Abstract:
A surgical system with a variable controller that allows the user to selectively vary the level of venting performance.

Description:
BACKGROUND OF THE INVENTION  
       [0001]    This invention relates generally to the field of cataract surgery and more particularly to a method of operating a surgical system or console. 
         [0002]    The human eye in its simplest terms functions to provide vision by transmitting light through a clear outer portion called the cornea, and focusing the image by way of the lens onto the retina. The quality of the focused image depends on many factors including the size and shape of the eye, and the transparency of the cornea and lens. 
         [0003]    When age or disease causes the lens to become less transparent, vision deteriorates because of the diminished light which can be transmitted to the retina. This deficiency in the lens of the eye is medically known as a cataract. An accepted treatment for this condition is surgical removal of the lens and replacement of the lens function by an artificial intraocular lens (IOL). 
         [0004]    In the United States, the majority of cataractous lenses are removed by a surgical technique called phacoemulsification. During this procedure, a thin phacoemulsification cutting tip is inserted into the diseased lens and vibrated ultrasonically. The vibrating cutting tip liquefies or emulsifies the lens so that the lens may be aspirated out of the eye. The diseased lens, once removed, is replaced by an artificial lens. 
         [0005]    A typical ultrasonic surgical device suitable for ophthalmic procedures consists of an ultrasonically driven handpiece, an attached cutting tip, and irrigating sleeve and an electronic control console. The handpiece assembly is attached to the control console by an electric cable and flexible tubings. Through the electric cable, the console varies the power level transmitted by the handpiece to the attached cutting tip and the flexible tubings supply irrigation fluid to and draw aspiration fluid from the eye through the handpiece assembly. 
         [0006]    The operative part of the handpiece is a centrally located, hollow resonating bar or horn directly attached to a set of piezoelectric crystals. The crystals supply the required ultrasonic vibration needed to drive both the horn and the attached cutting tip during phacoemulsification and are controlled by the console. The crystal/horn assembly is suspended within the hollow body or shell of the handpiece by flexible mountings. The handpiece body terminates in a reduced diameter portion or nosecone at the body&#39;s distal end. The nosecone is externally threaded to accept the irrigation sleeve. Likewise, the horn bore is internally threaded at its distal end to receive the external threads of the cutting tip. The irrigation sleeve also has an internally threaded bore that is screwed onto the external threads of the nosecone. The cutting tip is adjusted so that the tip projects only a predetermined amount past the open end of the irrigating sleeve. 
         [0007]    In use, the ends of the cutting tip and irrigating sleeve are inserted into a small incision of predetermined width in the cornea, sclera, or other location. The cutting tip is ultrasonically vibrated along its longitudinal axis within the irrigating sleeve by the crystal-driven ultrasonic horn, thereby emulsifying the selected tissue in situ. The hollow bore of the cutting tip communicates with the bore in the horn that in turn communicates with the aspiration line from the handpiece to the console. A reduced pressure or vacuum source in the console draws or aspirates the emulsified tissue from the eye through the open end of the cutting tip, the cutting tip and horn bores and the aspiration line and into a collection device. The aspiration of emulsified tissue is aided by a saline flushing solution or irrigant that is injected into the surgical site through the small annular gap between the inside surface of the irrigating sleeve and the cutting tip. Once the hard parts of the lens is emulsified and removed, the ultrasonic cutting step is typically followed by Irrigation/Aspiration (I/A) step that removes the softer lens material by aspirating only. 
         [0008]    While the fragments of the material to be aspirated are reduced to the size which may flow uninhibited through tip of the handpiece, occasionally they block the aspiration port without going though. In these cases the user typically vents (i.e. releases vacuum from the aspiration line). The act of venting allows user to release the blocking fragment, so he/she can reposition it, to attempt further aspiration. Also in some instances, the aspiration port may accidentally capture a tissue that was not intended for aspiration, such as iris or posterior capsule. In these cases the user employs venting as well, to release the captured tissue to prevent tissue damage. 
         [0009]    Venting process typically involves opening a vent valve to release vacuum and bringing system pressure to vent source pressure. Depending on the venting system type (fluid or air vented) the vent source pressure would vary. For example air vented system would vent to the ambient pressure (i.e. 0.) A liquid venting system may vent to the irrigation bottle, i.e. to the hydrostatic pressure that is function of the bottle height. Also, some instruments may utilize different or additional methods of venting, such as aspiration pump reversal. In all cases, the system pressure is automatically brought to a fixed level determined by the system design. 
         [0010]    While fixed pressure venting typically accomplishes the task, wide variety of the modern phaco tips and accessories, as well as wide range of a modern system settings (such bottle height and vacuum limit), can affect the consistency of the venting action user gets. In addition, a variety of evolved user techniques contributes to the variability of the vent performance. For example, a certain user technique can result in under-venting, forcing user to use reflux more often. In other cases, a user technique can be prone to over-venting, resulting in excessive lens material regurgitation. Depending upon the surgical technique being employed, this automatic operation can result to too much or too little vacuum being vented. This is particularly true with the large number of different types of tips, techniques and accessories currently available. 
         [0011]    Therefore, a need continues to exist for a method of variably controlling aspiration venting on surgical consoles. 
       BRIEF SUMMARY OF THE INVENTION  
       [0012]    The present invention improves upon the prior art by providing a surgical system with a variable controller that allows the user to selectively vary the level of venting performance. Accordingly, one objective of the present invention is to provide a surgical console control system. 
         [0013]    Another objective of the present invention is to provide a surgical console control system allowing the user to adjust or control the venting operation. 
         [0014]    These and other advantages and objectives of the present invention will become apparent from the detailed description and claims that follow. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0015]      FIG. 1  is a perspective view of an exemplary surgical control console that may be used with the present invention. 
           [0016]      FIG. 2  is a schematic illustration of a system and cassette that can be used with the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0017]    System  10  of the present invention generally includes surgical console  12  and cassette  14 . Console  12  may be any suitably modified commercially available surgical console, such as the INFINITI® Vision System available from Alcon Laboratories, Fort Worth, Tex. Cassette  14  may be any suitably modified commercially available surgical cassettes, such as those described in U.S. Pat. Nos. 5,267,956, 5,364,342 and 5,499,969 (Beuchat, et al.), U.S. Pat. No. 5,899,674 (Jung, et al.) or U.S. Pat. No. 6,962,488 B2 (Davis, et al.). Cassette  14  is held in operative association with console  12  by means well-known in art. 
         [0018]    As seen in  FIG. 2 , console  12  generally contains aspiration pump mechanism  16 , which may be any suitable flow or vacuum based pump, such pumps being widely known in the art. For example, pump mechanism  16  may be a peristaltic pump roller head that interacts with a peristaltic pump tube formed by aspiration line  20  and aspiration exhaust line  34 . Aspiration line  20  is connected to surgical handpiece  22  on one end and end  18  of aspiration line  20  opposite handpiece  22  interacts with pump mechanism  16  so as to draw fluid through handpiece  22  thereby providing handpiece  22  with an aspiration function. Aspiration line  20  is intersected between handpiece  22  and  18  by aspiration vent line  24 . In fluid communication with aspiration vent line  24  is pressure sensor  26 , which may be one of a variety of invasive or non-invasive pressure sensors well-known in the art. 
         [0019]    Cassette  14  generally contains fluid reservoir  28 . Extending from reservoir  28  at or near bottom  29  is aspiration vent line  32 , which fluidly connects to aspiration vent line  24  through vent valve  30 . Aspirant or exhaust from pump mechanism  16  is directed into reservoir  28  through aspiration exhaust line  34 . Reservoir  28  may also vent to ambient through reservoir vent line  36  which may contain antimicrobial filter  38 . 
         [0020]    As discussed above, while it is preferred that pump mechanism  16  be a peristaltic roller head and that aspiration line  20  and aspiration exhaust line  34  be formed in one continuous length so as to form a peristaltic pump tube that interacts with pump mechanism  16 , one skilled in the art will recognize that aspiration line  20  and aspiration exhaust line  34  may be formed as a separate piece or pieces or may be formed integrally with cassette  14  and that pump mechanisms  16  other than peristaltic pump roller heads may be used, such as linear peristaltic pumps. 
         [0021]    In addition, pressure sensor  26  is depicted as being contained within console  12 . One skilled in the art will recognize that portions of pressure sensor  26 , such as a pressure diaphragm (not shown) may be contained in or on cassette  14  and interact with a force transducer or other means (not shown) contained within console  12 . 
         [0022]    In use, cassette  14  is installed on or within console  12  and held in operative association with console  12  in cassette receiving area  5  of console  12  by means well-known in the art. System  10  is primed initially with clean surgical fluid so that a small amount of fluid fills reservoir  28 . During surgery, pump mechanism  16  draws aspirant through handpiece  22  and into reservoir  28 . If the vacuum within aspiration line  20  is too high and needs to be vented, vent valve  30  is opened allowing aspirant to be drawn from reservoir  28  at or near bottom  29  (reservoir  28  being at or near ambient) and into aspiration line  20  (which contains a vacuum) through aspiration vent line  24 . One skilled in the art will recognize that by varying the vertical position of reservoir  28  relative to aspiration line  20 , various vent head pressures may be achieved. In addition, pump  16  may also be reversed, while monitoring pressure sensor  26 , so as to pressurize aspiration line  20  and thereby help reduce the vacuum in aspiration line  20  in an expeditious manner. 
         [0023]    The present invention includes allowing the user to adjust the venting operation of vent valve  30  and pump  16 . Such adjustment can be made through any of a variety of input devices or mechanisms normally found on commercially available surgical consoles, such as touch screen  113  on console  12  or footswitch  115  connected to control console  12 , by software commands well within the capabilities of one skilled in the art. Such adjustments may be made in any of a number of ways, such as varying the timing of the operation vent valve  30 , variably changing the requested drop in vacuum or varying the amount of aspiration fluid displaced. In addition, system  10  can contain pre-programmed “levels” of venting adjustment (e.g., aggressive, moderate, mild), with the user selecting a desired level. 
         [0024]    This description is given for purposes of illustration and explanation. It will be apparent to those skilled in the relevant art that changes and modifications may be made to the invention described above without departing from its scope or spirit.