various embodiments of the present invention may avoid difficulties associated with previous articulating optical surgical probes . in particular , certain embodiments of the present invention may provide a single rigid cannula with a small diameter not only capable of insertion into very small incisions but also capable of articulating in a controlled fashion through a range of angles . thus , such embodiments of the present invention combine the advantages of a relatively rigid articulating optical surgical probe with the controllable articulation of dual cannula probes that require a larger diameter . particular embodiments of the present invention include a single rigid cannula with a slotted tip of resilient material secured to a pull wire . tension in the pull wire causes the slotted tip to bend in a particular direction , while releasing the tension allows the resilient tip to restore to its straight position . pull - wire technology has been used previously to deviate a distal end of a surgical catheter , but not in a small - diameter , rigid cannula used in handheld optical surgical probes nor with the degree of angular movement used in the relatively small spaces found within the interior of an eye . consequently , the application of pull - wire tension in the context of hand - held surgical probes is uniquely advantageous . in particular embodiments of the present invention , one or more of the optical fibers used in the endoprobe 10 may also be used as the pull - wire . fig1 is a schematic of an articulating optical surgical endoprobe 10 , according to a particular embodiment of the present invention , with a handle 12 suitable for being held in a single hand and a cannula 14 . ( for ease of illustration , the handle 12 and cannula 14 are not shown to scale and certain external features of the handle 12 , such as the control mechanism for an internal pull - wire , are not shown .) the proximal end of the endoprobe 10 is connected to one or more light sources ( not shown ) that provide laser and / or illumination light by connection to at least one optical fiber running through the interior of the endoprobe 10 . the cannula 14 is formed of a rigid biocompatible material , such as stainless steel . endoprobes , according to various embodiments of the present invention , use a “ single ” rigid cannula , referring to the fact that there is no other relatively rigid , self - supporting cannula formed separately inside or outside the single cannula and / or independently movable with respect to the single cannula . however , the term “ single ” is not intended to exclude the use of multiple layers or coatings to form the single cannula , nor does it exclude the use of soft polymer sleeves or sheaths that conform to the shape of the cannula . the cannula 14 has a slotted tip 20 at a distal end ( referring to the end farthest from the surgeon during use ). the slotted tip 20 may articulate in a selected direction in a controllable manner by applying tension to a pull wire secured within the slotted tip 20 ( not shown in fig1 ). the slotted tip 20 is formed from a resilient material , referring to a material that can restore to the straight orientation after the tension from the pull - wire is removed . the resilient material for the slotted material may be , for example , nitinol , which can be both sufficiently rigid to insert through an incision hub and sufficiently resilient to restore after articulation . other metals , such as spring steel , or other materials with similar properties known in the art could be used . depending on the particular slot configuration of the slotted tip , it may be possible to use relatively rigid materials that are not exceptionally elastic , such as stainless steel , ni - base super - alloys , co — cr alloys , or the like without applying so much force as to exceed the yield point and permanently deform the material . the resilient materials may themselves be biocompatible , or they could be enclosed in another material , such as a polymer sheath , to prevent contact with tissue . the cannula 14 and the slotted tip 20 can be , but need not be , formed from the same material . the cannula 14 and / or the slotted tip 20 may also be coated with a stiffening material , such as synthetic diamond or metal plating ( e . g ., chromium ), to provide improved stiffness for insertion into an incision hub and to reduce the likelihood of breakage . fig2 illustrates an end view of an example of a slotted tip 20 according to a particular embodiment of the present invention . in the embodiment depicted in fig2 , a pull - wire 22 is secured to what is shown as the top side of the slotted tip 20 . the slotted tip 20 encloses two optical fibers 24 and 26 , an illumination fiber 24 having a diameter of 183 μm and a laser fiber 26 having a diameter of 108 μm . allowing for the width of the slotted tip 20 , this allows for the diameter of the cannula 14 to be made smaller relative to dual cannula systems . fig3 a - 3h illustrate various slot designs for the slotted tip 20 according to particular embodiments of the present invention ( respectively labeled as “ 20 a ,” “ 20 b ,” etc ., and collectively referred to as “ slotted tip 20 ”). in fig3 a , slots deeper than the radius of the slotted tip 20 a are cut into the side of the slotted tip 20 a toward which the slotted tip 20 a is to bend . shallow slots are cut into the opposite side permitting that side to bend as well . fig3 b and 3c illustrate straight and curved “ keyhole ” slots having a wider base as the slot extends deeper into the respective slotted tips 20 b and 20 c . the wider base reduces the amount of force required to deviate the slotted tip 20 b or 20 c to its curved position , potentially making the endoprobe 10 more comfortable to use . fig3 d - 3g illustrate slot designs that can be used for more rigid tip materials to allow the slotted tip 20 to resiliently restore to the straight position after being deviated into the curved position . in fig3 d , slots that are generally oblong along the length of the cannula 14 are set opposed to shallow back slots , which tends to reduce the force required to deviate the slotted tip 20 d to the curved position . in fig3 e , a continuous spiral cut , allowing the slotted tip 20 e to bend , is interspersed with back slots ( in this case , keyhole slots ), causing the slotted tip 20 e to bend in the direction of the back slots . fig3 f shows a spiral cut pattern wherein the spiral path is perpendicular to the longitudinal axis of the slotted tip 20 f on one side , causing the slotted tip 20 f to preferentially deviate toward the side where the spiral path is perpendicular . fig3 g shows a spiral cut pattern with the cut widened selective on one side , causing slotted tip 20 g to selectively deviate toward the side where the spiral cut is wider . fig3 h shows a slotted tip 20 h formed out of a wound wire of material , such as by winding material drawn into wires around a mandrel . at a proximal and distal end of the slotted tip 20 h the coils of the wound wire are welded together . in the intermediate region between the proximal and distal ends , one side of the tube has widened interstitial slots formed between the coils of the wound wire , causing the slotted tip 20 h to selectively deviate toward the widened slots when tension is applied via the pull - wire . forming the slotted tip 20 of a wound wire of material may have advantages by permitting the use of materials that can more easily be formed into wires than tubes . although a single wound wire is shown in fig3 h , multiple wire strands could also be used . fig4 a - 4k illustrate various mechanisms for increasing the tension in the pull - wire 22 according to particular embodiments of the present invention . in fig4 a and 4b , the pull - wire 22 is wound on a pinion 40 secured between a control button 42 and a base 44 . the pinion 40 comprises two surfaces , a smaller diameter surface r which rolls between the control button 42 and a base 44 , and a larger diameter surface r about which the pull wire 22 winds . the radial difference between the smaller and larger diameter surfaces r and r results in a differential displacement δ1 in the pull wire as the pinion 40 rotates and translates . by selecting appropriate diameters for the smaller and larger diameter surfaces r and r , a relatively small amount of pull wire displacement δ1 can be achieved during a relatively large amount of control button translation , providing the user with precise control over the deflection in the slotted tip 20 . in one embodiment , the smaller diameter surface r comprises gear teeth with mating gear teeth on the control button 42 and the base 44 . this may reduce the likelihood of slippage . fig4 c and 4d illustrate a lever arm 50 with a sliding actuation pin 52 held in place by a fixed pin 54 at a pivot of the arm . a control button ( not shown ) can be used to advance the sliding pin 52 , permitting the proximal portion of the lever arm 50 to rise , thus rotating a lanyard 56 at a distal end of the lever arm 50 to apply tension to the pull - wire 22 . fig4 e and 4f show a pull - wire 22 threaded over a sliding pin 60 and a first fixed pin 62 and anchored to a second fixed pin 64 . advancing a control button 66 attached to the sliding pin 60 increases the tension in the pull - wire 22 . fig4 g and 4h illustrate a pull - wire 22 threaded over a sliding pin 70 that is directed in a generally upward direction by a guide track 72 as a control button 74 is advanced . the path of the guide track 72 determines how the tension in the pull - wire 22 varies as the control button is advanced , thus providing a smooth and controlled increase in tension . in the case of a linear guide , like the one illustrated in fig4 g and 4h , the pull - wire take up will occur in the latter portion of the advancement of the control button 74 . in the alternative configuration shown in fig4 i , the guide track 72 is reshaped to provide greater take - up of the pull - wire at the beginning of the advancement by the control button 74 to produce a more balanced increase in tension throughout the stroke of the control button 74 . in fig4 j , the guide track 72 inclines even more sharply so that most of the tension increase takes place early in the stroke of the control button 74 . fig4 k illustrates an alternative embodiment of the guide track 72 with detents 80 , allowing for distinct “ stops ” along the path corresponding to different angles of the slotted tip 20 . a shelf or surface with detents can be also be used with any of the various embodiments of endoprobe 10 using a sliding pin or similar actuation mechanism , including any of the embodiments shown in fig4 a - 4k . while certain embodiments of the present invention have been described above , these descriptions are given for purposes of illustration and explanation . variations , changes , modifications and departures from the systems and methods disclosed above that would be apparent to one skilled in the art may be adopted without departure from the scope of the present invention as recited in the following claims .
an articulating optical surgical probe includes a handle sized to fit in a single hand and a single rigid cannula extending from the handle having a diameter of 20 ga or less . the probe further includes a slotted tip at a distal end of the cannula and at least one optical fiber extending through the handle , the single rigid cannula and the slotted tip , and a pull - wire secured to the slotted tip . when the pull - wire exerts tension on the slotted tip , the slotted tip will deviate from straight to a bend angle controlled by the tension in the pull - wire . the slotted tip is formed from a resilient material that will restore to the straight position when the tension exerted by the pull - wire is released .