Patent Publication Number: US-2021169633-A1

Title: Treating eye diseases by deploying a stent

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application claims the benefit of priority under 35 U.S.C. § 119 to U.S. Provisional Patent Application No. 62/568,862, filed Oct. 6, 2017, which is herein incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to treating eye diseases and conditions. The present embodiments relate generally to apparatus and methods for treating medical conditions, and more specifically, to systems and methods for improving or restoring blood flow using one or more stents. 
     BACKGROUND 
     Diseases of the eye, specifically age-related macular degeneration (AMD), glaucoma, and diabetic retinopathy, affect a large percentage of the population. In the example of AMD, currently approved treatments include surgically implanting a miniature lens (VisionCare), monthly injections of the anti-cancer drug Avastin into the eye, injecting a therapeutic antibody into the eye (Macugen, pegaptanib), and/or photo or laser treatment to destroy “abnormal” blood vessels. However, these therapies are deficient in one or more aspects, necessitating improved approaches. 
     In a general sense, the pathogenesis of some of these eye diseases and conditions may be similar, if not the same, as those seen for cardiac diseases and for abdominal aorta conditions. However, the anatomy of the vasculature behind the eye is significantly smaller, includes more branches, and includes a more tortuous blood flow pathway than the anatomy of the vasculature of the cardiac system and the abdominal aorta. As such, treatment of such eye diseases may require increased precision by medical professionals, which may increase the time and/or cost of such treatments. 
     The systems, devices, and methods of the current disclosure may rectify some of the deficiencies described above or address other aspects of the prior art. 
     SUMMARY 
     Examples of the present disclosure relate to, among other things, medical devices and related methods. Each of the examples disclosed herein may include one or more of the features described in connection with any of the other disclosed examples. 
     In one example, a medical device may include an expandable strut structure configured for insertion within an ophthalmic artery, an internal carotid artery, or both of the ophthalmic artery and the internal carotid artery. The expandable strut structure may include a diverter element extending from the strut structure towards a free end. The diverter element may be positioned to change a direction of blood flow toward the ophthalmic artery. 
     Examples of the medical device may include any one or more of the following features. In a further example, the diverter element may be configured to be positioned upstream of the ophthalmic artery. The diverter element may be configured to be positioned downstream of the ophthalmic artery. The diverter element may configured to extend at an angle relative to an axis of the ophthalmic artery. The strut structure may include a first portion configured to be positioned upstream of the ophthalmic artery and a second portion configured to be positioned downstream of the ophthalmic artery. The strut structure may include a first portion configured for insertion within the internal carotid artery and the diverter element may extend from the first portion toward the ophthalmic artery. The strut structure may include a first portion configured for insertion within the internal carotid artery and a second portion configured for insertion in the ophthalmic artery. The strut structure may include at least one arm terminating in a holding element. The strut structure may further include a deflection element configured to deflect a flap of tissue positioned in at least one of the internal carotid artery, the ophthalmic artery, or within an ostium at a junction between the internal carotid artery and the ophthalmic artery. The expandable strut structure may include a strut element configured to deflect a flap of tissue in a junction between the internal carotid artery and the ophthalmic artery. 
     In a further aspect, a method of treating an eye of a patient may include positioning an expandable strut structure within any vessel that supplies blood to the eye or associated structures. These vessels include but are not limited to: at least one of an internal carotid artery, an ophthalmic artery, or within an ostium at a junction between the internal carotid artery and the ophthalmic artery, supra orbital artery (SOA), the supra trochlear artery (STA), the dorsal nasal artery (DNA), the middle meningeal artery (MMA), the facial arteries (FA), and branches thereof. The method may further include increasing blood flow to any artery supplying blood to the eye, including but not limited to towards the ophthalmic artery via a diverter element associated with the expandable strut structure. 
     Examples of the method may include any one or more of the following features. The step of increasing blood flow may result in an increase in one or more nutrients (e.g., oxygen) delivered to an eye of the patient. Treating the eye may include treating at least one disease or condition of the eye. The at least one disease or condition may include macular degeneration. The step of increasing blood flow may include altering blood flow through the strut structure via the diverter. The step of positioning the expandable strut structure may include positioning the expandable strut structure such that a first portion of the strut structure may be positioned within the internal carotid artery upstream of the ophthalmic artery, and a second portion of the structure may be positioned within the internal carotid artery downstream of the ophthalmic artery. The step of positioning the expandable strut structure may further include positioning a third portion of the stent structure within the ophthalmic artery. 
     In a further aspect, a method of altering blood flow through the vasculature of an eye may include disrupting an eddy flow of blood in any artery that supplies blood to the eye, including but not limited to at least one of an ophthalmic artery, an internal carotid artery, or both of the ophthalmic artery and the internal carotid artery via a diverter element of an expandable strut structure positioned within the vasculature of the eye. 
     Examples of the method may further include any one or more of the following features. The method may include treating at least one disease or condition of the eye. The at least one disease or condition may include macular degeneration. 
     In a further aspect, a method of treating an eye of a patient may include positioning an expandable strut structure within at least one of an internal carotid artery, an ophthalmic artery, or an ostium at a junction between the internal carotid artery and the ophthalmic artery. Additionally, the method may include directing blood flow towards the ophthalmic artery via a diverter element associated with the expandable strut structure. 
     Examples of the method may further include any one or more of the following features. The step of directing blood flow may result in an increase in oxygen delivery to the eye of the patient. Treating the eye may include treating at least one disease or condition of the eye. The at least one disease or condition may include macular degeneration. The step of directing blood flow may include altering blood flow through the strut structure via the diverter. The step of positioning the expandable strut structure may include positioning the expandable strut structure such that a first portion of the strut structure may be positioned within the internal carotid artery upstream of the ophthalmic artery, and a second portion of the structure may be positioned within the internal carotid artery downstream of the ophthalmic artery. The step of positioning the expandable strut structure may further include positioning a third portion of the stent structure within the ophthalmic artery. The diverter element may extend from the first portion of the strut structure towards the ophthalmic artery. The diverter element may include a first end coupled with the expandable strut structure and a second end free form contact with the expandable strut structure. The step of directing blood flow may include directing blood flow at an angle with respect to an axis of the ophthalmic artery via the diverter element. 
     In a further aspect, a method of treating an eye of a patient may include positioning an expandable frustoconical strut structure within an ostium at a junction between an internal carotid artery and an ophthalmic artery. Additionally, the method may include directing blood flow within the ophthalmic artery via the expandable frustoconical strut structure. 
     Examples of the method may further include any one or more of the following features. The step of positioning the expandable frustoconical strut structure may include positioning an entirety of the expandable frustoconical strut structure within the ostium. The step of positioning the expandable frustoconical strut structure may include locating the expandable frustoconical strut structure such that no portion of the expandable frustoconical strut structure is located within the internal carotid artery. The expandable frustoconical strut structure may include a first end having a first cross-sectional dimension and a second end having a second cross-sectional dimension larger than the first cross-sectional dimension, and the step of positioning the expandable frustoconical strut structure may include positioning the first end distally of the second end within the ostium. The step of directing blood flow within the ophthalmic artery via the expandable frustoconical strut structure may include directing blood flow towards the ophthalmic artery via a diverter element associated with the expandable frustoconical strut structure. The step of directing blood flow may include altering a direction of blood flow through the strut structure via the diverter element. The step of directing blood flow may result in an increase in oxygen delivery to the eye of the patient. Treating the eye may include treating at least one disease or condition of the eye, wherein the at least one disease or condition may include macular degeneration. 
     In a further aspect, a method of treating an eye of a patient may include positioning an expandable strut structure within an arterial system of the patient. Additionally, the step of positioning the expandable strut structure may include positioning a majority of the expandable strut structure within an internal carotid artery of the patient and positioning a strut of the expandable strut structure within at least one of an ophthalmic artery of the patient or an ostium between the ophthalmic artery and the internal carotid artery of the patient. Additionally, the method may include deflecting tissue via the strut. 
     Examples of the method may further include any one or more of the following features. The strut may be the only portion of the expandable strut structure located within the at least one of the ophthalmic artery or the ostium. The strut may include at least one of an increased thickness or an increased rigidity relative to a remainder of the expandable strut structure. Treating the eye may include treating at least one disease or condition of the eye, and the at least one disease or condition may include macular degeneration. 
     Both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the features, as claimed. As used herein, the terms “comprises,” “comprising,” “having,” “including,” or other variations thereof, are intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements, but may include other elements not expressly listed or inherent to such a process, method, article, or apparatus. Additionally, the term “exemplary” is used herein in the sense of “example,” rather than “ideal.” As used herein, the terms “about,” “substantially,” and “approximately,” indicate a range of values within +/−5% of the stated value unless otherwise stated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the present disclosure and together with the description, serve to explain the principles of the disclosure. 
         FIGS. 1 and 2  illustrate an anatomical location of interest relating to the eye of a patient; 
         FIG. 3  illustrates an exemplary stent, according to aspects of the present disclosure; 
         FIGS. 4-11  illustrate various features of the exemplary stents, according to aspects of the present disclosure; 
         FIG. 12  illustrates an eddy in a blood flow path of the vasculature of the eye; 
         FIGS. 13-17  illustrate further features of the exemplary stents of the present disclosure; 
         FIG. 18  illustrates a common location of an obstruction in the vasculature of the eye; 
         FIGS. 19A and 19B  illustrate an arrangement of a self-expanding support member or ring according to the present disclosure; 
         FIGS. 20A and 20B  illustrate a further arrangement of a self-expanding support member or ring according to the present disclosure; and 
         FIGS. 21-30  illustrate further exemplary arrangements of flow diverting structures according to the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to examples of the present disclosure described above and illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
     The terms “proximal” and “distal” are used herein to refer to the relative positions of the components of an exemplary medical device or insertion device. When used herein, “proximal” refers to a position relatively closer to the exterior of the body or closer to a medical professional using the medical device or insertion device. In contrast, “distal” refers to a position relatively further away from the medical professional using the medical device or insertion device, or closer to the interior of the body. Further, as used herein, dimensions measured in French, abbreviated Fr or F, are three times the size of the same dimension as measured in mm. Thus, a 3-mm diameter catheter is 9 French in diameter. 
       FIGS. 1 and 2  illustrate an anatomical area of interest relating to an eye of a patient. For example, such an anatomical area of interest may include all of the vasculature in the fluid flow path to and from the eye, the rear of the eye, portions of the eye, or regions near the eye. By way of example only, as shown in  FIG. 1 , the vasculature of the eye includes the Internal Carotid Artery (ICA)  2 , the Ophthalmic Artery (OA)  4 , and the junction  6  between the ICA  2  and the OA  4 , which is also referred to as the ostium. As shown, OA  4  is illustrated as extending generally at a right angle relative to the ICA  2 . In other arrangements, however, the OA  4  extends at an acute angle relative to ICA  2 . In some patients, a flap of tissue (not shown), may extend between OA  4  and ICA  2 . That is, in some arrangements, the flap of tissue may be positioned in junction  6 . Additional areas of the anatomy may include the vascular system which is commonly referred to as the terminal branches (not shown). These areas include, but are not limited to, the Supra Orbital Artery (SOA), the Supra Trochlear Artery (STA), the Dorsal Nasal Artery (DNA), and the Facial Arteries (FA). It is noted that the anatomical structures described herein may additionally be referred to by other terminology. Hayreh et al. (Brit. J. Ophthal., 46, 65 (1962)), the entirety of which is herein incorporated by reference, describes the anatomy relating to the eye as including the ICA (I), the OA (O) branching off of the ICA in a portion called the “short limb” (S); “angle a” (AA) as a distinctive turn in the OA near the end of the OA near the ICA; the “long limb” (LL) as the portion of the OA before it penetrates into the dural sheath; “angle b”; and then the distal portion of the OA as it extends to the eye. The junction (J) between the ICA and the OA includes the ostium (OS). One skilled in the art will readily recognize that these are typical or common structures; not all patients/humans have these exact same structures, e.g., there are human population variations. 
     Diseases and conditions of the eye (e.g., AMD, glaucoma, diabetic retinopathy etc.) may result in decreased blood flow to and around the eye, which is believed to contribute to oxygen depletion in and around the eye. Decreased blood flow to and around the eye may also contribute to depletion of one or more additional nutrients such as, for example, glucose or amino acids, as well as an increase waste products in the eye. According to examples of the present disclosure, diseases and conditions of the eye may be directly mediated by improved blood flow to the vasculature of the eye (e.g., the posterior of the eye). For example, the systems, devices, and methods described herein may restore or increase the amount of oxygen (and/or other nutrients) that reaches the eye or an eye area which may include removing or opening a blockage (or partial blockage) in one or more vascular systems that support the eye. Opening a blockage or partial blockage may include increasing or restoring blood flow to or around the eye. Increasing blood flow may include, but is not limited to, increasing the blood flow rate. That is, examples of the present disclosure may be directed to one or more intravascular medical devices and/or methods intended or configured to sufficiently unblock or at least partially restore blood flow in a blocked or partially blocked artery such that oxygen content (and/or the content of other nutrients) is increased distal to the blockage, as well as improving the removal of waste products that are also distal to the blockage. For example, in some arrangements, the present disclosure is directed to devices and methods for restoring blood flow through the ostium or junction  6 . In additional arrangements, the disclosure is directed to using such devices and methods to restore or increase blood flow and/or or restore or increase oxygen levels, to the eye or a portion thereof. Restoring or increasing oxygen flow may include using the devices and methods described herein, or equivalent devices and methods, but is not to be limited thereby. 
     For example, stents may be inserted (e.g., percutaneously) into an anatomical vessel or duct for various purposes. Stents may maintain or restore patency in a formerly blocked or constricted passageway (e.g., following a balloon angioplasty procedure or an atherectomy procedure). A stent of the present disclosure, or a portion thereof, may be sized to conform to the anatomy in which it is placed. Without intending to limit the scope of the present disclosure, exemplary stent diameters may range from less than about 1.5 mm to about 3 mm for stents or portions of a stent that are placed in the OA  4 . A stent or a portion of a stent in the ICA  2  is typically larger. Exemplary stent length may range from 0.5 mm or longer for stents or portions of a stent that are placed in the OA  4 . A stent or a portion of a stent in the ICA  2  is typically longer. 
     As shown in  FIG. 3 , an exemplary stent  10  may include a plurality or framework of struts  11  which may be adapted and configured for placement in the ICA  2  and/or the OA  4 . Stent  10  may be either self-expandable and/or non-self-expandable (e.g., expandable via a balloon or other mechanical device). For example, self-expanding stents may be delivered to a target site in a compressed configuration and subsequently expanded by removing a delivery sheath/catheter, removing trigger wires, and/or releasing diameter reducing ties. Such self-expanding stents may expand primarily based on their own expansive force without the need for further mechanical expansion. Optionally, stent  10  may be comprised of a shape-memory alloy such as Nitinol. Shape-memory alloy may be employed to cause the stent  10  to return to a predetermined configuration (e.g., expanded configuration) upon removal of the sheath or other device maintaining the stent  10  in its pre-deployment configuration. Non-self-expanding struts may be delivered to a target site in a compressed configuration and expanded upon the application of an outward radial force. For example, a balloon (not shown) may be positioned within a lumen  14  of stent  10  and inflated so as to expand stent  10 . 
     As noted above, one or more trigger wires (not shown) may be used to restrain a “Z-stent” or Gianturco style stent comprising a series of substantially straight segments interconnected by a series of bent segments. The trigger wires may be disposed through, and pull upon, the bent segments to pull the stent  10  closely against a delivery catheter. Optionally, trigger wires may be used in conjunction with different stent designs, such as cannula-cut stents having relatively acute or pointed bends. The designs of cannula-cut stents may facilitate compression of the stent to a relatively small delivery profile due to the tight bends of the apices. With such stents, the trigger wires may be looped around one or more vertices formed beneath the proximal and/or distal apices, e.g., a location where an individual apex splits into two separate strut segments. 
     Optionally, stent  10  may include a cover (not shown) thereon. The cover of stent  10  may be comprised of or coated with a lubricious material so as to facilitate movement between stent  10 , a delivery catheter, and/or a vessel wall. Additionally, the cover may be positioned on an internal surface, an external surface, or both the internal surface and the external surface of stent  10 . In some arrangements, stent  10  may be embedded within the cover. Further, such a coating or cover may be substance eluting (e.g., drug-eluting). For example, such a drug-eluting coating or cover may release any one or more drugs or substances for the treatment of restenosis. Additionally, such a cover or coating may only be provided on one or more portions of stent  10 . For example, in some arrangements, such a cover or coating may be positioned on a diverter (discussed below) of stent  10 . The cover or coating may optionally comprise expanded polytetrafluoroethylene (ePTFE) or any other appropriate material. Stent  10 , or the cover thereof, may also include one of more markers, typically radiopaque markers. For example, stent  10  and/or the cover thereof may be coated or impregnated with one or more radiopaque markers  13  to aid in the proper placement of stent  10  within the target anatomy, e.g., the ostium or junction  6  of ICA  2  and OA  4 . Additionally, stent  10  may comprise an opening or port  12  extending through a circumferential surface thereof. As shown, port  12  may be free from stent struts  11  and may be unobscured by a stent covering. Port  12  may be dimensionally compatible with an opening into the OA  4  at the ostium  6  such that the OA  4  will be unobscured by stent  10  once it is placed within the vasculature. In other words, port  12  may be sized and shaped so as to surround the opening into the OA  4  at the ostium  6 . In some arrangements, port  12  may be generally circular or rounded, as shown in  FIG. 3 . In additional arrangements, port  12  may extend circumferentially about the entire circumference of stent  10 . In such an arrangement, a first portion and a second portion of stent  10  may be coupled together via one or more struts thereby forming a circumferential port, unobscured by a stent covering, therebetween. 
     The use of catheter delivery systems for positioning and deploying therapeutic devices, such as balloons, stents and embolic devices, in the vasculature of the human body has become a standard procedure for treating endovascular diseases. It has been found that such devices are particularly useful in treating areas where traditional operational procedures are impossible or pose a great risk to the patient. Advancements in catheter deployment systems have provided an alternative treatment in such cases. Some of the advantages of catheter delivery systems are that they provide methods for treating blood vessels by an approach that has been found to reduce the risk of trauma to the surrounding tissue, and they also allow for treatment of blood vessels that in the past would have been considered inoperable. 
     As noted above, the OA  4 , particularly the portion of the OA  4  near the ICA  2  (e.g., ostium or junction  6 ) presents a challenging anatomy for stent  10  placement and function. The anatomy of junction  6  typically comprises a very sharp angle. Further, the OA  4  comprises a short section near the ICA  2 , called the short limb  16 , followed by a sharp bend, called angle A  18  ( FIG. 4 ). Often, prior art stents (e.g., aortic stents) lack the desired sealing ability at either end of the stent, in other words, they lack the desired radial force against the arterial wall at the stent ends. Also, such devices often include a relatively large profile which may not be appropriately sized for insertion in the small and tortuous vasculature of the eye. Finally, such stents often have relatively acute points that may prevent them from being used in acute angle anatomies for fear of trauma with the artery wall after an extended amount of time in the patient. In some arrangements, a generally nonsymmetrical stent  10  having at least one relatively rounded apex that is less invasive in an expanded state than stents with more acute apices may alleviate the above problems, while providing an improved compliance to the ICA  2  and OA  4 , and increased radial force if used as a sealing and/or alignment stent, as well as a desirable ability to be crimped to a readily introducible diameter. 
     A portion of such a stent  10  may include a first width that is less than a second width of the axial opening of the retaining member. The axial opening may extend longitudinally between first and second ends of the main body of the retaining member. 
     In one arrangement, the stent  10  may comprise at least one coupling portion comprising a longitudinal strut portion having the first width that is less than the second width of the axial opening of the retaining member. The coupling portion may extend proximally from a proximal apex of the stent  10 . The coupling portion may include a projection. In one example, the longitudinal strut portion and the projection of the coupling portion may collectively may form a “t” shape. The lateral projection may be disposed proximal to the first end of the main body of the retaining member when the stent is restrained. 
     The present disclosure relates generally to stents for use in body vessels to treat medical conditions, and more specifically, to treat conditions of the eye and/or vasculature supplying blood flow to the eye. 
     In particular, this present disclosure relates to a stent  10  having opposing sets of curved apices, where the curved section of one set of apices has a radius of curvature that is greater than the curved section of another set of apices, and may present a lower profile than conventional stents. This configuration presents an asymmetrical stent. Specifically, embodiments of the stents disclosed herein may maintain a low profile while improving compliance with highly tortuous anatomy (such as, for example, the anatomy found in the region between the ICA  2  and the OA  4 ) while providing improved radial sealing force compared to some current devices. In another example, one or more stents described herein may provide support and spacing within the larger context of a stent or stent-graft device that will allow, for example, placement of ancillary stents and/or stent-grafts. 
     Examples of the present disclosure may include a stent  10  that includes at least one proximal apex and at least one distal apex connected with the proximal apices by a plurality of generally straight portions; where each proximal apex includes a first curved portion and each distal apex comprises a second curved portion; where the first curved portion and the second curved portion each includes at least one radius of curvature, and the radius of curvature of at least one of the proximal apices is greater than the radius of curvature of at least one of the distal apices. 
     In another arrangement, examples of the present disclosure may include at least one wire formed into a stent  10  and including a ring of alternating opposed, generally curved apices where a radius of curvature of a plurality of the apices in a first direction is greater than a radius of curvature of the apices in an opposite direction. Advantageously, the rounded apices may provide atraumatic contact with a vessel, while the combination of more rounded and less rounded apices provides for a low-profile stent that includes desirable compressibility during introduction and desirable compliance and sealing profiles when deployed in a vessel. 
     In some examples, the present disclosure may be directed to an intravascular stent  10  that has a pattern or configuration that permits the stent  10  to be tightly compressed or crimped onto a catheter to provide an extremely low profile and to prevent relative movement between the stent  10  and the catheter. Such a stent  10  also may be highly flexible along its longitudinal axis to facilitate delivery through tortuous body lumens, but which is stiff and stable enough radially in its expanded condition to maintain the patency of a body lumen such as an artery when the stent is implanted therein. 
     In some examples of the present disclosure, a stent  10  may include a plurality of cylindrical rings that are interconnected to form the stent  10 . Such a stent may be mounted on a balloon catheter, if it is balloon expandable, or mounted on or in a catheter without a balloon, if it is self-expanding. 
     Each of the cylindrical rings making up the disclosed stents  10  may have a proximal end and a distal end and a cylindrical outer wall surface that extends between the proximal end and the distal end of the cylindrical ring. Generally, the cylindrical rings have a serpentine or undulating shape which includes at least one U-shaped element, and typically each ring has more than one U-shaped element. The cylindrical rings may be interconnected by at least one undulating link which may attach one cylindrical ring to an adjacent cylindrical ring. The undulating links may be highly flexible and allow the stent  10  to be highly flexible along its longitudinal axis. At least some of the undulating links have a curved portion that extends transverse to the stent longitudinal axis for a predetermined distance that coincides with one of the U-shaped elements. More specifically, the curved portion extends in a transverse manner such that it would intersect with the corresponding U-shaped element, however, the corresponding U-shaped element is shorter in length than other U-shaped elements in the same ring. Thus, when the stent  10  is compressed or crimped onto the catheter, the curved portions do not overlap or intersect with the adjacent U-shaped element since that element is shorter in length than similar U-shaped elements in the particular ring. In this manner, the stent  10  can be compressed or crimped to a much tighter or smaller diameter onto the catheter which permits low profile delivery as well as a tight gripping force on the catheter to reduce the likelihood of movement between the stent and the catheter during delivery and prior to implanting the stent  10  in the vessel. 
     The undulating links may take various configurations but in general have an undulating or serpentine shape. The undulating links can include bends connected by substantially straight portions wherein the substantially straight portions are substantially perpendicular to the stent longitudinal axis. 
     Not only do the undulating links that interconnect the cylindrical rings provide flexibility to the stent, but the positioning of the links also enhances the flexibility by allowing uniform flexibility when the stent  10  is bent in any direction along its longitudinal axis. Uniform flexibility along the stent  10  derives in part from the links of one ring being circumferentially offset from the links in an adjacent ring. Further, the cylindrical rings are configured to provide flexibility to the stent  10  in that portions of the rings can flex or bend and tip outwardly as the stent  10  is delivered through a tortuous vessel. 
     The cylindrical rings typically are formed of a plurality of peaks and valleys, where the valleys of one cylindrical ring are circumferentially offset from the valleys of an adjacent cylindrical ring. In this configuration, at least one undulating link attaches each cylindrical ring to an adjacent cylindrical ring so that at least a portion of the undulating links is positioned within one of the valleys and it attaches the valley to an adjacent peak. 
     While the cylindrical rings and undulating links generally are not separate structures (e.g., they may include a one-piece monolithic stent  10  structure), they have been conveniently referred to as rings and links for ease of identification. Further, the cylindrical rings can be thought of as comprising a series of U&#39;s, W&#39;s and Y-shaped structures in a repeating pattern. Again, while the cylindrical rings are not divided up or segmented into U&#39;s, W&#39;s and Y&#39;s, the pattern of the cylindrical rings resemble such configuration. The U&#39;s, W&#39;s and Y&#39;s promote flexibility in the stent primarily by flexing and by tipping radially outwardly as the stent  10  is delivered through a tortuous vessel. 
     A stent  10  of the present disclosure can be made in several ways. In one embodiment, metallic rings are cut by a laser using conventional laser cutting procedures. The rings are then mounted on an inner polymeric tube which has been pre-mounted on a Teflon mandrel. After the rings have been mounted and positioned on the inner polymeric tube, an outer polymeric tube is mounted over the metallic rings and the inner polymeric tube. A shrink tubing is then mounted over the outer polymeric tube and it is subjected to laser bonding so that the shrink tubing contracts and applies pressure to the outer polymeric tube causing it to compress against the metallic rings and the inner polymeric tube. Further, heat from the laser causes the outer and inner polymeric tubes to partially melt and fuse together. An appropriate bonding agent can be used to help adhere the inner and outer tubes together. The shrink tubing and the supporting Teflon mandrel are removed and the stent pattern is then formed by a laser to remove unwanted portions of the polymer material, so that a pattern of metallic rings encased by the polymer material are attached to each other by polymeric links as previously disclosed. 
     According to a further arrangement, an exemplary stent  10  may be made by first dip coating a mandrel into a polymer which corresponds to the inner polymeric material. The metallic rings, which previously were laser cut from a tube, are mounted on the inner polymer material and positioned to form the stent pattern. The outer layer or outer polymer material may be deposited over the metal rings either by spray coating or by dip coating the outer polymeric material over the rings and the inner polymeric material. Then, the mandrel is removed and the unwanted portions of the polymers can be machined by using laser cutting as previously described. 
     Examples of the present disclosure may include at least one stent  10  adapted and configured to the anatomy of the vascular system that supplies blood flow to the eye. In some examples, as noted above, the vascular system includes the ICA  2 , the OA  4 , or combinations or portions thereof. In some examples, at least one stent  10  is configured for insertion into one or more segments of the anatomy selected from the group including the short limb  16  of the OA  4 , angle A  18  of the OA  4 , the ostium, the junction  6  between the OA  4  and the ICA  2 , the portions of the ICA  2  upstream and downstream of the OA  4 , and combinations thereof. 
     In some examples, the stent  10  is a single or unitary structure (e.g., one-piece monolithic structure) configured to the anatomy of the OA  4 , a portion of the OA  4 , the ICA  2 , or combinations thereof. For example, a single stent  10  or a portion thereof may be adapted to conform to the anatomy of the short limb  16 . In another example, a single stent or a portion thereof may be adapted to conform to the anatomy of both the ICA  2  and the OA  4 , e.g., in the junction  6  between the ICA  2  and the OA  4 . 
     In some embodiments, the stent  10  is a multiple-piece structure or multi-segment structure configured to the anatomy of the OA  4 , a portion of the OA  4 , the ICA  2 , or combinations thereof. For example, a stent according to this embodiment, or a portion thereof, may be adapted to conform to the anatomy of the short limb  16 . In another example, a stent of this embodiment, or a portion thereof, may be adapted to conform to the anatomy of both the ICA  2  and the OA  4 , e.g., in the junction between the ICA and the OA. 
       FIG. 4  shows stent  30  configured for insertion within the ostium of the OA  4 . Some embodiments of stent  30  may be configured to open the OA  4  or the flap (not shown) in the junction  6  between the ICA  2  and the OA  4 . As shown in  FIG. 4 , stent  30  has a proximal end (closer to the ICA  2 ) that is wider than a distal end (within OA  4 ). Stent  30  therefore has a frustoconical, or tapered shaped. The proximal end is dimensioned (e.g., has a diameter) so as to be seated at the ostium or junction  6  between the OA  4  and the ICA  2 . The distal end is dimensioned (e.g., has a diameter) so as to be seated in the OA  4 . Stent  30  does not extend into the ICA  2 . 
       FIG. 5  shows a stent  40  configured for insertion within both the ICA  2  and the OA  4 , with strut or stent elements that span the junction  6 . That is, at least a distal portion of stent  40  is dimensioned (e.g., has a diameter) so as to be seated in the OA  4 , while at least a proximal portion of stent  40  is dimensioned (e.g., has a diameter) so as to be seated in the ICA  2 . 
       FIG. 6  shows a stent  50  configured for insertion within the OA  4 , with struts or arms  51  that extend into the short limb  16 .  FIG. 6  further illustrates an additional feature that may be added to any stent of the present disclosure, namely one or more holding elements  52  or barbs, configured to hold or retrain the stent  50  in place. As shown, stent  50  includes a proximal end (closer to the ICA  2 ) that is wider than a distal end (within OA  4 ). Stent  50  therefore has a frustoconical, or tapered shaped. The proximal end is dimensioned (e.g., has a diameter) so as to be seated at the ostium or junction  6  between the OA  4  and the ICA  2 . The distal end is dimensioned (e.g., has a diameter) so as to be seated in the OA  4 . Stent  50  does not extend into the ICA  2 . Further, each arm  51  may include one end coupled, joined, or otherwise formed with stent  50  and another end free from connection to stent  50  or another arm  51 . A longitudinal extent (e.g., in the direction of the OA  4 ) of arms  51  is longer than a longitudinal extend of stent  50 . While only two arms  51  are shown, the disclosure is not so limited. Rather in some arrangements any number of arms  51 , equidistantly or non-equidistantly spaced about a periphery of stent  50 , may be used. 
       FIG. 7  shows stent  60  configured for insertion within the OA  4  and including one or more extensions or longer struts  61  that allow a portion of the stent  60  to extend further into the short limb  16 . That is, multiple segments or portions of stent  60  may be connected to one another via struts  61 , as shown. The proximal end (closer to ICA  2 ) is dimensioned (e.g., has a diameter) so as to be seated at the ostium or junction  6  between the OA  4  and the ICA  2 . The distal end (closer to the OA  4 ) is dimensioned (e.g., has a diameter) so as to be seated in the OA  4 . Stent  60  does not extend into the ICA  2 . While only two struts  61  are shown, the disclosure is not so limited. Rather in some arrangements any number of struts  61 , equidistantly or non-equidistantly spaced about a periphery of stent  60 , may be used. As shown, a longitudinal extent (e.g., in the direction of the OA  4 ) of struts  61  may be longer than the longitudinal extent of the multiple portions or segments of strut  60 . 
       FIG. 8  shows a stent  70  configured for insertion within the ICA  2 , and including a stent element  71  configured to open or hold down the flap (not shown) in the OA  4  that is on the proximal end (e.g., the end closest to ICA  2 ) of the OA  4 . That is, stent element  71  may be positioned so as to bias (e.g., deflect) such a flap in a manner to further increase an opening side of the ostium in the junction  6 . As shown, a thickness (and/or rigidity) of stent element  71  may be larger than a thickness of a remainder of stent  70 . Optionally, stent element  71  may be the only portion of stent  70  extending into the OA  4 . In other arrangements, stent  70  may include multiple stent elements  71 . While stent element  71  is shown at a downstream end of a remainder of stent  70 , in other arrangements, stent element  71  may be arranged upstream of a remainder of stent  70 . 
       FIG. 9  shows a stent  80  configured for insertion within the ICA  2  and including a portion  81  configured for insertion within the ICA  2  and a portion  82  configured for insertion within the OA  4 . That is, stent  80  at least partially spans the junction between the ICA  2  and the OA  4 . As shown, at least a portion of portion  82  may remain within ICA  2 . Additionally, at least some of the struts of portion  82  may be spaced closer to one another than at least some of the struts of portion  81 . Accordingly, stent  80  may have a varied density of struts. In other arrangements, a density of struts of stent  80  may be continuous. 
       FIG. 10  illustrates a stent  90  configured for insertion within the ICA  2  and including a portion  91  in the ICA  2  that is distal to (e.g., downstream of) the OA  4  and a portion  92  in the ICA  2  that is proximal to (e.g., upstream) the OA  4 .  FIG. 10  also shows one or more stent struts  93  (optional) that extend at least partially into the ostium at the junction  6  between the ICA  2  and the OA  4 . Similarly,  FIG. 11  illustrates a stent  100  configured for insertion within the ICA  2  and including a portion  91  that is distal to (e.g., downstream of) the OA  4  and a portion  92  that is proximal to (e.g., upstream) the OA  4 . As shown, stent  100  may further include one or more stent struts  101  (optional) that extend into the short limb  16 . The one or more stent struts  101  may include a free end positioned distally of the junction  6  and uncoupled from a remainder of stent  100 . 
     Any of the stents described herein may optionally include one or more components to adjust blood flow between the ICA  2  and the OA  4 . For example, as shown in  FIG. 12 , an exemplary eddy blood flow pattern in the area between the ICA  2  and the OA  4  is illustrated. As can be seen, during natural blood flow through the vasculature, a circular or non-linear movement or redirection of blood may occur (e.g., an eddy) which may alter or diminish the blood flow supply flowing from the ICA  2  to the OA  4 . As shown, the eddy may be located upstream of the OA  4  and along a wall of the ICA  2 . For example, such an eddy may reduce a blood flow rate or amount of blood that flows from the ICA  2  through the OA  4 , and then continues on to the eye. As noted above, a reduced amount or rate of blood flow may also result in reduced oxygen supply to the eye, which may further contribute to the eye diseases and conditions noted above. Further, any one or more obstructions (e.g., partial and/or complete obstructions, narrowing of a vessel, and/or lesions) may further contribute to reduced blood flow from the ICA  2  through the OA  4 . Accordingly, any one or more of the examples herein described may further include a structure or element configured to guide or direct flow in a desired manner. 
     For example, a diverter element or structure may be used in conjunction with any of the stents disclosed herein. Each diverter element may include a strut terminating in a free end. That is, in one embodiment, such an element may have a first end coupled to, joined with, or formed monolithically as a one-piece structure with a remainder of any of the disclosed stents herein, and a second end, opposite the first end, uncoupled, unjoined, or otherwise free from contact with a remainder of any of the disclosed stents herein. Moreover, such a diverter element may extend at an angle relative to the ophthalmic artery. As used herein, a diverter may include one or more element(s) or structure(s) that channel blood flow through the lumen  14  defined by the stent body or an element or structure that is used to bypass one or more portions of the stent. In other words, a diverter may mediate, affect, and/or alter blood flow, specifically eddies, so as to improve or increase a blood flow rate and/or an amount of blood flowing from the ICA  2  to the OA  4  and/or promote and/or optimize the laminar flow of blood through the stent lumen  14  and/or the vessel within which the stent is inserted. That is, a diverter may reduce the amount or impact of eddies. 
       FIG. 13  illustrates a stent  110  including a diverter  111  which may change or alter the blood flow dynamics between the ICA  2  and the OA  4 , preferably increasing the amount of blood entering the OA  4 . That is, as blood flow travels from the ICA  2  toward the OA  4 , the blood flow may impact or be disrupted by re-diverter  111  which may guide or otherwise facilitate the flow of blood from ICA  2  to OA  4 . Diverter  111  may include an extension of a proximalmost strut of stent  110 , and has an atraumatic shape so as to not cause damage to surrounding blood vessel walls. Diverter  111  also may include a dimension (e.g., thickness, width, etc.) that is larger than the strut from which it extends. In this way, it may present sufficient surface area facing the oncoming blood flow to deviate a desired amount of flow. In a  FIG. 14  illustrates a further arrangement of a stent  120  including diverter  121  that changes or alters the blood flow dynamics between the ICA  2  and the OA  4 , preferably increasing the amount of blood entering the OA  4 .  FIG. 13  shows stent  110  positioned distal (e.g., downstream) of the OA  4 , while  FIG. 14  shows stent  120  positioned proximal (e.g., upstream) of the OA  4 . 
       FIG. 15  illustrates a stent  130  that includes a diverter  131  that changes or alters the blood flow dynamics between the ICA  2  and the OA  4 , preferably increasing the amount of blood entering the OA  4 . Additionally, stent  130  includes both a distal (e.g., downstream) stent portion  132  and a proximal (e.g., upstream) stent portion  133 . As shown, diverter  131  may extend from the proximal (e.g., upstream) stent portion  133  and toward the OA  4 . Additionally, stent  130  includes a portion extending into the OA  4 . The diverter  131  may be angled relative to the ICA  4  so as to direct blood flow impacting the diverter  131 . 
       FIG. 16  shows a stent  140  configured for insertion within both the ICA  2  and the OA  4  and including a stent portion  141  that extends into the short limb  16  of the OA  4 , a distal (e.g., downstream) stent portion  142  and a proximal (e.g., upstream) stent portion  143 . As shown, a spacing between adjacent struts of stent portion  141  may be closer than a spacing between adjacent struts of either stent portion  142  and stent portion  143 . 
       FIG. 17  illustrates an additional arrangement including a combination of multiple stents. For example, a first stent  150 A is configured for insertion within the ICA  2  proximal (e.g., upstream) of the OA  4  and a second stent  150 B is configured for insertion within the ICA  2  distal (e.g., downstream) of the OA  4 . Stent  150 A may further include a distal portion  151  comprising one or more flow diverter elements. Stent  1506  may further include a proximal portion  152  comprising one or more flow diverter elements. As shown, each diverter of stent  150 A and stent  1506  may be angled so as to direct blood flow into OA  4 . In some arrangements, each of the diverters of stent  150 A and stent  1506  may be generally parallel to one another. 
     As noted above, any decrease in blood flow between the ICA  2  and the OA may be the result of one or more obstructions or constrictions within the vasculature. Thrombus, lesions, or other obstructions may be located in any of the ICA  2 , the OA  4 , the junction  6 , or combinations thereof.  FIG. 18  illustrates a common location of a thrombus or obstruction  20  in the OA  4 . 
       FIG. 19A  illustrates an arrangement of a self-expanding support member or ring according to further arrangements. For example, as shown in  FIG. 19A , a support ring  160  may include a pair of legs  162  extending from a base  164 , each leg  162  being in the form of a loop. Free ends of ring  160  extend from base  164  opposite of legs  162 . The legs  162  may be biased outwardly (e.g., away from) one another. In some examples, support ring  160  may comprise shape-memory alloy such as, for example, Nitinol. Support ring  160  may be delivered in a compressed configuration (not shown) via any appropriate device (e.g., a catheter or the like) to a location within one or both of ICA  2  and OA  4 . Upon reaching the desired location, support ring  160  may be expelled from the delivery device (e.g., catheter) and allowed to expand, as shown in  FIG. 19B . Upon expansion, legs  162  may apply an outward force F on opposite sides of OA  4  force the ostium between ICA  2  and OA  4  open. While support ring  160  is described as being a self-expandable, in other arrangements, support ring  160  may be expanded through via any appropriate method. Additionally,  FIG. 20A  illustrates a further arrangement of a self-expanding support member. For example, as shown in  FIG. 20A , a support ring  170  may include a single (e.g., only one) leg  172 . Similar to support ring  160 , support ring  170  may be delivered in a compressed configuration (not shown) via any appropriate device (e.g., a catheter or the like) to a location within one or both of ICA  2  and OA  4 . Upon reaching the desired location, support ring  170  may be expelled from the delivery device (e.g., catheter) and allowed to expand, as shown in  FIG. 20B . Upon expansion, leg  172  may apply an outward force F on a side of OA  4  to force the ostium between ICA  2  and OA  4  open. 
       FIGS. 21-24  illustrate further exemplary arrangements of flow diverting structures according to the disclosure. For example, as shown in  FIG. 21 , a stent  180  may have a proximal end  182  and a distal end  184  and a length extending therebetween. As shown, stent  180  may have a tapered profile (e.g., proximal end  182  may have a first cross-sectional dimension while distal end  184  may have a second cross-sectional dimension different than the first cross-sectional dimension.) While not illustrated, stent  180  may include any number, arrangement, or shape of struts extending along the length. Additionally, although not shown, stent  180  may optionally include a covering, as described above. In the arrangement shown in  FIG. 21 , stent  180  may include a diverter in the form of a helical or partial helical element  186 . As shown, element  186  may extend about or along an internal surface or diameter of stent  180 , and may protrude inwardly from that internal stent surface. Element  186  may comprise a track or guide such that blood flow impacting element  186  or passing through stent  180  may be directed to flow along element  186  and/or toward OA  4  ( FIG. 1 ). Element  186  may include one or more loops  188  extending along the length of stent  180 . While three complete loops  188  are illustrated as equidistantly spaced along the length of stent  180  in  FIG. 21 , the disclosure is not so limited. Rather, any number of loops  188 , equidistantly or not equidistantly, spaced along the length of stent  180  may be employed. Further, one or more features of element  186  may be adjusted as desired to achieve a desired flow of blood towards the OA  4 . For example, the number of loops  186  per unit length (or pitch of helix), orientation of the element  186  (e.g., a left or right orientation of element  186 ), width of element  186  (e.g., a dimension of element  186  extending from a surface of stent  180  towards a central longitudinal axis L of stent  180 ), a height of element  186 , a length of element  186  (e.g., element  186  may extend the entire length of stent  180  or less than the entire length of stent  180 ), and a number of elements  186  may be varied to achieve a desired effect on a flow of blood. For example, any one or more of the above-noted features of element  186  may be varied to achieve a venturi effect on a flow of blood passing through stent  180 . 
     In a further arrangement, as shown in  FIG. 22 , a stent  190  may have a length extending between a proximal end  192  and a distal end  194 . As shown, stent  190  may have a tapered profile (e.g., proximal end  192  may have a first cross-sectional dimension while distal end  194  may have a second cross-sectional dimension different than the first cross-sectional dimension.) While not illustrated, stent  190  may include any number, arrangement, or shape of struts extending along the length of stent  190 . Additionally, although not shown, stent  180  may optionally include a covering, as described above. Rather than the inclusion of element  186 , however, stent  190  may include a bump or projection  196 . Projection  196  may extend radially inward from an internal circumferential wall toward a longitudinal axis L of stent  190 . While only a single projection  196  is illustrated, in other arrangements, multiple projections  196  may extend from the internal circumferential wall of stent  190 . Indeed, the number and arrangement of projections may be modified as desired so as to effect a flow of blood. For example, the number of projections  196  per unit length of stent  190 , a dimension of a periphery of the projection  196  (e.g., a diameter), and/or a height of projection  196  extending from the circumferential wall of stent  190  toward longitudinal axis L. For example, any one or more of the above-noted features of projection  196  may be varied to achieve a venturi effect on a flow of blood passing through stent  190 . 
     In a further arrangement, as shown in  FIG. 23 , a stent  200  may have a length extending between a proximal end  210  and a distal end  212 . While not illustrated, stent  200  may include any number, arrangement, or shape of struts extending along the length of stent  200 . Additionally, although not shown, stent  200  may optionally include a covering, as described above. Further, as shown in  FIG. 23 , stent  200  may include a raised annular ring or partial ring  216 . Ring  216  may extend about at least a portion of an internal circumferential surface of stent  200  and protrude radially inwardly towards longitudinal axis L. While only a single ring  216  is illustrated, in other arrangements, multiple rings  216  may extend from the internal circumferential wall of stent  200 . Indeed, the number and arrangement of rings  216  may be modified as desired so as to effect a flow of blood. For example, the number of rings (or partial rings)  216  per unit length of stent  200 , a length of ring  216  (e.g., an arc length) extending about the circumferential surface of stent  200 , a width of ring  216 , and/or a height of ring  216  extending from the circumferential wall of stent  200  toward longitudinal axis L. For example, any one or more of the above-noted features of ring  216  may be varied to achieve a venturi effect on a flow of blood passing through stent  200 . 
     Additionally, as shown in  FIG. 24 , a stent  220  may include each of a helical element  186 , a protrusion  196 , and a ring  216 . That is, as shown in  FIG. 24 , any of the blood flow diverting elements described in  FIGS. 21-23  may be used in combination with one another so as to impart a desired effect on a flow of blood passing through stent  220 . In such a manner, a flow of blood may be directed or guided toward OA  4 . 
       FIGS. 25 and 26  illustrate further exemplary arrangements of flow diverting structures according to the disclosure. As shown in  FIG. 25 , for example, a flow diverter  230  may be positioned within the ICA  2  so as to modify a flow of blood passing through the ICA  2 . As shown, flow diverter  230  is supported via a mounting bracket or element  232 . Mounting element  232  may be a bracket, frame, stent, ring or other such structure. For example, mounting element  232  may be an expandable (e.g., self-expandable Nitinol) ring such that upon positioning within the ICA  2 , mounting element  232  may expand so as to contact walls of ICA  2 , thus maintaining mounting element  232  in position relative to ICA  2 . Alternatively, mounting element  232  may be secured to walls of the ICA  2  via any appropriate mechanism such as, for example, sutures, barbs, medical adhesives, or the like. While  FIG. 25  illustrates mounting element  232  being constructed as a stepped or tapering structure, in other arrangements, mounting element  232  need not be stepped or tapered. 
     As shown in  FIG. 25 , mounting element  232  may be mounted within ICA  2  upstream of OA  4 , and coupled to an upstream end of flow diverter  230 . In other arrangements, mounting element  232  may be mounted within ICA  2  downstream of OA  4 , and coupled to a downstream end of flow diverter  230 . Still further, multiple mounting elements  232  (e.g., one coupled to an upstream end of flow diverter  230  and one coupled to a downstream end of flow diverter  230 ) may secure flow diverter  230  at a location within the ICA  2 . In either arrangement, mounting element(s)  232  may enable a flow of blood to pass therethrough and around flow diverter  230 . Flow diverter  230  may include a selectively inflatable balloon. In some arrangements, the balloon can be pre-inflated to a set size and positioned within ICA  2 . Alternatively, the balloon can have an adjustable degree of inflation such that flow diverter  230  can dynamically modify a flow of blood passing through the ICA  2 . Such a balloon may be inflated via an inflation lumen (e.g., a portion of a delivery catheter and/or a separate shaft, not shown). In some arrangements, the balloon may be filled with saline or a liquid polymer. 
     In any such arrangement, however, flow diverter  230  may modify a flow of blood passing through the vasculature. For example, flow diverter  230  may increase a velocity and alter a direction of the flow of blood. That is, the shape and/or size of flow diverter  230  may be selected so as to interfere with a flow of blood passing through ICA  2  by funneling, directing, or otherwise urging at least some of the flow of blood towards and/or into OA  4 , as indicated by the arrows  234  in  FIG. 25 . 
     In an alternative arrangement, flow diverter  230  may be positioned within the ICA  2  via one or more arms  236 . Arms  236  may include any one or more of string, suture material, or struts and may secure or mount flow diverter  230  within ICA  4 . Each arm  236  may be secured to a wall of the ICA  4  via an anchor  238  including one or more of a suture, barb, adhesive or the like. In either arrangement, flow diverter  230  may adjust a velocity and/or direction of blood flow through ICA  2 , as indicated by the arrows  234  in  FIG. 26 . 
       FIG. 27  illustrates a further arrangement of a flow diverter  240 . Flow diverter  240  may be a funnel-shaped cylindrical member. Flow diverter  240  includes an upstream end  242  and a downstream end  244 . As shown, upstream end  242  may have a dimension (e.g., diameter) larger than a dimension (e.g., diameter) of downstream end  244 . Additionally, at least a portion of flow diverter  240  (e.g., upstream end  242 ) is positioned within ICA  2  while a further portion of flow diverter  240  (e.g., downstream end  244 ) is mounted within OA  4 . As a flow of blood travels within the ICA  2  towards the OA, flow diverter  240  may funnel, guide, direct, or otherwise urge blood flow to enter OA  4 . As shown, flow diverter  240  may include a bend between upstream end  242  and downstream end  244 . Further, downstream end  244  may have a cross-sectional dimension configured for insertion within OA  4 . For example, downstream end  244  may have a cross-sectional dimension (e.g., diameter) that is approximately the same as the cross-sectional dimension (e.g., diameter) of OA  4 . Further, upstream end  242  may have a cross-sectional dimension (e.g., diameter) that is approximately the same as the cross-sectional dimension (e.g., diameter) of ICA  2 . In some arrangements, flow diverter  240  may include an impermeable cover such that a flow of blood passing through flow diverter  240  does not pass through a side wall of flow diverter  240 , but rather, is conveyed from upstream end  242  to downstream end  244 . 
     In a further arrangement, a flow diverter  250  may be mounted within the ICA  2 , as shown in  FIG. 28 . Flow diverter  250  may include an upstream ring  252  (e.g., a ring positioned upstream of OA  4 ) and a downstream ring  254  (e.g., a ring positioned downstream of OA  4 ). In some arrangements, upstream ring  252  may be distinct and uncoupled from downstream ring  254 . In other arrangements, upstream ring  252  may be coupled to downstream ring  254 . Upstream ring  252  and downstream ring  254  may be formed of a self-expandable material such as, for example, Nitinol. A leaflet or valve  256  may be pivotably or otherwise moveably positioned between upstream ring  252  and downstream ring  254  (e.g., via a suture on one end of valve  256 ). That is, valve  256  may move so as to adjust an amount or velocity of blood entering OA  4 . Valve  256  may move in accordance with systolic and diastolic pressure variations in a flow of blood. Movement of valve  256  may clean, wash, or otherwise prevent buildup of particulate on valve  256  as the flow of blood moves across a surface of valve  256 . In an alternative arrangement, valve  256  may not be moveable. Rather, valve  256  may be secured so as to remain in place, thereby statically guiding, funneling, urging, or otherwise directing the flow of blood toward OA  4 . Valve  256  may be comprised of any one or more of polyester, ePTFE, other polymers, and/or tissue. In a further arrangement, a plurality of valves  256  may be arranged to guide or direct the flow of blood toward the OA  4 . 
     In a further arrangement, as shown in  FIG. 29 , a stent  260  may be positioned within the ICA  2 . Additionally, stent  260  may include a strut or diverter arm  262 . As shown in  FIG. 29 , diverter arm  262  may extend at an angle relative to a longitudinal axis of stent  260 . Arm  262  may emanate from stent  260  at a position opposite the opening (e.g., ostium) to the OA  4 , and extend in a downstream direction towards the side of ICA  2  closest to the OA  4 . Arm  262  may have a free end near the ostium to the OA  4 . Any of the angle, shape, thickness, and length of diverter arm  262  may be adjusted to modify an amount or velocity of blood entering OA  4 . For example, diverter arm  262  may be angled so as to urge a flow of blood towards OA  4 , as indicated by arrows  264  in  FIG. 29 . In some arrangements, diverter arm  262  may be coated or otherwise include a covering having one or more characteristics so as to modify a flow of blood. For example, in some arrangements, diverter arm  262  may be comprised of a bio-stable material such as ePTFE, thereby preventing a reaction between the flow of blood and diverter arm  262 . In some arrangements, the entirety of stent  260 , including diverter arm  262 , may be coated, covered, or otherwise formed of ePTFE. 
     In a further arrangement, as shown in  FIG. 30 , a flow diverter  270  may include a covering  272  at least partially covering a plurality of spokes, struts, or fins  274 . As shown, fins  274  may extend radially outwardly away from a longitudinal axis L of flow diverter  270 . Fins  274  may have any shape and/or arrangement so as to focus or guide a flow of blood impacting fins  274  toward the OA  4 . In addition, a number, an angle, a spacing, and/or a material of fins  274  may be adjusted so as to modify and/or guide the flow of blood toward the OA  4 . For example, flow diverter  270  may include an opening  276  through which a flow of blood may be guided toward OA  4 . As shown, opening  276  may extend through covering  272 . In some arrangements, opening  276  may be received at least partially within OA  4 . 
     Arrangements of the present disclosure may include percutaneous access and treatment of vascular structures at the rear of the eye, intended to provide devices and treatment methods for diseases of the eye related to compromised vascular flow. These methods include, but are not limited to, treatment for the symptoms related to Age Related Macular Degeneration, Glaucoma and Diabetic Retinopathy by placement of a stent in the ICA/OA ostium to provide treatment to stenosis in Ophthalmic/Internal Carotid Artery (ICA/OA) ostium, thereby restoring normal, near normal or improved blood flow to the rear of the eye, including the retina, choroid, and/or associated structures. 
     Another embodiment the present disclosure may include reducing and/or removing any blockage in the oxygen pathway to the eye. In this and other embodiments, reducing blockage(s) includes but is not limited to piercing or penetrating the blockage. In some arrangements, piercing and penetrating the blockage refers to obtaining sufficient blood and/or fluid flow through or around the blocked vascular area sufficient to provide a therapeutically beneficial amount of oxygen to the eye or a portion of the eye. 
     Another example of the present disclosure includes supplying oxygen to the eye or near the eye, wherein, in this embodiment, the source of the oxygen is external. 
     Another example of the present disclosure includes a medical device, such as a stent or the like, that may be used to open, clear, or improve vascular flow to or around the eye, wherein vascular flow mediates the amount of oxygen that is delivered to the eye. 
     The present disclosure relates generally to stents for use in body vessels to treat medical conditions. In particular, examples of the disclosure relate to novel asymmetric stents having opposing sets of curved apices, where the curved section of one set of apices has a radius of curvature that is greater than the curved section of the other set of apices, and may present a lower profile than conventional stents. The lower profile may present advantages for use in patients with particularly tortuous or small-diameter vessels. 
     In some embodiments, an asymmetric portion of a stent or a first asymmetric stent having a greater radius is configured for placement in the ICA  2 . In other arrangements, an asymmetric portion of a stent or a second asymmetric stent having a smaller radius is configured for placement in the OA  4 . 
     The asymmetric stent may be configured such that, when used with a graft, it will provide a sufficiently strong radial force at the graft&#39;s end openings to hold the graft material open against the vessel wall. Also, the stent is intended to be short in length (e.g., 0.5 mm, 1 mm, 2 mm in length) so that the graft will include flexibility sufficient to accommodate a patient&#39;s anatomy. This combination of flexibility and strong radial force provides an improved seal between the stent and artery wall. In addition, enhanced flexibility is provided as well, particularly when one or more stents are used to provide short segments and better accommodate curves. 
     For some of these embodiments, one or more layers of the implant device or stent may be configured to anchor or fix the implant device in a clinically beneficial position. For some embodiments, the implant device may be disposed in whole or in part within the vascular defect (e.g., obstruction, lesion, thrombus, vessel construction, etc.) in order to anchor or fix the device with respect to the vascular structure or defect. The one or more layers of the implant device may be configured to span an opening, neck or other portion of a vascular defect in order to isolate the vascular defect, or a portion thereof, from the patient&#39;s nominal vascular system in order to allow the defect to heal or to otherwise minimize the risk of the defect to the patient&#39;s health. 
     One or more stents according to the present disclosure may be manufactured from a super-elastic material. Solely by way of example, the super-elastic material may comprise a shape-memory alloy, such as a nickel titanium alloy (nitinol). If the stent comprises a self-expanding material such as nitinol, the stent may be heat-set into the desired expanded state, whereby the stent can assume a relaxed configuration in which it assumes the preconfigured first expanded inner diameter upon application of a certain cold or hot medium. Alternatively, the stent may be made from other metals and alloys that allow the stent to return to its original, expanded configuration upon deployment, without inducing a permanent strain on the material due to compression. Solely by way of example, the stent may comprise other materials such as stainless steel, cobalt-chrome alloys, amorphous metals, tantalum, platinum, gold and titanium. The stent also may be made from non-metallic materials, such as thermoplastics and other polymers. 
     The stent may be formed from a tube by laser cutting the pattern of cylindrical rings and undulating links in the tube. The stent also may be formed by laser cutting a flat metal sheet in the pattern of the cylindrical rings and links, and then rolling the pattern into the shape of the tubular stent and providing a longitudinal weld to form the stent. 
     The number and location of undulating links that interconnect adjacent cylindrical rings can be varied as the application requires. Since the undulating links typically do not expand when the cylindrical rings of the stent expand radially outwardly, the links are free to continue to provide flexibility and to also provide a scaffolding function to assist in holding open the artery. The addition or removal of the undulating links has very little impact on the overall longitudinal flexibility of the stent. Each undulating link is configured so that it promotes flexibility whereas some prior art connectors actually reduce flexibility of the stent. 
     Because of the undulating configuration of the links, the stent has a high degree of flexibility along the stent axis, which reduces the tendency of stent fishscaling. Stent fishscaling can occur when the stent is bent and portions of the stent project outward when the stent is in the unexpanded condition. The present disclosure includes undulating links so as to reduce the likelihood of fishscaling. 
     Further, because of the positioning of the links, and the fact that the links do not expand or stretch when the stent is radially expanded, the overall length of the stent is substantially the same in the unexpanded and expanded configurations. In other words, the stent will not substantially shorten upon expansion. 
     In operation, a wire guide may be advanced to the target site, and the cannula may be advanced over the wire guide to position the apparatus at the desired location in proximity to the target site, with the atraumatic tip reducing the likelihood of injury to bodily passageways during delivery. The outer sheath may be disposed over the cannula and the stent-graft during insertion to the target site. Upon proper positioning at the target site using a desired imaging modality, the outer sheath is then retracted to expose at least a portion of the stent. 
     When the stent is at least partially exposed, and it is desirable to deploy the proximal end of the stent, the cannula may be rotated in a clockwise direction until the longitudinal strut portions are aligned with the axial openings of the retaining member, e.g., in a reverse manner from which the longitudinal strut portions were loaded and secured to the retaining member. The proximal end of the stent then is allowed to self-expand due to the resilient nature of the struts, which will be inclined to move radially outward when no longer constrained by the outer wall portions. The remainder of the stent may be deployed by further retraction of the outer sheath or actuation of any other devices that are radially constraining the remainder of the stent. 
     Advantageously, the proximal end of the stent is radially restrained without the use of conventional trigger wires that span a full longitudinal length of the delivery system. Accordingly, the radial profile of the delivery system may be reduced without the provision of multiple trigger wires and one or more associated sleeves to house the trigger wires, thereby reducing packing density of the system. Moreover, deployment may be simplified as reduced deployment forces are expected to be needed relative to the use of conventional trigger wires. 
     Some embodiments of a delivery system for deployment of an implant device to treat a patient&#39;s vasculature include a microcatheter having an inner lumen extending the length thereof. The inner lumen provides a passageway for an implant device to treat a patient&#39;s vasculature. Some implant device embodiments may include one or more self-expanding resilient layers of thin coupled filaments, the layers defining a longitudinal axis between a proximal end and a distal end. Such embodiments can assume a radially-constrained, axially-elongated state configured for delivery through a microcatheter, with the thin woven filaments extending longitudinally from the proximal end to the distal end being radially adjacent to each other. The delivery system further includes an elongated delivery apparatus having a proximal end and a distal end releasably secured to a proximal portion (e.g., a hub or the like) of the implant device. 
     Access to a variety of blood vessels of a patient may be established, including arteries such as the femoral artery, the radial artery, cervical access, and the like, in order to achieve percutaneous access to a vascular defect. In general, the patient may be prepared for surgery, the access artery is exposed via a small surgical incision, and access to the lumen is gained using the Seldinger technique where an introducing needle is used to place a wire over which a dilator or series of dilators may dilate a vessel allowing an access sheath to be inserted into the vessel. This would allow the device to be used percutaneously. With an access sheath in place, a guiding catheter is used to provide a safe passageway from the entry site to a region near a treatment site. Exemplary guidewires for vascular use may include the Synchro2® made by Boston Scientific and the Glidewire Gold Neuro® made by MicroVention Terumo. Typical guidewire sizes may include 0.014 inches (0.36 mm) and 0.018 inches (0.46 mm). Once the distal end of the microcatheter is positioned at the site, often by locating its distal end through the use of radiopaque marker material and fluoroscopy, the catheter is cleared. For example, if a guidewire has been used to position the microcatheter, it may be withdrawn from the microcatheter, and then the delivery apparatus may be advanced through the microcatheter. 
     Once the implant device is deployed at a desired treatment site, the microcatheter may then be withdrawn. Characteristics of the implant device and delivery apparatus discussed herein generally allow for retraction of the implant device after initial deployment into the vascular defect, but before detachment of the implant device. Therefore, it may also be possible and desirable to withdraw or retrieve an initially deployed implant device after the fit within the vascular defect has been evaluated in favor of a differently-sized implant device. The tip of a catheter, such as the microcatheter, may be advanced into or adjacent to the vascular site or vascular defect. An example of a suitable microcatheter having an inner lumen diameter of about 0.51 mm to about 0.56 mm is the Rapid Transit®. manufactured by Cordis Corporation. Examples of some suitable microcatheters may include microcatheters having an inner lumen diameter of about 0.66 mm to about 0.71 mm, such as the Rebar® by Ev3 Company, the Renegade Hi-Flow® by Boston Scientific Corporation, and the Mass Transit® by Cordis Corporation. Suitable microcatheters having an inner lumen diameter of about 0.79 mm to about 0.84 mm may include the Marksmen® by Chestnut Medical Technologies, Inc. and the Vasco 28® by Balt Extrusion. A suitable microcatheter having an inner lumen diameter of about 1.0 mm to about 1.04 mm includes the Vasco 35® by Balt Extrusion. These microcatheters are listed as exemplary embodiments only, and other suitable microcatheters may also be used with any of the embodiments discussed herein. 
     It is understood that the present disclosure is not be limited solely to changing vascular flow in order to improve or restore the amount of oxygen that is delivered to the eye. For example, in some arrangement, the vascular flow may be unaffected for the most part, but the amount or concentration of hemoglobin may be increased, thereby increasing the amount of oxygen that may be delivered to the eye. One skilled in the art may recognize that there are other biological systems or capabilities that may be used to increase the amount of oxygen that is delivered to the eye. 
     It is understood that any process, device, or agent that increases the availability of oxygen to the eye or eye region is included within the scope of the present disclosure. These processes, devices, and agents include, but are not limited to internal sources of oxygen, e.g., through the vascular system. These processes, devices, and agents include, but are not limited to external sources of oxygen, e.g., an injection into the eye or eye region with one or more substances that carries oxygen, a substance that captures or concentrates oxygen, a device that manufactures oxygen and/or one of more substances that result in an increase the amount of oxygen. 
     The present disclosure includes a system comprising one or more medical devices, (e.g., a stent) and an associated delivery apparatus; said system is used for increasing the amount of oxygenated blood in the eye area, or for increasing the amount of oxygen that is or can be delivered to the eye. 
     The disclosure further includes the use of one of more diagnostic devices or agents that allow a person to monitor oxygen content in the eye. 
     In another embodiment, a medical device or agent is capable of delivering drugs to the ostium for the purpose of improving vascular blood flow at the ostium and within the OA  4 . These drugs may include (but are not limited to) one or more of: a low dose PDE5 inhibitor (sildenafil), a VEGF-a inhibitor (ranibizumab/bevacizumab), a cytotoxic coating (Taxol/Rapamyacin), and/or a cytostatic coating (Sirolimus), other pharmaceuticals used to improve vascular blood flow, or combinations thereof. 
     In one embodiment, the ophthalmological disease or disorder treated or prevented by any of the methods or compositions described herein is age-related macular degeneration. Vision changes that can be associated with macular degeneration include distortions and/or blind spots (scotoma) detected using an Amsler grid, changes in dark adaptation (diagnostic of rod cell health), changes in color interpretation (diagnostic of cone cell health), and/or a decrease in visual acuity. Examples of age-related macular degeneration are normeovascular (also known as “dry”) and neovascular (also known as “wet” or “exudative”) macular degeneration. 
     In one embodiment, the dry age-related macular degeneration is associated with the formation of drusen. In one embodiment, treating or preventing dry macular degeneration encompasses treating or preventing an abnormality of the retinal pigment epithelium and/or underlying vasculature, known as choriocapilaries. Examples of abnormalities of the retinal pigment epithelium include geographic atrophy, non-geographic atrophy, focal hypopigmentation, and focal hyperpigmentation. In another embodiment, treating or preventing wet age-related macular degeneration encompasses treating or preventing choroidal neovascularization or pigment epithelial detachment. 
     In some embodiments, wet age-related macular degeneration is classified according to the appearance of its choroidal neovascularization (CNV), into classic, occult or mixed (classic and occult) CNV types, as determined by an angiography, known as fluorescence angiography. Classic, occult or mixed (classic and occult) CNV classification can be based on the time, intensity and level of definition of dye appearance, and leakage from the CNV, as assessed by the fluorescein angiography. In some embodiments, the subject has classic CNV (e.g., pure classic) or mixed CNV (predominantly or minimally classic CNV). In some embodiments, the subject has occult CNV (e.g., pure occult CNV). In certain embodiments, the ophthalmological disease or disorder is a cataract (e.g., age-related cataract), diabetic macula edema, macular telangiectasia (e.g., type 1 or 2 macular telangiectasia), anterior ischemic optic neuropathy (AION) (either arteritic or non-arteritic), amaurosis fugax, atrophic macular degeneration, chorioretinopathy (e.g., central serous chorioretinopathy), retinal inflammatory vasculopathy, pathological retinal angiogenesis, age-related maculopathy, retinoblastoma, Pseudoxanthoma elasticum, a vitreoretinal disease, choroidal sub-retinal neovascularization, central serous chorioretinopathy, ischemic retinopathy, hypertensive retinopathy or diabetic retinopathy (e.g., nonproliferative or proliferative diabetic retinopathy, such as macular edema or macular ischemia), retinopathy of prematurity (e.g., associated with abnormal growth of blood vessels in the vascular bed supporting the developing retina), venous occlusive disease (e.g., a retinal vein occlusion, branch retinal vein occlusion or central retinal vein occlusion), arterial occlusive disease (e.g., branch retinal artery occlusion (BRAO), central retinal artery occlusion or ocular ischemic syndrome), central serous chorioretinopathy (CSC), cystoid macular edema (CME) (e.g., affecting the central retina or macula, or after cataract surgery), retinal telangiectasia (e.g., characterized by dilation and tortuosity of retinal vessels and formation of multiple aneurysms, idiopathic JXT, Leber&#39;s miliary aneurysms, or Coats&#39; disease), arterial macroaneurysm, retinal angiomatosis, radiation-induced retinopathy (RIRP), or rubeosis iridis (e.g., associated with the formation of neovascular glaucoma, diabetic retinopathy, central retinal vein occlusion, ocular ischemic syndrome, or chronic retinal detachment).