Patent Publication Number: US-2018049916-A1

Title: Subretinal injection apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation-in-Part to 15/091,924 filed Apr. 6, 2016 and claims priority of U.S. Provisional Application No. 62/144,034 filed Apr. 7, 2015, the contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     I. Field of the Invention 
     The present invention relates generally to medical devices and, more particularly, to a subretinal injection device for the injection of fluid under the retina of a human eye during retinal surgery. 
     II. Description of Related Art 
     During retinal surgery it is oftentimes necessary to inject fluids underneath the retina. Injection of fluids underneath the retina is difficult to accomplish for a number of different reasons. 
     For example, the amount of space underneath the retina is very limited. As such, in order to inject the fluid underneath the retina it is necessary to insert a cannula into the eyeball so that the open end of the cannula is positioned beneath the retina. This is typically accomplished by using a conventional syringe. 
     However, in order to actually inject the fluid underneath the retina, it is necessary for the surgeon to depress the syringe actuator in order to inject the fluid from the cannula and simultaneously maintain the open end of the cannula essentially motionless so that it remains underneath the retina. This procedure is difficult to perform especially for surgeons with small hands. Furthermore, in the event that the syringe moves during the injection process, unacceptable damage to the retina can result. 
     SUMMARY OF THE PRESENT INVENTION 
     The present invention provides a medical device which overcomes the above-mentioned disadvantages of the previously known retinal injection devices. 
     In brief, the present invention provides a subretinal injection device having an injection syringe. The injection syringe includes a needle adapted for insertion behind the retina of the eye. The syringe includes a barrel which defines a chamber which contains the fluid for injection. 
     An injection needle is then fluidly connected to one end of the syringe chamber. The other end of the syringe chamber is closed by a plunger which is slidably mounted to the syringe. Consequently, upon depression of the plunger into the syringe, the plunger forces the fluid contained within the syringe out through the needle. 
     In order to control the actuation of the plunger, and thus the injection of fluid into the eye, an air pump is fluidly connected to the outer end of the plunger. Consequently, upon an increase of the air pressure by the air pump, the plunger is displaced within the syringe thus injecting the fluid from the syringe. 
     Preferably, the air pump includes an injection needle which is fluidly connected to the plunger by a flexible tube. The tube, however, is fluidly sealed. Consequently, fluid can be displaced from the injection syringe by simply increasing the air pressure to the injection syringe but without manually moving the injection syringe. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       A better understanding of the present invention will be had upon reference to the following detailed description when read in conjunction with the accompany drawing, wherein like reference characters refer to like parts throughout the several views, and in which: 
         FIG. 1  is a view illustrating a preferred embodiment of the subretinal injection device of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE PRESENT INVENTION 
     With reference to the drawing, a preferred embodiment of an apparatus  10  according to the present invention is shown for subretinal injection in a human eye. The device  10  includes a first syringe  12  with an outwardly extending cannula or needle  14 . The needle  14  is adapted for insertion into the human patient&#39;s eye behind the retina. The needle  14  size is in the range of 23 gauge to 39 gauge at the top of the needle  14 . 
     In the conventional fashion, the syringe  12  includes a plunger  16  within the syringe  12  so that the displacement of the plunger  16  injects fluid from the open end of the cannula  14 . Consequently, the entire volume between the plunger  16  and the cannula  14  is filled with a fluid intended for injection during the medical procedure. 
     In order to axially displace the plunger  16  in the syringe  12 , the syringe  12  is fluidly connected by a tube  34  to an air pump  20 . Although any conventional means may be used to fluidly connect the syringe  12  to the air pump  20 , the fluid connection between the cylinder  20  and the syringe  12  is airtight and includes an elongated flexible conduit  34 . 
     The air pump  20  preferably includes a plunger  34  slidably mounted within an elongated tube  22 . The plunger  24  is initially positioned adjacent one end of the tube  22  while the elongated flexible tube  34  is fluidly connected to the opposite end  30  of the cylinder  20 . Consequently, displacement of the plunger  24  within the cylinder  20  fluidly pumps air from the cylinder  20 , through the tube  24 , and into the syringe  12  at the end of the plunger  16  opposite from the injection cannula  14 . 
     Any means may be used to displace the plunger  24  in the tube  22  in order to inject fluid from the syringe  12  out through the cannula  14 . However, as shown in the drawing, an actuator handle  26  is preferably connected to the plunger  24  so that the plunger  24  may be manually or machine displaced in its tube  22  by the doctor or other medical personnel. Furthermore, a handle  26  is preferably connected to the plunger  24  to facilitate the manual displacement of the plunger  24  in the fluid pump  22  and thus the displacement of the plunger  16  in the syringe  12 . 
     During an operation, the cannula  14  is first inserted by the doctor behind the retina. Thereafter, injection of fluid from the syringe  12  is controlled by displacing the actuator  26 . Since the actuator  26  is only indirectly fluidly connected to the syringe  12  by the flexible tube  34 , the syringe  12  remains stationary during the injection process. 
     Having described my invention, many modifications thereto will become apparent to those skilled in the art to which it pertains without deviation from the spirit of the invention as defined by the scope of the appended claims.