Patent Publication Number: US-9402767-B2

Title: Ocular implant architectures

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 13/366,073, filed Feb. 3, 2012, now U.S. Pat. No. 8,372,026; which is a continuation of U.S. application Ser. No. 12/236,254, filed Sep. 23, 2008, now abandoned; which claims priority to U.S. Provisional Application No. 61/033,746, filed Mar. 4, 2008. U.S. application Ser. No. 12/236,254 is also a continuation-in-part of U.S. application Ser. No. 11/860,318, filed Sep. 24, 2007, now U.S. Pat. No. 7,740,604. The disclosures of the preceding patents and patent applications are incorporated by reference as if fully set forth herein. 
    
    
     INCORPORATION BY REFERENCE 
     All publications and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. 
     FIELD OF THE INVENTION 
     The present invention relates generally to devices that are implanted within the eye. More particularly, the present invention relates to devices that facilitate the transfer of fluid from within one area of the eye to another area of the eye. 
     BACKGROUND OF THE INVENTION 
     According to a draft report by The National Eye Institute (NEI) at The United States National Institutes of Health (NIH), glaucoma is now the leading cause of irreversible blindness worldwide and the second leading cause of blindness, behind cataract, in the world. Thus, the NEI draft report concludes, “it is critical that significant emphasis and resources continue to be devoted to determining the pathophysiology and management of this disease.” Glaucoma researchers have found a strong correlation between high intraocular pressure and glaucoma. For this reason, eye care professionals routinely screen patients for glaucoma by measuring intraocular pressure using a device known as a tonometer. Many modern tonometers make this measurement by blowing a sudden puff of air against the outer surface of the eye. 
     The eye can be conceptualized as a ball filled with fluid. There are two types of fluid inside the eye. The cavity behind the lens is filled with a viscous fluid known as vitreous humor. The cavities in front of the lens are filled with a fluid know as aqueous humor. Whenever a person views an object, he or she is viewing that object through both the vitreous humor and the aqueous humor. 
     Whenever a person views an object, he or she is also viewing that object through the cornea and the lens of the eye. In order to be transparent, the cornea and the lens can include no blood vessels. Accordingly, no blood flows through the cornea and the lens to provide nutrition to these tissues and to remove wastes from these tissues. Instead, these functions are performed by the aqueous humor. A continuous flow of aqueous humor through the eye provides nutrition to portions of the eye (e.g., the cornea and the lens) that have no blood vessels. This flow of aqueous humor also removes waste from these tissues. 
     Aqueous humor is produced by an organ known as the ciliary body. The ciliary body includes epithelial cells that continuously secrete aqueous humor. In a healthy eye, a stream of aqueous humor flows out of the anterior chamber of the eye through the trabecular meshwork and into Schlemm&#39;s canal as new aqueous humor is secreted by the epithelial cells of the ciliary body. This excess aqueous humor enters the venous blood stream from Schlemm&#39;s canal and is carried along with the venous blood leaving the eye. 
     When the natural drainage mechanisms of the eye stop functioning properly, the pressure inside the eye begins to rise. Researchers have theorized prolonged exposure to high intraocular pressure causes damage to the optic nerve that transmits sensory information from the eye to the brain. This damage to the optic nerve results in loss of peripheral vision. As glaucoma progresses, more and more of the visual field is lost until the patient is completely blind. 
     In addition to drug treatments, a variety of surgical treatments for glaucoma have been performed. For example, shunts were implanted to direct aqueous humor from the anterior chamber to the extraocular vein (Lee and Scheppens, “Aqueous-venous shunt and intraocular pressure,” Investigative Ophthalmology (February 1966)). Other early glaucoma treatment implants led from the anterior chamber to a sub-conjunctival bleb (e.g., U.S. Pat. No. 4,968,296 and U.S. Pat. No. 5,180,362). Still others were shunts leading from the anterior chamber to a point just inside Schlemm&#39;s canal (Spiegel et al., “Schlemm&#39;s canal implant: a new method to lower intraocular pressure in patients with POAG?” Ophthalmic Surgery and Lasers (June 1999); U.S. Pat. No. 6,450,984; U.S. Pat. No. 6,450,984). 
     SUMMARY OF THE INVENTION 
     One aspect of the invention provides an ocular implant having a first spine; a second spine; a first strut extending in an axial direction Z between the first spine and the second spine; a second strut extending in an axial direction Z between the first spine and the second spine; wherein an angular dimension θ of a first edge of each strut undulates as the strut extends in the axial direction Z between the first spine and the second spine; and wherein a radius r of an outer surface of each strut remains substantially constant as the strut extends the axial direction Z between the first spine and the second spine. 
     Yet another aspect of the invention provides an ocular implant having a first spine section; a second spine section; and a first frame extending between the first spine section and the second spine section, the frame having a diameter of between 0.005 inches and 0.04 inches, the ocular implant being adapted to be disposed within a canal of Schlemm in a human eye. 
     In some embodiments, the first spine section, the second spine section, and the first frame form portions of a single tubular wall. Each spine section may optionally have only a single spine. In some embodiments, each spine section has an arcuate shape in lateral cross section. In some embodiments, the first spine has a first circumferential extent and the first frame has a second circumferential extent, wherein the second circumferential extent is greater than the first circumferential extent. 
     In some embodiments, the first frame has a first strut and a second strut and may have only two struts. Each strut may optionally have an arcuate shape in lateral cross section. 
     In embodiments in which the first strut has a first edge (partially defining, e.g., a first opening in the ocular implant), an angular dimension θ of the first edge may undulate as the strut extends in an axial direction Z between the first spine and the second spine. An angular dimension θ of the first edge may also first increase, then decrease, as the strut extends in an axial direction Z between the first spine and the second spine. Also, a radius r of the first edge may remain substantially constant as the strut extends in axial dimension Z between the first spine and the second spine. 
     In some embodiments, the first strut has a thickness that is substantially constant in a radial direction. In some embodiments, the first strut has a width extending in an arc along a circumferential direction. In some embodiments, the first strut has a length extending in an axial direction that is generally parallel to a longitudinal axis of the ocular implant. 
     The first spine section and the second spine section may be axially aligned with one another. A shape of the second strut may also be a mirror image of a shape of the first strut. 
     Some embodiments of the ocular implant have a second frame extending between the second spine and a third spine. Some embodiments of the ocular implant have a first opening extending between the first edge of the first strut and the first edge of the second strut. In some embodiments, a second edge of the first strut and a second edge of the second strut defining a second opening. In some embodiments, the first strut, the second strut, the first spine section, and the second spine section all define a cylindrical volume. 
     Some embodiments of the ocular implant have a therapeutic agent (e.g., an anti-glaucoma drug such as a prostaglandin analog like latanprost) deposited on the frame and spine sections. 
     Still another aspect of the invention provides an ocular implant having a first spine; a second spine; a first frame comprising a first strut and a second strut; each strut extending in an axial direction Z between the first spine and the second spine; a first opening of the ocular implant extending between a first edge of the first strut and a first edge of the second strut; a second edge of the first strut and a second edge of the second strut defining a second opening; wherein an angular dimension θ of the first edge of each strut undulates as the strut extends in the axial direction Z between the first spine and the second spine; and wherein a radius r of an outer surface of each strut remains substantially constant as the strut extends the axial direction Z between the first spine and the second spine. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric view showing a body that may be used to form an ocular implant in accordance with one exemplary embodiment of the invention. The body comprises a first spine, a second spine, and a first frame disposed between the first spine and the second spine. The first frame comprises a first strut and a second strut. 
         FIG. 2  is an isometric view of the body shown in the previous figure. In the embodiment of  FIG. 2 , the body is shaped to form an ocular implant having an outer surface defining a generally cylindrical volume. An inner surface of the body defines an elongate channel. The ocular implant may be inserted into Schlemm&#39;s canal of a human eye to facilitate the flow of aqueous humor out of the anterior chamber. 
         FIG. 3A  is a plan view showing a portion of the ocular implant shown in the previous figure. The ocular implant includes a first frame comprising a first strut and a second strut. In the exemplary embodiment of  FIG. 3A , each strut undulates in a circumferential direction while, at the same time, extending in the axial direction Z between a first spine and a second spine. 
         FIG. 3B  is a lateral cross-sectional view of the ocular implant shown in the previous figure. Section line B-B intersects the first strut and second strut of the ocular implant at the point where the circumferential undulation of these struts is at it&#39;s maximum. These struts form a frame having circumferential extent that is illustrated using dimension lines in  FIG. 3B . 
         FIG. 3C  is a lateral cross-sectional view of the ocular implant of  FIG. 3A  taken along section line C-C. Section line C-C intersects a spine of the ocular implant at the point where the width of the spine is at a minimum. A circumferential extent of the spine illustrated using dimension lines in  FIG. 3C . With reference to  FIG. 3C  and  FIG. 3B , it will be appreciated that the circumferential extent of frame is greater than the circumferential extent of the spine. 
         FIG. 4  is an isometric view showing a portion of the ocular implant shown in the previous figure. With reference to  FIG. 4 , it will be appreciated that the outer surfaces of the first spine, the second spine, the first strut, and the second strut define a generally cylindrical volume V. The shape of the ocular implant may be described using the cylindrical coordinates shown in  FIG. 4 . 
         FIG. 5  is an enlarged plan view showing a portion of the ocular implant shown in the previous figure. In  FIG. 5 , a number of section lines are shown crossing the first strut and the second strut of the ocular implant. In the embodiment of  FIG. 5 , each strut undulates in a circumferential direction while, at the same time, extending in axial direction Z between the first spine and the second spine. The circumferential undulation of the first strut is illustrated in  FIG. 6  using lateral cross-sectional drawings labeled with cylindrical coordinates. 
         FIG. 6A through 6E  are lateral cross-sectional views of the ocular implant shown in the previous figure. These cross-sectional views correspond to the section lines shown in the previous figure. With reference to these cross-sectional views, it will be appreciated that the angular dimension θ associated with a first edge of the first strut undulates as the first strut extends in an axial direction Z between the first spine and the second spine. In the embodiment of  FIG. 6 , the radius r of the outer surface of the first strut remains substantially constant as the first strut extends in the axial direction Z between the first spine and the second spine. 
         FIG. 7  shows a plurality of cylindrical coordinate values corresponding with the cross-sectional views shown in the previous figure. 
         FIG. 8  is an isometric view of an ocular implant in accordance with an additional exemplary embodiment of the invention. 
         FIG. 9  is a plan view of the ocular implant shown in the previous figure. In the embodiment of  FIG. 9 , the ocular implant has an at rest shape that is generally curved. 
         FIG. 10  shows the ocular implant of the previous figure in place within a human eye. 
         FIG. 11  is an enlarged plan view showing a portion of the eye shown in the previous figure. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description should be read with reference to the drawings, in which like elements in different drawings are numbered identically. The drawings, which are not necessarily to scale, depict exemplary embodiments and are not intended to limit the scope of the invention. Examples of constructions, materials, dimensions, and manufacturing processes are provided for selected elements. All other elements employ that which is known to those of skill in the field of the invention. Those skilled in the art will recognize that many of the examples provided have suitable alternatives that can be utilized. 
       FIG. 1  is an isometric view showing a body  100  that may be used to form an ocular implant in accordance with one exemplary embodiment of the invention. Body  100  comprises a first spine  102 , a second spine  104 , and a first frame  106  disposed between first spine  102  and second spine  104 . In the embodiment of  FIG. 1 , first frame  106  comprises a first strut  120  and a second strut  122 . With reference to  FIG. 1 , it will be appreciated that each strut extends between first spine  102  and second spine  104 . 
     First strut  120  of first frame  106  comprises a first edge  124 A and a second edge  126 A. With reference to  FIG. 1 , it will be appreciated that second strut  122  has a shape that is a mirror image of the shape of first strut  120 . Second strut  122  comprises a first edge  124 B and a second edge  126 B. Second edge  126 B of second strut  122  and second edge  126 A of first strut  120  define a second opening  130 . Second opening  130  generally divides first frame  106  into first strut  120  and second strut  122 . 
     With continuing reference to  FIG. 1 , it will be appreciated that body  100  comprises a plurality of spines and a plurality of frames. In the embodiment of  FIG. 1 , these spines and frames are arranged in an ABAB pattern. Each spine has a first lateral extent  132  and each frame has a second lateral extent  134 . With reference to  FIG. 1 , it will be appreciated that second lateral extent  134  is greater than first lateral extent  132 . 
       FIG. 2  is an isometric view of body  100  shown in the previous figure. In the embodiment of  FIG. 2 , body  100  is shaped to form an ocular implant  136  having an outer surface  138  defining a generally cylindrical volume. An inner surface  140  of body  100  defines an elongate channel  142 . Ocular implant  136  may be inserted into Schlemm&#39;s canal of a human eye to facilitate the flow of aqueous humor out of the anterior chamber. This flow may include axial flow along Schlemm&#39;s canal, flow from the anterior chamber into Schlemm&#39;s canal, and flow leaving Schlemm&#39;s canal via outlets communicating with Schlemm&#39;s canal. When in place within the eye, ocular implant  136  will support trabecular mesh tissue and Schlemm&#39;s canal tissue and will provide for improved communication between the anterior chamber and Schlemm&#39;s canal (via the trabecular meshwork) and between pockets or compartments along Schlemm&#39;s canal. 
     Elongate channel  142  of ocular implant  136  fluidly communicates with a first opening  128  as well as inlet portion  101 . Various fabrication techniques may be used to fabricate ocular implant  136 . For example, ocular implant  136  can be fabricated by providing a generally flat sheet of material and laser cutting the sheet of material to form body  100  shown in  FIG. 1 . The body  100  may then be formed into a generally tubular shape as shown in  FIG. 2 . Any adjoining edges (such as edges  103 ) may be, optionally, welded. By way of a second example, ocular implant  136  may be fabricated by providing a tube and laser cutting openings in the tube to form the shape shown in  FIG. 2 . 
     As shown in  FIG. 2 , ocular implant  136  comprises a first spine  102  and a second spine  104 . A first frame  106  of ocular implant  136  is disposed between first spine  102  and second spine  104 . In the embodiment of  FIG. 2 , first frame  106  comprises a first strut  120  that extends between first spine  102  and second spine  104 . First frame  106  also comprises a second strut  122 . Second strut  122  also extends between first spine  102  and second spine  104   
     First strut  120  of first frame  106  comprises a first edge  124 A and a second edge  126 A. As shown in  FIG. 1 , first edge  124 A has a convex surface, and second edge  126 A has a concave surface. Second strut  122  has a shape that is a mirror image of the shape of first strut  120 . In  FIG. 2 , first opening  128  of ocular implant  136  can be seen extending between first edge  124 A of first strut  120  and a first edge  124 B of second strut  122 . A second edge  126 B of second strut  122  and second edge  126 A of first strut  120  define a second opening  130 . Second opening  130  and additional openings (e.g., first opening  128 ) defined by ocular implant  136  allow aqueous humor to flow laterally across and/or laterally through ocular implant  136 . As shown in  FIG. 2 , openings  128  and  130  are shorter than the opening of elongate channel  142  extending along one side of implant  136 . 
     Ocular implant  136  can be fabricated from various biocompatible materials possessing the necessary structural and mechanical attributes. Both metallic and non-metallic materials may be suitable. Examples of metallic materials include stainless steel, tantalum, gold, titanium, and nickel-titanium alloys known in the art as Nitinol. Nitinol is commercially available from Memry Technologies (Brookfield, Conn.), TiNi Alloy Company (San Leandro, Calif.), and Shape Memory Applications (Sunnyvale, Calif.). 
     Ocular implant  136  may include one or more therapeutic agents. One or more therapeutic agents may, for example, be incorporated into a polymeric coating that is deposited onto the outer surfaces of the struts and spines of the ocular implant. The therapeutic agent may comprise, for example, an anti-glaucoma drug. Examples of anti-glaucoma drugs include prostaglandin analogs. Examples of prostaglandin analogs include latanprost. 
       FIG. 3A  is a plan view showing a portion of ocular implant  136  shown in the previous figure. Body  100  of ocular implant  136  comprises a first spine  102 , a second spine  104 , and a first frame  106  disposed between first spine  102  and second spine  104 . In the embodiment of  FIG. 3A , first frame  106  comprises a first strut  120  and a second strut  122 . As shown, each strut undulates in a circumferential direction while, at the same time, extending in the axial direction Z between first spine  102  and second spine  104 . 
       FIG. 3B  is a lateral cross-sectional view of ocular implant  136  taken along section line B-B. Section line B-B intersects first strut  120  and second strut  122  at the point where the circumferential undulation of these struts is at its maximum. First strut  120  and second strut  122  form first frame  106 . First frame  106  has a first circumferential extent  144  in the embodiment of  FIG. 3B . 
       FIG. 3C  is a lateral cross-sectional view of ocular implant  136  taken along section line C-C. Section line C-C intersects first spine  102  at the point where the width of first spine  102  is at a minimum. At this point, first spine  102  has a second circumferential extent  146 . Second circumferential extent  146  of first spine  102  is illustrated using dimension lines in  FIG. 3C . With reference to  FIG. 3C  and  FIG. 3B , it will be appreciated that first circumferential extent  144  of first frame  106  is greater than second circumferential extent  146  of first spine  102 . 
       FIG. 4  is an isometric view showing a portion of ocular implant  136  shown in the previous figure. With reference to  FIG. 4 , it will be appreciated that the outer surfaces of first spine  102 , second spine  104 , first strut  120 , and second strut  122  define a portion of a generally cylindrical volume V. The shape of ocular implant  136  may be described using the cylindrical coordinates shown in  FIG. 4 . These cylindrical coordinates include a radius r, an angle θ and an axial dimension Z. Cylindrical coordinates may be conceptualized as an extension of two dimensional polar coordinates to include a longitudinal or axial dimension Z. The two dimensions of a typical polar coordinate system are radius r and angle θ. In the embodiment of  FIG. 4 , dimension Z extends along a longitudinal axis  148  of cylindrical volume V. 
     As shown in  FIG. 4 , first strut  120  extends in axial direction Z between first spine  102  and second spine  104 . Second strut  122  also extends between first spine  102  and second spine  104 . In the embodiment of  FIG. 4 , the radius r of the outer surface of each strut remains substantially constant. The angular dimension θ of a first edge  124 A of first strut varies as first strut  120  extends in the axial direction Z between first spine  102  and second spine  104 . Similarly, the angular dimension θ of a second edge  126 A of second strut varies as second strut  122  extends in the axial direction Z between first spine  102  and second spine  104 . 
       FIG. 5  is an enlarged plan view showing a portion of ocular implant  136  shown in the previous figure. In  FIG. 5 , a number of section lines are shown crossing first strut  120  and second strut  122  of ocular implant  136 . In the embodiment of  FIG. 5 , each strut undulates in a circumferential direction while, at the same time, extending in axial direction Z between first spine  102  and second spine  104 . The circumferential undulation of first strut  120  is illustrated in the next figure using lateral cross-sectional drawings labeled with cylindrical coordinates. 
       FIGS. 6A through 6E  are lateral cross-sectional views of ocular implant  136  shown in the previous figure. These cross-sectional views correspond to the section lines shown in the previous figure. With reference to these cross-sectional views, it will be appreciated that the angular dimension θ associated with first edge  124 A of first strut  120  undulates as first strut  120  extends in an axial direction Z between the first spine and the second spine. In the embodiment of  FIG. 6 , the radius r of the outer surface of first strut  120  remains substantially constant as first strut  120  extends in axial direction Z between the first spine and the second spine. 
       FIG. 7  shows a plurality of cylindrical coordinate values corresponding with the cross-sectional views shown in the previous figure. With reference to the numerical values shown in  FIG. 7 , it will be appreciated that the numerical value of angular dimension θ of first edge  124  first increases, then decreases, as first strut  120  extends in an axial direction Z between the first spine and the second spine. The numerical value r remains constant as first strut  120  extends in axial direction Z between the first spine and the second spine. 
       FIG. 8  is an isometric view of an ocular implant  236  in accordance with an additional exemplary embodiment of the invention. As shown in  FIG. 8 , ocular implant  236  comprises a first spine  202  and a second spine  204 . A first frame  206  of ocular implant  236  is disposed between first spine  202  and second spine  204 . In the embodiment of  FIG. 8 , first frame  206  comprises a first strut  220  that extends between first spine  202  and second spine  204 . First frame  206  also comprises a second strut  222 . With reference to  FIG. 8 , it will be appreciated that second strut  222  also extends between first spine  202  and second spine  204 . 
     Ocular implant  236  of  FIG. 8  defines a channel  242  that opens into a first opening  228 . In  FIG. 8 , first opening  228  of ocular implant  236  can be seen extending between first strut  220  and second strut  222 . First strut  220  and second strut  222  also define a second opening  230 . First opening  228 , second opening  230 , and the additional openings shown in  FIG. 8 , allow aqueous humor to flow laterally across and/or laterally through ocular implant  236 . 
     In the embodiment of  FIG. 8 , an inlet portion  250  is formed near a proximal end of ocular implant  236 . Inlet portion  250  may extend through the trabecular meshwork into the anterior chamber of the eye when a portion of the ocular implant lies in Schlemm&#39;s canal. 
     In the embodiment of  FIG. 8 , a blunt tip  252  is disposed at a distal end of ocular implant  236 . In some useful embodiments of ocular implant  236 , blunt tip  252  has a generally rounded shape. In the embodiment shown in  FIG. 8 , blunt tip  252  has a generally hemispherical shape. The generally rounded shape of blunt tip  252  may increase the likelihood that body  200  will track Schlemm&#39;s canal as ocular implant  236  is advanced into the canal during an implant procedure. 
     In  FIG. 8 , ocular implant  236  is pictured assuming a generally straight shape. Embodiments of ocular implant  236  are possible which have a generally curved resting shape. Ocular implant  236  may be fabricated, for example, by laser cutting a tube to create the shape shown in  FIG. 8 . When this is the case, it may be desirable to rotate a straight tubular workpiece during the laser cutting process. After the laser cutting process, the ocular implant can be heat-set so that the ocular implant is biased to assume a selected shape (e.g., a generally curved shape). 
       FIG. 9  is a plan view of ocular implant  236  shown in the previous figure. In the embodiment of  FIG. 9 , ocular implant  236  has an at rest shape that is generally curved. This at rest shape can be established, for example, using a heat-setting process. The ocular implant shape shown in  FIG. 9  includes a distal radius RA, a proximal radius RC, and an intermediate radius RB. In the embodiment of  FIG. 9 , distal radius RA is larger than both intermediate radius RB and proximal radius RC. Also in the embodiment of  FIG. 9 , intermediate radius RB is larger than proximal radius RC and smaller than distal radius RA. In one useful embodiment, distal radius RA is about 0.310 inches, intermediate radius RB is about 0.215 inches and proximal radius RC is about 0.105 inches. 
     In the embodiment of  FIG. 9 , a distal portion of the ocular implant follows distal radius RA along an arc extending across an angle AA. A proximal portion of the ocular implant follows proximal radius RC along an arc extending across an angle AC. An intermediate portion of the ocular implant is disposed between the proximal portion and the distal portion. The intermediate portion follows radius RB and extends across an angle AB. In one useful embodiment, angle AA is about 55 degrees, angle AB is about 79 degrees and angle AC is about 60 degrees. 
     Ocular implant  236  may be used in conjunction with a method of treating a patient. Some such methods may include the step of inserting a core member into a lumen defined by ocular implant  236 . The core member may comprise, for example, a wire or tube. The distal end of the ocular implant may be inserted into Schlemm&#39;s canal. The ocular implant and the core member may then be advanced into Schlemm&#39;s canal until the ocular implant has reached a desired position. The core member may then be withdrawn from the ocular implant. 
       FIG. 10  shows ocular implant  236  of the previous figure in place within a human eye. The eye of  FIG. 10  includes an anterior chamber that is covered by a cornea. The iris of the eye is visible through the cornea and the anterior chamber. The anterior chamber is filled with aqueous humor which helps maintain the generally hemispherical shape of the cornea. 
     Whenever a person views an object, he or she is viewing that object through the cornea, the aqueous humor, and the lens of the eye. In order to be transparent, the cornea and the lens can include no blood vessels. Accordingly, no blood flows through the cornea and the lens to provide nutrition to these tissues and to remove wastes from these tissues. Instead, these functions are performed by the aqueous humor. A continuous flow of aqueous humor through the eye provides nutrition to portions of the eye (e.g., the cornea and the lens) that have no blood vessels. This flow of aqueous humor also removes waste from these tissues. 
     Aqueous humor is produced by an organ known as the ciliary body. The ciliary body includes epithelial cells that continuously secrete aqueous humor. In a healthy eye, a stream of aqueous humor flows out of the eye as new aqueous humor is secreted by the epithelial cells of the ciliary body. This excess aqueous humor enters the blood stream and is carried away by venous blood leaving the eye. 
     The structures that drain aqueous humor from the anterior chamber include Schlemm&#39;s canal and a large number of veins that communicate with Schlemm&#39;s canal via a plurality of outlets. In  FIG. 10 , Schlemm&#39;s canal  20  can be seen encircling the iris of the eye. Ocular implant  236  may be inserted into Schlemm&#39;s canal  20  to facilitate the flow of aqueous humor out of the anterior chamber. This flow may include axial flow along Schlemm&#39;s canal, flow from the anterior chamber into Schlemm&#39;s canal, and flow leaving Schlemm&#39;s canal via outlets communicating with Schlemm&#39;s canal. When in place within the eye, ocular implant  236  will support trabecular mesh tissue and Schlemm&#39;s canal tissue and will provide for improved communication between the anterior chamber and Schlemm&#39;s canal (via the trabecular meshwork) and between pockets or compartments along Schlemm&#39;s canal. 
       FIG. 11  is an enlarged plan view showing a portion of the eye shown in the previous figure. With reference to  FIG. 11 , it will be appreciated that ocular implant  236  extends through Schlemm&#39;s canal  20  across an angle G. Various implant sizes are possible, and different implant sizes may span a different angle G when placed in Schlemm&#39;s canal. Examples of angular spans that may be suitable in some applications include 60°, 90°, 150° and 180°. 
     In  FIG. 11 , an inlet portion  250  of ocular implant  236  is shown extending through trabecular mesh  22 . Aqueous humor may exit anterior chamber  24  and enter Schlemm&#39;s canal  20  by flowing through inlet portion  250  of ocular implant  236 . Aqueous humor may also exit anterior chamber  24  and enter Schlemm&#39;s canal  20  by flowing through the trabecular mesh  22  of the eye. With reference to  FIG. 11 , it will be appreciated that the spines of ocular implant  236  support trabecular mesh  22 . 
     Aqueous humor exits Schlemm&#39;s canal  20  by flowing through a number of outlets. After leaving Schlemm&#39;s canal  20 , aqueous humor travels through a network passages and veins and is absorbed into the blood stream. Schlemm&#39;s canal typically has a non-circular cross-sectional shape whose diameter can vary along the canal&#39;s length and according to the angle at which the diameter is measured. In addition, there may be multiple partial pockets or partial compartments (not shown in these figures) formed along the length of Schlemm&#39;s canal. The shape and diameter of portions of Schlemm&#39;s canal and the existence and relative location of partial pockets or compartments may limit or prevent fluid flow from one point of Schlemm&#39;s canal to another. Hence, each outlet from Schlemm&#39;s canal may drain only a portion of Schlemm&#39;s canal. This condition may be improved by placing ocular implant  236  in Schlemm&#39;s canal. Ocular implant  236  shown in  FIG. 11  includes a plurality of struts, spines and openings. When in place within the eye, ocular implant  236  will support trabecular mesh tissue and Schlemm&#39;s canal tissue and will provide for improved communication between the anterior chamber and Schlemm&#39;s canal and between pockets or compartments along Schlemm&#39;s canal. 
     In  FIG. 11 , first opening  228  of ocular implant  236  is shown facing radially outward in Schlemm&#39;s canal  20 . Aqueous humor can exit Schlemm&#39;s canal  20  by flowing through outlets that radiate away from and communicate with Schlemm&#39;s canal  20 . After flowing through these outlets, this excess aqueous humor can enter the venous bloodstream be carried out of the eye by venous blood flow. The diameter of ocular implant  236  can range from 0.005 inches to 0.04 inches, preferably from 0.005 inches to 0.02 inches, in order to lie within and support Schlemm&#39;s canal. 
     While exemplary embodiments of the present invention have been shown and described, modifications may be made, and it is therefore intended in the appended claims to cover all such changes and modifications which fall within the true spirit and scope of the invention.