Abstract:
A pattern-generating intraocular probe is provided that includes a cannula including a diffractive optical element (DOE), the DOE being patterned such that an on-axis illumination of the DOE produces an emitted beam forming a linear pattern; and a handpiece connected to a proximal of the cannula.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Ophthalmic illuminators allow a physician to illuminate the interior structure of the eye such as the vitreous and the retina during medical procedures. For example, an endoscopic ophthalmic illuminator (endo-illuminator) includes an optical fiber within the bore of a cannula. By driving a proximal of the optical fiber with a suitable light source, light emitted from a distal of the fiber illuminates the desired portion of the eye during a surgical procedure. Alternatively, a physician may illuminate the eye with fiber optic illumination while using an ophthalmic microscope. 
         [0002]    A specialized ophthalmic illumination procedure has been developed to determine retinal fundus topography information. For example, a fundus camera has been configured to include a diffractive optical element (DOE) that projects a grid or line pattern onto the retina. To simplify the optical configuration, fundus lenses have been developed such as disclosed in U.S. Pat. No. 7,422,327 that include a volume hologram DOE that is illuminated off-axis. Such a DOE would thus be relatively transparent to the remaining on-axis optical lenses in the fundus camera. However, the off-axis illumination and the addition of the DOE lens still introduces some complexity for a fundus camera. 
         [0003]    Accordingly, there is a need in the art for an improved ophthalmic illumination for retinal topography determinations. 
       SUMMARY OF THE INVENTION 
       [0004]    In accordance with a first aspect of the disclosure, a pattern-generating intraocular probe is provided that includes a cannula including a diffractive optical element (DOE), the DOE being patterned such that an on-axis illumination of the DOE produces an emitted beam forming a linear pattern; and a handpiece connected to a proximal of the cannula. 
         [0005]    In accordance with a second aspect of the disclosure, a method is provided that includes inserting a cannula into an eye, wherein the cannula includes a diffractive optical element (DOE) patterned such that an on-axis illumination of the DOE produces an emitted beam forming a linear pattern; and illuminating the DOE through a lumen of the cannula so as to produce the on-axis illumination such that the emitted beam forms the linear pattern on a retinal fundus. 
         [0006]    In accordance with a third aspect of the invention, an intraocular probe is provided that includes a handpiece; a needle having a proximal connected to the handpiece; and a diffractive optical element (DOE) sealing a distal of the needle, the DOE being patterned to project a plurality of parallel lines onto a retina. 
         [0007]    These and other aspects, forms, objects, features, and benefits of the present invention will become apparent from the following detailed drawings and description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    In the accompanying drawings, which are incorporated in and constitute a part of the specification, embodiments of the invention are illustrated, which, together with a general description of the invention given above, and the detailed description given below, serve to exemplify the embodiments of this invention. 
           [0009]      FIG. 1  is a cross-sectional view of an intraocular pattern-projecting probe for determining retinal topography. 
           [0010]      FIG. 2  illustrates several example projected patterns for the probe of  FIG. 1 . 
           [0011]      FIG. 3  shows how pathologies causing bumps or depressions in the retinal fundus distort the linear patterns projected by the probe of  FIG. 1 . 
           [0012]      FIG. 4  is a view of the probe of  FIG. 1  projecting its linear pattern onto a retina as manipulated by a clinician. 
           [0013]      FIG. 5  is a flowchart for a method of determining retinal topography. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    The present disclosure relates generally to the field of ophthalmic medicine, and more particularly to devices and methods for determining retinal topography. For the purposes of promoting an understanding of the principles of the invention, reference will now be made to embodiments or examples illustrated in the drawings, and specific language will be used to describe these examples. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alteration and further modifications in the described embodiments, and any further applications of the principles of the invention as described herein are contemplated as would normally occur to one skilled in the art to which the disclosure relates. 
         [0015]    To provide an improved ability for retinal topography determination, an intraocular probe  100  is provided that includes an on-axis diffractive optical element  105  as shown in  FIG. 1 . A cannula or needle  110  includes diffractive optical element  105  at a distal to allow an emitted beam  115  projected by diffractive optical element  105  to properly diverge to illuminate the retinal field. A handpiece piece  120  includes a laser projector  125  having a laser source  130  driving collimating optics  135 . Laser projector  125  is aligned with a lumen of cannula  105  so that a resulting collimated laser beam  140  emitted from collimating optics  135  travels longitudinally through the lumen to orthogonally (on-axis) intersect with diffractive optical element  105 . Handpiece  120  includes a battery  145  to power laser source  130  such as a green laser diode. Other color sources may also be used. Diffractive optical element  105  hermetically seals the distal of cannula  105  to prevent fluids such as balanced saline solution from flooding cannula  105  and affecting laser source  130  and other components. 
         [0016]    As known in the diffractive optical arts, diffractive optical element  105  includes an etched planar surface that forms complex microstructures. By proper configuration of the resulting microstructures, a designer can tune a diffractive optical element to project virtually an infinite variety of patterns. With regard to determining retinal topography, the desired pattern includes one or more pluralities of parallel lines. If diffractive optical element  105  is configured to project a single plurality of parallel lines, emitted beam  115  will form a pattern such as patterns  205  or  210  in  FIG. 2 . Alternatively, if diffractive optical element  105  is configured to form two pluralities of orthogonally-oriented parallel lines, emitted beam  115  will form grid patterns such a patterns  215  and  220 . 
         [0017]    An example projected pattern on a retinal fundus  312  is shown in  FIG. 3 . The projected pattern illuminates retina structure  318 . As discussed above, the off-axis illumination of fundus  312  maintains the linearity of parallel lines  316 . However, a bump such as resulting from a retinal pathology causes curves  320 . A surgeon may directly observe such irregularities or they may be imaged and studied off line using a fundus camera. 
         [0018]    To illuminate a retinal fundus to determine its topography, a clinician may first use a trocar to pierce the sclera. The trocar is directed so as to place a trocar cannula providing access to the eye&#39;s interior at an angle that is off-axis with regard to the retina. As seen in  FIG. 4 , the clinician may grasp handpiece  120  so as to maneuver cannula  105  through the trocar cannula (not illustrated) to project diverging beam  115  onto the retinal fundus. Because the projected pattern is incident at an angle relative to the fundus perpendicular, any bumps or depressions in the retinal surface will result in curvature of the lines in the projected pattern. A clinician  400  (or a fundus camera) has an on-axis view through the eye&#39;s pupil at the illuminated fundus. Since probe  100  need only be several inches long, it is convenient for a clinician to place probe  100  so as to project the desired pattern onto the retina. Moreover, the clinician need merely rotate handpiece  120  about its longitudinal axis to rotate the resulting pattern. For example, if the handpiece is rotated 90 degrees, pattern  205  of  FIG. 2  becomes pattern  210 . Alternatively, probe  100  may include a slide lever (not illustrated) that rotates cannula  110  and DOE  105  relative to handpiece  120 . 
         [0019]    As compared to modifications of fundus lenses such as disclosed in U.S. Pat. No. 7,422,327, probe  100  may be made relatively inexpensively in that cannula  110  may be readily disconnected from handpiece  120  through operation of connector  150  as shown in  FIG. 1 . The remaining handpiece  120  is thus reusable such that cannula  110  and its diffractive optical element  105  may be readily removed and discarded after a medical procedure. Moreover, unlike fundus camera approaches, emitted beam  115  is not projected through the eye&#39;s pupil but instead is properly projected off-axis as shown in  FIG. 4 . In addition, cannula  105  needs no optical fiber to guide collimated beam  140  towards diffractive optical element  105 . In general, propagation through an optical fiber will tend to introduce perturbations because of corresponding perturbations in refractive index of the fiber core. Such perturbations may then cause the projected linear pattern to become diffused. 
         [0020]    Because diffractive optical element  105  is illuminated on-axis, its construction is less expensive as compared to the volume holography necessary for diffractive optical elements designed to receive off-axis illumination. In that regard, diffractive optical element  105  may be readily patterned using a computer-generated calculation of the fringe spacing and orientation to form the microstructure on the planar surface of diffractive optical element  105 . This spacing and orientation results in the desired plurality (or pluralities) of parallel lines in the resulting pattern on the retina. The diffractive optical element manufacturer, having calculated the desired spacing and orientation, may then pattern the surface of the optical element accordingly using, for example, a photo-resist laser. Photolithographic techniques may then be used to finish construction of diffractive optical element  105 . Alternatively, holographic exposure techniques may be used to form diffractive optical element (DOE)  105 . 
         [0021]    An example method of use for probe  100  with regard to imaging of the retinal illumination using a fundus camera will now be discussed with regard to the flowchart of  FIG. 5 . A clinician may first position intraocular probe  100  through a trocar cannula into the eye interior as discussed with regard to  FIG. 2  and illuminate DOE  105  at  502 . Advantageously, the clinician may position probe  100  to achieve the desired off-axis illumination discussed with regard to  FIG. 4 . DOE  105  then diffracts collimated laser beam to form the desired linear pattern on the retinal fundus at  504 . The retina then reflects and scatters the resulting pattern at  506 . The optics within the fundus camera may then focus the scattered light at  510  to form an image so that the fundus topography may be determined at  512 . Such a determination may be made solely by the clinician. Alternatively, an image processor may process the image to determine the fundus topography. It will be appreciated that a clinician may determine the fundus topography solely from judging the projected linear pattern and without the use of a fundus camera. 
         [0022]    While the present invention has been illustrated by the above description of embodiments, and while the embodiments have been described in some detail, it is not the intention of the applicant to restrict or in any way limit the scope of the invention to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicant&#39;s general or inventive concept. It is understood that all spatial references, such as “longitudinal axis,” “horizontal,” “vertical,” “diagonal,” “top,” “upper,” “lower,” “bottom,” “left,” and “right,” are for illustrative purposes only and can be varied within the scope of the disclosure.