Abstract:
The present invention includes a corneal marker having an adjustable element providing for orientation of the marker to the astigmatic axis of a patient&#39;s eye under examination, a handle secured to the corneal marker and a stem secured to and extending below the handle. The stem is weighted to facilitate alignment of the corneal marker to the corneal surface of the patient&#39;s eye under examination during corrective eye surgery according to the corneal light reflex from the eye in response to an illumination source.

Description:
PRIORITY CLAIM 
       [0001]    This application claims priority from earlier filed U.S. Provisional Patent Application Ser. No. 61/072,758 filed Apr. 2, 2008. The foregoing application is hereby incorporated by reference in its entirety as if fully set forth herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates generally to an ocular marking system and method and, more specifically, a corneal marking system and method to mark the astigmatic axis on the corneal surface of the eye prior to a surgical procedure to correct the ocular condition of astigmatism. 
       BACKGROUND OF THE INVENTION 
       [0003]    Astigmatism, an optical defect which blurs vision, is usually caused by an irregular curvature of the cornea. In a perfectly shaped eye, the cornea is spherical, and bends all incoming light in the same way, producing a sharply focused image on the back of your eye (retina). In individuals with astigmatism, the cornea is asymmetrically curved, similar to the surface of a football, with one axis of the ball curved more steeply than the opposite axis of the ball. This causes the light rays to be bent differently, which causes the image to be blurred. 
         [0004]    The blurred vision from the astigmatism can be measured and is designated as the astigmatic refractive error. The astigmatic refractive error is measured in terms of its power and axis. The astigmatic power is measured in diopters, and the axis is measured in degrees representing the direction on a 360 degree scale. The axis reflects the direction of the steepest or flattest meridian of the cornea. The axis of astigmatism is unique to each individual. 
         [0005]    The goal of treating astigmatism is to address the uneven curvature that causes blurred vision. Astigmatism may be corrected with eyeglasses, contact lenses, or surgery. Surgical correction of astigmatism can include laser (such as Lasik or Prk) as well as LRI (Limbal Relaxing Incisions, which are deep incisions in the peripheral cornea that flatten the steep meridian) and astigmatic intraocular lenses (at the time of cataract surgery). 
         [0006]    A cataract is a condition where the normally clear lens of the eye becomes progressively opaque. This opacification typically occurs over an extended period of time, and the amount of light that passes through the lens decreases with increasing degrees of opacity. As the ability of the cataract lens to transmit light decreases the ability of the eye to perceive images also decreases. Blindness ultimately can result. Since there are no known methods for eliminating the opacity of a cataract lens, it generally is necessary to surgically remove the opaque lens to permit the unobstructed passage of light through the pupil to the retina. 
         [0007]    In cataract surgery, the cloudy natural lens is removed from the eye. The focusing power of the natural lens can be restored by replacing it with a permanent artificial lens or intraocular lens (IOL) implant. These lenses are placed in the eye and thus closely simulate the optics of the natural lens which they are replacing. During cataract surgery, the astigmatic error can be corrected by either performing Limbal Relaxing Incisions in the peripheral cornea to flatten the steeper meridian, or by inserting a specialized IOL which can correct the astigmatism (a toric IOL). 
         [0008]    Regardless of whether astigmatism is corrected with an LRI or with a toric intraocular lens, it is essential to align the surgical intervention with the exact astigmatic axis. Prior to the surgery it is necessary to mark the astigmatic axis onto a patient&#39;s cornea as accurately as possible. 
         [0009]    A variety of methods and instruments are currently used to mark the cornea prior to surgery. Most involve a small handheld instrument (e.g., U.S. Pat. No. 6,217,596) that is pressed against the cornea prior to surgery, marking reference horizontal or vertical axis. After the eye surgery has started, and the patient is lying down, the reference marks are used to mark the cornea a second time at the direction of the astigmatic axis. This two-step methodology has several shortcomings and introduces several significant sources of error. In particular, error is introduced when the surgeon uses the alignment reference marks made in the first step to then mark the astigmatic axis in the second step. While the alignment is done while the patient is sitting upright, the marking is done while the patient is lying down. The eye undergoes movement within the socket comprising translation and rotation (“cyclotorsion”) as the patient is moved from the upright measuring position to the prone surgery position. Multiple techniques known in the art to accommodate this movement include those disclosed in U.S. Pat. No. 4,476,862 and U.S. Pat. No. 4,705,035. If the eye movement is not taken into consideration when the patient lies down the direction of the axis of astigmatism will not be properly accounted for. Mathematically, missing the axis of astigmatism to be treated by 10 to 15 degrees can lead to a treatment under-correction of 50% or more. 
         [0010]    Finally, the change in orientation encountered with the patient lying down with surgeon now approaching the patient from the side or from the forehead can be inherently confusing when attempting to mark the axis which was measured with the patient sitting. Difficulty with centration and rotation compound the multiple errors already introduced. 
         [0011]    One system and method that avoids many of these problems is described in U.S. patent application Ser. No. 12/047,261, which is directed to a corneal marking device assembly mounted onto a trial frame apparatus that can be adjusted by using the adjustment features on the trial frame apparatus. The corneal marking device assembly provides the stabilized structure through which the surgeon can observe the eye, measure characteristic features of the eye and mark the corneal surface with a corneal marking device housed in the corneal marking device assembly. While this system reduces disadvantages associated with traditional hand-held devices, however, the use of a trial frame apparatus can be cumbersome. 
         [0012]    Accordingly, there is a need for a non-cumbersome system and method that reduces errors associated with the traditional two-step methodology for marking the astigmatic axis on the cornea. 
       SUMMARY OF THE INVENTION 
       [0013]    The present invention addresses the systematic errors introduced by marking the cornea using traditional hand-held device in a two-step methodology by providing a novel system and method for marking the astigmatic axis in one simple step while a patient is sitting prior to eye surgery. 
         [0014]    A preferred embodiment of the present invention includes a corneal marker, a handle secured to the corneal marker and a stem secured to and extending below the handle. The stem is weighted to facilitate alignment of the corneal marker to the corneal surface of a patient&#39;s eye under examination during corrective eye surgery according to the corneal light reflex from the eye in response to an illumination source. With the preferred corneal marking device, the corneal marker has a substantially cylindrical central hub and a plurality of radial blades connected and substantially perpendicular to the central hub. A substantially cylindrical ring gauge is configured to rotatably fit adjacent the central hub. Preferably the handle includes a first substantially horizontal portion secured to the stem and a second substantially vertical portion secured to at least one of the corneal marker and ring gauge. 
         [0015]    In one embodiment, the plurality of radial blades are configured to leave a perceptible impression upon the corneal surface of the eye under examination. In an alternative embodiment, the plurality of radial blades are configured to apply ink to the corneal surface of the eye under examination. 
         [0016]    In an alternative embodiment, the corneal marking device includes a rotation member configured to allow movement of at least one of the corneal marker and ring gauge independent of the handle to facilitate alignment of the plurality of radial blades to the corneal surface of a patient&#39;s eye under examination during corrective eye surgery. 
         [0017]    A method for marking a corneal surface of an eye of a patient includes adjusting a corneal marking device to the desired setting based on a patient&#39;s eye under examination; illuminating the eye under examination with a light source; retracting eyelid of eye under examination; observing the corneal light reflex produced by the light source; aligning a corneal marking device associated with the mounting apparatus with an unobstructed corneal surface of the eye under examination using a weight secured to the corneal marking device to position the corneal marking device based on the corneal light reflex produced by the light source; and if the corneal marking device is aligned, marking the unobstructed corneal surface of the eye under examination. The patient&#39;s eye not under examination may be covered. 
         [0018]    As will be readily appreciated from the foregoing summary, the present invention provides an improved corneal marking system and method to mark the corneal surface of the eye prior to a surgical procedure to correct the ocular condition of astigmatism and thus improve the outcome of astigmatic refractive surgeries. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    Preferred and alternative examples of the present invention are described in detail below with reference to the following drawings: 
           [0020]      FIG. 1  is an isometric view of the preferred embodiment corneal marker of the present invention; 
           [0021]      FIG. 2  is an isometric view of one embodiment of the present invention showing the corneal marker, ring gauge, and handle and stem assembly, wherein the handle and stem assembly further includes a rotation feature that allows the stem to rotate freely with respect to the handle; and 
           [0022]      FIG. 3  is an isometric view of the preferred embodiment of the corneal marker of the present invention; 
           [0023]      FIG. 4  is an isometric view of the one embodiment of the corneal marker of the present invention showing optional corneal marker cap threads; 
           [0024]      FIG. 5  is an isometric view of the preferred embodiment of the corneal marker ring gauge of the present invention; 
           [0025]      FIG. 6  is a partial exploded isometric view of one embodiment of the present invention showing the corneal marker and ring gauge along with optional washer and cap; 
           [0026]      FIG. 7  is an isometric view of one embodiment of the present invention incorporating a cylindrical compression spring. 
           [0027]      FIG. 8  is flow diagram showing a preferred method of corneal marking by a surgeon utilizing a preferred embodiment of the present invention; and 
           [0028]      FIG. 9  is an isometric view of one embodiment of the corneal marking device of the present invention showing preferred hand placement for utilization of the device. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0029]    A description of the preferred embodiments of the present invention is presented with reference to  FIGS. 1-9 .  FIG. 1  shows one embodiment of a corneal marking device  10  of the present invention. The corneal marking device  10  includes a corneal marker  20 , a ring gauge  40 , a handle  50  and a weighted stem  60 . The preferred weighted stem  60  includes a proximate end  62  located near the handle  50  and a distal end  62  located remote to the handle  50 . The stem  60  may be of varying lengths or thickness, but is preferably of sufficient weight to facilitate orientation of the handle  50  to a patient&#39;s eye under examination when in operation, but not so heavy to be uncomfortable for the surgeon during operation of the corneal marking device  10 . 
         [0030]    The handle  50  is preferably sized to fit comfortably within a surgeon&#39;s hand, but may be of varying lengths or thickness. The handle  50  is attached to the proximate end  62  of the stem  60  and extends away from the stem to support the corneal marker  20  and ring gauge  40 . The handle  50  preferably includes a generally horizontal handle portion  52  proximate to the point of connection with the stem  60  and a generally vertical handle portion  54  that connects to and supports the corneal marker  20  and ring gauge  40 . In a preferred embodiment, the horizontal handle portion  52  attaches to the stem  60  at a 90 degree angle and is relatively short in length. In a preferred embodiment, the horizontal handle portion  52  joins the vertical handle portion  54  at an angle of approximately 135 degrees, and the vertical handle portion  54  in turn joins the ring gauge  40  at an angle of approximately 135 degrees, resulting in stem  60  and ring gauge  40  being generally parallel to each other. The shapes, lengths, and angles of association as between the stem  60 , the handle  50  and the corneal marker  20  and ring gauge  40  supported thereby may vary greatly within the scope of the present invention. 
         [0031]      FIG. 2  shows an alternative embodiment of the corneal marking device  10  wherein a part of the horizontal handle portion  52  is substantially encased by a cylindrical attachment  56  that is configured to allow the horizontal handle portion  52  to rotate freely within the cylindrical attachment  56 , making it easier for the surgeon to hold the handle without interfering with the freedom to rotate and otherwise maintain the corneal marking device in the desired position. 
         [0032]    A preferable aspect of the present invention is that the stem  60  acts as a weight or anchor to orient the corneal marker or means for marking the astigmatic axis of an unobstructed corneal surface of an eye under examination according to the corneal light reflex from the eye in response to an illumination source while the surgeon is holding the handle  50 . In the preferred embodiment, the corneal marker or means for marking includes the corneal marker  20  and ring gauge  40 , but other known marking devices may also be used. The use of a weighted stem in the present invention acts to offset and therefore force into a generally vertical position the corneal marker  20  and ring gauge  40  to allow the surgeon to align the corneal marking device  10  to enable proper marking of the astigmatic axis in a single-step process. In addition to the preferred embodiment described above, various other embodiments of the handle  50  and stem  60  assemblies are contemplated to facilitate this aspect of the present invention. For example, in one embodiment, the horizontal handle portion  52  and the vertical handle portion  54  may be separate but movably connected via an attachment that allows the horizontal handle portion  52  and the vertical handle portion  54  to move independent of each other, again to facilitate maintenance of the corneal marking device in the desired position. In yet another embodiment, the corneal marking device  10  may include a stem  60  connected only to a vertical handle portion  54 . In yet another embodiment, the stem  60  may be configured as a small geometric weight to facilitate orientation of the vertical handle portion  54  vertically and parallel the patient&#39;s head. 
         [0033]      FIG. 3  shows in greater detail the preferred corneal marker  20  of the corneal marking device  10  that is used to mark the patient&#39;s eye under examination. The corneal marker  20  preferably includes a substantially cylindrical central hub  22  that is attached to four perpendicular radial blades  24  that flare outward from the central hub  22  and are joined at a central ring  26  located within the diameter of the central hub  22 . The central ring  26  is the preferred alignment assembly used to align the corneal marking device  10  according to the corneal light reflex of the patient&#39;s eye under examination. In alternative embodiments, alignment assemblies of different shapes and structures may be used, for example, an oval, square, rectangle or other shaped structure, preferably located within the diameter of the central hub  22 , so long as it facilitates alignment of the corneal marking device  10  according to the corneal light reflex of the patient&#39;s eye under examination through use of some type of cross-hair configuration. Each of the four blades  24  is preferably curved along a first side  25  to match the corneal curvature of an eye. Each of the four blades is preferably configured with a sharp edge  28  along the first side  25  to enable marking, but not cutting, of the cornea. Marking may be accomplished solely by the pressure or the sharp edge  28  of the blades  24  upon the cornea, which leaves a perceptible impression for a period of time, or by application of ink to the sharp edge  28  of the blades  24 , which in turn leaves visible marking on the cornea. As shown further with reference to  FIG. 4 , an alternative embodiment of the corneal marker  20  may include threads  32  along the outside surface  30  of the central hub  22 . 
         [0034]    The ring gauge  40  of the corneal marking device  10  is better understood with reference to  FIG. 5 . In a preferred embodiment, the ring gauge  40  is substantially cylindrical in shape, and includes an inner surface  42 , an outer surface  44 , a top surface  46  and a means of connection  48  to the vertical handle portion  54 . The diameter of the ring gauge  40  is such that the inner surface  42  of the ring gauge  40  fits securely adjacent the outside surface  30  of the central hub  20  around the outer diameter of the central hub  20 . The ring gauge  40  preferably includes markings  45  on the outer surface  44  and markings  47  on the top surface  46  corresponding to 0-180 degrees in 10 degree increments. In alternative embodiments, the markings may be located on additional, fewer than or other surfaces of the ring gauge  40 . The means of connection  48  between the ring gauge  40  and the vertical handle portion  54  of the handle  50  may include molding the ring gauge  40  directly to the handle  50 , or otherwise permanently connecting the ring gauge  40  and the handle  50 , or may include a detachable means of connection between the ring gauge  40  and the handle  50  (not show), such as but not limited to mechanical fittings, clasps, or other connections well known in the art. 
         [0035]      FIG. 6  shows a preferred embodiment of the corneal marking device  10  shown in  FIG. 4 , wherein the threads  32  are used in conjunction with a washer  70  and cap  72  having internal threads (not shown) corresponding to the threads  32  to enable the cap to be removably attached to the central hub  22 . When used with the washer  70 , this secures the ring gauge  40  to the central hub  22  while allowing the user to manually rotate the central hub  22  inside the ring gauge  40  without excessive force to align at least one of the radial blades  24  with the markings  45  on the outer surface  44  of the ring gauge  40  for designation of the astigmatic axis. In contemplated alternative embodiments, various other means may be used to maintain the ring gauge  40  adjacent to the central hub  22  while allowing the user to manually rotate the central hub  22  inside the ring gauge  40  without excessive force, e.g., using friction fit, a snap ridge movably connecting the ring gauge  40  to the central hub  22 , etc. In an alternative embodiment, shown in  FIG. 7 , a cylindrical compression spring  80  may be oriented around the central hub  22  positioned between the radial blades  24  and ring gauge  40  to allow the manual rotation of the radial blades around the central hub. In this embodiment, the central hub  22  may further include a protruding lip  82  positioned to maintain the ring gauge  40  adjacent to the central hub  22  while allowing the user to manually rotate the central hub  22  inside the ring gauge  40  without excessive force. This embodiment would further allow a means of limiting the force transmitted to the cornea by the radial blades  24  in operation of the corneal marking device  10 . 
         [0036]    The preferred method of corneal marking by a surgeon is described with reference to the flow diagram of  FIG. 8  utilizing the assembled corneal marking device  10  shown more fully in  FIGS. 1 and 6 , and in operational context as provided by reference to  FIG. 9 . At block  100 , the corneal marker  20  is dialed or oriented so that one of the four blades  24  is aligned to the desired axis on the ring gauge  40  using the markings  45  on the outer surface  44  or the markings  47  on the top surface  46  of the ring gauge  40  for designation of the astigmatic axis of the patient&#39;s eye under examination. At block  102 , in a preferred embodiment, a patient&#39;s eye not under examination is covered. 
         [0037]    At block  104 , the patient eye under examination is illuminated to allow the surgeon to observe the resultant corneal light reflex. This preferably occurs after anesthetic drops are applied to the patient&#39;s eye under examination and the patient is in a sitting position. In the preferred embodiment, the eye is illuminated using a fixation light held by the surgeon in one hand while holding the corneal marking device  10  in the other hand. This may also be accomplished using other sources of illumination held by the surgeon, other persons or associated with a movable or stationary fixture. 
         [0038]    At block  106 , the eyelid of the patient&#39;s eye under examination is retracted. At block  108 , the corneal marking device  10  is aligned such that the corneal light reflex is aligned in the central ring  26  located within the diameter of the central hub  22 . This is preferably accomplished by using the sight line of the fixation light (similar to aiming a rifle) to observe the resultant corneal light reflex. The corneal marking device is preferably held with the surgeon&#39;s thumb underneath the horizontal handle portion  52  of the handle  50  with the surgeon&#39;s index or middle finger on top of the horizontal handle portion  52 , but may be held in a variety of ways according to surgeon preference. The handle  50  is preferably held tightly enough to position the corneal marking device  10  while still allowing the weight of the stem  60  to maintain the vertical handle portion  54  in a vertical position. 
         [0039]    A check is made at decision block  110  whether the cornea is properly aligned based on the corneal light reflex being aligned in the central ring  26  located within the diameter of the central hub  22 . If not, the logic returns to block  108 . If the cornea is properly aligned, the logic continues to block  112 , where the four blades  24  of the corneal marking device  10  are applied to the cornea of the patient&#39;s eye under examination with sufficient force to leave four radial marks on the corneal surface from the sharp edge  28  along the first side  26  of the blades  24 . Marking may be accomplished solely by the pressure or the sharp edge  28  of the blades  24  of the corneal marking device  10  upon the cornea, which leaves a perceptible impression for a period of time, or by application of ink to the sharp edge  28  of the blades  24 , which in turn leaves visible marking on the cornea. 
         [0040]    While the preferred embodiment of the invention has been illustrated and described, as noted above, many changes can be made without departing from the spirit and scope of the invention. For example, the interface between the corneal marker and ring gauge may be altered such that the ring gauge sits within the inner diameter of the corneal marker to provide rotational alignment of the radial blades. In yet an alternative embodiment, the radial blades may be internal to a larger corneal marker rather than flare outward from the corneal marker. Accordingly, the scope of the invention is not limited by the disclosure of the preferred embodiment. Instead, the invention should be determined entirely by reference to the claims that follow.