Patent Publication Number: US-2007106301-A1

Title: Sclerotomy adapter

Description:
BACKGROUND OF THE INVENTION  
      This invention relates generally to the field of microsurgery and, more particularly, to posterior segment ophthalmic microsurgery.  
      Current vitreoretinal techniques in which surgical instruments are inserted into the eye require the dissection of the conjunctiva and the creation of pars plana scleral incisions through the sclera. The dissection of the conjunctiva typically involves pulling back the conjunctiva about the eye so as to expose large areas of the sclera. Following the creation of the incisions, surgical instruments are passed through these incisions and the inserted instruments are observed through the pupil using a microscope and corrective optics. These instruments are used to manipulate and/or dissect retinal tissues within the eye as well as to implement the specific retinal treatment technique (e.g., photocoagulation). Many scleral incisions created for vitreoretinal surgery are made large enough to accommodate the required instruments, the inserted portions being typically 19 or 20 gauge (approximately 1 mm) in diameter. After completing the specific treatment procedure, the inserted instruments are removed from the incisions in the sclera. Because the incisions through the sclera are large enough to pass 19 or 20 gauge instruments, the incisions are typically too large to self-seal. Thus, the incisions must be sutured shut. Following the suturing of the scleral incisions, the surgical personnel reposition the conjunctiva in its normal position and suture the conjunctival incision. While such methods and techniques have proven to be effective in the treatment of vitreoretinal disease, there is a strong motivation to move away from procedures requiring sutures and instead look to greatly simplified sutureless procedures. Therefore, recently some surgical instruments have been miniaturized so that the cannulas or shafts of the instruments are on the order of 23 or 25 gauge. While many surgeons prefer to use smaller gauge instruments, larger gauge instruments must sometimes also be used during a surgical procedure. This requires that the scierotomy be made larger enough to accommodate the larger instruments. The larger incision; however, may leak when smaller gauge instruments are used later in the procedure.  
      Therefore, a need continues to exist for an adapter for a sclerotomy that facilitates the use of smaller gauge instrument with incisions sized to accommodate larger gauge instruments.  
     BRIEF SUMMARY OF THE INVENTION  
      The present invention improves upon the prior art by providing a thin walled, hubbed cannula with an exterior diameter of approximately that of a 20 gauge surgical instrument and in interior bore having a diameter that is slightly larger than a 23 gauge or 25 gauge surgical instrument. The scleral contact surface of the hub of the adapter also can be rounded to provide a pivot point for the surgical instrument shaft, thereby reducing bending forces on the relatively thin shaft of the instrument.  
      Accordingly, one objective of the present invention is to provide a sclerotomy adapter.  
      Another objective of the present invention is to provide a thin walled cannula with a hub.  
      Another objective of the present invention is to provide a sclerotomy adapter that helps reduce bending forces on a surgical instrument.  
      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 DRAWING  
       FIG. 1  is an end view of the sclerotomy adapter of the present invention.  
       FIG. 2  is a longitudinal cross-sectional view of the sclerotomy adapter of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      As best seen in  FIGS. 1 and 2 , sclerotomy adapter  10  of the present invention generally includes hub  12  integrally formed with cannula or shaft  14 . Adapter  10  may be formed of any suitable material such as stainless steel or titanium, but molded or machined thermoplastic is preferred. Adapter  10  contains bore  16  that extends the entire length of adapter  10  through hub  12  and cannula  14 . Hub  12  may be round or oval in plan view with a minor diameter of approximately between 0.50 inches and 0.70 inches and a major diameter of approximately between 0.80 inches and 0.10 inches. Cannula  14  extends approximately between 0.100 inches and 0.200 inches distally from hub  12 , with between approximately 0.145 inches being most preferred. Preferably, tip  22  of cannula  14  is rounded for ease of insertion into an incision. Cannula  14  has an outside diameter that approximates the outer diameter of 20 gauge surgical instruments, on the order of between 0.034 inches and 0.038 inches. Bore  16  has a diameter that is slightly larger than the outer diameter of 23 gauge or 25 gauge surgical instruments. Hub  12  contains chamfered or beveled portion  18  at the entrance to bore  16 , for example, cut at a 45° angle, which assists in the insertion of a surgical tool into bore  16 . Hub  12  also contains rounded shoulders  20  that contact the incision and prevent hub  12  from entering the incision. Shoulders  20  also help provide a pivot point for adapter  10  that assists in preventing bending of a surgical tool while being used with adapter  10 .  
      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.