Patent Publication Number: US-2022233768-A1

Title: Method and apparatus for subretinal injection

Description:
PRIORITY CLAIM 
     This application claims the benefit of priority of U.S. Provisional Patent Application Ser. No. 63/141,051 titled “METHOD AND APPARATUS FOR SUBRETINAL INJECTION,” filed on Jan. 25, 2021, whose inventors are Niels Alexander Abt and Reto Grüebler, which is hereby incorporated by reference in its entirety as though fully and completely set forth herein. 
    
    
     BACKGROUND 
     Field 
     Embodiments of the present disclosure generally relate to devices for ophthalmic treatment, and more particularly, to an apparatus and method for performing subretinal injection. Subretinal injection generally refers to injection of fluid or other therapeutic substances or stem cells into a subretinal space between a retina and a retinal pigment epithelium (RPE) of an eye. 
     Description of the Related Art 
     Certain diseases of the eye are treatable via injection into the subretinal space including, e.g., age-related macular degeneration (AMD) and retinal degenerative diseases and genetic defects. Typical practice requires at least two persons to administer the subretinal injection. For example, a lead surgeon may guide the injection instrument, e.g., a syringe/needle, and visually monitor the injection site, while a skilled surgical assistant pushes the fluid from the syringe and monitors the injection volume. Accordingly, typically, a first syringe is prepared with a small gauge needle and containing a non-treatment fluid, e.g., balanced salt solution (BSS). In the first step of the procedure, the first syringe is inserted through the retina into the subretinal space. While the surgeon handles the first syringe and visually monitors the injection site, the assistant manually injects the non-treatment fluid and monitors the injection volume. Next, the first syringe is removed from the eye. 
     A second syringe is prepared with a small gauge needle and containing a treatment fluid, e.g., including a therapeutic. In the second step of the procedure, the second syringe is inserted through the retina into the subretinal space at about the same location as the first syringe. While the surgeon handles the second syringe and visually monitors the injection site, the assistant manually injects the treatment fluid and monitors the injection volume. Consequently, there are many disadvantages with using a handheld injection instrument to manually control the injection in a two-step process. Some of these disadvantages are described below. 
     First, performing the injection with the injection instrument being handheld, as described above, can result in tearing of the retina. In particular, tearing of the retina can result from inadvertent movement of the syringe/needle due to external forces from outside the eye while the needle is inserted through the retina. The external forces may include inadvertent movements on the part of the surgeon during handling of the syringe or on the part of the assistant during manual control of the fluid injection. 
     Furthermore, manual control of the fluid injection, as described above, can have a number of additional disadvantages. Typically, manual control of the fluid injection involves manual depression of the plunger. For example, manual control of the fluid injection can result in incorrect injection volume, which can result in over- or under-dosing or excessive retinal stretch. In another example, manual control of the fluid injection can result in a high flow velocity into the subretinal space which can damage the retina or the RPE, e.g., causing rhegmatogenous-like retinal detachment with changes in retinal morphology or RPE atrophy. In yet another example, manual control of the fluid injection can result in a high shear force in the needle which can be detrimental to the biologic activity of various therapeutics, e.g., drugs, stem cells, viral vectors, carried by the injection fluid. 
     In addition, removing the first needle and inserting the second needle through the retina, as described above, can have further disadvantages. For example, making several insertions through the retina can contribute to retinal tearing. In another example, forming two different holes in the retina, one for each injection step, increases the potential for fluid to leak from the subretinal space. 
     Each of the problems described above can negatively impact the ophthalmic treatment being administered and/or carry an increased safety risk. Therefore, what is needed in the art are improved devices for ophthalmic treatment including an improved apparatus and method for subretinal injection. 
     SUMMARY 
     The present disclosure generally relates to devices for ophthalmic treatment, and more particularly, to an apparatus and method for performing subretinal injection. 
     In certain embodiments, an apparatus is provided for performing a subretinal injection into a subretinal space between a retina and a retinal pigment epithelium of an eye. The apparatus includes an injection needle having a proximal end and a distal end, the distal end configured to be insertable into the subretinal space at a position on a surface of the retina. The apparatus includes a multi-lumen tubing having a distal end coupled to the proximal end of the injection needle and a proximal end coupled to a fluid control unit, the multi-lumen tubing having a first lumen and a second lumen. The apparatus includes a stabilizer configured to immobilize the injection needle at the position on the surface of the retina. The fluid control unit has a first fluid reservoir containing a non-treatment solution and a second fluid reservoir containing a treatment solution. The fluid control unit is configured to inject the non-treatment solution from the first fluid reservoir to the subretinal space via the first lumen and to inject the treatment solution from the second fluid reservoir into the subretinal space via the second lumen. 
     In certain embodiments, a method is disclosed for performing a subretinal injection into a subretinal space between a retina and a retinal pigment epithelium of an eye. The method includes inserting a distal end of an injection needle into the subretinal space at a position on a surface of the retina, the injection needle having a proximal end coupled to a distal end of a multi-lumen tubing, the multi-lumen tubing having a proximal end coupled to a fluid control unit. The method includes immobilizing the injection needle at the position on the surface of the retina by applying a pressure or fluid through a first lumen of the multi-lumen tubing to extend a stabilizer beyond a distal end of the first lumen to contact the surface of the retina. The method includes injecting a non-treatment solution from the fluid control unit to the subretinal space via a second lumen of the multi-lumen tubing. The method includes injecting a treatment solution to the subretinal space via a third lumen of the multi-lumen tubing using the fluid control unit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of its scope, and may admit to other equally effective embodiments. 
         FIG. 1A  is a schematic view of an exemplary injection apparatus for performing a subretinal injection, according to certain embodiments. 
         FIG. 1B  is a transverse sectional view of a portion of an eye illustrating the retina and retinal pigment epithelium. 
         FIG. 1C  is an enlarged side sectional view taken along the section line of  FIG. 1A  illustrating an exemplary multi-lumen tubing, according to certain embodiments. 
         FIG. 1D  is a top isometric view of a portion of the injection apparatus of  FIG. 1A . 
         FIG. 2A  is a schematic view of an exemplary inserter device, which may be used with the injection apparatus described herein, according to certain embodiments. 
         FIG. 2B  is a schematic view of another exemplary inserter device, which may be used with the injection apparatus described herein, according to certain embodiments. 
         FIG. 2C  is a schematic view of the injection apparatus of  FIG. 1A  illustrating an exemplary inserter device combined therewith, according to certain embodiments. 
         FIG. 2D  is an enlarged side sectional view of a portion of  FIG. 2C  illustrating an exemplary injection needle, used in connection with the injection apparatus described herein, according to certain embodiments. 
         FIG. 3  is an isometric view of an exemplary injection apparatus for performing a subretinal injection used during operation, according to certain embodiments. 
         FIG. 4  is a diagram illustrating a method of performing a subretinal injection, according to certain embodiments. 
         FIGS. 5A, 6A, 7A, 8A, 9A, 10A, 11A, and 12A  are transverse sectional views of an eye at different operations of the method of  FIG. 4 , according to certain embodiments. 
         FIGS. 5B, 6B, 7B, 8B, 9B, 10B, 11B, and 12B  are sectional views taken along section lines of  5 A,  6 A,  7 A,  8 A,  9 A,  10 A,  11 A, and  12 A, respectively, according to certain embodiments. 
         FIG. 7C  is an enlarged sectional view of a portion of  FIG. 7A  illustrating an exemplary stabilizer, which may be used with the injection apparatus described herein, according to certain embodiments. 
         FIG. 9C  is an enlarged sectional view of a portion of  FIG. 9A  illustrating formation of a bleb in the subretinal space, according to certain embodiments. 
         FIG. 13A  is an isometric view of another exemplary injection needle, which may be used with the injection apparatus described herein, according to certain embodiments. 
         FIG. 13B  is a side sectional view of the injection needle of  FIG. 13A  illustrating the injection needle inserted into the subretinal space, according to certain embodiments. 
         FIG. 14A  is an isometric view of yet another exemplary injection needle, which may be used with the injection apparatus described herein, according to certain embodiments. 
         FIG. 14B  is a side sectional view of the injection needle of  FIG. 14A  illustrating the injection needle inserted into the subretinal space, according to certain embodiments. 
         FIG. 15  is a top isometric view of another exemplary stabilizer, which may be used with the injection apparatus described herein, according to certain embodiments. 
         FIG. 16  is a top isometric view of yet another exemplary stabilizer, which may be used with the injection apparatus described herein, according to certain embodiments. 
         FIG. 17  is a top isometric view of yet another exemplary stabilizer, which may be used with the injection apparatus described herein, according to certain embodiments. 
         FIG. 18  is a schematic view of an exemplary guidewire, which may be used with the injection apparatus described herein, according to certain embodiments. 
     
    
    
     To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. 
     DETAILED DESCRIPTION 
     The present disclosure generally relates to devices for ophthalmic treatment, and more particularly, to an apparatus and method for performing subretinal injection. 
     Embodiments of the present disclosure describe an apparatus for performing a subretinal injection. In general, the apparatus includes an injection needle attached to a tubing which can be secured within the eye using a stabilizer such that the injection instrument does not need to be held throughout the entire procedure. This provides decoupling of the injection needle from undesirable movements that would otherwise occur when the injection instrument is handheld. Furthermore, the tubing of the apparatus is coupled to a fluid pump outside the eye in order to automate the actual fluid injection process. Automated control of fluid injection can improve control over injection volumes as well as improve control of important flow related parameters of the injection fluid compared to manual control of fluid injection. Additionally, the tubing of the apparatus is a multi-lumen tubing which provides a plurality of parallel flow paths from separate fluid reservoirs to the injection needle so that the injection can be performed using only one needle. Having to insert only one needle through the retina can reduce damage to the retina which could otherwise occur from repeated piercing of the retina. 
       FIG. 1A  is a schematic view of an exemplary injection apparatus  100  for performing a subretinal injection.  FIG. 1B  is a transverse sectional view of a portion of an eye  10 .  FIGS. 1A-1B  are, therefore, described together herein for clarity. In particular, the injection apparatus  100  is configured to perform a subretinal injection into a subretinal space  50  between a retina  20  and a retinal pigment epithelium (RPE)  30  of the eye  10  ( FIG. 1B ). As illustrated in  FIG. 1A , the injection apparatus  100  generally includes an injection needle  110 , a multi-lumen tubing  120 , a stabilizer  130 , and a fluid control unit  140 . 
     Referring to  FIG. 1A , the injection needle  110  has a proximal end  112  and a distal end  114 . The distal end  114  of the injection needle  110  is configured to be inserted into the subretinal space  50  at a target position on a surface  22  of the retina  20  ( FIG. 1B ). The injection needle  110  includes a connector piece  116  (described in more detail below) at the proximal end  112  that connects the injection needle  110  to the multi-lumen tubing  120 . The multi-lumen tubing  120  has a distal end  122  attached to the proximal end  112  of the injection needle  110  through the connector piece  116  and a proximal end  124  attached to the fluid control unit  140 . 
       FIG. 1C  is an enlarged side sectional view taken along the section line of  FIG. 1A  illustrating an exemplary multi-lumen tubing  120 . The multi-lumen tubing  120  includes an outer wall  126   o  surrounding three lumens  128   a ,  128   b , and  128   c . Although  FIG. 1C  shows three lumens, more or less lumens can be used (e.g., two or more lumens, from two to four lumens, two lumens, or four lumens). The lumens  128   a - c  are divided by inner walls  126   i  intersecting the outer wall  1260 . The lumens  128   a - c  are radially surrounding a center longitudinal axis  120   x  of the multi-lumen tubing  120 . In the embodiments of  FIG. 1C , one or more of the lumens  128   a - c  have different sizes. For example, each of the lumens  128   a ,  128   b  extend one-quarter of the way around the multi-lumen tubing  120  in a circumferential direction. On the other hand, the lumen  128   c  extends halfway around the multi-lumen tubing  120  in the circumferential direction. Therefore, in the embodiments of  FIG. 1C , a volume of the lumen  128   c  may be twice as much as a volume of each of the lumens  128   a ,  128   b . In some other embodiments, each of the lumens  128   a - c  has the same size. In certain embodiments, the multi-lumen tubing  120  is formed from a polymer such as silicone, polyurethane (PUR), polyamide (PA) (e.g., nylon), polyethylene (PE), polyether block amide (PEBA), polytetrafluoroethylene (PTFE), polyimide (PI), fluorinated ethylene propylene (FEP), perfluoroalkoxy alkane (PFA), polyether ether ketone (PEEK), liquid crystal polymer (LCP), ethylene tetrafluoroethylene (ETFE), a terpolymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride (THV), a thermoplastic elastomer (TPE), or combinations thereof. In some embodiments, the injection needle  110  and the multi-lumen tubing  120  are formed from the same or different materials. 
     The fluid control unit  140  includes a fluid pump  142  for driving flow through the multi-lumen tubing  120 . Although  FIG. 1A  shows a syringe pump, the fluid pump  142  can include at least one of a Vernier Flow Control (VFC) pump or another type of pressure control pump, a volume control pump, a variable volume control pump, a peristaltic pump, a lever-actuated pump, a valve-actuated pump, or a venturi pump. The fluid control unit  140  also includes three fluid reservoirs  144   a ,  144   b , and  144   c  for storing a plurality of fluids  145   a - c . Although  FIG. 1A  shows three fluid reservoirs, more or less fluid reservoirs can be used. Referring to  FIG. 1A , each of the fluid reservoirs  144   a - c  is a syringe configured to be actuated by the syringe pump. In certain embodiments, the plurality of fluids  145   a - c  include a non-treatment solution  145   a , a treatment solution  145   b , and a working fluid  145   c.    
     In operation, the fluid pump  142  is configured to drive flow of each of the plurality of fluids  145   a - c  from the fluid reservoirs  144   a - c , respectively, through the lumens  128   a - c , respectively, of the multi-lumen tubing  120  ( FIG. 1C ). As further described below, when the injection needle  110  is first inserted into the retina  20 , initially working fluid  145   c  is configured to flow through the port  118   c  of the connector piece  116  ( FIG. 1D ) to extend the stabilizer  130  and stabilize the injection needle  110 . Then, the non-treatment solution  145   a  and the treatment solution  145   b  are configured to flow through the ports  118   a ,  118   b , respectively, of the connector piece  116  ( FIG. 1D ) in order to separately inject each of the fluids  145   a ,  145   b  into the subretinal space  50  ( FIG. 1B ). Note that  FIG. 1A  illustrates stabilizer  130  in an extended state. Additional details regarding the operations of stabilizer  130  are provided with respect to  FIG. 1D . 
     In some embodiments, the non-treatment solution  145   a  includes an ophthalmic irrigation solution having physiological pH and osmotic pressure (e.g., BSS). In some embodiments, the treatment solution  145   b  includes a therapeutic substance for treating the eye  10  (e.g., anti-VEGF, tissue plasminogen activator (tPA), stem cells, viral vectors for gene therapy, other drugs, or combinations thereof). In some embodiments, the working fluid  145   c  includes a fluid for extending the stabilizer  130  (e.g., perfluorocarbon liquid (PFCL), BSS, saline, air, N 2 , other liquids or gases, or combinations thereof). 
     The fluid control unit  140  includes a controller  146  for controlling operation of the fluid pump  142 . In certain embodiments, the controller  146  includes a wireless receiver  147   a  having an antenna  147   b  for receiving instructions wirelessly from a control console. The fluid control unit  140  includes a power supply  148  for powering the fluid pump  142  and the controller  146 . In some embodiments, the power supply  148  includes at least one of a battery, one or more spring, or a gas container. In some other embodiments, power is provided by at least one of gravity force or manual actuation. In some other embodiments, the fluid control unit  140  also includes a plurality of valves for regulating fluid flow from the fluid reservoirs  144   a - c.    
       FIG. 1D  is top isometric view of a portion of the injection apparatus  100  of  FIG. 1A . Referring to  FIG. 1D , the connector piece  116  has three ports  118   a ,  118   b ,  118   c  corresponding to and disposed within the distal ends of the lumens  128   a - c , respectively, of the multi-lumen tubing  120 . The two separate ports  118   a ,  118   b  of the connector piece  116  merge together toward the distal end  114  of the injection needle  110 . The port  118   c , on the other hand, is separate from each of the ports  118   a ,  118   b  and fluidly isolated therefrom. The port  118   c  is fluidly coupled to the stabilizer  130  as shown. 
     Referring to  FIGS. 1A and 1D , the stabilizer  130  is shown in the extended or activated position where the stabilizer  130  extends from the port  118   c  of the connector piece  116 . In the extended position, the stabilizer  130  stabilizes the injection needle  110  and controls the location of injection of the non-treatment solution  145   a  in order to help force the location of the bleb which is described in more detail below with regard to  FIGS. 4 and 9A-9C . In the embodiments of  FIGS. 1A and 1D , the stabilizer  130  is a balloon  132 , or bag, having a pair of wings  132   a ,  132   b . In some other embodiments, the balloon  132  can have any suitable shape including without limitation, round, oval, or polygonal. The balloon  132  may be formed from plastic, metal, polymer, nitinol, or combinations thereof. 
     Before the stabilizer  130  is in the extended position as shown in  FIGS. 1A and 1D , the stabilizer  130  is disposed within the port  118   c  of the connector piece  116  as shown in  FIG. 2D  and described in detail below. In certain embodiments, to actuate the stabilizer  130  to the extended position, the working fluid  145   c  (e.g., PFCL) is injected from the fluid reservoir  144   c  of the fluid control unit  140  ( FIG. 1A ) through the lumen  128   c  to fill the balloon  132  with PFCL. In the extended position, the wings  132   a ,  132   b  of the balloon  132  extend substantially along an axis perpendicular to the center longitudinal axis  120   x  of the multi-lumen tubing  120 . In some embodiments, in the extended position, the balloon  132  has a flattened profile. For example, in some embodiments, a width of the balloon  132  measured parallel to the surface  22  of the retina  20  is greater (e.g. at least 2× greater, at least 5× greater, or at least 10× greater) than a height of the balloon  132  measured orthogonal to the surface  22 . Beneficially, the flattened profile increases the contact surface area between the balloon  132  and the surface  22 . In certain embodiments, the balloon  132  is held in place primarily due to the weight of the working fluid  145   c  in the balloon  132 . Note that  FIGS. 1A and 1D  show only one example of a stabilizer. Additional examples, which may operate differently are described further in relation to  FIGS. 15-17 . 
     In the extended position, the stabilizer  130  is configured to immobilize the injection needle  110  at a target position on the surface  22  of the retina  20 , which reduces the likelihood of the injection needle  110  being removed from the subretinal space  50  during the treatment due to light inadvertent forces. As used herein, immobilizing the injection needle  110  generally refers to limiting movement of the injection needle  110  relative to the retina  20  in order to maintain the injection needle  110  at the target position on the surface  22  of the retina  20  throughout the treatment. That is to say that immobilizing the injection needle  110  does not refer to limiting the injection needle  110  to zero or no movement. Instead, the injection needle  110  should still retain some limited degree of freedom while being maintained at the target position so that light and/or inadvertent forces can be safely applied without tearing the retina  20 . In addition, the injection needle  110  should still be removable from the retina  20  even in the extended position in the event that enough force is applied to the injection needle  110 . Allowing the injection needle  110  to be removed in response to a large enough pull force prevents harm the eye  10  or major tearing. Additional details regarding the stabilizer  130  and its operations are provided with respect to  FIGS. 5-12 . 
       FIG. 2A  is a schematic view of an exemplary inserter device  250 , which may be used with the injection apparatus  100  described herein. In general, the inserter device  250  is configured to be releasably coupled to the injection needle  110  to provide a rigid structure for inserting the injection needle  110  into the eye  10  and further into the subretinal space  50 . The inserter device  250  includes a cannula  254  which is a portion of the inserter device  250  directly engaging the injection needle  110  and which is insertable into the eye  10 . The cannula  254  has a bore for surrounding the multi-lumen tubing  120 . In the embodiments of  FIG. 2A , the cannula  254  has an enclosed bore extending longitudinally from a proximal end  254   a  to a distal end  254   b  thereof. 
     The cannula  254  extends from a body  256  which is a portion of the inserter device  250  configured to be gripped and handled by the surgeon or surgical assistant. The body  256  has an injection needle release knob  258  for releasing the injection needle  110  from the cannula  254  when the injection needle  110  is properly positioned and immobilized within the eye  10 . It is contemplated that the release knob  258  may function in several different ways. For example, the release knob  258  may be a slide which moves a release mechanism to disengage the cannula  254  from the connector piece  116  allowing the cannula  254  to be retracted away from the injection needle  110 . In certain embodiments, the release mechanism includes a pair of inner and outer tubes enclosing the connector piece  116 , the inner and outer tubes having respective openings such that turning the inner tube to align the openings releases the injection needle  110 . In certain other embodiments, the release mechanism includes a cone tube which moves inside a ring surrounding and holding the connector piece  116  such that inserting the cone tube enlarges the inner diameter of the ring to release the injection needle  110 . In certain other embodiments, the release mechanism includes two half-shells enclosing the connector piece  116  and held together by a ring such that moving the ring releases the injection needle  110 . Alternatively, the cannula  254  may be spring-loaded such that pressing the release knob  258  causes the cannula  254  to be retracted away from the injection needle  110 . Alternatively, utilizing the U-shaped cannula  264  (described in more detail below) the release knob  258  may push the cannula  264  to one side thereby disengaging the cannula  264  from the connector piece  116  through a slit  265  formed along a length of the cannula  264 . In the embodiments of  FIG. 2A , the inserter device  250  is configured to remain coupled to the multi-lumen tubing  120  outside the eye  10 , namely because the enclosed bore prevents the cannula  254  from being removed from around the multi-lumen tubing  120 . Note that  FIG. 2A  shows only one example of an inserter device. An additional example, which may operate differently is described further in relation to  FIG. 2B . 
       FIG. 2B  is a schematic view of another exemplary inserter device  260 , which may be used with the injection apparatus  100  described herein. Referring to  FIG. 2B , the inserter device  260  is constructed and arranged similarly to the inserter device  250  of  FIG. 2A , except where noted, and corresponding description thereof may be incorporated herein without limitation. In one or more embodiments, the cannula  264  has a slit  265  extending longitudinally from a proximal end  264   a  to a distal end  264   b  thereof. In some embodiments, the cannula  264  has a U-shape in cross-section. In some embodiments, the slit  265  has a minimum width greater than an outer diameter of the multi-lumen tubing  120 . In such embodiments, the inserter device  260  is configured to be decoupled from the multi-lumen tubing  120  outside the eye  10  by sliding the multi-lumen tubing  120  through the slit  265 . 
       FIG. 2C  is a schematic view of the injection apparatus  100  of  FIG. 1A  illustrating an exemplary inserter device  250  combined therewith.  FIG. 2D  is an enlarged side sectional view of a portion of  FIG. 2C  illustrating an exemplary injection needle  110 , used in connection with the injection apparatus  100  described herein.  FIGS. 2C-2D  are, therefore, described together herein for clarity. The injection apparatus  100  is shown in a configuration ready to start the subretinal injection procedure. For example, the inserter device  250  is coupled to the injection needle  110 , and the cannula  254  of the inserter device  250  is surrounding the multi-lumen tubing  120 . Furthermore, the stabilizer  130  is in the retracted position being disposed inside the port  118   c  of the connector piece  116  which is disposed within the distal end  254   a  of the cannula  254 .  FIG. 2D  illustrates a straight injection needle  110 . In other words, the injection needle  110  extends from the proximal end  112  of the injection needle  110  to the distal end  114  of the injection needle  110  at a constant angle which is substantially parallel to the center longitudinal axis  120   x  of the multi-lumen tubing  120 . In certain embodiments, as shown in  FIG. 2D , the cannula  254  of the inserter device  250  extends beyond the distal end  122  of the multi-lumen tubing  120  and surrounds the connector piece  116  of the injection needle  110 . In some embodiments of  FIG. 2D , the cannula  254  has an inner diameter corresponding to an outer diameter of the connector piece  116 . 
       FIG. 3  is an isometric view of an exemplary injection apparatus  300  for performing a subretinal injection. Referring to  FIG. 3 , the injection apparatus  300  is used in connection with a surgical microscope  302  and an operating table  304 . In certain optional embodiments illustrated in  FIG. 3 , the fluid control unit  140  is attached to the surgical microscope  302 . In certain other optional embodiments illustrated in  FIG. 3 , the fluid control unit  140  is attached to and/or rested on a forehead  62  of a patient  60  lying on the operating table  304 . There are several advantages, described below, associated with positioning the fluid control unit  140  on the surgical microscope  302  or the forehead  62  as shown in  FIG. 3 . 
     A first advantage is that attaching the fluid control unit  140  to a fixed object reduces the likelihood of external forces being applied to the multi-lumen tubing  120 , which reduces the likelihood of the injection needle  110  coming out or tearing the retina  20 . In other words, attaching the fluid control unit  140  to a fixed object helps achieve decoupling of the fluid control unit  140  from objects that move which reduces the impact of external forces. 
     Another advantage is that by positioning the fluid control unit  140  in close proximity to the eye  10  (e.g., on the surgical microscope  302  or the forehead  62 ) as compared to some other embodiments where the fluid control unit  140  is positioned at a further distance from the eye  10 , a total relative length of the multi-lumen tubing  120  is reduced. This thereby reduces a dead volume of each of the plurality of fluids  145   a - c  in the multi-lumen tubing  120  between the fluid reservoirs  144   a - c  and the eye  10 . Because the cost of therapeutic treatment fluids is often very high, reducing fluid waste due to the dead volume, in the multi-lumen tubing  120  for example, can result in significant cost savings. It is also contemplated that reducing the distance between the fluid control unit  140  and the eye  10  reduces the elasticity of the system providing more rigid fluid control. 
     In some other embodiments, the dead volume in the multi-lumen tubing  120  can be reduced by using a micro-lumen tubing which has a reduced outer diameter and reduced cross-sectional flow area relative to standard tubing. For example, it is contemplated that micro-lumen tubing may have an outer diameter of about 0.3 mm or less, whereas standard tubing has an outer diameter of about 0.4 mm. 
     In some other embodiments, the dead volume in the multi-lumen tubing  120  can be reduced by front loading each of the plurality of fluids  145   a - c  into the multi-lumen tubing  120 . In such embodiments, the injection needle  110  is configured to be removed from the distal end  122  of the multi-lumen tubing  120  ( FIG. 2D ) so that each of the plurality of fluids  145   a - c  can be loaded directly into a distal end  122  of one of the lumens  128   a - c . In other words, the plurality of fluids  145   a - c  are stored within a portion of the multi-lumen tubing  120  instead of within the fluid reservoirs  144   a - c . In such embodiments, the dead volume in the multi-lumen tubing  120  upstream of the plurality of fluids  145   a - c  (i.e., between the fluid reservoirs  144   a - c  and the plurality of fluids  145   a - c , respectively) can be filled with a relatively low cost chaser fluid (e.g., air, N 2 , BSS, saline, other liquids or gases, or combinations thereof). In such embodiments, the chaser fluid is pressurized by the fluid pump  142 , which in turn pressurizes the fluid stored in the multi-lumen tubing  120 . In some embodiments, the lumen  128   b  is front-loaded with the treatment solution  145   b , which is relatively more costly, while the lumens  128   a ,  128   c  receive the non-treatment solution  145   a  and the working fluid  145   c , respectively, from the fluid reservoirs  144   a ,  144   c , respectively. 
       FIG. 4  is a diagram illustrating a method  400  of performing a subretinal injection using the injection apparatus  100  described herein. In preparation for the subretinal injection, the sclera  12  is incised using a trocar cannula which consists of a valved cannula  152  ( FIG. 5A ) and a trocar. Typically, a pre-packaged trocar cannula having a hub at a proximal end is inserted into the eye  10  to the point that a bottom surface of the hub contacts the sclera  12 . Then, the trocar is removed from the eye  10  leaving the valved cannula  152  in place as shown in  FIG. 5A . Although not shown, in  FIGS. 5A-12A  the bottom surface of the hub of the valved cannula  152  may be parallel to or flush with the surface of the eye  10 . At operation  402 , the cannula  254  of the inserter device  250  is inserted into the eye  10  through the valved cannula  152  ( FIGS. 5A-5B ). 
     At operation  404 , the distal end  114  of the injection needle  110  is inserted into the subretinal space  50  at a target position on the surface  22  of the retina  20  ( FIGS. 6A-6B ). In some embodiments, the depth of the injection needle  110  is controlled visually. For example, in some embodiments, optical coherence tomography (OCT) imaging data can be utilized during surgery to provide visual confirmation that the distal end  114  of the injection needle  110  is disposed within the proper layer of the eye  10 , namely in the subretinal space  50 . In certain embodiments, the connector piece  116  functions as an end stop to prevent the injection needle  110  from being inserted too far into the eye  10  (e.g., through the RPE  30  or the Bruch&#39;s membrane  40 ), which can damage the eye  10 . In some embodiments, the length of the injection needle  110  measured from the connector piece  116  to the distal end  114  thereof is selected so that the distal end  114  is correctly positioned between the retina  20  and the RPE  30  when the connector piece  116  is in contact with the surface  22  of the retina  20 . In some embodiments, the length of the injection needle  110  may be selected based on a pre-operative determination of the thickness of the retina  20 . 
     In some other embodiments illustrated in  FIGS. 13A-13B , the depth of the injection needle  1310  is controlled by using an end stop  1300 . In some other embodiments illustrated in  FIGS. 14A-14B , the depth of the injection needle  1410  is controlled by using a curved injection needle  1410 . Additional details regarding these embodiments are provided below. 
     At operation  406 , the injection needle  110  is immobilized at the target position on the surface  22  of the retina  20  using a stabilizer  130 . In certain embodiments illustrated in  FIGS. 7A-7C , a pressure or fluid is applied through the lumen  128   c  of the multi-lumen tubing  120  to extend the stabilizer  130  beyond a distal end  122  of the lumen  128   c  to place the stabilizer  130  in contact with the surface  22  of the retina  20 . The stabilizer  130  is configured to securely contact the retina  20  in such a way that the injection needle  110  is immobilized at the target position on the surface  22  of the retina  20 . In certain embodiments, the stabilizer  130  is formed from a material which is conformal to the surface  22  of the retina  20  to increase the contact area therebetween. 
     At operation  408 , after the stabilizer  130  is in contact with the surface  22  of the retina  20 , the cannula  254  of the inserter device  250  is retracted from the eye  10  ( FIGS. 8A-8B ). After the cannula  254  is retracted, the injection needle  110  and the multi-lumen tubing  120  are decoupled from external forces. As used herein, external forces generally include any forces applied to the injection needle  110  or the multi-lumen tubing  120  from outside the eye  10 . For example, external forces generally include light and/or inadvertent movement of any part of the injection apparatus  100  by the surgeon or surgical assistant. In certain embodiments, the decoupling limits the effect of external forces associated with injection of the non-treatment solution  145   a  (operation  410 ) or injection of the treatment solution  145   b  (operation  412 ). In some other embodiments using a handheld injection instrument to manually control the injection in a two-step process, as described earlier, the decoupling limits the effect of external forces associated with movement of handheld instruments. 
     In certain embodiments illustrated in  FIGS. 8A-8B , excess length of the multi-lumen tubing  120  is provided in an unconstrained state inside the eye  10  to facilitate decoupling. It will be appreciated that when external forces are applied to the multi-lumen tubing  120 , the excess length enables movement of the multi-lumen tubing  120  inside the eye  10  without transfer of force to the injection needle  110 . In some embodiments using the inserter device  260  of  FIG. 2B , the inserter device  260  is decoupled from the multi-lumen tubing  120  after the retracting by sliding the multi-lumen tubing  120  through the slit  265 . 
     At operation  410 , a non-treatment solution  145   a  is injected from the fluid control unit  140  to the subretinal space  50  via the lumen  128   a  of the multi-lumen tubing  120  ( FIGS. 9A-9C ). In some embodiments for example, the fluid pump  142  drives flow of the non-treatment solution  145   a  through the lumen  128   a  to inject the non-treatment solution  145   a  from the fluid reservoir  144   a  to the subretinal space  50 . In certain embodiments, injection of the non-treatment solution  145   a  forms a bleb in the subretinal space  50  between the retina  20  and the RPE  30  ( FIG. 9C ). In certain embodiments, the bleb is a localized hemispherical lifting of the retina  20  which is visible through the surgical microscope. Thus, formation of the bleb by the non-treatment solution  145   a  provides visual confirmation that the distal end  114  of the injection needle  110  is disposed within the proper layer of the eye  10 , namely in the subretinal space  50 . 
     At operation  412 , a treatment solution  145   b  is injected from the fluid control unit  140  to the subretinal space  50  via the lumen  128   b  of the multi-lumen tubing  120  ( FIGS. 10A-10B ). In certain embodiments, the fluid pump  142  drives flow of the treatment solution  145   b  through the lumen  128   b  to inject the treatment solution  145   b  from the fluid reservoir  144   b  to the subretinal space  50 . In certain embodiments, injecting each of the non-treatment solution  145   a  and the treatment solution  145   b  is performed hands-free. In certain embodiments, the fluid pump  142  drives flow of each of the non-treatment solution  145   a , the treatment solution  145   b , and the working fluid  145   c  without manual actuation of the plurality fluid reservoirs  144   a - c . In some embodiments, the fluid pump  142  operates according to instructions received from the controller  146 . In some embodiments, the controller  146  receives control signals via the wireless receiver  147   a . In certain embodiments, the surgeon or surgical assistant may control pressure or volume of injection of each of the plurality of fluids  145   a - c  using a foot pedal which is in wireless communication with the controller  146  via the wireless receiver  147   a  and the antenna  147   b.    
     At operation  414 , the injection needle  110  is remobilized by retracting the stabilizer  130  into the distal end  122  of the lumen  128   c . Thus, the stabilizer  130  is removed from being in contact with the surface  22  of the retina  20 . In certain embodiments, the working fluid  145   c  is removed from the lumen  128   c  using vacuum pressure to cause the stabilizer  130  to retract therein. In some embodiments, the stabilizer  130  is removed from being in contact with the surface  22  of the retina  20  without being retracted into the distal end  122  of the lumen  128   c.    
     At operation  416 , the multi-lumen tubing  120  and the injection needle  110  coupled thereto are removed from the eye  10  ( FIGS. 12A-12B ). Without the stabilizer  130  in contact with the retina  20 , the injection needle  110  is able to be removed from within the subretinal space  50  by slight tension force applied to the multi-lumen tubing  120 . In some embodiments, a retinal port formed by insertion of the injection needle  110  through the retina  20  may be relatively small compared to typical procedures owing to the various benefits of the apparatus and methods disclosed herein. In such embodiments, the retinal port may remain unpatched without issue. In some other embodiments, the retinal port may be filled with a sealing agent (e.g., fibrin glue, collagen, cyanoacrylate, cellular attachment factors, fibronectin, laminin, extracellular matrix-based hydrogels, polyacrylic acid, zinc polycarboxylate cement, silicone adhesive, or an ophthalmic viscosurgical device (OVD), or viscoelastic plug). In some other embodiments, the viscosity of the treatment solution  145   b  may be adequate to seal the retinal port. 
     Various alternative embodiments are described in detail below. It will be appreciated that the following embodiments may be combined with the injection apparatus  100  and method  400  without limitation.  FIG. 13A  is an isometric view of another exemplary injection needle  1310 , which may be used with the injection apparatus  100  described herein. Referring to  FIG. 13A , an end stop  1300  is disposed around the injection needle  1310  between the proximal end  1312  and the distal end  1314 . In the embodiments of  FIG. 13A , the end stop  1300  is an annular disk having a center bore  1302  for receiving the injection needle  1310  therethrough. The end stop  1300  has first and second opposing faces  1304 ,  1306  which are facing parallel to a longitudinal axis of the center bore  1302 . In some other embodiments, the end stop  1300  may have a non-circular profile (e.g., a polygonal or oval profile). In some embodiments, the end stop  1300  has an inner diameter corresponding to an outer diameter of the injection needle  1310  to form an interference fit therebetween. In some other embodiments, the end stop  1300  may be integral with the injection needle  1310  or coupled to the injection needle  1310  by an adhesive or fastener. 
       FIG. 13B  is a side sectional view of the injection needle  1310  of  FIG. 13A  illustrating the injection needle  1310  inserted into the subretinal space  50 . The second face  1306  is in contact with the surface  22  of the retina  20  when the distal end  1314  of the injection needle  1310  is inserted into the subretinal space  50 . The distance between the distal end  1314  and the second face  1306  is selected so that the distal end  1314  is correctly positioned between the retina  20  and the RPE  30  when the second face  1306  is in contact with the surface  22  of the retina  20 . Therefore, the end stop  1300  prevents the injection needle  1310  from being inserted too far into the eye  10  (e.g., through the RPE  30  or the Bruch&#39;s membrane  40 ), which can damage the eye  10 . In some other embodiments, the second face  1306  is tapered to facilitate insertion of the end stop  1300  through the sclera. 
       FIG. 14A  is an isometric view of yet another exemplary injection needle  1410 , which may be used with the injection apparatus  100  described herein. Referring to  FIG. 14A , the injection needle  1410  is curved. For example, in certain embodiments, the injection needle  1410  has a first portion  1417  extending substantially parallel to the center longitudinal axis  120   x  of the multi-lumen tubing  120  and a second portion  1418  extending at an angle α 1  different from the first portion  1417 . In certain embodiments, the angle α 1  of the second portion  1418  is about 45 degrees or less (e.g., about 30 degrees or less or from about 10 degrees to about 30 degrees). 
       FIG. 14B  is a side sectional view of the injection needle  1410  of  FIG. 14A  illustrating the injection needle  1410  inserted into the subretinal space  50 . Referring to  FIG. 14B , an angle α 2  between the second portion  1418  of the injection needle  1410  and the surface  32  of the RPE  30  is less than an angle (α 1 +α 2 ) between the first portion  1417  and the surface  32 . Because of the angle α 2  of the second portion  1418 , the injection needle  1410  enters the subretinal space  50  at a shallower angle than the angle (α 1 +α 2 ) between the first portion  1417  and the surface  32 . For example, compare the lower entry angle α 2  of the curved injection needle  1410  ( FIG. 14B ) to the relatively higher entry angle of the straight injection needle  1310  ( FIG. 13B ). Beneficially, the curve of the injection needle  1410  helps correctly position the distal end  1414  between the retina  20  and the RPE  30 , thereby helping prevent the injection needle  1410  from being inserted too far into the eye  10  (e.g., through the RPE  30  or the Bruch&#39;s membrane  40 ). 
       FIG. 15  is a top isometric view of another exemplary stabilizer  1530 , which may be used with the injection apparatus  100  described herein. In the embodiments of  FIG. 15 , the stabilizer  1530  is shown in the extended position. In the retracted position, the stabilizer  1530  may be disposed within the port  118   c  of the connector piece  116  and/or disposed inside the lumen  128   c  of the multi-lumen tubing  120 . Referring to  FIG. 15 , the stabilizer  1530  is a wire  1532  formed from a shape memory alloy or a material having a high degree of elasticity (e.g., nitinol). The wire  1532  is coupled to the connector piece  116  of the injection needle  110 . In certain embodiments illustrated in  FIG. 15 , the wire  1532  is formed into a pair of wings  1532   a ,  1532   b . In some other embodiments, the wire  1532  can be formed into any suitable shape including without limitation, round, oval, or polygonal. In the retracted position, the wire  1532  is disposed within the port  118   c  of the connector piece  116  and/or within the lumen  128   c  such that the wings  1532   a ,  1532   b  are folded generally parallel to the center longitudinal axis  120   x  of the multi-lumen tubing  120 . In some embodiments, a working fluid  145   c  (e.g., PFCL) is injected from the fluid reservoir  144   c  of the fluid control unit  140  ( FIG. 1A ) through the lumen  128   c  to apply a pressure to extend the wire  1532  from the lumen  128   c . In the extended position, the wings  1532   a ,  1532   b  may extend substantially along an axis perpendicular to the center longitudinal axis  120   x  of the multi-lumen tubing  120 . In some embodiments, the wire  1532  is held in place primarily due to frictional forces between the wire  1532  and the surface  22  of the retina  20 . In some embodiments, in the extended position, the wire  1532  has a flattened profile. For example, in some embodiments, a width of the wire  1532  measured parallel to the surface  22  of the retina  20  is greater (e.g. at least 2× greater, at least 5× greater, or at least 10× greater) than a height of the wire  1532  measured orthogonal to the surface  22 . 
       FIG. 16  is a top isometric view of yet another exemplary stabilizer  1630 , which may be used with the injection apparatus  100  described herein. In the embodiments of  FIG. 16 , the stabilizer  1630  is shown in the extended position. In the retracted position, the stabilizer  1630  may be disposed within the port  118   c  of the connector piece  116  and/or disposed inside the lumen  128   c  of the multi-lumen tubing  120 . In certain embodiments illustrated in  FIG. 16 , which can be combined with other embodiments disclosed herein without limitation, the stabilizer  1630  includes a plurality of barbs  1634  disposed on a structure  1632  (e.g., a balloon, a wire, a plate, or combinations thereof). The structure  1632  is shown in phantom to more clearly illustrate the barbs  1634  disposed on an underside thereof. The barbs  1634  are configured to increase friction between the stabilizer  1630  and the surface  22  of the retina  20 . In some other embodiments, other friction-inducing elements may be incorporated on the structure  1632  in addition to or as a substitute for the plurality of barbs  1634  (e.g., rough texture, teeth, spines, or combinations thereof). In certain embodiments illustrated in  FIG. 16 , the structure  1632  includes a pair of wings  1632   a ,  1632   b . In some other embodiments, the structure  1632  can have any suitable shape including without limitation, round, oval, or polygonal. In some embodiments, in the extended position, the structure  1632  has a flattened profile. For example, in some embodiments, a width of the structure  1632  measured parallel to the surface  22  of the retina  20  is greater (e.g. at least 2× greater, at least 5× greater, or at least 10× greater) than a height of the structure  1632  measured orthogonal to the surface  22 . 
       FIG. 17  is a top isometric view of yet another exemplary stabilizer  1730 , which may be used with the injection apparatus  100  described herein. In the embodiments of  FIG. 17 , the stabilizer  1730  is shown in the extended position. In the retracted position, the stabilizer  1730  may be disposed within the port  118   c  of the connector piece  116  and/or disposed inside the lumen  128   c  of the multi-lumen tubing  120 . Referring to  FIG. 17 , the stabilizer  1730  includes a plate  1732  and glue  1734 . The plate  1732  may be formed from plastic, metal, polymer, nitinol, or combinations thereof. The glue  1734  can include an adhesive material based on at least one of fibrin, cyanoacrylates, gelatin, thrombin, polyethylene glycol, albumin, or glutaraldehyde. In some other embodiments, a non-adhesive material such as a viscoelastic material can be used for temporary physical bonding. In some other embodiments, the plate  1732  can have a profile which conforms to the surface  22  of the retina  20  and acts a suction cup to hold the plate  1732  in place. In some other embodiments, a vacuum pressure (e.g., from about 1 mmHg (millimeters of mercury) to about 650 mmHg) can be applied to a volume between the plate  1732  and the surface  22  of the retina  20 . 
     In certain embodiments, the glue  1734  is pre-applied to the plate  1732  when the plate  1732  is folded inside the connector piece  116  (e.g., on an underside of the plate  1732  facing the surface  22  of the retina  20 ). In certain embodiments illustrated in  FIG. 17 , when the underside of the plate  1732  is in contact with the surface  22  of the retina  20 , the glue  1734  is configured to at least lightly adhere the plate  1732  to the surface  22  of the retina  20 . In some embodiments, the glue  1734  may increase friction between the plate  1732  and the surface  22  of the retina  20  without securing the surfaces together. In some other embodiments, the glue  1734  is applied via the lumen  128   c  in combination with the extension of the plate  1732 . In some embodiments illustrated in  FIG. 17 , the plate  1732  includes a pair of wings  1732   a ,  1732   b . In some other embodiments, the plate  1732  can have any suitable shape including without limitation, round, oval, or polygonal. In some embodiments, in the extended position, the plate  1732  has a flattened profile. For example, some embodiments, a width of the plate  1732  measured parallel to the surface  22  of the retina  20  is greater (e.g. at least 2× greater, at least 5× greater, or at least 10× greater) than a height of the plate  1732  measured orthogonal to the surface  22 . 
       FIG. 18  is a schematic view of an exemplary guidewire  1800 , which may be used with the injection apparatus  100  described herein. In certain embodiments, the guidewire  1800  is substituted in place of the inserter device  250 . The guidewire  1800  is disposed along the outer wall  126   o  of the multi-lumen tubing  120  generally parallel to the center longitudinal axis  120   x . In certain embodiments illustrated in  FIG. 18 , the guidewire  1800  extends to the distal end  122  of the multi-lumen tubing  120 . In certain embodiments, the guidewire  1800  extends at least partially along the length of the multi-lumen tubing  120  including extending along a portion of the multi-lumen tubing  120  that is inserted into the eye  10 . In some embodiments, the guidewire  1800  extends from the proximal end  124  to the distal end  122  of the multi-lumen tubing  120 . The guidewire  1800  is more rigid than the multi-lumen tubing  120 . The guidewire  1800  is configured to provide axial stiffness in the direction of the center longitudinal axis  120   x  in order to apply sufficient axial pressure to the injection needle  110  to insert the distal end  114  of the injection needle  110  into the subretinal space  50  at the target position on the surface  22  of the retina  20  without the use of the inserter device  250 . The guidewire  1800  has a bending stiffness less than the axial stiffness in order to limit the transfer of undesirable bending forces from outside the eye  10  to the injection needle  110 . 
     In some other embodiments where the inserter device  250  is not used, other mechanisms may be used to provide variable stiffness to the multi-lumen tubing  120 . In certain embodiments, for example, the multi-lumen tubing  120  may have a higher stiffness during insertion of the distal end  114  of the injection needle  110  into the subretinal space  50  (operation  404 ) and a lower stiffness to decouple the injection needle  110  from external forces after the injection needle  110  is immobilized at the target position on the surface  22  of the retina  20  (operation  406 ) (e.g., during at least one of retraction of the cannula  254  (operation  408 ), injection of the non-treatment solution  145   a  (operation  410 ), or injection of the treatment solution  145   b  (operation  412 )). In some embodiments, only a portion of the multi-lumen tubing  120  that is inserted into the eye  10  has variable stiffness. In some other embodiments, the entire length of the multi-lumen tubing  120  has variable stiffness. 
     In some other embodiments, application of electrical voltage to the multi-lumen tubing  120  changes the stiffness thereof. For example, at least a portion of the multi-lumen tubing  120  has a lower stiffness without the application of electrical voltage and a higher stiffness when electrical voltage is applied. In such embodiments, at least a portion of the multi-lumen tubing  120  may be formed form a material which undergoes a chemical or physical change induced by electrical voltage to impart greater stiffness to the multi-lumen tubing  120 . 
     In some other embodiments, application of pneumatic pressure to the multi-lumen tubing  120  changes the stiffness thereof. For example, at least a portion of the multi-lumen tubing  120  has a lower stiffness without the application of pneumatic pressure and a greater stiffness when pneumatic pressure is applied. In such embodiments, one or more lumens of the multi-lumen tubing  120  may be filled with pneumatic pressure to increase the stiffness. 
     In some other embodiments, the multi-lumen tubing  120  may include a plurality of structural segments which impart a greater stiffness under compression and lower stiffness under tension. Thus, the multi-lumen tubing  120  may have a relatively greater stiffness when placed under compression during insertion of the distal end  114  of the injection needle  110  into the subretinal space  50  (operation  404 ). After the injection needle  110  is immobilized at the target position on the surface  22  of the retina  20  (operation  406 ), the multi-lumen tubing  120  may be placed under tension to induce a lower stiffness in order to decouple the injection needle  110  from external forces. 
     In summary, embodiments of the present disclosure improve the efficacy and safety of subretinal injection for treatment of ophthalmic conditions. In particular, embodiments of the present disclosure provide hands-free and precisely controlled fluid injection ensuring correct injection volume and dosing, proper flow velocity into the subretinal space without harming the retina or the RPE, and proper shear force in the needle to help maintain biologic activity of various therapeutics carried by the injection fluid. Furthermore, embodiments of the present disclosure decouple the injection needle from external forces preventing inadvertent movement of the injection needle which can cause tearing of the retina. Furthermore, embodiments of the present disclosure provide two injection steps, i.e., injection of a non-treatment solution and a treatment solution, without removing the injection needle from the subretinal space mitigating damage to the retina caused by re-entry of the injection needle. 
     While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. 
     Example Embodiments 
     Embodiment 1: The apparatus of claim  1 , wherein the injection needle and the multi-lumen tubing are configured to be decoupled from external forces after the injection needle is immobilized at the position on the surface of the retina. 
     Embodiment 2: The apparatus of claim  9 , wherein the stabilizer comprises nitinol wire, wherein the nitinol wire is extended by applying pressure or fluid thereto, and wherein, in the extended position, the nitinol wire has first and second wings extending substantially along an axis perpendicular to a longitudinal axis of the distal end of the multi-lumen tubing. 
     Embodiment 3: The apparatus of claim  9 , wherein the stabilizer comprises barbs configured to increase friction between the stabilizer and the surface of the retina. 
     Embodiment 4: The apparatus of claim  9 , wherein the stabilizer comprises glue and a plate, wherein the glue is disposed on a surface of the plate, and wherein, when the surface of the plate is in contact with the surface of the retina, the glue is configured to increase friction therebetween. 
     Embodiment 5: The method of claim  15 , further comprising decoupling the inserter device from the multi-lumen tubing after the retracting.