Patent Publication Number: US-2006004444-A1

Title: Macular and scleral support surgical device for ocular restraint in progressive high myopia

Description:
FIELD OF THE INVENTION  
      The present invention relates generally to ocular support bands, and more particularly to a flexible band device for supporting the macular region of the eye.  
     BACKGROUND OF THE INVENTION  
      Degenerative myopia is a significant cause of world blindness and visual disability. It is said to be the seventh ranking cause of legal blindness in the United States of America, while being the fourth ranking cause in Hong Kong. Overall, blindness most commonly occurs from myopic macular degeneration, retinal detachment, cataract and glaucoma, and of these, myopic macular degeneration is the most important. There is no universally accepted treatment to prevent the condition. It is thought to be due to decompensation of the nerve and supporting tissues of the part of the retina of the eye, the macular, which is used for fine vision. One cause of the damage is the axial overgrowth of the eye during the regular growth phase, followed by further increments of stretching during the adult years. By middle age, stressed eye tissues begin to show degeneration and failure of function; crucially, this includes the delicate nerves of the retina.  
      A scleral reinforcement procedure has been employed for some 50 years in an attempt to prevent macular degeneration. The concept is to graft a strengthening layer of donor or autologous tissue over the weak scleral shell of the eye to reinforce it. This has been found to have limited success, especially in adult eyes. Surgical fabrics have been used in a few studies but with no accepted success. One example of a device of this type is taught in U.S. Pat. No. 6,126,687, issued Oct. 3, 2000 to Peyman. This patent teaches the use of a strip of mesh-like material to apply pressure to the posterior portion of the eye as a treatment for age-related macular degeneration. Many surgeons have found such mesh-like materials difficult to use, in that the suturing of the mesh fabric material creates gathering, folds, pulls and creases in the fabric that are problematic. Thus, surgeons have generally reverted to the use of bands of donor sclera for the reinforcement of the distensible scleral wall of the eye. These grafts take the form of a strip of donor sclera tissue placed over the posterior part of the eye and secured by sutures to the outer coat of the eye to be treated to retard growth and stretching.  
      Scleral buckling is a related common surgical technique used by ophthalmologists in the repair of retinal detachments. Buckles, made usually of silicone rubber, are sutured to the wall of the eye in such a way as to produce an indentation, so approximating the wall of the eye to an underlying detached retina.  
     SUMMARY OF THE INVENTION  
      To restrain the overgrowth and stretching of a selected eye, with pathological conditions, such as axial myopia, by the surgical application of a thin flexible restraint composed of manmade materials well accepted as being appropriate for long-term implantation in the human body and previously used in surgery of the eye and it&#39;s adnexa. The most numerous individuals for whom this treatment would be helpful are those with progressive stretching axial elongation which causes vision loss through severe damage to the various tissues of the eye.  
      Generally, the present invention is a flexible macular and scleral support device that includes a thin flexible material such as surgical mesh fabric with flexible reinforced end portions. The device is positioned posterior to the eye globe and the reinforced ends are sutured to anterior portions of the scleral ring. Preferably, a side edge of the band is formed with a concave curved edge to be placed proximate to the optic nerve without making contact or applying pressure to the nerve or its blood supply. When properly positioned the device prevents further axial elongation of the eye. In alternative embodiments the band may be formed as a generally linear strap, a three legged or “Y” shaped strap or a four legged “X” shaped strap. A further alternative embodiment includes a circumferential band that is engagable with the legs of the posterior support band to secure the placement of the legs and to provide further support to the eye.  
      It is an advantage of the macular and scleral support device of the present invention that it provides improved posterior support to an eye globe.  
      It is another advantage of an embodiment of the macular and scleral support device of the present invention that it provides improved posterior eye support in three or more quadrants of the eye.  
      It is a further advantage of the macular and scleral support device of the present invention that it includes attachment legs having reinforced end portions that inhibit unwanted folding and buckling of the end portions at suture attachment points.  
      It is yet another advantage of the macular and scleral support device of the present invention that it is comprised of a mesh fabric that becomes engaged in position with the eye due to reactive scarring.  
      It is yet a further advantage of an embodiment of the macular and scleral support device of the present invention that it includes a circumferential band which is engagable to the leg portions of the posterior support band for providing secure positioning for the leg portions and enhanced eye globe support.  
      These and other objects and advantages of the present invention will no doubt become apparent to those skilled in the art upon reading the following detailed description which makes reference to the several figures of the drawings. 
    
    
     IN THE DRAWINGS  
       FIG. 1  is a top plan view of a first embodiment of the macular and scleral support device of the present invention;  
       FIG. 2  is a side elevational view of the support band depicted in  FIG. 1 ;  
       FIG. 3  is a posterior view of the support band depicted in  FIGS. 1 and 2  as applied to a right eye;  
       FIG. 4  is an anterior view of the device depicted in  FIG. 3 ;  
       FIG. 5  is a posterior view depicting an alternative positional engagement of the support band from that which is depicted in  FIG. 3 ;  
       FIG. 6  is a top plan view of an alternative macular and scleral support band embodiment of the present invention;  
       FIG. 7  is a posterior view of the support band of  FIG. 6  as applied to a right eye;  
       FIG. 8  is an anterior view of the device depicted in  FIG. 7 ;  
       FIG. 9  is a top plan view of another embodiment of the macular and scleral support band of the present invention;  
       FIG. 10  is a top plan view of a further embodiment of the macular and scleral support band of the present invention;  
       FIG. 11  is a posterior view of the support band of  FIG. 10  as applied to a right eye;  
       FIG. 12  is an anterior view of the device depicted in  FIG. 11 ;  
       FIG. 13  is a perspective view of a circumferential support band that is included within an alternative embodiment of the macular and scleral support device of the present invention; and  
       FIG. 14  is a side elevational view of an alternative macular and scleral support device of the present invention including a circumferential band that is engagable with a posterior support band. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Eyes with high axial myopia overgrow during the years in which the body is growing. Thus, in most cases, myopia is fairly stable following the cessation of corporeal growth, which occurs at about 17 years for a woman and 20 years for a man. In degenerative or progressive myopia, another factor is the presence of a weak collagen fiber in the tough scleral shell of the eye. The eye being a pressurized sphere, the thinned, posterior wall of the eye stretches, and so elongation of the eye may continue after the cessation of corporeal growth. The retina is progressively damaged by the continued stretching of the eye, resulting in degenerative changes which cause vision loss later in life. The accepted complications of this process involve retinal tears and detachments, premature cataract, and glaucoma, but most especially, macular degeneration. This latter problem causes uncorrectable vision loss later in life. The timing and severity of this loss is not easily predicted.  
      In the present invention, the applicant has developed a device which provides more extensive permanent positive mechanical external support to the parts of the eye globe most involved in the causation of the pathological changes of degenerative myopia. Generally, the flexible ocular restraint band of the present invention includes a thin flexible strap device that is made of a central woven, non-absorbable, surgical fabric, with a solid surgical quality material, such as (but not limited to) silicone rubber or a natural material at the strap ends. The combination allows a firm flexible but non-extensible device to be fashioned so as to provide a structural connection between the weak posterior pole of the eye and the thicker anterior scleral ring. While doing so, it is designed to also address the issue of equatorial growth and stretching. The device is sutured at its reinforced ends, with various degrees of tension, to the globe of the eye, and the reinforced ends prevent undesirable gathering, folds, pulls and creases of the fabric material. The creation of uneven pressure upon the outer surface of the eye is thus avoided. The surgical fabric, being porous, allows reactive scar tissue to enter its interstices, a process which may secure the implant and add to the mechanical bracing of the weak wall of the eye. Four alternative embodiments are described in detail herebelow, however the present invention is not to be limited thereto.  
       FIG. 1  is a top plan view depicting a first embodiment of the present invention and  FIG. 2  is a side elevational view of the device depicted in  FIG. 1 . As depicted in  FIGS. 1 and 2 , the device  10  is generally formed as a strip of fabric material having a length L of approximately 70 millimeters and a width W of approximately 10 millimeters. These dimensions are deemed adequate for an adult eye, however the present invention is not to be limited to such dimensions as the object of the invention is that it be sutured to wrap behind the eye, and the eyes of different patients will have differing dimensions. The band  10  is preferably formed of a flexible material, such as a 1 mm Dacron surgical mesh fabric, and it includes end portions  14  and  16  and a central portion  20  between the end portions. One or both of the end portions  14  and  16  is bonded with a firm support material  24  that provides a flexible stiffness to the end portion of the band. In the preferred embodiment, the support material  24  at the end portions  14  and  16  is comprised of a silicone rubber that is heat bonded to the mesh fabric at the ends of the band. As is depicted in the side view of  FIG. 2 , the thickness of the support material  24  at the end portions  14  and  16  may be approximately 1.5 millimeters, where the thickness of the central mesh fabric  20  is approximately 1 millimeter.  
      The support material  24  may be bonded to varying lengths at the ends of the band to produce differing reactive scar tissue effects. That is, due to the location of particular eye muscle groups and the degree of reactive scar tissue desired, the length that the support material  24  may be bonded to the fabric mesh may vary from a minimum of approximately 5 mm (as depicted at end  14  of  FIGS. 1 and 2 ) to a device where each support material portion  24  is approximately 25 mm or approximately one third of the length of the band  10 , to a band in which the support material portion is bonded throughout the entire length of the band. Additionally, the device can be fabricated where the length of the support material  24  at a first end  14  differs from the length of the support material at the other end  16 , as is depicted in  FIGS. 1 and 2 . It is to be understood that the present invention is not intended to be limited as to the nature of the materials (solid or woven) which are specified herein. That is, the device may be made from elements of natural material, and may be made from several materials that are laminated, cemented, fused, bonded, sewn or otherwise joined together.  
      As depicted in  FIG. 1 , it is not necessary that the band be formed with straight side edges, and the device  10  depicted in  FIG. 1  preferably includes a central portion having curved side edges  28  and  30 . The device having this curved side edge configuration, where one side edge  28  is concave and the other side edge  30  is convex, is advantageous in applying it to the patient&#39;s eye, in that it can be more readily sutured to the eye in an orientation around the optic nerve which protrudes from the posterior portion of the eye, as is described more fully with the aid of  FIGS. 3 and 4 . As has been indicated hereabove, the band is designed to be sutured to the anterior scleral portions of the eye and two suture attachment points  32  may be included, as are shown at each end  14  and  16  of the band within the support material  24 . A significant feature of the present invention is that the support material  24  at the ends provides reinforcement to the mesh material at the ends, which prevents undesirable gathering, folding and pulling of the mesh material proximate the suture points, which will generally occur where the ends  14  and  16  lack the reinforcement provided by the support material  24 .  
       FIGS. 3 and 4  depict the surgical attachment of the ocular support band  10  to a right eye globe, wherein  FIG. 3  is a posterior depiction and  FIG. 4  is an anterior depiction. As depicted in  FIG. 3 , the band  10  is placed around the posterior portion of the eye  36  such that the concave curve of side edge  28  curves around the optical nerve  37  that projects rearwardly from the eye  36 . As will be understood by those skilled in the art, the band  10  is preferably implanted under the superior rectus muscle  38 , over the insertion of the superior oblique muscle  39 , medial to the lateral rectus muscle  40  and superior to the inferior rectus muscle  41 . It is therefore positioned to provide posterior support to the eye between the optic nerve  37  and the insertion of the inferior oblique muscle  42 . One sequence for surgical fixture to the eye is as follows.  
      The support arm for the superonasal location  43  is placed under the superior rectus muscle  38  and sutured to the globe of the anterior scleral ring (as depicted in  FIG. 4 ). The arm to be placed inferonasally  44  is then passed over the insertion of the superior oblique muscle  39  anteriorally (nasal to the lateral rectus muscle  40 ) and then behind the insertion of the inferior oblique muscle  42  and superior to the inferior rectus muscle  41 . During this passage twisting of the device  10  is prevented. The end in the inferornasal quadrant  44  is maneuvered to slip the central portion of the band over the posterior pole of the eye. It is then trimmed to length and sutured, with the desired tension to the scleral ring (as depicted in  FIG. 4 ).  
      The curved side edge  28  aids in the positioning of the band  10  to avoid any contact with or pressure upon the optic nerve  44  and its blood supply, or any vortex veins that are identifiable. The band  10  may be sutured to the eye  40  with some tension, however the chief purpose of the band  10  is to prevent further rearward elongation of the eye, as a means to prevent further degeneration of the macular portion of the eye. The band  10  thus provides a posterior tensioned, support, in the fashion of a sling, sutured to the anterior globe in the superonasal and inferonasal quadrants at two suture points. It provides a new broad support to the posterior pole of the eye, as well as to the equatorial regions of two of the globe&#39;s four quadrants. It&#39;s materials have been well proven, by daily surgical use, to be un-degraded by long-term implantation in the body&#39;s tissues.  
      In some patients the band  10  may be advantageously placed in alternative locations in order to provide the desired support to the posterior pole of the eye, and  FIG. 5  is a posterior view (right eye) that is similar to  FIG. 3  that depicts such an alternative band positioning. As depicted in  FIG. 5 , an upper support arm of the band  10  is positioned in the superonasal location  43  under the superior rectus muscle  38  and sutured to the globe at the anterior scleral ring. The band is then passed over the insertion of the superior oblique muscle  39  anteriorally (nasal to the lateral rectus muscle  40 ) and then behind or over the insertion of the inferior oblique muscle  42 . The lower end is then passed into the inferotemporal quadrant  47 . It is then trimmed to length and sutured, with the desired tension to the scleral ring. It is therefore to be understood that in  FIG. 5  the device is positioned and sutured in the superonasal and inferotemporal quadrants at two suture points where the curved edge  28  is positioned such that the device avoids any contact with or pressure upon the optic nerve and its blood supply, and any vortex veins that are identified.  
       FIG. 6  is a top plan view that depicts a first alternative embodiment  50  of the present invention, which can be thought of as an enhanced band from that depicted in  FIGS. 1 and 2  where a third leg  54  of the band is fabricated. In comparing the device  10  of  FIG. 1  and the device  50  of  FIG. 6 , it is seen that the device of  FIG. 6  is basically a “T” or “Y” shape having an integrally formed leg  54  that projects laterally from a side  30  of the band depicted in  FIG. 1 . The features and dimensions of the embodiment  50  depicted in  FIG. 6  such as the length, width and thickness of the band are essentially the same as the band  10  depicted in  FIGS. 1 and 2 . The additional leg  54  may have a length of approximately 40 millimeters and it includes a reinforced end portion  58  comprising the support material  62  that is utilized with the ends  14  and  16  of the device  10 . The end portion  62  of the additional leg may include suture points  66  within it such that it can be sutured to a further point along the anterior scleral ring of the eye.  
       FIGS. 7 and 8  depict the surgical attachment of the ocular support band  50  to a right eye, wherein  FIG. 7  is a posterior depiction and  FIG. 8  is an anterior depiction. As depicted in  FIG. 7 , the band  50  is placed around the posterior portion of the eye  36  such that the concave curve of side edge  28  curves around the optical nerve  37  that projects rearwardly from the eye  36 . As is seen in  FIG. 8 , the ends  14 ,  16  and  54  of the band  50  are wrapped towards the anterior portion of the eye, where sutures  32  are formed to join the support material portion  24  of the ends  14  and  16  to the scleral ring of the eye  36 , and sutures  66  are used to join the leg  54  to the scleral ring. The leg  54  provides additional posterior support to the eye through the placement of the leg  54  within a third quadrant of the eye, and the curved edge  28  is preferably positioned to avoid any contact with or pressure upon the optic nerve and its blood supply, or any vortex veins that are identified. The band  50  may be sutured to the eye  40  with some tension, however the chief purpose of the band  50  is to prevent further rearward elongation of the eye, as a means to minimize or to prevent further degeneration of the macular portion of the eye.  
      The band  50  uses the same materials to provide a posterior support with three suture points, one being in each of three of the four quadrants of the globe of the eye. This form provides support to an even greater area of the portions of the globe which are involved in the over-growth and stretching of the eye found in cases of degenerative myopia. The legs of the band  50  may be advantageously engaged in differing eye quadrants for different patients, and, with reference to the discussion hereabove regarding the device  10  as depicted in  FIGS. 3 and 5 , the lower leg of the band  50  may be advantageously engaged in either the inferonasal quadrant or the inferotemporal quadrant of the eye globe. Similarly the leg  54  of band  50  may be engaged in either the superotemporal or the inferotemporal quadrants.  
      Yet another embodiment  80  of the present invention is depicted in a top plan view in  FIG. 9 . In comparing this embodiment  80  with the embodiment  50  depicted in  FIG. 6 , it is seen that this embodiment is formed as a band having four support legs  14 ,  16 ,  84  and  86 , rather than the three legs  14 ,  16  and  54  depicted in  FIG. 6 . The device can generally be thought of as comprising the device  50  depicted in  FIG. 6  where the additional leg  54  has been cut lengthwise to form two thinner separable legs  84  and  86 , where each can have at least one suture point  90  formed in the support material  94  of the end portion of each leg. The length, width and thickness of the support material end portions  94  and mesh portions forming the device  80  are generally the same as those of the devices depicted in  FIGS. 1-8 . Arms  84  and  86  may be engaged in one or both of the temporal quadrants of the eye.  
      The embodiment  80  uses the same materials to provide a posterior support with four suture points, one being in each of the four quadrants of the globe of the eye. This form provides support to other selected portions of the globe which are identifiable as being involved in the over-growth and stretching of the eye found in cases of degenerative myopia.  
       FIG. 10  is a top plan view that depicts a further alternative embodiment  100  of the present invention, which can be thought of as an enhanced band from that depicted in  FIG. 6 , where a fourth leg of the band is fabricated. In comparing the device  100  of  FIG. 10  with the previously described devices, it is seen that the device  100  is basically an “X” shape having a central portion  104  and four integrally formed legs  108 ,  112 ,  116  and  120 . The features and dimensions of the embodiment  100  depicted in  FIG. 10 , such as the length, width and thickness of the band are essentially the same as the band  10  depicted in  FIGS. 1 and 2 . Each leg may have a length of approximately 40 mm, including a reinforced end portion  124  comprising the support material  62  that is utilized with the ends  14  and  16  of the device  10 . Each end portion  124  may include suture points  128  such that it can be sutured to a desired location along the anterior scleral ring of the eye. As with the support band embodiments depicted hereabove, the device  100  preferably includes a concave curved side edge  132  of the body portion  104  that corresponds to the curved side edge  28  of the prior embodiments. Attachment provides support to all four of the eye&#39;s quadrants.  
       FIGS. 11 and 12  depict the surgical attachment of the ocular support band  100  to a right eye, wherein  FIG. 11  is a posterior depiction and  FIG. 12  is an anterior depiction. As depicted in  FIG. 11 , the band  100  is placed around the posterior portion of the eye  36  such that the concave curve of side edge  132  curves around the optical nerve  37  that projects rearwardly from the eye  36 . As is seen in  FIG. 12 , the ends  124  of the legs  108 ,  112 ,  116  and  120  are wrapped towards the anterior portion of the eye, where sutures  140  are formed to join the support material portion  124  of the legs to the scleral ring of the eye  36 . Each one of the legs is placed within a quadrant of the eye, and the curved edge  132  is preferably positioned to avoid any contact with or pressure upon the optic nerve and its blood supply, or any vortex veins that are identified. The band  100  may be sutured to the eye with some tension, however the chief purpose of the band  100  is to prevent further rearward elongation of the eye, as a means to prevent further degeneration of the macular portion of the eye. The band  100  uses the same materials as the embodiments described above to provide a posterior support with four suture points. This form provides further support to an even greater area of the portions of the globe which are involved in the over-growth and stretching of the eye found in case of degenerative myopia.  
      An alternative embodiment of a macular and scleral support device of the present invention is depicted in  FIGS. 13 and 14 , wherein  FIG. 13  is a perspective view of a circumferential support band that is engagable with a posterior support band described hereabove, and  FIG. 14  is a side elevational view of a right eye globe having a circumferential and posterior support band engaged thereto. As depicted in  FIG. 13 , the circumferential band is generally rectangular and typically has a length of approximately 100 millimeters and a width of approximately 5-25 millimeters and is comprised of the same materials as the posterior support bands described hereabove. The ends  152  of the circumferential band  150  are preferably, though not necessarily, reinforced with a firm support material  153  (such as has been described hereabove with regard to the posterior support bands) that provides a flexible stiffness to the end portions of the circumferential band  150 , and acts to prevent folding and pulling of the mesh material proximate suture points at the ends of the band  150 .  
      As depicted in  FIG. 14 , the circumferential band  150  is placed around the equator of the eye globe  36  to provide further support for the eye alone or in combination with a posterior support band  154 , such as any of the bands  10 ,  50 ,  80  and  100  described hereabove. The band  150  is located anterior to the insertion of the superior and inferior oblique muscles (not shown), and is placed under each of the four rectus muscles  158 . The band  150  is preferably installed following the engagement of the posterior support band  154  as described above, although it may alternatively be prepositioned before installation of the posterior support band. The ends  152  of the circumferential band  150  are joined together with sutures  164 , and the circumferential band  150  is preferably engaged by sutures  168  to the legs of the posterior support band  154  where there is a crossing of the circumferential band with the legs of the posterior support band. The suturing  168  of the legs of the posterior support band  154  to the circumferential band  150  acts to secure the placement of the legs and prevent future movement of the posterior support band and the circumferential band. The circumferential band also provides equatorial support to the eye globe. When placed in otherwise unsupported quadrants of the eye, the band is to be positioned with episcleral sutures of non-absorbable material.  
      The device of the present invention appears to be quite effective in adult eyes. While it does reinforce the thin, stretched sclera, it does not materially shorten the eye, nor does it reduce future macular complications from the existing length of the eye. The basic concept of the invention is a mechanical solution to what is basically a mechanical problem for eyes of 27 mm length, or greater. The goal is to prevent further stretching which would cause even more progressive damage later in life. Further enhancements of the present invention are contemplated wherein chemical or physical agents are incorporated within the fabric of the band to either retard or stimulate the growth of scarring tissue in or on the weak natural sclera of the eye. The present invention should be considered at almost any patient age if the eye exceeds 27 mm in length and risk of future myopic macular degeneration is significant. Additionally, if the intraocular pressure is over approximately 16 mm Hg, pressure reducing drops should be administered to keep the pressure in the lower teens. This is, after all, the force which stretches the eye further.  
      While the present invention has been shown and described with regard to certain preferred embodiments, it is to be understood that modifications in form and detail will no doubt be developed by those skilled in the art upon reviewing this disclosure. It is therefore intended that the following claims cover all such alterations and modifications that nevertheless include the true spirit and scope of the inventive features of the present invention.