of high-speed memory connected directly with, in close proximity to, or integrated as part of the processor  810 . The system  800  can copy data from the memory  815  and/or the storage device  830  to the cache  812  for quick access by the processor  810 . In this way, the cache can provide a performance boost that avoids processor  810  delays while waiting for data. These and other modules can control or be configured to control the processor  810  to perform various actions. Other system memory  815  may be available for use as well. The memory  815  can include multiple different types of memory with different performance characteristics. The processor  810  can include any general purpose processor and a hardware module or software module, such as module  1   832 , module  2   834 , and module  3   836  stored in storage device  830 , configured to control the processor  810  as well as a special-purpose processor where software instructions are incorporated into the actual processor design. The processor  810  may essentially be a completely self-contained computing system, containing multiple cores or processors, a bus, memory controller, cache, etc. A multi-core processor may be symmetric or asymmetric. 
     To enable user interaction with the computing device, an input device  845  can represent any number of input mechanisms, such as a microphone for speech, a touch-sensitive screen for gesture or graphical input, keyboard, mouse, motion input, speech and so forth. An output device  835  can also be one or more of a number of output mechanisms known to those of skill in the art. In some instances, multimodal systems can enable a user to provide multiple types of input to communicate with the computing device  800 . The communications interface  840  can generally govern and manage the user input and system output. There is no restriction on operating Off any particular hardware arrangement and therefore the basic features here may easily be substituted for improved hardware or firmware arrangements as they are developed. 
     Storage device  830  is a non-volatile memory and can be a hard disk or other types of computer readable media which can store data that are accessible by a computer, such as magnetic cassettes, flash memory cards, solid state memory devices, digital versatile disks, cartridges, random access memories (RAMs)  825 , read only memory (ROM)  820 , and hybrids thereof. 
     The storage device  830  can include software modules  832 ,  834 ,  836  for controlling the processor  810 . Other hardware or software modules are contemplated. The storage device  830  can be connected to the system bus  805 . In one aspect, a hardware module that performs a particular function can include the software component stored in a computer-readable medium in connection with the necessary hardware components, such as the processor  810 , bus  805 , display  835 , and so forth, to carry out the function. 
       FIG. 8B  illustrates a computer system having a chipset architecture that can be used in executing the described method and generating and displaying a graphical user interface (GUI). Computer system is an example of computer hardware, software, and firmware that can be used to implement the disclosed technology. System can include a processor  855 , representative of any number of physically and/or logically distinct resources capable of executing software, firmware, and hardware configured to perform identified computations. Processor  855  can communicate with a chipset  860  that can control input to and output from processor  855 . In this example, chipset  860  outputs information to output  865 , such as a display, and can read and write information to storage device  870 , which can include magnetic media, and solid state media, for example. Chipset  860  can also read data from and write data to RAM  875 . A bridge  880  for interfacing with a variety of user interface components  885  can be provided for interfacing with chipset  860 . Such user interface components  885  can include a keyboard, a microphone, touch detection and processing circuitry, a pointing device, such as a mouse, and so on. In general, inputs to system can come from any of a variety of sources, machine generated and/or human generated. 
     Chipset  860  can also interface with one or more communication interfaces  890  that can have different physical interfaces. Such communication interfaces can include interfaces for wired and wireless local area networks, for broadband wireless networks, as well as personal area networks. Some applications of the methods for generating, displaying, and using the GUI disclosed herein can include receiving ordered datasets over the physical interface or be generated by the machine itself by processor  855  analyzing data stored in storage  870  or  875 . Further, the machine can receive inputs from a user via user interface components  885  and execute appropriate functions, such as browsing functions by interpreting these inputs using processor  855 . 
     It can be appreciated that exemplary systems  800  and  850  can have more than one processor  810  or be part of a group or cluster of computing devices networked together to provide greater processing capability. 
     For clarity of explanation, in some instances the present technology may be presented as including individual functional blocks including functional blocks comprising devices, device components, steps or routines in a method embodied in software, or combinations of hardware and software. 
     In some embodiments the computer-readable storage devices, mediums, and memories can include a cable or wireless signal containing a bit stream and the like. However, when mentioned, non-transitory computer-readable storage media expressly exclude media such as energy, carrier signals, electromagnetic waves, and signals per se. 
     Methods according to the above-described examples can be implemented using computer-executable instructions that are stored or otherwise available from computer readable media. Such instructions can comprise, for example, instructions and data which cause or otherwise configure a general purpose computer, special purpose computer, or special purpose processing device to perform a certain function or group of functions. Portions of computer resources used can be accessible over a network. The computer executable instructions may be, for example, binaries, intermediate format instructions such as assembly language, firmware, or source code. Examples of computer-readable media that may be used to store instructions, information used, and/or information created during methods according to described examples include magnetic or optical disks, flash memory, USB devices provided with non-volatile memory, networked storage devices, and so on. 
     Devices implementing methods according to these disclosures can comprise hardware, firmware and/or software, and can take any of a variety of form factors. Typical examples of such form factors include laptops, smart phones, small form factor personal computers, personal digital assistants, and so on. Functionality described herein also can be embodied in peripherals or add-in cards. Such functionality can also be implemented on a circuit board among different chips or different processes executing in a single device, by way of further example. 
     The instructions, media for conveying such instructions, computing resources for executing them, and other structures for supporting such computing resources are means for providing the functions described in these disclosures. 
     The above disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments which fall within the true spirit and scope of the present disclosure. Thus, to the maximum extent allowed by law, the scope of the present disclosure is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description.