Abstract:
A device for holding and aligning a trephine blade includes an elongated cylindrical component, a first alignment structure and a second alignment structure. The elongated cylindrical component extends along a first axis and comprises a hollow cylinder having an open proximal end, an open distal end, an inner cylindrical surface and an outer cylindrical surface. The first alignment structure is integral and co-planar with the proximal end and comprises a first circle attached to the inner cylindrical surface with one or more radially extending rods. The second alignment structure is arranged parallel to the first alignment structure within the hollow cylinder above the distal end and comprises a second circle attached to the inner cylindrical surface with one or more radially extending rods. The first and second circles are coaxial with the first axis and the first circle comprises a diameter that is greater than a diameter of the second circle.

Description:
CROSS REFERENCE TO RELATED CO-PENDING APPLICATIONS 
       [0001]    This application claims the benefit of U.S. provisional application Ser. No. 62/274,371 filed on Jan. 4, 2016 and entitled Trephine Alignment Device, the contents of which are expressly incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a device and a method for trephine alignment and in particular to a device for an ocular trephine alignment. 
       BACKGROUND OF THE INVENTION 
       [0003]    The present invention relates to medical devices, and specifically to surgical instruments with blades or “trephines.” A trephine is a surgical instrument with a cylindrical blade that is commonly used in medical procedures to create a circular incision around an area of interest. A trephine usually includes a hollow metal cylinder with one end of the cylinder having a sharp incising edge. Trephines are also used during ophthalmic surgery in order to correct a corneal defect of a living patient. Radial keratotomy, astigmatic keratotomy, penetrating keratoplasty, and lamellar keratoplasty are common surgical procedures that are known to utilize a trephine. Trephines are also used in corneal transplantation and in cadaveric surgical cornea recovery procedures. 
         [0004]    Radial and astigmatic keratotomies are refractive surgeries where the surgeon attempts to correct a patient&#39;s corneal curvature. In this procedure, the surgeon first determines the optical zone or specific portion of the cornea which is to remain uncut. Determining and marking this portion of the cornea is typically accomplished by using a trephine and/or specific dyes. When the trephine incising edge is pressed onto the corneal epithelial surface of a patient, it produces a visible imprint on the cornea that encircles and marks the cornea optical zone. The trephine edge can also be coated with marking ink which leaves an ink imprint on the cornea surface when pressed against the cornea epithelial tissue. In radial keratotomy and astigmatic keratotomy a blade is used to create precise incisions on the surface of the cornea outside the marked optical zone. Through specific incisions on the corneal tissue of the patient, the surgeon can modify and correct the corneal curvature. 
         [0005]    In a corneal transplantation procedure, a surgeon replaces all or part of a patient&#39;s diseased or damaged cornea with donated cadaveric corneal tissue. Penetrating keratoplasty is the procedure in which all layers of the living patient&#39;s cornea are replaced and lamellar keratoplasty is the procedure in which a portion or layer of a living patient&#39;s cornea is replaced. In keratoplasty procedures the center of the diseased or damaged portion of the cornea is marked through the use of dyes or by pressing or incising the cornea. The surgeon places a trephine over the center of the marked cornea and creates a circular incision on the corneal tissue. The diameter of the trephine is typically under 10.00 mm and will vary depending on the extent of the damaged or diseased area of the cornea. The surgeon removes the diseased or damaged portion of corneal tissue and replaces it with healthy donor cornea tissue by sewing it in place with sutures to the patient&#39;s remaining corneal tissue. 
         [0006]    In refractive eye surgery and corneal transplantation surgery, trained physicians utilize a combination of resources including microscopes, vacuum suction, specific dyes, blades, and smaller trephine diameter sizes in order to mark areas of a living patient&#39;s corneal tissue and stabilize their devices. Several types of devices have been proposed to hold a variety of different trephine diameters. For example, U.S. Pat. Nos. 4,319,575 and 4,429,696 are both multi-part devices that provide different diameter trephine blades by modifying the trephine blades to have an interior shoulder, outward radial arm projections and/or screw threads. Other patents have attempted to describe ways to align their device over a specific area of the eye to assist in refractive surgery and keratoplasty procedures. U.S. Pat. No. 6,632,232 and CN patent 102846429A utilize a single reticle or crosshair design to assist with alignment. While a single crosshair still requires the user to estimate the center of the patient&#39;s eye, some devices attempt to minimize this problem by utilizing a combination of microscopes, dyes, and/or physically marking the cornea prior or during the placement of the device to assist with the alignment. Other devices include U.S. Pat. No. 4,875,767 which proposes a device with sliding opaque disks with pinholes that obscures other portions of the eye while allowing the user to visualize the patient&#39;s fovea and physically mark the center of the cornea epithelium. U.S. Pat. No. 5,578,049 is a metal device that discloses two levels of overlapping indicator pointers used in conjunction with a microscope to estimate the center of the pupil. Although the overlapping indicator pointers may be useful at a number of distances, they may prove problematic the closer the user&#39;s vision approaches the top pointer, as it would obscure the bottom pointer. 
         [0007]    Cadaveric surgical cornea recoveries are typically performed by a tissue surgical recovery technician employed by a tissue bank. Tissue banks do not have the same resources that are available to hospitals and tissue recovery technicians are minimally trained compared to the rigorous instruction that physicians receive. The cadaveric surgical cornea recovery takes place in a variety of environments. While the optimal environment is an operating room, cadaveric surgical cornea recoveries also take place in morgue anterooms, pathology suites, and funeral homes. In a cadaveric surgical cornea recovery, a tissue recovery technician typically uses a larger diameter 18.00 mm sterile metal trephine. The larger diameter trephine is utilized to avoid contact with the corneal tissue and to create a circular incision on the sclera of the donor&#39;s eye. As a sterile procedure, the technician applies pressure to the speculum with one hand in order to stabilize the donor&#39;s eye and maintain eyelid separation. The technician utilizes their free hand to manually place the trephine over the center of the eye or pupil and manually rotates the trephine to create a circular incision on the sclera of the eye. The goal is to avoid any contact with the corneal tissue and to create a circular incision around the center of the eye, resulting in a specific uniform scleral width or scleral rim size. The scleral rim size is a determinant if the corneal tissue can be later processed for transplantation. If the scleral rim size is too small or too large in diameter, the tissue cannot be processed and utilized in keratoplasty surgeries for living patients. Additionally, if the corneal tissue is contacted during the procedure this may result in corneal epithelial damage that may render the tissue unusable for transplant. Placement of the larger diameter trephine on the sclera of the donor cadaver eye is estimated by the tissue recovery technician, resulting in inaccuracy that may render the surgically recovered cadaveric corneal tissue non-viable for transplant. 
         [0008]    It would be desirable to have a device and a method that provides a reproducible and accurate alignment of a trephine over an eye in order to extract intact and unmarked corneal tissue with uniform scleral width of specific dimensions. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention relates to a device and a method that provides a reproducible and accurate alignment of a trephine over an eye in order to extract intact and unmarked corneal tissue with uniform scleral width of specific dimensions. 
         [0010]    In general, one aspect of the invention provides a device for holding and aligning a trephine blade including an elongated cylindrical component extending along a first axis and comprising a hollow cylinder having an open proximal end, an open distal end, an inner cylindrical surface and an outer cylindrical surface. The device further includes a first alignment structure and a second alignment structure. The first alignment structure is integral and co-planar with the proximal end and comprises a first circle attached to the inner cylindrical surface with one or more radially extending rods. The second alignment structure is arranged parallel to the first alignment structure within the hollow cylinder above the distal end and comprises a second circle attached to the inner cylindrical surface with one or more radially extending rods. The first and second circles are coaxial with the first axis and the first circle comprises a diameter that is greater than a diameter of the second circle. 
         [0011]    Implementations of this aspect of the invention include the following. One of the radially extending rods of the second alignment structure comprises a free end that extends to a center of the second circle. The second circle comprises a diameter larger than a diameter of an object upon which the device is centered. The second circle comprises a diameter in the range of 6 mm to 8 mm, and the first circle comprises a diameter in the range of 8 mm to 10 mm. The hollow cylinder comprises one or more elongated openings extending along the first axis and being configured to allow light to pass through from the outside of the hollow cylinder into the inside of the hollow cylinder. The hollow cylinder comprises one or more apertures arranged near the distal end and being configured to allow light to pass through from the outside of the hollow cylinder into the inside of the hollow cylinder. The device further includes one or more inward extending steps formed in the inner cylindrical surface above the open distal end and below the second alignment structure and the one or more steps are shaped and dimensioned to level and frictionally support a non-cutting edge of one or more trephine blades with different diameters. A non-cutting edge of a trephine blade is removably attached to the distal end. The cylindrical component comprises plastic or other material that can be sterilized and provides sufficient friction for finger placement, manipulation of the device, and trephine attachment. 
         [0012]    In general, in another aspect, the invention provides a method for holding and aligning a trephine blade including the following: First, providing an elongated cylindrical component extending along a first axis and comprising a hollow cylinder having an open proximal end, an open distal end, an inner cylindrical surface and an outer cylindrical surface. Next, providing a first alignment structure being integral and co-planar with the proximal end and comprising a first circle attached to the inner cylindrical surface with one or more radially extending rods. Next, providing a second alignment structure arranged parallel to the first alignment structure within the hollow cylinder above the distal end and comprising a second circle attached to the inner cylindrical surface with one or more radially extending rods. Next, attaching a trephine blade to the distal end of the elongated component. The first and second circles are coaxial with the first axis and the first circle comprises a diameter that is greater than a diameter of the second circle. 
         [0013]    Among the advantages of the invention may be one or more of the following. Previous methods of surgically recovering cadaveric corneal tissue for transplant rely on the technician approximating trephine placement over the center of the eye or pupil, while avoiding contact with the cornea and rotating the trephine with one hand to create a circular incision on the sclera of the eye. The device of the present invention attaches to the trephine in order to assist in the proper alignment of the trephine during the incision procedure and other surgical procedures that require specific trephine placement. The device of the present invention fits trephines of different lengths and diameters, extends from the body of the trephine to provide an improved area for the user to hold and manipulate the trephine, facilitates ambient light to illuminate the trephine incising edge, provides a means for the user to visually confirm trephine fit and incorporates one or more visual reference structures. The device of the present invention reduces human error during trephine placement and trephine manipulation. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    Referring to the figures, wherein like numerals represent like parts throughout the several views: 
           [0015]      FIG. 1  is a perspective view of a trephine alignment device constructed in accordance with one embodiment of the invention, showing the front and top of the device; 
           [0016]      FIG. 2  is a perspective view of the trephine alignment device of  FIG. 1 , showing the front and bottom of the device; 
           [0017]      FIG. 3  is a front isomeric view of the trephine alignment device of  FIG. 1 ; 
           [0018]      FIG. 4  is a horizontal cross-sectional view of the trephine alignment device of  FIG. 1  along B-B′ plane, shown in  FIG. 3 ; 
           [0019]      FIG. 5  is a horizontal cross-sectional view of the trephine alignment device of  FIG. 1  along A-A′ plane, shown in  FIG. 3 ; 
           [0020]      FIG. 6  is a front isomeric view of the trephine alignment device of  FIG. 1  with an attached trephine; 
           [0021]      FIG. 7  is a lateral cross-sectional view of the trephine alignment device of  FIG. 6 , along plane C-C′; 
           [0022]      FIG. 8  is a perspective view of an assembly depicting the trephine alignment device of  FIG. 1  with an attached trephine positioned above an eye; 
           [0023]      FIG. 9  is a perspective view of the assembly of  FIG. 8  depicting the trephine alignment device positioned in contact with the eye; and 
           [0024]      FIG. 10  is a top view of the assembly of  FIG. 9 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    Referring to  FIG. 1  and  FIG. 2 , a trephine alignment device  100  includes an elongated hollow cylindrical body  16  extending along axis  55  and having an open proximal end (top end)  16   a , an open distal end (bottom end)  16   b , a cylindrical outer surface  16   c , and a cylindrical inner surface  16   d . The hollow cylindrical body  16  has an appropriate length and width for allowing multiple finger placement, manual manipulation, and visual alignment. In one example, body  16  has a length  50  of 58 mm, an outer diameter  52  of 23.4 mm, and a body thickness at the top end of 3 mm. In another example, the body thickness at the bottom end is reduced by about 1 mm to incorporate trephines of different diameters, as will be described below. In one example, the body  16  is dimensioned to incorporate an 18 mm trephine and a 19.5 mm trephine. The 18 mm trephine has an outer diameter of 19.6 mm and the 19.5 mm trephine has an outer diameter of 21.1 mm. The body  16  is made of plastic or other material that can be sterilized and provides sufficient friction for finger placement, device manipulation, and trephine attachment. The body  16 , as shown in  FIG. 1  is cylindrical, which facilitates rotational manipulation and trephine attachment. In other embodiments, opened and closed shapes other than cylindrical, such as triangular, polygonal, square, octagonal, hexagonal, and combinations thereof, among others, are used. In other embodiments, a bearing is used to allow for rotational control and trephine attachment. 
         [0026]    The top end  16   a  of the device  100  includes a visual reference structure  80  that is composed of a top inner circle  12  connected to the inside surface  16   d  of the body  16  with four rods  10 , as shown in  FIG. 5 . The center of the top inner circle  12  is the center of the device. In one example, the top inner circle  12  has an inner diameter in the range of 8 mm to 10 mm and the top rods  10  and inner circle  12  have a thickness of 1 mm. The top inner circle  12  and top rods  10  assist in aligning the trephine over the center of the eye, as will be described below. The top reference structure  80  is made out of the same material as the body  16 , e.g. plastic, or other sterilizable material. 
         [0027]    The front of the body  16  contains one or more apertures  30  and/or openings  14  that allow entrance of ambient light to illuminate the inside of the device and the trephine incising edge. In other embodiments, the body  16  of the device is made of an optically transparent material and in this case openings  14  may not be necessary. In one example, one or more semi-circular apertures  30  are positioned near the bottom  16   b  of the body  16 , as shown in  FIG. 1 . Apertures  30  allow the user to visually confirm that the trephine is fully inserted and level in the device. In this example, apertures  30  have a diameter of 3.175 mm. In one example, opening  14  has an elongated oval structure that has a length of 39.5 mm and a diameter of 4.5 mm, as shown in  FIG. 1 . In other embodiments, voids of other shapes and dimensions that increase the interior lighting of the device are used. In some embodiments, an independent light source is added to illuminate the trephine incising edge. 
         [0028]    Referring to  FIG. 2 , the bottom end  16   b  of the device  100  includes in the interior surface  16   d  different levels or steps  18 . Each step  18  is designed to fit a different size diameter trephine  26 , getting incrementally smaller in diameter deeper into the device, as shown in  FIG. 2  and  FIG. 7 . The trephine  26  slides into its appropriate step  18  and stops when it meets the next smaller step  18 . The trephine  26  is secured within the device  100  through friction between the outer surface of the trephine  26  and the interior surface of the device  16   d , and the trephine  26  is level when in contact with the next smaller step. In this example, the friction between the trephine  26  and interior surface of the device  16   d  is also of a magnitude that would allow the user to remove the trephine  26  from the device  100 . Multiple steps  18  are formed on the interior surface  16   d  of the bottom end  16   b  of the device  100  to fit various trephine sizes if the trephine is secured within the device. In other embodiments, multiple steps  18  are formed on the exterior surface  16   c  of the bottom end  16   b  of the device  100  so that the trephine  16  is secured on the outside of the device. Other variations for securing different size diameter trephines  26  include adding magnetic material to the bottom of the device  100 , sloping the interior or exterior bottom of the trephine alignment device, creating elastic attachment arms on the device, creating concentric channels in the thickness of the body  16  in the bottom of the device or modifying the design of the trephine to mechanically secure to the device via structures such as screw-threads. 
         [0029]      FIG. 3  is a front view of the trephine alignment device  100  showing two openings  14  and demonstrating the horizontal cross-sectional view along plane B-B′ from the middle of the device towards the bottom of the device, shown in  FIG. 4 , and the horizontal cross-sectional view along plane A-A′ from the middle of the device towards the top of the device, shown in  FIG. 5 . 
         [0030]    Referring to  FIG. 4 , in one embodiment, the bottom half of the device  100  includes a second visual reference structure  90  composed of a bottom inner circle  24  connected to the inside surface  16   d  of the body  16  with four bottom rods  20 . The center of the bottom inner circle  24  is the center of the device  100 . One of the rods  22  extends halfway into the bottom inner circle  24  and the free end of the extended rod  22  marks the center of the inner circle  24 . The bottom inner circle  24 , bottom rods  20 , and the extended rod  22  assist in aligning the trephine over the center of the eye, as will be described below. In one example, the bottom inner circle  24  has an inner diameter in the range of 6 mm to 8 mm, an inner circle thickness and a rod thickness of 1 mm and the extended rod  22  extends to the center of the bottom inner circle  24 . The bottom reference structure  90  is made out of the same material as the body  16 , e.g. plastic, or other sterilizable materials. 
         [0031]      FIG. 10  is a top view of the trephine alignment device  100  with an attached trephine in contact with the sclera of the eye, showing the line of sight down the device through the top visual reference structure  80  and bottom visual reference structure  90 . The top inner circle  12 , top rods  10 , bottom inner circle  24 , and extended rod  22  are visualized. The top inner circle  12  is larger in diameter than the bottom inner circle  24 . The bottom inner circle  24  is larger in diameter than the average cadaveric human pupil diameter. Typical human eye dimensions include a pupil diameter of 4 mm, iris diameter of 12 mm and globe diameter of 24 mm. 
         [0032]    Referring to  FIG. 8 , when device  100  is aligned over the center of the eye  60 , the pupil  32  is centered within the bottom inner circle  24 , the extended rod  22  marks the center of the pupil, and the bottom inner circle  24  is centered within the top inner circle  12 . By aligning the top visual reference structure  80 , the bottom visual reference structure  90 , and pupil  32 , the trephine is placed accurately over the eye  60 , as shown in  FIG. 10 . In this embodiment circles  12  and  24  are components of the top visual reference structure  80  and bottom reference structure  90 , respectively. In other embodiments other open or closed shapes, dimensions, and/or number of visual reference structures are used in order to assist in creating an aligned line of sight. 
         [0033]      FIG. 6  is a front view of the trephine alignment device  100  with an attached trephine  26  having a trephine incising edge  28 .  FIG. 7  is a lateral cross-sectional view of the trephine alignment device  100  along plane C-C′ showing the trephine  26  placement within the stepped bottom end  16   b  of device  100 . In this example, the interior of the bottom  16   b  of the device  100  contains different levels or steps  18 . Each step  18  is designed to fit a different size trephine, getting incrementally smaller deeper in the device, as was mentioned above. In this embodiment, the trephine alignment device  100  is a separate piece from the trephine  26 . In other embodiments, the trephine alignment device  100  is manufactured with an integrated trephine  26  as one piece. 
         [0034]    Other embodiments of the trephine alignment device  100  include one or more of the following. The trephine  26  includes holes throughout the trephine body and a wire or other material is threaded through the holes to create a number of visual reference structures. More than two reference visual structures are used. The visual reference structures may be open or closed structures that include non-circular shapes, such as rectangular, triangular, polygonal, hexagonal, or combinations thereof, among others. The top visual reference structure  80  may have a diameter that is smaller than the diameter of the bottom visual reference structure  90 . The diameter of the bottom visual reference structure  90  may be smaller than the area it encircles, such as the eye or the pupil  32 . In yet other embodiments, the top visual reference structure  80  includes the extended rod  22 . 
         [0035]    In operation, one uses the trephine alignment device  100  by inserting the trephine  26  into the bottom  16   b  of the device. The device  100  secures and levels the trephine  26  in the appropriate step  18  and the user visually confirms that the trephine  26  is fully inserted and level in the device through the apertures  30  before placing the trephine on the eye  60 , as shown in  FIG. 8 . Once the trephine  26  is secured in place, the user places the device  100  with the attached trephine over the eye  60  for the surgical corneal recovery procedure, as shown in  FIG. 9 . The user looks down the device  100  to align the trephine  26  over the center of the eye or pupil  32 . The top inner circle  12  is larger in diameter than the bottom inner circle  24 . The bottom inner circle  24  is larger in diameter than the average human pupil  32 . When aligned over the center of the eye  60 , the pupil  32  is centered within the bottom inner circle  24  with the extended rod  22  marking the center of the pupil, and the bottom inner circle  24  is centered within the top inner circle  12 . When the top visual reference structure  80 , bottom visual reference structure  90 , and pupil  32  are aligned, the trephine  26  is at the center of the eye  60 . When the device  100  is aligned and the trephine incising edge  28  is in contact with the sclera  36  of the eye, the user rotates the trephine alignment device  100  to create a circular incision on the sclera  36 . 
         [0036]    Among the advantages of the invention may be one or more of the following. One embodiment attaches to and levels a variety of trephine lengths and diameter sizes, including larger 18.00 mm diameter trephines without requiring the modification of the trephine. One embodiment elongates the holding area of the trephine which provides an improved area for the user to hold and manipulate the trephine, and allows the user to operate the device with one hand if necessary, such as a cadaveric surgical recovery procedure. One embodiment provides a generally open view through the device that allows the user to visualize different eye structures, such as the pupil, iris, and sclera. One embodiment facilitates ambient light from the environment to illuminate the incising edge of the trephine and other eye structures such as the pupil, iris, and sclera. One embodiment provides a means for the user to visually confirm trephine fit in the device. One embodiment comprises one or more alignment structures that assist in the proper alignment of the trephine over the center of the eye and allow the user to get as close to the device as needed without the alignment structures becoming obscured. One embodiment is made of a sterilizable plastic or polymer and would be less expensive to manufacture in one or multiple parts when compared to other materials, which would be beneficial to organizations concerned with cost effectiveness and/or limited resources such as organ and tissue banks. One embodiment is designed for users with limited training and resources available, and does not require microscopes, dyes, suction, etc. that other ophthalmic procedures utilize. One embodiment assists in creating accurate incisions on the sclera of the eye while avoiding contact with the corneal tissue. 
         [0037]    As described, the trephine alignment device  100  provides a reproducible and accurate alignment of a trephine over an eye in order to extract intact and unmarked corneal tissue with uniform scleral width of specific dimensions. The trephine alignment device  100  may also be useful for any procedure utilizing a trephine that requires accurate placement and manipulation. 
         [0038]    Several embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.