Patent Publication Number: US-2023157883-A1

Title: Liquid optical interface for laser eye surgery system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority to U.S. Provisional Application No.:61/721,693, filed Nov. 2, 2012. 
    
    
     BACKGROUND 
     The present disclosure relates generally to surgery. Although specific reference is made to tissue retention for laser eye surgery, embodiments as described herein can be used in one or more of many ways with many surgical procedures and devices, such as orthopedic surgery, robotic surgery and microkeratomes. 
     Cutting of materials can be done mechanically with chisels, knives, scalpels and other tools such as surgical tools. However, prior methods and apparatus of cutting can be less than desirable and provide less than ideal results in at least some instances. For example, at least some prior methods and apparatus for cutting materials such as tissue may provide a somewhat rougher surface than would be ideal. Although lasers having pulse short pulse durations have been proposed to cut tissue, these short pulsed lasers may use very high pulse repetition rates and the energy of these lasers can be difficult to measure in at least some instances. Pulsed lasers can be used to cut one or more of many materials and have been used for laser surgery to cut tissue. 
     Examples of surgically tissue cutting include cutting the cornea and crystalline lens of the eye. The lens of the eye can be cut to correct a defect of the lens, for example to remove a cataract, and the tissues of the eye can be cut to access the lens. For example the cornea can be cut to access the cataractous lens. The cornea can be cut in order to correct a refractive error of the eye, for example with laser assisted in situ keratomileusis (hereinafter “LASIK”). 
     Many patients may have visual errors associated with the refractive properties of the eye such as nearsightedness, farsightedness and astigmatism. Astigmatism may occur when the corneal curvature is unequal in two or more directions. Nearsightedness can occur when light focuses before the retina, and farsightedness can occur with light refracted to a focus behind the retina. There are numerous prior surgical approaches for reshaping the cornea, including laser assisted in situ keratomileusis, all laser LASIK, femto LASIK, corneaplasty, astigmatic keratotomy, corneal relaxing incision (hereinafter “CRI”), and Limbal Relaxing Incision (hereinafter “LRI”). Astigmatic Keratotomy, Corneal Relaxing Incision (CRI), and Limbal Relaxing Incision (LRI), corneal incisions are made in a well-defined manner and depth to allow the cornea to change shape to become more spherical. 
     Cataract extraction is a frequently performed surgical procedure. A cataract is formed by opacification of the crystalline lens of the eye. The cataract scatters light passing through the lens and may perceptibly degrade vision. A cataract can vary in degree from slight to complete opacity. Early in the development of an age-related cataract the power of the lens may increase, causing nearsightedness (myopia). Gradual yellowing and opacification of the lens may reduce the perception of blue colors as those shorter wavelengths are more strongly absorbed and scattered within the cataractous crystalline lens. Cataract formation may often progresses slowly resulting in progressive vision loss. 
     A cataract treatment may involve replacing the opaque crystalline lens with an artificial intraocular lens (IOL), and an estimated 15 million cataract surgeries per year are performed worldwide. Cataract surgery can be performed using a technique termed phacoemulsification in which an ultrasonic tip with associated irrigation and aspiration ports is used to sculpt the relatively hard nucleus of the lens to facilitate removal through an opening made in the anterior lens capsule. The nucleus of the lens is contained within an outer membrane of the lens that is referred to as the lens capsule. Access to the lens nucleus can be provided by performing an anterior capsulotomy in which a small round hole can be formed in the anterior side of the lens capsule. Access to the lens nucleus can also be provided by performing a manual continuous curvilinear capsulorhexis (CCC) procedure. After removal of the lens nucleus, a synthetic foldable intraocular lens (IOL) can be inserted into the remaining lens capsule of the eye. 
     Although prior methods and apparatus have been proposed to cut tissue, the fixation of tissue of these prior methods and apparatus can be less than ideal in at least some respects. For example, the prior microkeratomes that have been used to cut corneal tissue with blades can result in less than ideal fixation of the eye, and may provide incomplete or inaccurate cutting of the tissue in at least some instances. Also, at least some of the prior microkeratomes may result in temporary increases in intraocular pressure (hereinafter “IOP”) in at least some instances. Although prior laser systems have been proposed to cut tissue with short laser beam pulses, the methods and apparatus to couple the laser beam to the eye can be less than ideal in at least some instance. For example, at least some of the prior system can result in one or more of increased IOP, incomplete coupling to the eye, or patient movement relative to the laser in at least some instances. Although many patients have been successfully treated with the prior systems, the less than ideal coupling to the patient can result in a somewhat irregular treatment, or an incomplete treatment, for example. Work in relation to embodiments suggests that the coupling of the eye to the laser may be related to variability in the flow of suction to the eye. Also, the feedback provided to the physician can be less than ideal in at least some instances. The less than ideal coupling of the laser to the patient may result in patient movement, or the patient decoupling from the laser system, or both, such that the cutting of tissue may be less than ideal. 
     Thus, improved methods and apparatus to couple patients to treatment devices such as lasers would be helpful. 
     SUMMARY 
     The improved methods and apparatus for retention of an eye as described herein can be used to provide safe and effective retention for surgery such as laser eye surgery. The retention structure may comprise an annular structure to couple to an anterior surface of the eye, such as one or more of the cornea, the limbus, or the conjunctiva. The annular structure can be coupled to a suction line so as to couple the annular structure to the eye with suction. In many embodiments, a coupling sensor is coupled to one or more of the annular structure or the suction line to determine coupling of the retention structure to the eye, such that coupling of the retention structure to the eye can be measured quickly. The determination of coupling of the retention structure to the eye can be provided to the surgeon so that the surgeon can take appropriate action, and may allow the laser treatment to be paused or interrupted. A fluid collecting container can be coupled to the annular structure to receive and collect liquid or viscous material from the container. A fluid stop comprising a float valve or a porous structure can be coupled to an outlet of the fluid collecting container so as to inhibit passage of the liquid or viscous material when the container has received an amount of the liquid or viscous material greater than a volume of a patient interface container on the eye. The fluid stop can inhibit the passage of liquid or viscous material to structures downstream of the fluid stop such as a pressure regulator and vacuum pump, so as to provide consistent gas flow. The coupling sensor can be coupled upstream of the porous structure to provide a rapid measurement of the coupling of the retention structure to the eye, and may be coupled upstream of the fluid collecting container to further improve the response time of the coupling sensor. The liquid or viscous material may comprise a viscosity and a density greater than a gas such as air, and the liquid or viscous material may comprise one or more of a solvent, water, a liquid material, a solution, saline, a viscous material, or a viscoelastic material. The porous structure may comprise one or more of a filter, a membrane, a porous membrane having holes, a plate having holes, a hydrophobic material or a porous material. 
     In a first aspect, embodiments provide an apparatus to treat an eye. The apparatus comprises a patient interface. The patient interface comprises an annular structure to engage an anterior surface of the eye. The annular structure comprises an opening to receive a portion of the eye and channel to couple to the eye with suction, and an optically transmissive structure to transmit light through the opening of the annular structure. The optically transmissive structure and the annular structure define portions of an interface container when coupled to the eye, and the interface container comprises an interface container volume. A fluid collection container comprises an inlet and an outlet. The inlet is coupled to the channel of the annular structure, and the fluid collection container comprises a collection volume greater than the interface container volume. A porous structure has channels sized to pass gas and inhibit flow of a liquid or viscous material received from the fluid collection container. 
     In another aspect, embodiments provide a method of treating an eye. The method comprises coupling a patient interface to the eye with suction so as to define an optically transmissive interface container on the eye. The interface container has an interface container volume comprising one or more of a liquid or a viscous material. One or more of the liquid or viscous material is received from the patient interface into a fluid collection container. Flow of the liquid or viscous material is inhibited with a porous structure when the fluid collection container has received an amount of the liquid or viscous material greater than the chamber volume. 
     In another aspect, embodiments provide an apparatus to treat an eye. The apparatus comprises an annular structure to engage an anterior surface of the eye. The annular structure comprises an opening to receive a portion of the eye and a channel to couple to the eye with suction. A porous structure is coupled to the annular structure with a suction line, and has channels sized to pass gas and inhibit flow of a liquid or viscous material from the container. A coupling sensor is coupled to one or more of the annular structure or the suction line upstream of the porous structure to determine coupling of the annular structure to the eye. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    shows a perspective view showing a laser eye surgery system, in accordance with many embodiments; 
         FIG.  2    shows a simplified block diagram showing a top level view of the configuration of a laser eye surgery system, in accordance with many embodiments; 
         FIG.  3    shows is a simplified block diagram illustrating the configuration of an optical assembly of a laser eye surgery system, in accordance with many embodiments; 
         FIG.  4    shows a schematic diagram of the eye retention apparatus, in accordance with many embodiments; 
         FIGS.  5  and  6    show a perspective view and a cross sectional view, respectively, of an eye retention structure, in accordance with many embodiments; 
         FIGS.  7  and  8    show perspective view of a container assembly to collect fluid received from the retention ring structure, in accordance with many embodiments; 
         FIGS.  9 A and  9 B  show a fluid inhibiting structure comprising a porous structure to inhibit flow of a liquid or viscous material, in accordance with many embodiments; 
         FIG.  10    shows embodiments as described herein incorporated into an adaptive patient interface, in accordance with many embodiments; 
         FIG.  11    shows embodiments as described herein incorporated into a device and method for aligning an eye with a surgical laser, in accordance with many embodiments; 
         FIG.  12    shows embodiments as described herein incorporated into an apparatus for coupling an element to the eye, in accordance with many embodiments; 
         FIG.  13    shows embodiments as described herein incorporated into a servo controlled docking force device for use in ophthalmic applications, in accordance with many embodiments; and 
         FIG.  14    shows a method of treating a patient with the eye retention apparatus. 
     
    
    
     DETAILED DESCRIPTION 
     Methods and systems related to laser eye surgery are disclosed. In many embodiments, a laser is used to form precise incisions in the cornea, in the lens capsule, and/or in the crystalline lens nucleus. Although specific reference is made to tissue retention for laser eye surgery, embodiments as described herein can be used in one or more of many ways with many surgical procedures and devices, such as orthopedic surgery, robotic surgery and microkeratomes. 
     The embodiments as describe herein are particularly well suited for treating tissue, such as with the surgical treatment of tissue. In many embodiments, the tissue comprises an optically transmissive tissue, such as tissue of an eye. The embodiments as described herein can be combined in many ways with one or more of many known surgical procedures such as cataract surgery, laser assisted in situ keratomileusis (hereinafter “LASIK”), laser assisted subepithelial keratectomy (hereinafter “LASEK”). 
     Methods and systems related to laser treatment of materials and which can be used with eye surgery such as laser eye surgery are disclosed. A laser may be used to form precise incisions in the cornea, in the lens capsule, and/or in the crystalline lens nucleus, for example. The embodiments as described herein can be particularly well suited for coupling a retention structure to an eye so that movement of the eye can be decreased substantially, for example. 
     As used herein, the terms anterior and posterior refers to known orientations with respect to the patient. Depending on the orientation of the patient for surgery, the terms anterior and posterior may be similar to the terms upper and lower, respectively, such as when the patient is placed in a supine position on a bed. The terms distal and anterior may refer to an orientation of a structure from the perspective of the user, such that the terms proximal and distal may be similar to the terms anterior and posterior when referring to a structure placed on the eye, for example. A person of ordinary skill in the art will recognize many variations of the orientation of the methods and apparatus as described herein, and the terms anterior, posterior, proximal, distal, upper, and lower are used merely by way of example. 
     As used herein, the terms first and second are used to describe structures and methods without limitation as to the order of the structures and methods which can be in any order, as will be apparent to a person of ordinary skill in the art based on the teachings provided herein. 
     System Configuration 
       FIG.  1    shows a laser eye surgery system  2 , in accordance with many embodiments, operable to form precise incisions in the cornea, in the lens capsule, and/or in the crystalline lens nucleus. The system  2  includes a main unit  4 , a patient chair  6 , a dual function footswitch  8 , and a laser footswitch  10 . 
     The main unit  4  includes many primary subsystems of the system  2 . For example, externally visible subsystems include a touch-screen control panel  12 , a patient interface assembly  14 , patient interface vacuum connections  16 , a docking control keypad  18 , a patient interface radio frequency identification (RFID) reader  20 , external connections  22  (e.g., network, video output, footswitch, USB port, door interlock, and AC power), laser emission indicator  24 , emergency laser stop button  26 , key switch  28 , and USB data ports  30 . 
     The patient chair  6  includes a base  32 , a patient support bed  34 , a headrest  36 , a positioning mechanism, and a patient chair joystick control  38  disposed on the headrest  36 . The positioning control mechanism is coupled between the base  32  and the patient support bed  34  and headrest  36 . The patient chair  6  is configured to be adjusted and oriented in three axes (x, y, and z) using the patient chair joystick control  38 . The headrest  36  and a restrain system (not shown, e.g., a restraint strap engaging the patient&#39;s forehead) stabilize the patient&#39;s head during the procedure. The headrest  36  includes an adjustable neck support to provide patient comfort and to reduce patient head movement. The headrest  36  is configured to be vertically adjustable to enable adjustment of the patient head position to provide patient comfort and to accommodate variation in patient head size. 
     The patient chair  6  allows for tilt articulation of the patient&#39;s legs, torso, and head using manual adjustments. The patient chair  6  accommodates a patient load position, a suction ring capture position, and a patient treat position. In the patient load position, the chair  6  is rotated out from under the main unit  4  with the patient chair back in an upright position and patient footrest in a lowered position. In the suction ring capture position, the chair is rotated out from under the main unit  4  with the patient chair back in reclined position and patient footrest in raised position. In the patient treat position, the chair is rotated under the main unit  4  with the patient chair back in reclined position and patient footrest in raised position. 
     The patient chair  6  is equipped with a “chair enable” feature to protect against unintended chair motion. The patient chair joystick  38  can be enabled in either of two ways. First, the patient chair joystick  38  incorporates a “chair enable” button located on the top of the joystick. Control of the position of the patient chair  6  via the joystick  38  can be enabled by continuously pressing the “chair enable” button. Alternately, the left foot switch  40  of the dual function footswitch  8  can be continuously depressed to enable positional control of the patient chair  6  via the joystick  38 . To further protect against unintended chair motion, power supplied to the patient chair  6  may automatically be cut off using a switch. 
     In many embodiments, the patient control joystick  38  is a proportional controller. For example, moving the joystick a small amount can be used to cause the chair to move slowly. Moving the joystick a large amount can be used to cause the chair to move faster. Holding the joystick at its maximum travel limit can be used to cause the chair to move at the maximum chair speed. The available chair speed can be reduced as the patient approaches the patient interface assembly  14 . 
     The emergency stop button  26  can be pushed to stop emission of all laser output, release vacuum that couples the patient to the system  2 , and disable the patient chair  6 . The stop button  26  is located on the system front panel, next to the key switch  28 . 
     The key switch  28  can be used to enable the system  2 . When in a standby position, the key can be removed and the system is disabled. When in a ready position, the key enables power to the system  2 . 
     The dual function footswitch  8  is a dual footswitch assembly that includes the left foot switch  40  and a right foot switch  42 . The left foot switch  40  is the “chair enable” footswitch. The right footswitch  42  is a “vacuum ON” footswitch that enables vacuum to secure a liquid optics interface suction ring to the patient&#39;s eye. The laser footswitch  10  is a shrouded footswitch that activates the treatment laser when depressed while the system is enabled. 
     In many embodiments, the system  2  includes external communication connections. For example, the system  2  can include a network connection (e.g., an RJ45 network connection) for connecting the system  2  to a network. The network connection can be used to enable network printing of treatment reports, remote access to view system performance logs, and remote access to perform system diagnostics. The system  2  can include a video output port (e.g., HDMI) that can be used to output video of treatments performed by the system  2 . The output video can be displayed on an external monitor for, for example, viewing by family members and/or training. The output video can also be recorded for, for example, archival purposes. The system  2  can include one or more data output ports (e.g., USB) to, for example, enable export of treatment reports to a data storage device. The treatments reports stored on the data storage device can then be accessed at a later time for any suitable purpose such as, for example, printing from an external computer in the case where the user is without access to network based printing. 
       FIG.  2    shows a simplified block diagram of the system  2  coupled with a patient eye  43 . The patient eye  43  comprises a cornea, a lens, and an iris. The iris defines a pupil of the eye  43  that may be used for alignment of eye  43  with system  2 . The system  2  includes a cutting laser subsystem  44 , a ranging subsystem  46 , an alignment guidance system  48 , shared optics  50 , a patient interface  52 , control electronics  54 , a control panel/GUI  56 , user interface devices  58 , and communication paths  60 . The control electronics  54  is operatively coupled via the communication paths  60  with the cutting laser subsystem  44 , the ranging subsystem  46 , the alignment guidance subsystem  48 , the shared optics  50 , the patient interface  52 , the control panel/GUI  56 , and the user interface devices  58 . 
     In many embodiments, the cutting laser subsystem  44  incorporates femtosecond (FS) laser technology. By using femtosecond laser technology, a short duration (e.g., approximately 10 −13  seconds in duration) laser pulse (with energy level in the micro joule range) can be delivered to a tightly focused point to disrupt tissue, thereby substantially lowering the energy level required as compared to the level required for ultrasound fragmentation of the lens nucleus and as compared to laser pulses having longer durations. 
     The cutting laser subsystem  44  can produce laser pulses having a wavelength suitable to the configuration of the system  2 . As a non-limiting example, the system  2  can be configured to use a cutting laser subsystem  44  that produces laser pulses having a wavelength from 1020 nm to 1050 nm. For example, the cutting laser subsystem  44  can have a diode-pumped solid-state configuration with a 1030 (+/−5) nm center wavelength. 
     The cutting laser subsystem  44  can include control and conditioning components. For example, such control components can include components such as a beam attenuator to control the energy of the laser pulse and the average power of the pulse train, a fixed aperture to control the cross-sectional spatial extent of the beam containing the laser pulses, one or more power monitors to monitor the flux and repetition rate of the beam train and therefore the energy of the laser pulses, and a shutter to allow/block transmission of the laser pulses. Such conditioning components can include an adjustable zoom assembly to adapt the beam containing the laser pulses to the characteristics of the system  2  and a fixed optical relay to transfer the laser pulses over a distance while accommodating laser pulse beam positional and/or directional variability, thereby providing increased tolerance for component variation. 
     The ranging subsystem  46  is configured to measure the spatial disposition of eye structures in three dimensions. The measured eye structures can include the anterior and posterior surfaces of the cornea, the anterior and posterior portions of the lens capsule, the iris, and the limbus. In many embodiments, the ranging subsystem  46  utilizes optical coherence tomography (OCT) imaging. As a non-limiting example, the system  2  can be configured to use an OCT imaging system employing wavelengths from 780 nm to 970 nm. For example, the ranging subsystem  46  can include an OCT imaging system that employs a broad spectrum of wavelengths from 810 nm to 850 nm. Such an OCT imaging system can employ a reference path length that is adjustable to adjust the effective depth in the eye of the OCT measurement, thereby allowing the measurement of system components including features of the patient interface that lie anterior to the cornea of the eye and structures of the eye that range in depth from the anterior surface of the cornea to the posterior portion of the lens capsule and beyond. 
     The alignment guidance subsystem  48  can include a laser diode or gas laser that produces a laser beam used to align optical components of the system  2 . The alignment guidance subsystem  48  can include LEDs or lasers that produce a fixation light to assist in aligning and stabilizing the patient&#39;s eye during docking and treatment. The alignment guidance subsystem  48  can include a laser or LED light source and a detector to monitor the alignment and stability of the actuators used to position the beam in X, Y, and Z. The alignment guidance subsystem  48  can include a video system that can be used to provide imaging of the patient&#39;s eye to facilitate docking of the patient&#39;s eye  43  to the patient interface  52 . The imaging system provided by the video system can also be used to direct via the GUI the location of cuts. The imaging provided by the video system can additionally be used during the laser eye surgery procedure to monitor the progress of the procedure, to track movements of the patient&#39;s eye  43  during the procedure, and to measure the location and size of structures of the eye such as the pupil and/or limbus. 
     The shared optics  50  provides a common propagation path that is disposed between the patient interface  52  and each of the cutting laser subsystem  44 , the ranging subsystem  46 , and the alignment guidance subsystem  48 . In many embodiments, the shared optics  50  includes beam combiners to receive the emission from the respective subsystem (e.g., the cutting laser subsystem  44 , the ranging subsystem  46 , and the alignment guidance subsystem  48 ) and redirect the emission along the common propagation path to the patient interface. In many embodiments, the shared optics  50  includes an objective lens assembly that focuses each laser pulse into a focal point. In many embodiments, the shared optics  50  includes scanning mechanisms operable to scan the respective emission in three dimensions. For example, the shared optics can include an XY-scan mechanism(s) and a Z-scan mechanism. The XY-scan mechanism(s) can be used to scan the respective emission in two dimensions transverse to the propagation direction of the respective emission. The Z-scan mechanism can be used to vary the depth of the focal point within the eye  43 . In many embodiments, the scanning mechanisms are disposed between the laser diode and the objective lens such that the scanning mechanisms are used to scan the alignment laser beam produced by the laser diode. In contrast, in many embodiments, the video system is disposed between the scanning mechanisms and the objective lens such that the scanning mechanisms do not affect the image obtained by the video system. 
     The patient interface  52  is used to restrain the position of the patient&#39;s eye  43  relative to the system  2 . In many embodiments, the patient interface  52  employs a suction ring that is vacuum attached to the patient&#39;s eye  43 . The suction ring is then coupled with the patient interface  52 , for example, using vacuum to secure the suction ring to the patient interface  52 . In many embodiments, the patient interface  52  includes an optically transmissive structure having a posterior surface that is displaced vertically from the anterior surface of the patient&#39;s cornea and a region of a suitable liquid (e.g., a sterile buffered saline solution (BSS) such as Alcon BSS (Alcon Part Number 351-55005-1) or equivalent) is disposed between and in contact with the posterior surface and the patient&#39;s cornea and forms part of a transmission path between the shared optics  50  and the patient&#39;s eye  43 . The optically transmissive structure may comprise a lens  96  having one or more curved surfaces. Alternatively, the patient interface  22  may comprise an optically transmissive structure having one or more substantially flat surfaces such as a parallel plate or wedge. In many embodiments, the patient interface lens is disposable and can be replaced at any suitable interval, such as before each eye treatment. 
     The control electronics  54  controls the operation of and can receive input from the cutting laser subsystem  44 , the ranging subsystem  46 , the alignment guidance subsystem  48 , the patient interface  52 , the control panel/GUI  56 , and the user interface devices  58  via the communication paths  60 . The communication paths  60  can be implemented in any suitable configuration, including any suitable shared or dedicated communication paths between the control electronics  54  and the respective system components. 
     The control electronics  54  can include any suitable components, such as one or more processor, one or more field-programmable gate array (FPGA), and one or more memory storage devices. In many embodiments, the control electronics  54  controls the control panel/GUI  56  to provide for pre-procedure planning according to user specified treatment parameters as well as to provide user control over the laser eye surgery procedure. 
     The control electronics  54  may comprise a processor/controller  55  (referred to herein as a processor) that is used to perform calculations related to system operation and provide control signals to the various system elements. A computer readable medium  57  (also referred to as a database or a memory) is coupled to the processor  55  in order to store data used by the processor and other system elements. The processor  55  interacts with the other components of the system as described more fully throughout the present specification. In an embodiment, the memory  57  can include a look up table that can be utilized to control one or more components of the laser system as described herein. 
     The processor  55  can be a general purpose microprocessor configured to execute instructions and data, such as a Pentium processor manufactured by the Intel Corporation of Santa Clara, Calif. It can also be an Application Specific Integrated Circuit (ASIC) that embodies at least part of the instructions for performing the method in accordance with the embodiments of the present disclosure in software, firmware and/or hardware. As an example, such processors include dedicated circuitry, ASICs, combinatorial logic, other programmable processors, combinations thereof, and the like. 
     The memory  57  can be local or distributed as appropriate to the particular application. Memory  57  may include a number of memories including a main random access memory (RAM) for storage of instructions and data during program execution and a read only memory (ROM) in which fixed instructions are stored. Thus, memory  57  provides persistent (non-volatile) storage for program and data files, and may include a hard disk drive, flash memory, a floppy disk drive along with associated removable media, a Compact Disk Read Only Memory (CD-ROM) drive, an optical drive, removable media cartridges, and other like storage media. 
     The user interface devices  58  can include any suitable user input device suitable to provide user input to the control electronics  54 . For example, the user interface devices  58  can include devices such as, for example, the dual function footswitch  8 , the laser footswitch  10 , the docking control keypad  18 , the patient interface radio frequency identification (RFID) reader  20 , the emergency laser stop button  26 , the key switch  28 , and the patient chair joystick control  38 . 
       FIG.  3    is a simplified block diagram illustrating an assembly  62 , in accordance with many embodiments, that can be included in the system  2 . The assembly  62  is a non-limiting example of suitable configurations and integration of the cutting laser subsystem  44 , the ranging subsystem  46 , the alignment guidance subsystem  48 , the shared optics  50 , and the patient interface  52 . Other configurations and integration of the cutting laser subsystem  44 , the ranging subsystem  46 , the alignment guidance subsystem  48 , the shared optics  50 , and the patient interface  52  may be possible and may be apparent to a person of skill in the art. 
     The assembly  62  is operable to project and scan optical beams into the patient&#39;s eye  43 . The cutting laser subsystem  44  includes an ultrafast (UF) laser  64  (e.g., a femtosecond laser). Using the assembly  62 , optical beams can be scanned in the patient&#39;s eye  43  in three dimensions: X, Y, Z. For example, short-pulsed laser light generated by the UF laser  64  can be focused into eye tissue to produce dielectric breakdown to cause photodisruption around the focal point (the focal zone), thereby rupturing the tissue in the vicinity of the photo-induced plasma. In the assembly  62 , the wavelength of the laser light can vary between 800 nm to 1200 nm and the pulse width of the laser light can vary from 10 fs to 10000 fs. The pulse repetition frequency can also vary from 10 kHz to 500 kHz. Safety limits with regard to unintended damage to non-targeted tissue bound the upper limit with regard to repetition rate and pulse energy. Threshold energy, time to complete the procedure, and stability can bound the lower limit for pulse energy and repetition rate. The peak power of the focused spot in the eye  43  and specifically within the crystalline lens and the lens capsule of the eye is sufficient to produce optical breakdown and initiate a plasma-mediated ablation process. Near-infrared wavelengths for the laser light are preferred because linear optical absorption and scattering in biological tissue is reduced for near-infrared wavelengths. As an example, the laser  64  can be a repetitively pulsed 1031 nm device that produces pulses with less than 600 fs duration at a repetition rate of 120 kHz (+/−5%) and individual pulse energy in the 1 to 20 micro joule range. 
     The cutting laser subsystem  44  is controlled by the control electronics  54  and the user, via the control panel/GUI  56  and the user interface devices  58 , to create a laser pulse beam  66 . The control panel/GUI  56  is used to set system operating parameters, process user input, display gathered information such as images of ocular structures, and display representations of incisions to be formed in the patient&#39;s eye  43 . 
     The generated laser pulse beam  66  proceeds through a zoom assembly  68 . The laser pulse beam  66  may vary from unit to unit, particularly when the UF laser  64  may be obtained from different laser manufacturers. For example, the beam diameter of the laser pulse beam  66  may vary from unit to unit (e.g., by +/−20%). The beam may also vary with regard to beam quality, beam divergence, beam spatial circularity, and astigmatism. In many embodiments, the zoom assembly  68  is adjustable such that the laser pulse beam  66  exiting the zoom assembly  68  has consistent beam diameter and divergence unit to unit. 
     After exiting the zoom assembly  68 , the laser pulse beam  66  proceeds through an attenuator  70 . The attenuator  70  is used to adjust the transmission of the laser beam and thereby the energy level of the laser pulses in the laser pulse beam  66 . The attenuator  70  is controlled via the control electronics  54 . 
     After exiting the attenuator  70 , the laser pulse beam  66  proceeds through an aperture  72 . The aperture  72  sets the outer useful diameter of the laser pulse beam  66 . In turn the zoom determines the size of the beam at the aperture location and therefore the amount of light that is transmitted. The amount of transmitted light is bounded both high and low. The upper is bounded by the requirement to achieve the highest numerical aperture achievable in the eye. High NA promotes low threshold energies and greater safety margin for untargeted tissue. The lower is bound by the requirement for high optical throughput. Too much transmission loss in the system shortens the lifetime of the system as the laser output and system degrades over time. Additionally, consistency in the transmission through this aperture promotes stability in determining optimum settings (and sharing of) for each procedure. Typically to achieve optimal performance the transmission through this aperture as set to be between 88% to 92%. 
     After exiting the aperture  72 , the laser pulse beam  66  proceeds through two output pickoffs  74 . Each output pickoff  74  can include a partially reflecting mirror to divert a portion of each laser pulse to a respective output monitor  76 . Two output pickoffs  74  (e.g., a primary and a secondary) and respective primary and secondary output monitors  76  are used to provide redundancy in case of malfunction of the primary output monitor  76 . 
     After exiting the output pickoffs  74 , the laser pulse beam  66  proceeds through a system-controlled shutter  78 . The system-controlled shutter  78  ensures on/off control of the laser pulse beam  66  for procedural and safety reasons. The two output pickoffs precede the shutter allowing for monitoring of the beam power, energy, and repetition rate as a pre-requisite for opening the shutter. 
     After exiting the system-controlled shutter  78 , the optical beam proceeds through an optics relay telescope  80 . The optics relay telescope  80  propagates the laser pulse beam  66  over a distance while accommodating positional and/or directional variability of the laser pulse beam  66 , thereby providing increased tolerance for component variation. As an example, the optical relay can be a keplerian afocal telescope that relays an image of the aperture position to a conjugate position near to the xy galvo mirror positions. In this way, the position of the beam at the XY galvo location is invariant to changes in the beams angle at the aperture position. Similarly the shutter does not have to precede the relay and may follow after or be included within the relay. 
     After exiting the optics relay telescope  80 , the laser pulse beam  66  is transmitted to the shared optics  50 , which propagates the laser pulse beam  66  to the patient interface  52 . The laser pulse beam  66  is incident upon a beam combiner  82 , which reflects the laser pulse beam  66  while transmitting optical beams from the ranging subsystem  46  and the alignment guidance subsystem  48 . 
     Following the beam combiner  82 , the laser pulse beam  66  continues through a Z-telescope  84 , which is operable to scan focus position of the laser pulse beam  66  in the patient&#39;s eye  43  along the Z axis. For example, the Z-telescope  84  can include a Galilean telescope with two lens groups (each lens group includes one or more lenses). One of the lens groups moves along the Z axis about the collimation position of the Z-telescope  84 . In this way, the focus position of the spot in the patient&#39;s eye  43  moves along the Z axis. In general, there is a relationship between the motion of lens group and the motion of the focus point. For example, the Z-telescope can have an approximate 2×beam expansion ratio and close to a 1:1 relationship of the movement of the lens group to the movement of the focus point. The exact relationship between the motion of the lens and the motion of the focus in the z axis of the eye coordinate system does not have to be a fixed linear relationship. The motion can be nonlinear and directed via a model or a calibration from measurement or a combination of both. Alternatively, the other lens group can be moved along the Z axis to adjust the position of the focus point along the Z axis. The Z-telescope  84  functions as z-scan device for scanning the focus point of the laser-pulse beam  66  in the patient&#39;s eye  43 . The Z-telescope  84  can be controlled automatically and dynamically by the control electronics  54  and selected to be independent or to interplay with the X and Y scan devices described next. 
     After passing through the Z-telescope  84 , the laser pulse beam  66  is incident upon an X-scan device  86 , which is operable to scan the laser pulse beam  66  in the X direction, which is dominantly transverse to the Z axis and transverse to the direction of propagation of the laser pulse beam  66 . The X-scan device  86  is controlled by the control electronics  54 , and can include suitable components, such as a motor, galvanometer, or any other well known optic moving device. The relationship of the motion of the beam as a function of the motion of the X actuator does not have to be fixed or linear. Modeling or calibrated measurement of the relationship or a combination of both can be determined and used to direct the location of the beam. 
     After being directed by the X-scan device  86 , the laser pulse beam  66  is incident upon a Y-scan device  88 , which is operable to scan the laser pulse beam  66  in the Y direction, which is dominantly transverse to the X and Z axes. The Y-scan device  88  is controlled by the control electronics  54 , and can include suitable components, such as a motor, galvanometer, or any other well known optic moving device. The relationship of the motion of the beam as a function of the motion of the Y actuator does not have to be fixed or linear. Modeling or calibrated measurement of the relationship or a combination of both can be determined and used to direct the location of the beam. Alternatively, the functionality of the X-Scan device  86  and the Y-Scan device  88  can be provided by an XY-scan device configured to scan the laser pulse beam  66  in two dimensions transverse to the Z axis and the propagation direction of the laser pulse beam  66 . The X-scan and Y-scan devices  86 ,  88  change the resulting direction of the laser pulse beam  66 , causing lateral displacements of UF focus point located in the patient&#39;s eye  43 . 
     After being directed by the Y-scan device  88 , the laser pulse beam  66  passes through a beam combiner  90 . The beam combiner  90  is configured to transmit the laser pulse beam  66  while reflecting optical beams to and from a video subsystem  92  of the alignment guidance subsystem  48 . 
     After passing through the beam combiner  90 , the laser pulse beam  66  passes through an objective lens assembly  94 . The objective lens assembly  94  can include one or more lenses. In many embodiments, the objective lens assembly  94  includes multiple lenses. The complexity of the objective lens assembly  94  may be driven by the scan field size, the focused spot size, the degree of telecentricity, the available working distance on both the proximal and distal sides of objective lens assembly  94 , as well as the amount of aberration control. 
     After passing through the objective lens assembly  94 , the laser pulse beam  66  passes through the patient interface  52 . As described above, in many embodiments, the patient interface  52  includes a patient interface lens  96  having a posterior surface that is displaced vertically from the anterior surface of the patient&#39;s cornea and a region of a suitable liquid (e.g., a sterile buffered saline solution (BSS) such as Alcon BSS (Alcon Part Number 351-55005-1) or equivalent) is disposed between and in contact with the posterior surface of the patient interface lens  96  and the patient&#39;s cornea and forms part of an optical transmission path between the shared optics  50  and the patient&#39;s eye  43 . 
     The shared optics  50  under the control of the control electronics  54  can automatically generate aiming, ranging, and treatment scan patterns. Such patterns can be comprised of a single spot of light, multiple spots of light, a continuous pattern of light, multiple continuous patterns of light, and/or any combination of these. In addition, the aiming pattern (using the aim beam  108  described below) need not be identical to the treatment pattern (using the laser pulse beam  66 ), but can optionally be used to designate the boundaries of the treatment pattern to provide verification that the laser pulse beam  66  will be delivered only within the desired target area for patient safety. This can be done, for example, by having the aiming pattern provide an outline of the intended treatment pattern. This way the spatial extent of the treatment pattern can be made known to the user, if not the exact locations of the individual spots themselves, and the scanning thus optimized for speed, efficiency, and/or accuracy. The aiming pattern can also be made to be perceived as blinking in order to further enhance its visibility to the user. Likewise, the ranging beam  102  need not be identical to the treatment beam or pattern. The ranging beam needs only to be sufficient enough to identify targeted surfaces. These surfaces can include the cornea and the anterior and posterior surfaces of the lens and may be considered spheres with a single radius of curvature. Also the optics shared by the alignment guidance: video subsystem does not have to be identical to those shared by the treatment beam. The positioning and character of the laser pulse beam  66  and/or the scan pattern the laser pulse beam  66  forms on the eye  43  may be further controlled by use of an input device such as a joystick, or any other appropriate user input device (e.g., control panel/GUI  56 ) to position the patient and/or the optical system. 
     The control electronics  54  can be configured to target the targeted structures in the eye  43  and ensure that the laser pulse beam  66  will be focused where appropriate and not unintentionally damage non-targeted tissue. Imaging modalities and techniques described herein, such as those mentioned above, or ultrasound may be used to determine the location and measure the thickness of the lens and lens capsule to provide greater precision to the laser focusing methods, including 2D and 3D patterning. Laser focusing may also be accomplished by using one or more methods including direct observation of an aiming beam, or other known ophthalmic or medical imaging modalities, such as those mentioned above, and/or combinations thereof. Additionally the ranging subsystem such as an OCT can be used to detect features or aspects involved with the patient interface. Features can include fiducials placed on the docking structures and optical structures of the disposable lens such as the location of the anterior and posterior surfaces. 
     In the embodiment of  FIG.  3   , the ranging subsystem  46  includes an OCT imaging device. Additionally or alternatively, imaging modalities other than OCT imaging can be used. An OCT scan of the eye can be used to measure the spatial disposition (e.g., three dimensional coordinates such as X, Y, and Z of points on boundaries) of structures of interest in the patient&#39;s eye  43 . Such structure of interest can include, for example, the anterior surface of the cornea, the posterior surface of the cornea, the anterior portion of the lens capsule, the posterior portion of the lens capsule, the anterior surface of the crystalline lens, the posterior surface of the crystalline lens, the iris, the pupil, and/or the limbus. The spatial disposition of the structures of interest and/or of suitable matching geometric modeling such as surfaces and curves can be generated and/or used by the control electronics  54  to program and control the subsequent laser-assisted surgical procedure. The spatial disposition of the structures of interest and/or of suitable matching geometric modeling can also be used to determine a wide variety of parameters related to the procedure such as, for example, the upper and lower axial limits of the focal planes used for cutting the lens capsule and segmentation of the lens cortex and nucleus, and the thickness of the lens capsule among others. Additionally the ranging subsystem such as an OCT can be used to detect features or aspects involved with the patient interface. Features can include fiducials placed on the docking structures and optical structures of the disposable lens such as the location of the anterior and posterior surfaces. 
     The ranging subsystem  46  in  FIG.  3    includes an OCT light source and detection device  98 . The OCT light source and detection device  98  includes a light source that generates and emits an OCT source beam with a suitable broad spectrum. For example, in many embodiments, the OCT light source and detection device  98  generates and emits the OCT source beam with a broad spectrum from 810 nm to 850 nm wavelength. The generated and emitted light is coupled to the device  98  by a single mode fiber optic connection. 
     The OCT source beam emitted from the OCT light source and detection device  98  is passed through a pickoff/combiner assembly  100 , which divides the OCT source beam into a sample beam  102  and a reference portion  104 . A significant portion of the sample beam  102  is transmitted through the shared optics  50 . A relative small portion of the sample beam is reflected from the patient interface  52  and/or the patient&#39;s eye  43  and travels back through the shared optics  50 , back through the pickoff/combiner assembly  100  and into the OCT light source and detection device  98 . The reference portion  104  is transmitted along a reference path  106  having an adjustable path length. The reference path  106  is configured to receive the reference portion  104  from the pickoff/combiner assembly  100 , propagate the reference portion  104  over an adjustable path length, and then return the reference portion  106  back to the pickoff/combiner assembly  100 , which then directs the returned reference portion  104  back to the OCT light source and detection device  98 . The OCT light source and detection device  98  then directs the returning small portion of the sample beam  102  and the returning reference portion  104  into a detection assembly, which employs a time domain detection technique, a frequency detection technique, or a single point detection technique. For example, a frequency domain technique can be used with an OCT wavelength of 830 nm and bandwidth of 100 nm. 
     Once combined with the UF laser pulse beam  66  subsequent to the beam combiner  82 , the OCT sample beam  102  follows a shared path with the UF laser pulse beam  66  through the shared optics  50  and the patient interface  52 . In this way, the OCT sample beam  102  is generally indicative of the location of the UF laser pulse beam  66 . Similar to the UF laser beam, the OCT sample beam  102  passes through the Z-telescope  84 , is redirected by the X-scan device  86  and by the Y-scan device  88 , passes through the objective lens assembly  94  and the patient interface  52 , and on into the eye  43 . Reflections and scatter off of structures within the eye provide return beams that retrace back through the patient interface  52 , back through the shared optics  50 , back through the pickoff/combiner assembly  100 , and back into the OCT light source and detection device  98 . The returning back reflections of the sample beam  102  are combined with the returning reference portion  104  and directed into the detector portion of the OCT light source and detection device  98 , which generates OCT signals in response to the combined returning beams. The generated OCT signals that are in turn interpreted by the control electronics to determine the spatial disposition of the structures of interest in the patient&#39;s eye  43 . The generated OCT signals can also be interpreted by the control electronics to measure the position and orientation of the patient interface  52 , as well as to determine whether there is liquid disposed between the posterior surface of the patient interface lens  96  and the patient&#39;s eye  43 . 
     The OCT light source and detection device  98  works on the principle of measuring differences in optical path length between the reference path  106  and the sample path. Therefore, different settings of the Z-telescope  84  to change the focus of the UF laser beam do not impact the length of the sample path for an axially stationary surface in the eye of patient interface volume because the optical path length does not change as a function of different settings of the Z-telescope  84 . The ranging subsystem  46  has an inherent Z range that is related to the light source and detection scheme, and in the case of frequency domain detection the Z range is specifically related to the spectrometer, the wavelength, the bandwidth, and the length of the reference path  106 . In the case of ranging subsystem  46  used in  FIG.  3   , the Z range is approximately 4-5 mm in an aqueous environment. Extending this range to at least 20-25 mm involves the adjustment of the path length of the reference path via a stage ZED,  106  within ranging subsystem  46 . Passing the OCT sample beam  102  through the Z-telescope  84 , while not impacting the sample path length, allows for optimization of the OCT signal strength. This is accomplished by focusing the OCT sample beam  102  onto the targeted structure. The focused beam both increases the return reflected or scattered signal that can be transmitted through the single mode fiber and increases the spatial resolution due to the reduced extent of the focused beam. The changing of the focus of the sample OCT beam can be accomplished independently of changing the path length of the reference path  106 . 
     Because of the fundamental differences in how the sample beam  102  (e.g., 810 nm to 850 nm wavelengths) and the UF laser pulse beam  66  (e.g., 1020 nm to 1050 nm wavelengths) propagate through the shared optics  50  and the patient interface  52  due to influences such as immersion index, refraction, and aberration, both chromatic and monochromatic, care must be taken in analyzing the OCT signal with respect to the UF laser pulse beam  66  focal location. A calibration or registration procedure as a function of X, Y, and Z can be conducted in order to match the OCT signal information to the UF laser pulse beam focus location and also to the relative to absolute dimensional quantities. 
     There are many suitable possibilities for the configuration of the OCT interferometer. For example, alternative suitable configurations include time and frequency domain approaches, single and dual beam methods, swept source, etc, are described in U.S. Pat. Nos. 5,748,898; 5,748,352; 5,459,570; 6,111,645; and 6,053,613. 
     The system  2  can be set to locate the anterior and posterior surfaces of the lens capsule and cornea and ensure that the UF laser pulse beam  66  will be focused on the lens capsule and cornea at all points of the desired opening. Imaging modalities and techniques described herein, such as for example, Optical Coherence Tomography (OCT), and such as Purkinje imaging, Scheimpflug imaging, confocal or nonlinear optical microscopy, fluorescence imaging, ultrasound, structured light, stereo imaging, or other known ophthalmic or medical imaging modalities and/or combinations thereof may be used to determine the shape, geometry, perimeter, boundaries, and/or 3-dimensional location of the lens and lens capsule and cornea to provide greater precision to the laser focusing methods, including 2D and 3D patterning. Laser focusing may also be accomplished using one or more methods including direct observation of an aiming beam, or other known ophthalmic or medical imaging modalities and combinations thereof, such as but not limited to those defined above. 
     Optical imaging of the cornea, anterior chamber, and lens can be performed using the same laser and/or the same scanner used to produce the patterns for cutting. Optical imaging can be used to provide information about the axial location and shape (and even thickness) of the anterior and posterior lens capsule, the boundaries of the cataract nucleus, as well as the depth of the anterior chamber and features of the cornea. This information may then be loaded into the laser 3-D scanning system or used to generate a three dimensional model/representation/image of the cornea, anterior chamber, and lens of the eye, and used to define the cutting patterns used in the surgical procedure. 
     Observation of an aim beam can also be used to assist in positioning the focus point of the UF laser pulse beam  66 . Additionally, an aim beam visible to the unaided eye in lieu of the infrared OCT sample beam  102  and the UF laser pulse beam  66  can be helpful with alignment provided the aim beam accurately represents the infrared beam parameters. The alignment guidance subsystem  48  is included in the assembly  62  shown in  FIG.  3   . An aim beam  108  is generated by an aim beam light source  110 , such as a laser diode in the 630-650 nm range. 
     Once the aim beam light source  110  generates the aim beam  108 , the aim beam  108  is transmitted along an aim path  112  to the shared optics  50 , where it is redirected by a beam combiner  114 . After being redirected by the beam combiner  114 , the aim beam  108  follows a shared path with the UF laser pulse beam  66  through the shared optics  50  and the patient interface  52 . In this way, the aim beam  108  is indicative of the location of the UF laser pulse beam  66 . The aim beam  108  passes through the Z-telescope  84 , is redirected by the X-scan device  86  and by the Y-scan device  88 , passes through the beam combiner  90 , passes through the objective lens assembly  94  and the patient interface  52 , and on into the patient&#39;s eye  43 . 
     The video subsystem  92  is operable to obtain images of the patient interface and the patient&#39;s eye. The video subsystem  92  includes a camera  116 , an illumination light source  118 , and a beam combiner  120 . The video subsystem  92  gathers images that can be used by the control electronics  54  for providing pattern centering about or within a predefined structure. The illumination light source  118  can be generally broadband and incoherent. For example, the light source  118  can include multiple LEDs. The wavelength of the illumination light source  118  is preferably in the range of 700 nm to 750 nm, but can be anything that is accommodated by the beam combiner  90 , which combines the light from the illumination light source  118  with the beam path for the UF laser pulse beam  66 , the OCT sample beam  102 , and the aim beam  108  (beam combiner  90  reflects the video wavelengths while transmitting the OCT and UF wavelengths). The beam combiner  90  may partially transmit the aim beam  108  wavelength so that the aim beam  108  can be visible to the camera  116 . An optional polarization element can be disposed in front of the illumination light source  118  and used to optimize signal. The optional polarization element can be, for example, a linear polarizer, a quarter wave plate, a half-wave plate or any combination. An additional optional analyzer can be placed in front of the camera. The polarizer analyzer combination can be crossed linear polarizers thereby eliminating specular reflections from unwanted surfaces such as the objective lens surfaces while allowing passage of scattered light from targeted surfaces such as the intended structures of the eye. The illumination may also be in a dark-field configuration such that the illumination sources are directed to the independent surfaces outside the capture numerical aperture of the image portion of the video system. Alternatively the illumination may also be in a bright field configuration. In both the dark and bright field configurations, the illumination light source maybe be used as a fixation beam for the patient. The illumination may also be used to illuminate the patients pupil to enhance the pupil iris boundary to facilitate iris detection and eye tracking. A false color image generated by the near infrared wavelength or a bandwidth thereof may be acceptable. 
     The illumination light from the illumination light source  118  is transmitted through the beam combiner  120  to the beam combiner  90 . From the beam combiner  90 , the illumination light is directed towards the patient&#39;s eye  43  through the objective lens assembly  94  and through the patient interface  94 . The illumination light reflected and scattered off of various structures of the eye  43  and patient interface travel back through the patient interface  94 , back through the objective lens assembly  94 , and back to the beam combiner  90 . At the beam combiner  90 , the returning light is directed back to the beam combiner  120  where the returning light is redirected toward the camera  116 . The beam combiner can be a cube, plate, or pellicle element. It may also be in the form of a spider mirror whereby the illumination transmits past the outer extent of the mirror while the image path reflects off the inner reflecting surface of the mirror. Alternatively, the beam combiner could be in the form of a scraper mirror where the illumination is transmitted through a hole while the image path reflects off of the mirrors reflecting surface that lies outside the hole. The camera  116  can be an suitable imaging device, for example but not limited to, any silicon based detector array of the appropriately sized format. A video lens forms an image onto the camera&#39;s detector array while optical elements provide polarization control and wavelength filtering respectively. An aperture or iris provides control of imaging NA and therefore depth of focus and depth of field and resolution. A small aperture provides the advantage of large depth of field that aids in the patient docking procedure. Alternatively, the illumination and camera paths can be switched. Furthermore, the aim light source  110  can be made to emit infrared light that would not be directly visible, but could be captured and displayed using the video subsystem  92 . 
       FIG.  4    shows a schematic diagram of an apparatus  200  to treat eye  43  comprising components of laser system  2  and patient interface assembly  52  as described herein. The patient interface assembly  52  may comprise a docking structure  210  and an eye retention structure  250 . The docking structure  210  may comprise a docking cone and the eye retention structure  250  may comprise a suction ring. The patient interface assembly comprises an axis  258  substantially aligned with an axis of the laser system  2  and an axis of the eye  43 . The axis  258  extends through an inner channel of docking structure  210  and an inner channel of the eye retention structure  250 , and the axis  258  can be substantially concentric with respect to both of these structures. The eye retention structure  250  and the docking structure  210  may comprise components of the patient interface assembly, and these structures may be separable so as to define separate components of the patient interface assembly  52 . Alternatively, the eye retention structure  250  and the docking structure  210  can be provided together as a substantially inseparable component of the patient interface assembly  52 . 
     The docking structure  210  may comprise an anterior end portion  216  to couple to a receptacle of laser system  2 , and a posterior end portion  214  to couple to the eye retention structure  250 . The docking structure  210  may comprise a conical structure extending between anterior end portion  216  and posterior end portion  214 . The docking structure  210  may comprise an optically transmissive structure  212  comprising an optically transmissive material and may comprise one or more of a first curved surface, a second curved surface, a first flat surface, a second flat surface, and a lens, a plate, or a wedge. The optically transmissive structure  214  may comprise lens  96 , for example. 
     The optically transmissive structure  212  can be located on the docking structure  210  or the eye retention structure  250 , or combinations thereof, for example. The posterior surface of the optically transmissive structure  210  and the inner surface of the eye retention structure substantially define an interface fluid container  218  when placed on the eye. The interface fluid container  218  comprises an interface fluid container volume. 
     The eye retention structure  250  comprises a posterior end portion having an opening  251  sized to receive at least a portion of the cornea  43 C of eye  43 . The eye retention structure  250  is coupled to one or more suction lines  220  to retain the eye  43  when the cornea  43 C extends into opening  251 . The one or more suction lines  220  may comprise a plurality of suction lines. The plurality of suction lines  220  may comprise first suction line  222  and second suction line  224 . 
     The first suction line  222  extends from a suction ring of eye retention structure  250  to a vacuum source such as an eye retention structure vacuum pump  237 . A plurality of components is coupled to suction line  222 , and may be coupled along first suction line  222  in series. A first fluid collector comprising a first container  231  is coupled to eye retention structure  250  to receive fluid from eye retention structure  250 . Line  222  may comprise tubing extending at least partially between eye retention structure  250  and first fluid collector comprising container  231 , for example. The first fluid collector comprising first container  231  may comprise any one or more of many structures suitable to collect a liquid or viscous material as described herein, and the first fluid collector  231  may comprise a catchment, for example. Container  231  comprises an inlet  331  and an outlet  333 . Container  231  comprises a container volume approximately corresponding to an amount of liquid stored in container  231  when a liquid is drawn into container  231  through inlet  331  with suction of outlet  333 . A first fluid stop  232  is coupled to outlet  333  of first container  231 . The first fluid stop  232  comprises a float valve  232 F or a porous structure  232 P to pass a gas such as air and inhibit flow of a liquid or viscous material as described herein, so as to stop substantially the flow of the liquid or viscous. The first fluid stop  232  comprises an inlet  335  and an outlet  337 . The inlet  335  is coupled to the outlet  333  of the container  231 . The outlet  337  of the fluid stop  232  is coupled to a suction monitor  233 , which can be positioned along first suction line  222  in order to monitor suction of the line. In many embodiments, suction monitor  233  comprising the pressure sensor is positioned along the suction line downstream of the porous structure  232 P and in many embodiments placed along the suction line  222  between the fluid stop  232  and a solenoid valve  234 . The pressure sensor can be coupled to control electronics  54  with communication paths  60 , as described herein. The pressure sensor may comprise one or more of many transducers responsive to pressure of suction line  222 , and such transducers are known to a person of ordinary skill in the art. The suction solenoid valve  234  can be coupled to control electronics  54  with communication paths as described herein. The first suction line  222  may comprise a suction line monitor  235  to monitor suction downstream of suction solenoid valve  234 . The suction line monitor  235  can be coupled to the first suction line  222  between suction solenoid valve  234  and a suction vacuum regulator  236 . The suction vacuum regulator  236  can be provided along first suction line  222  so as to provide a regulated amount of pressure to eye  43  with the suction ring, for example suction pressure between about 300 and 500 mm Hg (millimeters Mercury), for example. The outlet of the suction vacuum regulator  236  is coupled to an inlet of the eye retention structure vacuum pump  237 . The eye retention vacuum pump  237  may be coupled to control electronics  54  with communication paths  60 . 
     The components along first suction line  222  can be configured in one or more of many ways to couple eye retention structure  250  to eye  43 . In many embodiments, the first container  231  comprises a volume that is greater than a volume of container  218  of patient interface. When used to couple to the eye, retention structure  250  can be placed on eye  43  with the liquid or viscous material within container  218 , and suction applied to retention structure  250 . When the retention structure  250  is not sufficiently coupled to eye  43 , the fluid of container  218  can be drawn into container  231  with suction. When a sufficient amount of the liquid or viscous material has been drawn into container  231 , a portion of the liquid or viscous material is passed through outlet  333  and onto porous structure  232 P so as to inhibit flow of fluid through the porous structure. Where the first fluid stop  232  comprises the float valve  232 F, a portion of the liquid or viscous material is passed through outlet  333  and triggers the float valve  232 F to close so as to inhibit flow of fluid through the first fluid stop  232 . Alternatively, the fluid stop function of the porous structure  232 P or the float valve  232 F may be integrated into the fluid collector  241 . The volume of the container  231  greater than the volume of container  218  allows the physician to place substantial amounts of fluid within container  218  when coupling the retention structure  250  to the eye. In many embodiments, the volume of container  218  comprises at least about twice the volume of the container  231 , so that the user of system  2  has at least about two attempts to couple retention structure  250  to eye  43  before the flow of suction  222  is substantially inhibited by fluid stop  232 . In many embodiments, the container  218  comprises a volume of about 0.5 to 2 cubic centimeters (hereinafter “cc”) and container  231  comprises a volume within a range from about 1 to about 4 cc, for example. 
     In many embodiments, the ratio of container  231  to the ratio of container  218  can be limited such that the suction of line  222  can engage eye  2  with sufficient suction pressure in a sufficiently short amount of time, so that the retention structure can be readily used by a physician. In many embodiments, the volume of container  231  comprises no more than about twenty times the volume of container  218 , for example no more than about five times the volume of container  218 . 
     A coupling sensor  228  can be coupled to eye retention structure  250  in one or more of many ways, for example with a line  226  in order to monitor coupling of retention structure  250  to eye  43 . Coupling sensor  228  may comprise one or more of a force transducer, or a pressure transducer, for example. In many embodiments, line  226  is fluidically coupled to a posterior annular suction ring of retention structure  250  upstream of fluid stop  232  such that coupling sensor  228  can rapidly measure changes in suction pressure and issue a warning to the user or interrupt the laser, for example, when an amount of pressure of line  226  rises above a threshold amount. Line  226  may comprise tubing, for example. Line  226  can be coupled upstream of fluid stop  232  in many ways can be directly coupled to retention structure  250  or coupled to line  222  upstream of fluid stop  232  so as to monitor coupling of retention structure  250  to eye  43 . Coupling of line  226  upstream of fluid trap  232  can provide a more rapid response to changes in suction pressure than suction monitor  233  located downstream of fluid stop  232 . The coupling sensor  228  can be coupled to electronic control  54  with communication paths  60  and the output of coupling sensor  228  can be used to control operation of laser system  2  as described herein. 
     The fluid stop  232  comprising porous structure  232 P can be configured in one or more of many ways to inhibit flow of fluid along line  222  when container  231  has received a sufficient amount of the liquid or viscous material. The liquid or viscous material may comprise one or more of water, a liquid material, a solution, saline, a viscous material, or a viscoelastic material, for example. The liquid or viscous material may comprise a viscosity and density substantially greater than a gas such as air, and may be substantially incompressible, such that passage of the liquid or viscous material through the porous structure is substantially inhibited. The porous structure may comprise one or more of a filter, a membrane, a porous membrane having holes, a plate having holes or a hydrophobic material. The porous structure comprises channels, for example holes, sized so as to inhibit passage of the liquid or viscous material through the porous structure. The porous structure may comprise a membrane having holes formed in a hydrophobic material, the holes having a cross-sectional size of no more than about 10 um across so as to block the passage of the liquid or viscous material through the porous structure, for example. 
     The second suction line  224  extends from retention structure  250  to a vacuum source such as dock vacuum pump  247 . The second suction line  224  can provide suction to an interface between docking structure  210  and eye retention structure  250 , so as to suction clamp the docking structure  210  to the eye retention structure  250  when the patient is treated, for example. Line  224  may comprise tubing extending at least partially between eye retention structure  250  and second fluid collector comprising second container  241 , for example. Dock vacuum pump  247  is coupled to an anterior portion of eye retention structure  250  so as to engage the anterior portion of the eye retention structure with docking structure  210 , for example a docking cone. A second plurality of components is coupled to second suction line  224 , and may be coupled along second suction line  224  in series. A second fluid collector comprising a second container  241  is coupled to eye retention structure  250  to receive fluid the anterior portion of eye retention structure  250  used to connect to docking structure  210 . The second fluid collector comprising second container  241  may comprise any one or more of many structures suitable to collect a liquid or viscous material as described herein, and the second fluid collector  241  may comprise a catchment, for example. Second container  241  comprises an inlet  341  and an outlet  343 . Second container  241  comprises a container volume approximately corresponding to an amount of liquid stored in container  241  when a liquid is drawn into container  241  through inlet  341  with suction of outlet  343 . A second fluid stop  242  is coupled to outlet  343  of second container  241 . The second fluid stop  242  comprises a second porous structure  242 P or a second float valve  242 F to pass a gas such as air an inhibit flow of a liquid or viscous material as described herein, so as to stop substantially the flow of the liquid or viscous. The second fluid stop  242  comprises an inlet  345  and an outlet  347 . The inlet  345  is coupled to the outlet  343  of the second container  241 . The outlet  347  of the second fluid stop  242  is coupled to a dock monitor  243 , which can be positioned along second suction line  224  in order to monitor suction for coupling docking structure  210  to retention structure  250  as described herein. In many embodiments, suction monitor  243  comprising the pressure sensor is positioned along the second suction line downstream of the second porous structure  242 P or second float valve  242 F and in many embodiments placed along the second suction line  224  between the fluid second stop  242  and a second solenoid vale  244 . The pressure sensor can be coupled to control electronics  54  with communication paths  60 , as described herein. The pressure sensor may comprise one or more of many transducers responsive to pressure of suction line  224 , and such transducers are known to a person of ordinary skill in the art. The suction solenoid valve  244  can be coupled to control electronics  54  with communication paths as described herein. The second suction line  224  may comprise a suction line monitor  245  to monitor suction downstream of suction solenoid valve  244 . The suction line monitor  245  can be couple to an inlet of the vacuum pump  247 . The vacuum pump  247  may be coupled to control electronics  54  with communication paths  60 . 
     The second fluid collector comprising container  241  may comprise a volume less than first container  231 , for example. The second fluid collector may collect substantially less fluid than the first fluid collector, as the first line  222  may often couple to retention structure  250  at a location below second line  224 , for example. Decreasing the volume of the second container  241  may provide more rapid suction clamping of the docking structure  210  to the retention structure  250 . Alternatively, the container  241  may comprise a volume that is greater than container  231 , for example. 
     The coupling lines as described herein may comprise lines for fluidic coupling known to a person of ordinary skill in the art and may comprise one or more of tubing, flexible tubing, rigid tubing, plastic tubing, metal tubing or manifolds, for example. The containers as described herein may comprise similar materials and can be constructed by a person of ordinary skill in the art based on the teachings provided herein. 
       FIGS.  5  and  6    show a perspective view and a cross sectional view, respectively, of eye retention structure  250 . Eye retention structure  250  comprises opening  251  on a posterior end portion  252  dimensioned to receive the cornea  43 C of eye  43 . The posterior end portion  252  may comprise an elastic suction ring  260 . The eye retention structure  250  may comprise an anterior end portion  254  and an intermediate portion  256  extending between the posterior end portion  252  and the anterior end portion  254 . The posterior end portion  252 , the anterior end portion  254 , and the intermediate section  256  can be located about an axis  258  for alignment with an axis of the eye, and for alignment with an optical axis of system  2 , so as to align optical axis of system  2  with the eye  43 . The eye retention structure  250  may comprise a handle  290 . The first suction line  222  can be coupled to the interior of suction ring  260  with a channel  266  and an annular channel  268  extending substantially around an anterior portion suction ring  260  interior. 
     The suction ring  260  may comprise an elastomeric component comprising medical grade silicon, for example. The suction ring  260  may comprise an outer rim  262  and an inner rim  263 . The inner rim  263  and the outer rim  262  can be dimensioned so as to fit on a peripheral portion of cornea  43 C and may engage a portion of the conjunctiva of the eye over the sclera of the eye, for example. The inner and outer rim can be located at different locations along axis  258  such that outer rim  262  comprise a posterior end of eye retention structure  250 , and inner rime  263  is located anterior to the outer rim. The angle extending between outer rim  262  and inner rim  263  may correspond to an angle of the eye, so as to engage the eye and fix the eye with suction ring  260 . The inner rim  263  and outer rim  262  may comprise sealing blades to form a seal with the eye and vacuum clamp to eye  43 . The suction ring  260  may comprise a support bolster  267  to inhibit tissue movement between the inner rim  263  and the outer rim  262  upon application of suction. 
     The intermediate section  256  may comprise a stiff housing  270  to couple the eye to the docking structure  210 . A channel  272  can be formed in housing  270  to allow placement of fluid into the chamber  218  and release of fluid from chamber  218  so as to inhibit pressure increases when container  218  is formed with the anterior surface of the eye. The housing  270  may comprise an annular channel  274  formed in a posterior surface of the housing to receive the annular suction ring  260 . The housing  270  may comprise a passage defined with an inner surface  276 . The inner surface of housing  270  may comprise a conical surface, such as a frustum of a cone for example. The docking structure  210  comprising the optically transmissive structure  212  can position a posterior surface of the optically transmissive structure  212  at location  278  along the axis  258 . The volume of container  218  can be determined based on the dimensions of inner surface  278 , the position of posterior surface of structure  212  along axis  258  and the approximate location of the cornea  43 C along axis  258 . The approximate location of cornea  43 C along axis  258  may comprise correspond to the location of channel  274  which receives the suction ring. A substantial portion of container  218  can be define with stiff housing  270  such that container  218  comprises a substantially constant volume. The housing  270  can be rigid and may comprise a rigid material to add stiffness to the housing, for example a suitable plastic material. 
     The anterior end portion  254  may comprise an annular structure  280 . The annular structure  280  may comprise an annular groove to receive a gasket  282  to engaging the docking structure  210 . The annular structure  280  may extend substantially around anterior end portion  254  and comprise a portion of housing  270 . The annular structure  280  may comprise an opening  287  to couple to second line  224  as described herein. The annular structure  280  may comprise an inner annular surface  286  dimensioned so as to guide the docking structure  210  toward an annular seal  284 . The annular gasket  284  may comprise an inner rim  288  to contact the docking structure  210  and form a seal. The gasket  282  spaced apart from gasket  284 , such that suction of second line  224  forms a vacuum clamp. 
       FIGS.  7  and  8    show perspective view of a container assembly  300  comprising a plurality of containers to collect material received from the retention ring structure. The plurality of containers may comprise first container  231  and second container  241 . The first container  231  comprises inlet  331  and outlet  333 , and the second container  241  comprises inlet  341  and outlet  343 . The container assembly  300  comprises a mount  350  to hang the container assembly at a suitable location of system  2 . The container assembly  300  comprises an anterior portion  310  and a posterior portion  320 . The anterior portion may be joined to the posterior portion with a joint  315  extending there between. The joint  315  may comprise one or more of a snap fitting, a compression fitting, a friction fitting, ultrasonic weld, or an adhesive, for example. 
       FIGS.  9 A and  9 B  show fluid inhibiting structure comprising porous structure  232 P to inhibit flow a liquid or viscous material. The fluid inhibiting structure may comprise fluid stop  232  as described herein. The fluid stop  232  comprises inlet  335  and outlet  337 . As shown in  FIG.  9 A , the fluid stop  232  may comprise the porous structure  232 P. The porous structure  232 P can be located along the line  222 , such that the liquid or viscous material passed through inlet  335  is deposited on the porous structure  232 P. The liquid or viscous material can accumulate on the upstream side of porous structure  232 P so as to inhibit flow of fluid through the porous structure. When a sufficient amount of a fluid has accumulated on the upstream side of surface of porous structure  232 P, flow of fluid through the porous structure  232 P is substantially decreased and in many embodiments the flow is blocked. The porous structure  232 P may comprise one or more of many components commercially available from known suppliers of filters having one or more properties as described herein. As shown in  FIG.  9 B , the fluid stop  232  may comprise a float valve  232 F. The float valve  232 F can be located along the line  222 , such that the liquid or viscous material passed through inlet  334  can accumulate within the fluid stop  232 . When a sufficient amount of fluid has accumulated, the float valve  232 F will be trigger to close to block the flow. The second fluid stop  242  may comprise similar structures to first fluid stop  232 . 
       FIG.  10    shows embodiments as described herein incorporated into an adaptive patient interface. An adaptive patient interface is described in Patent Cooperation Treaty Patent Application (hereinafter “PCT”) PCT/US2011/041676, published as WO 2011/163507, entitled “ADAPTIVE PATIENT INTERFACE”. The eye retention structure  250  may comprise one or more structures and functions as described herein. The container  218  can be formed on the eye. The first suction line  222  can be coupled to the suction ring placed on the eye, and the first suction line coupled to the fluid collector comprising container  231  and porous structure  232 P as described herein. The coupling sensor  228  can be coupled to the suction ring and the first line  222  upstream of the porous structure  232 P as described herein, for example. The coupling sensor  228  is coupled to the control electronics with communication paths  60 . 
       FIG.  11    shows embodiments as described herein incorporated into a device and method for aligning an eye with a surgical laser. A device and method for aligning an eye with a surgical laser are described in PCT/IB2006/000002, published as WO 2006/09021, entitled “DEVICE AND METHOD FOR ALIGNING AN EYE WITH A SURGICAL LASER”. The eye retention structure  250  may comprise one or more structures and functions as described herein. The retention structure  250  may comprise the optically transmissive structure  212  as described herein having a concavely curved posterior surface that conforms substantially to a radius of curvature of the eye, such that the volume of the container  218  can be substantially zero when the retention ring structure is coupled to the eye. The radius of curvature of the concavely curved posterior surface example within a range from about 7 mm to about 12 mm, for example about 8.8 mm. In these embodiments, the fluid collector  231  and fluid stop  232  can be coupled to the suction line  222 . The first suction line  222  can be coupled to the suction ring placed on the eye, and the first suction line coupled to the fluid collector comprising container  231  and porous structure  232 P as described herein. The coupling sensor  228  can be coupled to the suction ring and the first line  222  upstream of the porous structure  232 P as described herein, for example. The coupling sensor  228  is coupled to the control electronics with communication paths  60  as described herein. The second line  224  to vacuum clamp the docking structure  210  can be coupled to the fluid collector comprising container  241  and fluid stop  242  comprising porous structure  242 P or float valve  242 F as described herein. 
       FIG.  12    shows embodiments as described herein incorporated into an apparatus for coupling an element to the eye. An apparatus for coupling an element to the eye is described in U.S. application Ser. No. 12/531,217, published as U.S. Pub. No. 2010/0274228, entitled “APPARATUS FOR COUPLING AN ELEMENT TO THE EYE”. The eye retention apparatus  250  can form container  218  having the volume when placed on the eye as described herein, and the optically transmissive structure  212  can be attached to retention structure  250  or docking structure  210 , for example. The first line  222  can be coupled to the fluid collector comprising container  231  and fluid stop  232  comprising porous structure  232 P as described herein. The coupling sensor  228  can be coupled to the suction ring and the first line  222  upstream of the porous structure  232 P as described herein, for example. The coupling sensor  228  can be coupled to the control electronics with communication paths  60  as described herein. The second line  224  to vacuum clamp the docking structure  210  can be coupled to the fluid collector comprising container  241  and fluid stop  242  comprising porous structure  242 P or float valve  242 F as described herein. 
       FIG.  13    shows embodiments as described herein incorporated into a servo controlled docking force device for use in ophthalmic applications. A servo controlled docking force device for use in ophthalmic applications is described in U.S. application Ser. No. 13/016,593, published as U.S. Pub. No. US 2011/0190739, entitled “SERVO CONTROLLED DOCKING FORCE DEVICE FOR USE IN OPHTHALMIC APPLICATIONS”. The eye retention apparatus  250  can form container  218  which may comprise a fluidic chamber having the volume when placed on the eye as described herein. The optically transmissive structure  212  can be attached to retention structure  250  or docking structure  210 , for example. The first line  222  can be coupled to the fluid collector comprising container  231  and fluid stop  232  comprising porous structure  232 P as described herein. The coupling sensor  228  can be coupled with the coupling line  226  to one or more of the suction ring or the first line  222  upstream of the porous structure  232 P as described herein, for example. The coupling sensor  228  can be coupled to the control electronics with communication paths  60  as described herein. 
       FIG.  14    shows a method  400  of treating a patient with the eye retention apparatus. 
     The method  300  may use one or more of the structures as described herein, and one or more functions of the one or more structures may be used to perform the method  400  as described herein. 
     At a step  405 , a fluid collector having a volume is provided with a porous structure. 
     At a step  410 , suction is provided to a suction line coupled to the fluid collector and the porous structure as described herein. 
     At a step  415 , the patient is placed on a support. 
     At a step,  420  a speculum is placed in the eye. 
     At a step  425 , the retention structure with the suction ring is placed on the eye to define container. 
     At a step  430 , the eye is aligned with the retention structure. 
     At a step  435 , coupling suction is applied to the eye. 
     At a step  440 , eye coupling is measured with suction upstream of the porous structure as described herein. 
     At a step  445 , suction is measured downstream of porous structure as described herein. 
     At a step  450 , provide an indication to the user when the eye retention structure is held to eye with suction based on coupling suction. 
     At a step  455 , a liquid or viscous solution is applied to container on eye. 
     At a step  460 —at least partial blockage of porous structure is identified when coupling suction above a threshold and downstream suction below a second threshold 
     At a step  465 , the above steps are repeated until the eye is coupled to the retention structure with suction. 
     At a step  470 , the docking structure is coupled to the retention structure with axial movement. 
     At a step  475 , suction is a applied to gap between retention structure and docking structure to clamp retention structure to docking structure with suction. 
     At a step  480 , eye coupling suction is measured. 
     At a step  485 , alignment of eye with retention structure is determined. 
     At a step  490 , the eye is at least partially treated with the laser. 
     At a step  495 , coupling suction is measured. 
     At a step  500 , a warning is provided to the user when eye coupling suction rises above a warning threshold. 
     At a step  505 , laser firing is interrupted when eye the measured coupling suction is above an interruption threshold pressure. 
     At a step  510 , an indicator is provided to the user when the measured coupling pressure is above the threshold pressure. 
     At a step  515 , the eye is re-aligned with the retention structure. 
     At a step  520 , the eye is re-coupled to the eye retention structure. 
     At a step  525 , the laser treatment is resumed. 
     At a step  530 , the laser treatment has been completed. 
     At a step  535 , the eye is decoupled from the retention structure. 
     At a step  540 , the retention structure is decoupled from docking structure 
     At a step  545 , the remaining portion of the eye surgery is completed, for example with removal of the lens and insertion of an IOL. 
     Although the above steps show method  400  of treating a patient in accordance with embodiments, a person of ordinary skill in the art will recognize many variations based on the teaching described herein. The steps may be completed in a different order. Steps may be added or deleted. Some of the steps may comprise sub-steps. Many of the steps may be repeated as often as if beneficial to the treatment. 
     One or more of the steps of the method  400  may be performed with the circuitry as described herein, for example one or more of the processor or logic circuitry such as the programmable array logic for field programmable gate array. The circuitry may be programmed to provide one or more of the steps of method  400 , and the program may comprise program instructions stored on a computer readable memory or programmed steps of the logic circuitry such as the programmable array logic or the field programmable gate array, for example. 
     While preferred embodiments of the present disclosure have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will be apparent to those skilled in the art without departing from the scope of the present disclosure. It should be understood that various alternatives to the embodiments of the present disclosure described herein may be employed without departing from the scope of the present invention. Therefore, the scope of the present invention shall be defined solely by the scope of the appended claims and the equivalents thereof.