Abstract:
Advances in filling apparatus, handheld tools, surgical techniques and intraoperative biometry for implanting and adjusting an accommodative liquid lens are disclosed. The lens may be attached to or retained within a handheld surgical tool, which can be fluidly connectable to a filling console to fill the lens with a liquid. In various embodiments, a filling console facilitates aspirating liquid out of the lens in order to ensure the absence of residual bubbles and filling of the lens with fluid during surgery, as well as during post-operative adjustments to the lens. Actuated by the surgeon, the filling console can aspirate fluid from the lens and inject fluid into the lens following insertion thereof.

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 13/473,012, filed on May 16, 2012, which claims priority to, and the benefits of, U.S. Provisional Application Ser. No. 61/486,562, filed on May 16, 2011, the entire disclosure of which is hereby incorporated by reference. 
    
    
     BACKGROUND 
     The human eye contains a natural crystalline lens that focuses light on the retina. The lens may become cloudy, forming a cataract, which makes it impossible to see clearly. When the cataract progresses and vision becomes greatly hindered, cataract surgery becomes necessary. This procedure removes the natural lens and replaces it with an implantable medical device called an intraocular lens (IOL). The IOL is an artificial lens conventionally made of plastic, silicone, or acrylic and performs the function of a normal lens. Current IOLs are made of soft materials, allowing them to be folded and implanted in the eye with a small incision. Standard IOLs are monofocal, providing a set focal point. 
     IOL implantation has become the standard of care after cataract extractions. Most IOLs are made of single piece of hard material, although some newer IOLs have a two-lens design, and lenses filled with clear fluid have also been proposed. Most current IOLs are prefabricated for their lens power and then placed in the eye, but again, a few designs involve intraocular filling of the liquid in the lens at the time of initial surgery or possibly at a subsequent time (e.g., for adjustment or should the liquid become opacified, or even simply to refill the liquid in the lens). A liquid-filled bag that provides accommodation—made from, for example, an elastic, biocompatible polymer—results in numerous benefits and advantages, e.g., the ability to adjust the lens following implantation; to customize the lens to the needs of each patient; to accommodate vision; sharper vision over a wide range of distances; and reduction of visual side effects such as glares and halos. See, e.g., U.S. Pat. No. 8,038,711, the entire disclosure of which is hereby incorporated by reference. 
     Tailoring a fillable IOL to the ocular needs and anatomy of a particular patient requires detailed knowledge of the implantation site and the response of the lens as it is filled. Although there exist approaches to measure the overall refractive power of an eye with implantable lenses at the time of surgery (before or after IOL implantation) and also in the perioperative period, we are aware of no biometric methods for guiding the refractive power of an IOL that is filled with liquid during initial surgery or at subsequent time periods. 
     SUMMARY 
     The present invention relates to advances in filling apparatus, handheld tools, surgical techniques and intraoperative biometry for implanting and adjusting the accommodative liquid lens (ALL or simply “lens”) of a liquid lens system (LLS). The ALL is implanted to replace the natural lens of an eye, interacting with the ciliary muscles, zonules, and capsule and compressing and expanding inside the eye as in normal accommodation. The LLS can also be used for presbyopia since many patients need glasses because of aging of the lens. 
     In broad overview, the lens may be supplied in a tightly rolled-up or compressed configuration that minimizes outer diameter and allows for a smaller surgical incision in the cornea during implantation. The lens may be attached to or retained within a handheld surgical tool, which can be fluidly connectable to a filling console to fill the ALL with a liquid such as silicone oil, hyaluranic acid (or a salt thereof, e.g., HEALON) or other fluid. In various embodiments, a filling console facilitates aspirating liquid out of the lens in order to ensure the absence of residual bubbles and filling of the lens with fluid during surgery, as well as during post-operative adjustments to the lens. Actuated by the surgeon, the filling console can aspirate fluid from the lens and inject fluid into the lens following insertion thereof. In various embodiments, the fluid used to fill the lens is supplied in a disposable (e.g., single-use) cartridge, which is snapped into the filling console for use and conveniently discharged thereafter. The cartridge may be formed of a biocompatible material. 
     In operation, the filling console may optionally receive signals from various sources, including optical imagery feedback; a sensor measuring the pressure inside the tip of the ALL; and/or flow or other sensors monitoring the total volume of fluid through the lens. For example, an optical calibration console (OCC) may give real-time feedback to the filling console in order to optimize clinical outcomes with respect to the amount of fluid filled inside the ALL. 
     Indeed, a problem with the conventional practice of filling lenses in the eye during cataract surgery is that it relies on estimates—i.e., on the surgeon&#39;s ability to fill a very small amount of fluid and estimate the amount of refraction needed. This can be very imprecise. Accordingly, embodiments of the present invention use biometry to provide feedback to the surgeon and the filling system in a closed-loop fashion to optimize filling and overall clinical outcome. 
     In a first aspect, the invention relates to a console for filling an accommodative liquid lens following implantation thereof. In various embodiments, the console comprises a reservoir for receiving a lens-filling fluid; a port for receiving a needle-and-tubing set; a pump for driving fluid from the reservoir to the port; and circuitry for controlling the pump to fill the lens via the needle-and-tubing set. The circuitry is responsive to signals indicative of optical imagery, ultrasound imagery, the pressure inside the lens, and/or the volume of fluid in the lens. In some implementations, the reservoir is configured to receive a disposable cartridge. Where the console&#39;s circuitry is responsive to signals indicative of the volume of fluid in the lens, the signals may be provided by a flow sensor. Where the console&#39;s circuitry is responsive to signals indicative of the pressure in the lens, the signals may be provided by a pressure sensor. 
     The circuitry may be responsive to optical-imagery signals provided by, for example, by an intraoperative aberrometry system (e.g., a system that performs intra-operative wavefront analysis) or another optical imaging system. Alternatively or in addition, the circuitry may be responsive to optical-imagery signals provided by an optical coherence tomography system and/or an ultrasound system. 
     In another aspect, the invention relates to a system for filling an accommodative liquid lens following implantation thereof. In various embodiments, the system comprises a reservoir for receiving a lens-filling fluid; a needle-and-tubing set comprising at least one of a pressure sensor or a flow sensor; a pump for driving fluid from the reservoir to the needle-and-tubing set; and circuitry for controlling the pump. The circuitry is responsive to the sensor(s) during filling. 
     In still another aspect, the invention relates to a method of filling an accommodative liquid lens following implantation thereof. In various embodiments, the method comprises the steps of flowing a lens-filling fluid into the lens; and automatically controlling the flow based on optical imagery, pressure inside the lens, and/or a volume of fluid in the lens. The flow may be controlled based at least in part on signals being provided by a flow sensor, a pressure sensor, and/or an intraoperative aberrometry system (e.g., performing intra-operative wavefront analysis) or other system to measure the refractive state inside the eye. The flow may be based on reducing optical aberrations and astigmatism. 
     In still another aspect, the invention relates to a system for filling an accommodative liquid lens following implantation thereof. In various embodiments, the system comprises a reservoir for receiving a lens-filling fluid; a needle-and-tubing set comprising a tube and a needle each having at least two separate lumens therethrough; one or more pumps for alternately driving fluid from the reservoir through one of the lumens or withdrawing fluid through the other lumen; and circuitry for operating the one or more pumps to aspirate and fill the lens via the needle. In some implementations, the lumens terminate in spaced-apart outlet ports on the needle. The system may include an air-bubble capture device (e.g., a filter or a pocket) for removing air bubbles from fluid passing through at least one of the lumens. 
     Yet another aspect of the invention relates to an accommodative liquid lens comprising a fillable interior portion containing (i) a fill liquid having a refractive index and (ii) a plurality of capsules containing a releasable material for altering the refractive index of the fill fluid. The capsules may be disposed within the fill liquid and/or along an interior wall of the lens. The material is releasable from the capsules upon exposure thereof to electromagnetic radiation, e.g., laser or radiofrequency radiation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention are better understood with reference to the following drawings. The elements of the drawings are not necessarily to scale relative to each other. 
         FIG. 1  graphically depicts the relationship between lens power versus fill volume of an ALL. 
         FIG. 2  graphically depicts the relationship between base Power and refractive index for an exemplary ALL. 
         FIG. 3  is a partial-cutaway view of an insertion device in accordance herewith. 
         FIG. 4  is a schematic cross-section of an exemplary filling-instrument tip. 
         FIG. 5  is a schematic cross-section of an exemplary filling instrument with air-bubble capture within the lumen thereof. 
         FIG. 6  is a schematic cross-section of an exemplary filling instrument with an air-bubble removal element within the lumen thereof. 
         FIG. 7  illustrates a filling console operable to fill a lens inserted using, for example, the insertion device shown in  FIG. 1 . 
         FIG. 8  shows a system for providing intraoperative wavefront abberometry in order to facilitate proper positioning and/or filling of the lens. 
     
    
    
     DETAILED DESCRIPTION 
     1. Overview 
     During the surgical procedure of implanting an ALL, capsulotomy and ablation of the cataract lens is performed. Capsulotomy may be performed using hand capsulorhexis techniques or using a laser (e.g., a femtosecond laser), making a small circular diameter centered on the lens or on the periphery. Phacoemulsification or laser ablation is performed and the lens is aspirated from the lens capsule. After the empty lens capsule is cleaned, the ALL is implanted and then inflated. 
     Before implantation into the eye, all the air from the ALL is evacuated. In one embodiment of the invention, the lens is initially filled with the appropriate filling liquid. This is done by accessing the internal contents of the lens through a refill port in the ALL, removing any air present, and then filling with the appropriate liquid. Before insertion into the eye, the ALL is evacuated entirely or almost entirely without any residual air because any residual volume is filled with the filling liquid. Typically, all air bubbles are removed as part of the assembly of the ALL. 
     Next, the ALL is injected into the empty lens capsule through a corneal incision and a capsulotomy. After injection into the eye, the lens is filled using the filling console. Filling the ALL completes two tasks: filling the lens to the appropriate volume, and adjusting the lens to the appropriate refractive power to provide emmetropia. The ALL must have the appropriate volume (within a clinically tolerable range) to operate properly. Proper operation includes the ability to accommodate, remain centered in the eye, adhere to the lens capsule, not damage the lens capsule, maintain an appropriate distance from the cornea and anterior chamber, and not damage surrounding tissue. For example, there is a range of volumes over which the lens capsule can transmit the appropriate force to cause the lens to accommodate. Above these volumes, the anatomical complex including the lens capsule, zonules, and ciliary muscle can no longer properly deform and accommodate the lens. In addition, an overfilled lens may damage the lens capsule and surrounding tissue or come too close to or make unwanted contact with the cornea. A underfilled lens, on the other hand, may have surface irregularities or folds that damage optical quality. Underfilling of an ALL may lower its ability to accommodate, or to conform and attach to the surrounding tissue or lens capsule, causing poor centration of the lens. 
     Fill volume may be used to adjust the optical refractive power of the lens.  FIG. 1  illustrates the optical power of an exemplary ALL as a function of fill volume. As fill volume is increased, optical power of the lens also increases. Therefore, the optical power of an ALL can be adjusted by adjusting its fill volume. The refractive power of an ALL can also be adjusted by changing the refractive index of filling fluid within the implant.  FIG. 2  illustrates an example of modifying refractive power by adjusting the fluid refractive index for an exemplary ALL. 
     2. Insertion Device 
     Refer now to  FIG. 3 , which illustrates an insertion device or “introducer”  100  that includes a hand-operated syringe-type plunger  105 . The plunger  105  slides within the bore  107  of a cylindrical housing  110 . Optionally, one or more O-rings  112  provide slidable frictional engagement with the interior wall of the bore  107  to facilitate smooth, controllable, hand-operated movement of the plunger  105 . Projecting from plunger  105  is a smaller-diameter insertion shaft  115 , which slides snugly within a plug  117  with bore  107  toward the distal end  120  of housing  110 . The insertion device  100  is supplied preloaded with lens  125 , which is rolled up or compressed within the bore  107 . Insertion shaft  115  terminates in a filling needle  130 , which, as described below, may have one or a plurality of lumens. Lens  125  resides at the end of the filling needle  130 , which may project into the interior of the lens for filling thereof following implantation. Filling needle  130  is supplied by an external (multi-lumen or single-lumen) tube  132 , which connects to a filling console as described below. A sensor  135 , e.g., a flow sensor, a pressure sensor, or both, may be located along the length of filling needle  130  and typically at the distal end thereof. If employed, the sensor  135  is electrically connected (e.g., via wires passing through tube  132  or conductive traces thereon) to the filling console. 
     In operation, the surgeon makes the ocular incision and passes the distal end  120  of the insertion device  100  therethrough, maneuvering the tip until it is properly positioned within the patient&#39;s eye. Driving the plunger  105  forward causes the lens  125  to pass through the terminal bore  138  of the insertion device  100 , finally being ejected into the patient&#39;s eye through the front end opening of the insertion device  100 . The tip of filling needle  130  enters or remains inside the lens  125 , through a resealable (and preferably self-sealing) valve, to facilitate filling thereof. Accordingly, the filling instrument provides fluidic continuity between the filling console and the internal contents of the introduced lens  125 . 
     The filling needle  130  may have one or multiple lumens, and may interact with the lens in one or multiple positions. For simple addition or removal of fluid, the filling instrument may have a single lumen that allows fluid to be injected into or aspirated from the lens. If fluid exchange is required, e.g., to faciliate “tuning” the refractive index of the fluid by exchanging a portion of the existing fluid for a fluid with a different refractive index, a dual-lumen system is preferable. Two lumens can be used to access the same position on the lens, with one injecting fluid and the other aspirating. In addition, the lumens may access different positions in the lens  125  to allow the fluid to mix therein before the needle  130  is removed. Preferably the filling instrument interacts with a single valve, although multiple valves may be accessed if desired—e.g., to provide better mixing or filling of the ALL. 
     The tip  140  of a multi-lumen filling needle  130  is shown in schematically  FIG. 4 . The two lumens  145 ,  147  are in fluidic connection with complementary lumens in tube  132 . One of the lumens  145 ,  147  may be used to infuse and the other used to aspirate fluid from the interior of lens  125 . Tip  140  enters the interior of lens  125  via a re-sealable valve  150 . Each of the lumens  145 ,  147  has an associated outlet port  152 ,  154 , respectively. Both of these ports clear the valve  150  and reside within the interior of lens  125  during filling; they are preferentially displaced axially along the length of the tip  140  to prevent, for example, flow from the infusion port from being directly aspirated from the aspiration port. Moreover, fluid mixing within lens  125  is enhanced due to the distance between the ports  152 ,  154 . It should be understood, however, that ports  152 ,  154  may both be on a single side, at the ends of the lumens, oriented in the same direction, oriented in different directions, etc. Moreover, there may be multiple ports on each lumen  145 ,  147 . In such embodiments it is preferable to design the ports to have enough area to prevent significant fluidic resistance for the particular geometry of the instrument. Infusion and aspiration may also occur at different times to allow mixing within the lens  125 . 
     In another embodiment, the tip  140  has a single infusion lumen terminating in a port. In this configuration fluid is either aspirated or infused through the single lumen. This has the advantage of lower flow resistance during filling because the aspiration lumen does not occupy a fraction of the total filling instrument tip diameter. However, it does not allow simultaneous infusion and aspiration. 
     If residual air bubbles are present in the lens  125  or in the line during filling, they can be removed by aspiration into the filling instrument using an air-bubble capture device or an air bubble filter. An exemplary air-bubble capture device  160  is shown in  FIG. 5 . The device is located within the handle or plunger of the insertion device  100 . When air is aspirated through bore  160 , it preferentially rises to the air-bubble capture pocket  160 , where it remains, even if fluid is later infused through the bore  107 . In other implementations, a maze may be used instead of the pocket  160  to entirely trap and capture the air bubble. Still another approach, shown in  FIG. 6 , is to use an air bubble filter  170 , once again located in the handle or plunger  105 . A semipermeable membrane  170  allows air but not the filling fluid to pass through it. Air bubbles in the inlet fluid line are removed as they diffuse across the semipermeable membrane  170  into a chamber  172 . The chamber  172  may be subjected to vacuum conditions to help remove air bubbles. 
     Although the foregoing air-bubble removal mechanisms are shown in a single lumen-insertion and filling instrument, this is not meant to be limiting, and they may be used in multiple-lumen systems, such as the dual-lumen system shown in  FIG. 4 . 
     3. Filling Console 
     The lens  125  may be filled using a filling console or unit  200 , as illustrated in  FIG. 7 . The console  200  includes a well  210  for receiving a disposable cartridge  212 , which contains the fluid that will fill the lens  125 . The well  210  is configured to securely but releasably receive cartridge  212  and establish a fluid connection to the capillary network within filling unit  200 , e.g., by piercing a seal on the cartridge. Typically a single-use cartridge is supplied with a single lens  125  and insertion device  100 . The cartridge may include more than one fluid reservoir, e.g., to hold fluids having different refractive indices to permit the refractive index of the lens  125  to be fine-tuned by varying the proportions of the different fluids introduced therein. In other embodiments, multiple cartridges may be inserted into multiple wells  210 . 
     The tube  132  includes two parallel (or concentric) lumens L 1 , L 2 . Tube  132  typically terminates in a fluid-tight connector that is releasably but securely received within a port  215  of the filling unit  200 . The connector and port are mated so that the lumens of the tube  132  align with fluid channels within filling unit  200 . A first fluid conduit  220  within filling unit  200  connects one end of the cartridge  212  (actually the forward port, not shown, within the well  210  that itself pierces the forward seal of and establishes fluid communication with the cartridge) to the outlet port aligned with lumen L 1  via a valve  222 . A second fluid conduit  225  connects the opposite end of the cartridge  212  (actually the rear port, not shown, within the well  210  that pierces the rear seal of and establishes fluid communication with the cartridge) to a pump  230 . The pump  230  is typically a mechanical pump (e.g., gear, diaphragm, peristaltic, pneumatic, syringe, etc.), but may also be, for example, an electrolytic pump or any other suitable pumping device. A third fluid conduit  232  connects the outlet port aligned with lumen L 2  to a vacuum suction  235  (i.e., an air pump) via a valve  237 . (Again, in multiple-reservoir systems, the console  200  would contain multiple instances of conduits  220 ,  225 , valve  222  and pump  230  to facilitate independent introduction of the different fluids into the lumen L 1 .) 
     Valves  222 ,  237 , pump  230  and vacuum suction  235  are controlled by governing circuitry  240 , which also receives signals from sensor(s)  135  and an optical system described below. A conventional user interface  245  enables the user to program (or alter the programming of) governing circuitry  240  and to operate the filling unit  200 . In some embodiments, user interface  245  includes a wireless transceiver that enables the user to program and operate the filling unit  200  using a wireless device, e.g., a “smart phone.” In general, the interface will include buttons and a screen display on filling unit  200  and/or generated by governing circuitry  240  for presentation on the user&#39;s wireless device. 
     The control logic underlying the governing circuitry  240  may be implemented as any software program, hardware device, or combination thereof that is capable of achieving the functionality described herein. For example, the governing circuitry  240  may be an application-specific integrated circuit (ASIC) or a field programmable gate array (FPGA). Alternatively, the governing circuitry  240  may be one or more general-purpose microprocessors (e.g., any of the PENTIUM microprocessors supplied by Intel Corp.) programmed using any suitable programming language or languages (e.g., C++, C#, java, Visual Basic, LISP, BASIC, PERL, etc.). Suitable control programming is straightforwardly implemented by those of skill in the art without undue experimentation. 
     In basic operation, following placement of the lens  125  within the patient&#39;s eye using the insertion device  100 , the surgeon activates the fill sequence via interface  245 . This causes governing circuitry  240  to operate pump  230  so that fluid from cartridge  212  is driven through the (open) valve  222 , through tube  132  and ultimately into lens  125  via filling needle  130 . If air is present in the system, it is withdrawn by suction  235  via conduit  232  through (open) valve  237 . To accommodate simultaneous fluid introduction and withdrawal, needle  130  is typically a dual-lumen needle, with each of the two lumens being fluidly coupled to the lumens L 1 , L 2  of tube  132 . 
     Governing circuitry  240  is typically programmed for careful control of the filling process so that the pressure inside the lens  125  (i.e., the fluid pressure at the outlet of the filling needle  130 ) does not exceed a given, critical value. The pressure may be measured by sensor  135 ; by governing circuitry  240  via, for example, pump  230 ; or by means of an external device. External monitoring devices include manual devices in mechanical contact with the lens  125  and remote monitoring systems using techniques including Brillouin scattering monitoring and acoustic/mechanical wave monitoring, such as ultrasound. In addition to controlling pressure by monitoring and adjusting the degree of filling, pressure may be controlled by supplying a desired pressure and allowing the implant to fill to that specific pressure. For example, a reservoir in fluidic continuity with the lens may be held at a given pressure, inflating the lens at that pressure until the pressures reach equilibrium. 
     At a minimum, pressure monitoring prevents damage to the lens  125  by overfilling, since as the volume of the lens increases, so does the pressure. The pressure inside the lens  125  may be maintained below a critical value in several ways. For example, if liquid is infused into the lens  125  pneumatically, then the governing circuitry  240  may keep injection pressure below the critical value. A pressure-release valve can also be used in the pneumatic drive as a fail-safe mechanism. As another example, if the liquid is infused using a mechanical pump  230 , the pressure inside the lens  125  may be controlled by integrating a pressure sensor at the point of highest hydraulic pressure. The governing circuitry  240  may monitor the pressure sensor and employ a conventional feedback system to prevent the pressure at this point from exceeding the critical value. As still another example, the governing circuitry  240  may meter the volume of fluid delivered to the lens  125  to prevent overfilling. 
     In addition to preventing overfilling, monitoring pressure provides a way of indirectly monitoring the interaction between the lens and surrounding tissue to ensure a conformal fit of the lens in the lens capsule. This can be used to have the lens fit appropriately in lens capsules of differing sizes. 
     Governing circuitry  240  may also receive signals from an intraoperative abberometry system, described in greater detail below, that obtains three-dimensional measurements of how the lens sits within the capsule of the patient&#39;s eye and refracts the eye&#39;s light. This information may be provided to the surgeon via interface  245  to guide the filling of the lens  125 , allowing the surgeon to re-shape the lens to optimize accommodation. For example, based on the observed measurements, the surgeon may operate the fill unit  200  (via user interface  245 ) to alter the amount of fluid within the lens  125  before withdrawing the filling needle  130  from the lens  125  (whereupon the self-sealing valve on the lens  125  reseals). 
     4. Monitoring 
     Monitoring the refractive power of the lens  125  is completed using a manual technique or using optical imagery feedback as described below. A manual technique, such as retinoscopy, can be used to determine error in the refractive power of the lens  125 , and the power can be subsequently adjusted by changing the degree of lens filling. The appropriate refractive power of the lens can be set by using measurement of refractive power, choosing and filling the appropriate lens to the correct level, or it can be measured and adjusted intraoperatively. Traditionally, IOL power is measured before the surgical procedure, the correct lens is identified, and it is subsequently implanted. This is considered an open-loop technique, as there is no feedback between the lens and the filling console. 
     To apply the open-loop technique, the desired refractive power of the lens is determined before the surgical implantation of the device. Refractive power can be determined before the surgical operation, as is commonplace in current cataract procedures, or intraoperatively, using an intraoperative aberrometer or equivalent device. In addition, geometric measurements of the lens capsule and surrounding tissue may be taken to determine the fill volume and correct lens. Once the desired refractive power is determined, the appropriate lens is chosen along with the proper fill volume. If different fluids (e.g., fluids with differing refractive indicies) are used with the lens, the appropriate combination is also determined. Fill volume is determined by considering the refractive power desired and the geometry of the lens capsule and surrounding anatomy. After insertion into the lens capsule, the filling console operates as described previously. 
     The filling console can also be used in a closed-loop fashion. In closed-loop operation the refractive properties of the lens and/or eye are monitored as the lens is filled. Filling is adjusted to provide the appropriate refractive outcome as optical parameters power are monitored. In particular, the filling console (with or without the surgeon&#39;s involvement) responds to signals indicative of the relevant optical parameters, which are then used to adjust the operation of the filling pump(s). For example, the most rudimentary method of completing this task is to use intraoperative retinoscopy to check refractive error, then manually adjust the lens accordingly and re-check. Preferably the refractive power of the lens is monitored throughout the procedure in an automated manner while the lens is filled. Using the filling console in closed-loop operation yields refractive outcomes that are less prone to error than prior techniques. This is because the actual power is monitored and adjusted in real-time. Open-loop techniques, by contrast, rely solely on data obtained before implantation, and cannot adjust for changes based on the procedure, or errors in the refractive calculations. 
     Optical imagery feedback—i.e., measurements indicating the optical positioning and performance of the implanted lens—may be used in closed-loop implementations to help the surgeon guide the lens and determine the proper level of lens filling. Suitable instruments include an aberrometer, a refractometer, or an imaging system to monitor geometry and calculate power, such as an optical coherence tomography system, or an ultrasound system. In addition, this instrument may use prior biometry measurements in conjunction with measurements during the filling of the lens  125 . For example, to determine appropriate power, an optical coherence tomography system may be used to monitor the lens profile in conjunction with information previously collected regarding the length of the eye, or refractive power of the cornea. Using prior information the lens geometry is adjusted to the refractive power and/or geometry. 
     In one embodiment, an intraoperative aberrometry system that obtains three-dimensional measurements of how the lens sits within the capsule and refracts the eye&#39;s light is employed, and the information obtained may be provided to the surgeon to guide the filling of the lens, allowing the surgeon to re-shape the lens to optimize refractive power, reduce or eliminate optical aberrations, and optimize accommodation. Using a measurement system that performs intra-operative wavefront analysis, for example, enables extremely precise, individualized vision-correction outcomes to be achieved—outcomes that would be impossible with traditional surgeon&#39;s perspective in filling the lens  125 . With reference to  FIG. 8 , a conventional intra-operative wavefront analysis system  300  includes a coherent light source, a beam-modification device for shaping and deflecting a beam of the coherent light source that is directed through the patient&#39;s eye to the retina, and a wavefront analyzer for receiving reflected light from the retina and analyzing a wavefront of the optical path in the eye. The wavefront analyzer may be based on a Shack-Hartmann sensor, for example. See, e.g., U.S. Pat. No. 8,029,136, the entire disclosure of which is hereby incorporated by reference; a suitable commercially available system  300  is the ORA system supplied by WaveTec Vision, Aliso Viejo, Calif. In some embodiments the output of the wavefront analysis is used directly by the filling console  200  in an automated feedback loop, e.g., to provide an automated fill and/or to stop a manual filling operation when clinical safety margins are approached. Ultrasound or optical coherence tomography can be used in a similar manner to calculate the optimal refraction of the lens and therefore give feedback on how much the lens should be filled. 
     The output of the wavefront analysis is provided to the governing circuitry  240  of the filling unit  200 . In some embodiments, governing circuitry  240  uses signals from the system  300  in an automated feedback loop, e.g., to provide an automated fill and/or to stop a manual filling operation when clinical safety margins are approached. In addition, optical information may be provided to the surgeon via user interface  245  to enable the surgeon to observe the optical performance of the introduced lens and alter the fill level and/or positioning to beneficially alter the performance. 
     Ultrasound can be used in a similar manner to calculate the optimal refraction of the lens and therefore give feedback on how much the lens  125  should be filled. Commercial systems such as the Zeiss IOLMaster  500  can be used to determine the appropriate orientation of the lens  125  as well as to screen the eye before and during surgery to make sure the correct size and refractive-strength lens is chosen. Ultrasound systems provide axial length and keratometry measurements as well as IOL power calculation, which varies with the level of lens filling. Ultrasound measurements along the visual axis can be used to ensure proper lens placement in terms of axial distance. 
     The filling console  200 , or a separate filling unit, may be used to refill the lens to re-adjust for post-surgical changes in accommodation and refraction. The filling console  200  is connected to a disposable tubing set with a small-gauge needle to pierce the cornea and enter the chamber of the lens  125 . Post-implantation assessment and refilling takes place after the eye has had time to heal and the lens has had time to settle—e.g., the day after surgery. The goal of this step is to make adjustments to optimize the patient&#39;s vision towards normal. The clinician may refill the lens  125  multiple times after surgery to achieve optimal vision. 
     The approach of the present invention may also be used to monitor and adjust for astigmatism. Certain configurations of the lens  125  have the ability to correct for astigmatism. Therefore, astigmatism and other aberrations can be monitored and corrected for during the surgical procedure. This can also be used when placing non-liquid lens such as Toric IOLs. For example, after a monofocal toric IOL is placed, the correct angular position can be determined with the optical system while the surgeon adjusts the position during the procedure. 
     In certain embodiments of the invention, the filling system is used with a non-invasive lens-tuning mechanism. Release capsules in the lens fill fluid may include a high concentration of solutes, nanoparticles, or a refractive fluid. Upon opening of the capsules by means of targeted laser ablation or actuation with radiofrequency exposure, the contents of the affected capsules are released into the lens fill fluid, thereby adjusting refractive power of the lens. Alternatively, the release capsules may be implanted along the interior wall of the lens. In a postoperative setting, the lens refractive power can be monitored with an optical instrument as described above as the release capsules are progressively opened. Upon reaching emmetropia, the procedure is completed. 
     The phrase “and/or,” as used herein should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Other elements may optionally be present other than the elements specifically identified by the “and/or” clause, whether related or unrelated to those elements specifically identified unless clearly indicated to the contrary. Thus, as a non-limiting example, a reference to “A and/or B,” when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A without B (optionally including elements other than B); in another embodiment, to B without A (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc. 
     As used in this specification, the term “substantially” or “approximately” means plus or minus 10% (e.g., by weight or by volume), and in some embodiments, plus or minus 5%. Reference throughout this specification to “one example,” “an example,” “one embodiment,” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the example is included in at least one example of the present technology. Thus, the occurrences of the phrases “in one example,” “in an example,” “one embodiment,” or “an embodiment” in various places throughout this specification are not necessarily all referring to the same example. Furthermore, the particular features, structures, routines, steps, or characteristics may be combined in any suitable manner in one or more examples of the technology. The headings provided herein are for convenience only and are not intended to limit or interpret the scope or meaning of the claimed technology. 
     Certain embodiments of the present invention have described above. It is, however, expressly noted that the present invention is not limited to those embodiments, but rather the intention is that additions and modifications to what was expressly described herein are also included within the scope of the invention. Moreover, it is to be understood that the features of the various embodiments described herein were not mutually exclusive and can exist in various combinations and permutations, even if such combinations or permutations were not made express herein, without departing from the spirit and scope of the invention. In fact, variations, modifications, and other implementations of what was described herein will occur to those of ordinary skill in the art without departing from the spirit and the scope of the invention. As such, the invention is not to be defined only by the preceding illustrative description.