Microcatheters and related systems for the treatment of ophthalmic diseases

Abstract

A system for treatment of one or more obstructions within vasculature behind an eye of a subject may include a microcatheter (1300) having a proximal portion, a distal tip portion, extending from the proximal portion, and the distal tip portion having a preformed shape, including at least a first curved portion (1335) and a second curved portion (1340), and the microcatheter further having an inner lumen; and a guidewire configured to be advanced through the inner lumen of the microcatheter for positioning of a distal end of the guidewire within the vasculature behind the eye of the subject, wherein, when the guidewire extends through the distal tip portion of the microcatheter (1300). the distal tip portion has a generally straight shape, and, when the guidewire does not extend through the distal tip portion of the microcatheter (1300), the distal tip portion is in the preformed shape.

Description

Attorney Docket No. 00170-0031-00304MICROCATHETERS AND RELATED SYSTEMS AND METHODS OF USE FOR THE TREATMENT OF OPHTHALMIC DISEASESCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority of U.S. Provisional Patent Application No. 63 / 690,078, filed on September 3. 2024, the entirety of which is incorporated herein by reference.FIELD OF THE INVENTION

[0002] The present disclosure relates to microcatheters, and related systems and methods of use, for the treatment of ophthalmic disease. More specifically, the present disclosure relates to microcatheters, systems, and methods for treatment of obstructions within vasculature behind an eye of a subject.BACKGROUND

[0003] Microcatheters are a routine component of modem endovascular neurosurgery and are an integral part of procedures used to diagnose and treat cerebral diseases. Neuro endovascular procedures utilizing microcatheters often focus on treatments such as opening a blocked artery (angioplasty), blocking a bleeding artery (embolization), or treating abnormally developed blood vessels (arteriovenous malformations (AVMs)). To address these various needs, microcatheter design has evolved from that of a simple tube to a structure of more complexity. A microcatheter should be strong, flexible, trackable, and steerable. While existing microcatheter design meets many of these criteria, they do not permit easy access to particularly challenging anatomic areas, such as the ophthalmic artery (OA), for treatment of retinal diseases, or more broadly, for treatment of eye diseases.Microcatheters have not been manufactured and used specifically for treatment of the OA to address retinal diseases, and existing devices do not address the unique anatomy of the vasculature behind the eye, including the OA.

[0004] As an example of a treatment for retinal diseases, such as age-related macular degeneration (AMD), angioplasty of the OA has been used. However, cerebral arteries, such as the OA, are not typically treated using angioplasty unless they are 70% or more stenosed, where the percentage stenosis is defined as: % stenosis = 1 —Dstenosisx 100, where L ^normal JDstenosis is the diameter of a stenosed segment of a cerebral artery and Dnormai is a diameter of a normal, proximal segment of the cerebral artery (also know n as the WASID method forAttomev Docket No. 00170-0031-00304 measuring stenosis). In these cases, treatment is indicated for patients that have had, or are at risk for, stroke. There are some cases in which 50% stenosis or more are treated, but that is very unusual. Symptoms of AMD patients do not include stroke. Further, for AMD, relatively less percentage stenosis of the OA, for example, less than 50% stenosis, can symptomatically affect the retina.

[0005] Typically, in angioplasty (cerebral, coronary, peripheral), any stenosis that is at 50% or less does not show an improvement over management by medication. Therefore, the risk to perform angioplasty is not taken. AMD patients having stenosis of 50% or less also have a different symptomatic profde as compared to patients that have had, or are at risk for, stroke. Thus, there is need for systems and related methods of use of such systems that can address stenosis treatment of the OA, including treatment of a stenosis at 50% or less.

[0006] The microcatheter and related systems and methods of the present disclosure are directed to addressing one or more of the problems described herein.SUMMARY

[0007] In some aspects of the present disclosure, a system for treatment of one or more obstructions within vasculature behind an eye of a subject may include a microcatheter having a proximal portion, a distal tip portion, extending from the proximal portion, and the distal tip portion having a preformed shape, including at least a first curved portion and a second curved portion, and the microcatheter further having an inner lumen; and a guidewire configured to be advanced through the inner lumen of the microcatheter for positioning of a distal end of the guidewire within the vasculature behind the eye of the subject, wherein, when the guidewire extends through the distal tip portion of the microcatheter, the distal tip portion has a generally straight shape, and, when the guidewire does not extend through the distal tip portion of the microcatheter, the distal tip portion is in the preformed shape.

[0008] In other aspects of the present disclosure, a method for accessing an ophthalmic artery (OA) of a subject for treatment of obstructions within vasculature behind an eye of the subject may include placing a microcatheter within the vasculature behind the eye, until a distal tip of the microcatheter is within an ostium of an ophthalmic artery (OA) of the subject, the microcatheter having a proximal portion, a distal tip portion, extending from the proximal portion, and the distal tip portion having a preformed shape, including at least a first curved portion and a second curved portion, and the microcatheter further having an inner lumen; and placing a guidewire within the vasculature behind the eye, until a distal end of the guidewire is positioned within an internal carotid artery (ICA) of the subject.Attomev Docket No. 00170-0031-00304BRIEF DESCRIPTION OF FIGURES

[0009] FIG. 1 is a schematic of an eye of a subject and the vasculature behind the eye.

[0010] FIG. 2 is a digital image showing an ophthalmic artery (OA) and an internal carotid artery (ICA).

[0011] FIG. 3A is a digital image showing the vasculature of a subject without age-related macular degeneration (AMD), and FIG. 3B is a digital image depicting the vasculature of a subject with AMD.

[0012] FIG. 4 is a schematic, three-dimensional depiction of an ICA and the segments thereof.

[0013] FIG. 5A is a digital image showing histopathology of a normal OA as it branches from the ICA, FIG. 5B is a digital image showing histopathology of an OA blocked at the ostium of the OA and the ICA, and FIG. 5C is a digital image showing histopathology of medial calcifications in the short limb (SL) of the OA.

[0014] FIG. 6A is a digital image that shows a prolapsed guidewire device, and FIG. 6B is a digital image that shows an accurately placed guidewire.

[0015] FIG. 7 is a digital image of an aortic arch of a subject.

[0016] FIG. 8 is a digital image of two ICAs of a subject.

[0017] FIG. 9 is a digital image of an OA branching from an ICA.

[0018] FIG. 10A is a digital image of one example of an OA takeoff from an ICA and FIG.10B is a digital image of another example of an OA takeoff from an ICA.

[0019] FIG. 1 1 is a digital image showing an example of short limb (SL) and a long limb (LL) of an OA.

[0020] FIGs. 12A and 12B are schematics of a system including a microcatheter and a guidewire, according to one embodiment of the present disclosure.

[0021] FIGs. 13A, 13B, and 13C show a microcatheter, according to one embodiment of the present disclosure, positioned within an ICA and an ostium of an OA.

[0022] FIGs. 14A, 14B, and 14C show a microcatheter, according to another embodiment of the present disclosure, positioned within an ICA and an ostium of an OA.

[0023] FIGs. 15A. 15B, and 15C show a microcatheter, according to still another embodiment of the present disclosure, positioned within an ICA and an ostium of an OA.

[0024] FIGs. 16A, 16B, and 16C show a microcatheter, according to yet another embodiment of the present disclosure, positioned within an ICA and an ostium of an OA.

[0025] FIG. 17 is a flowchart of a method for treatment of an obstruction or obstructions within vasculature behind an eye of a subject.Attomev Docket No. 00170-0031-00304

[0026] FIG. 18A is a schematic of a microcatheter and a guidewire positioned within an IC A.

[0027] FIG. 18B is a schematic of the microcatheter and the guidewire shown in FIG. 18A, according to one embodiment of the present disclosure.

[0028] FIG. 18C is a schematic of the microcatheter and the guidewire shown in FIG. 18A, according to another embodiment of the present disclosure.DETAILED DESCRIPTION

[0029] Various embodiments present disclosure relate generally to systems and methods for treatment of obstructions within vasculature behind an eye of a subject, such as a stenosis or blockage within an ophthalmic artery (OA) of a subject.

[0030] As used herein, the singular forms “a,” ”an.“ and ‘"the7’ include plural reference, unless the context dictates otherwise. The terms “approximately” and “about” refer to being nearly the same as a referenced number or value. More specifically, as used herein, the terms “approximately,” “generally,” and “about” should be understood to encompass ± 10% of a specified amount or value, unless otherwise specified. The use of the term “or” in the specification and in the claims is used to mean “and / or” unless explicitly indicated to refer to alternatives only, or the alternatives are mutually exclusive, although the disclosure supports a definition that refers to only alternatives and “and / or.” As used herein, “another” may mean at least a second or more. As used herein, the terms “comprises,” “comprising,” “include,” “including.” “have,” “having,” or other variations thereof, are intended to cover a nonexclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of elements may not include only those elements, but may include other elements not expressly listed or inherent to such a process, method, system, article, or apparatus. Additionally, the term “exemplary” is used herein in the sense of “example,” rather than “ideal.” In addition, the term “between” used in describing ranges of values is intended to include the minimum and maximum values described herein. The term “proximal” is used to describe the end of a device that is located closest to an operator of the device when using a device on a subject, and the term “distal” is used to describe the end of a device that is located closest to a subject on whom the device is being used or located farthest away from the operator.

[0031] The terms and expressions which are employed herein are used as terms of description and not of limitation, and there is no intention that in the use of such terms and expressions excludes any equivalents of the features shown and described or portions thereof,Attomev Docket No. 00170-0031-00304 but it is recognized that various modifications are possible within the scope of the disclosure claimed.

[0032] The present disclosure is directed to microcatheter devices (also referred to simply as microcatheters), which may also be referred to as intravascular aiming microcatheter devices (AMCs, or AMC in the singular), and related systems and methods. Specifically, the disclosure is directed to a microcatheter for use as part of a system for treatment of one or more obstructions (e.g., stenosis, lesions, or plaques) within anatomy of a subject, such as neurovascular anatomy or the vasculature behind an eye of a subject, for the purpose of increasing perfusion to the retina for the treatment of eye disease. In at least one embodiment, the microcatheter is used as part of a system to provide access to an OA of a subject, e.g., a human subject, for the treatment of age-related macular degeneration (AMD). The microcatheter and the related system may be used to provide access to other vasculature, including other vasculature behind an eye of a subject, and to provide treatment for other conditions.ANATOMY

[0033] The OA is an autoregulating, terminal branch of the internal carotid artery (ICA) and is the sole majority blood supply to the eye. The retina is fed by the OA (that is, blood flows from the OA to the retina) and rests in the back of the eye. It contains approximately 126 million photoreceptors. These photoreceptors are the most metabolically active tissue in the human body and are perpetually on the edge of ischemia. The photoreceptors reside in the outer retina, which is avascular and relies on diffusion to move nutrients in and waste out. Any disruption or blockage of normal blood flow rates to the retina impacts this flow and may cause devastating injury’ to photoreceptors. Even a luminal decrease of less than 50% of the OA can have a devastating effect on the photoreceptors.

[0034] FIG. 1 is a schematic of an eye 100 of a subject and the vasculature behind the eye 100, including the OA 105 as it branches off an ICA 110 and feeds a retina 115 (that is, the OA 105 supplies blood to the retina 115, as noted above). FIG. 1 also shows a petrous segment 120, a cavernous segment 125, and a clinoid segment 130 of the ICA 110, an optic nerve 135, a lacrimal artery 140, a lateral posterior ciliary’ artery 145, a lamina cribrosa 150, a sclera 155, a choroid 160, short posterior ciliary' arteries 165, a long posterior ciliary artery' 170, a central retinal artery (CRA) 175, and a medial posterior ciliary artery. Collectively, the above-noted arteries, shown in FIG. 1. make up the vasculature behind the eye 100 of a subject.Attomev Docket No. 00170-0031-00304

[0035] FIG. 2 is a digital image showing an OA 200 and an ICA 205, as well as a short limb (SL) 210 of the OA 200. an angle 'a 210 of the OA 200, a long limb (LL) 215 of the OA 200, an angle ‘b’ 220 of the OA 200, and a distal part 225 of the OA 200. The OA 200 shown FIG. 2 is a non-diseased OA.

[0036] FIG. 3 A is a digital image depicting the vasculature of a subject without age-related macular degeneration (AMD), and in particular, shows an ICA 300A and an OA 305 A, and FIG. 3B is a digital image depicting the vasculature of a subject with AMD, and shows an ICA 300B and an OA 305B. Note the OA 305B of the subject with AMD, shown in FIG. 3B, is blocked by stenosis 310.

[0037] In the embodiments described herein, the Bouthillier classification system is used as a reference to describe the segments of the ICA relative to the microcatheter and the related systems and methods. The focus of anatomy for use of the microcatheter and the related systems and methods of the present disclosure is on the C6 segment of the ICA, as the OA branch originates from this segment. FIG. 4 is a schematic, three-dimensional depiction of an ICA 400. and provides an example of the Bouthillier classification, showing a Cl segment 405, a C2 segment 410, a C3 segment 415, a C4 segment 420, a C5 segment 425, a C6 segment 430, and a C7 segment 435, as well as a location from which an OA 440 branches from the ICA 400. FIG. 4 also shows the tortuosity present in the ICA proper (that is, within the segments of the ICA shown in FIG. 4). Note, the ICA 400 presents in vivo as a three- dimensional. compound, multi-curve arterial segment.

[0038] FIG. 5 A is a digital image depicting histopathology of a normal OA 505 A as it branches from an ICA 500 A, FIG. 5B is a digital image depicting histopathology' of an OA 505B that is blocked at the ostium of the OA 505B and an ICA 500B by a lesion 510 (also referred to as a total occlusion OA), and FIG. 5C is a digital image depicting histopathology of an SL 515 of an OA 505C, with medial calcifications 520. The white space within these images corresponds to the noted portions of the vasculature, and is due to the histopathology7staining used to obtain these images. The images of vasculature of FIGs. 5B and 5C are from a subject diagnosed with AMD and would be targets for interventional treatments, such as treatments using the microcatheter and related systems and methods of the present disclosure, to restore functional blood flow to the eye.

[0039] In the example of the OA, treatment using the microcatheter and the related systems and methods of the present disclosure may be indicated in cases where OA stenosis is about 50% or less. In an example embodiment of the devices and systems of the present disclosure, OA stenosis in the range of about 15% to about 50%, about 20% to about 40%, or about 30%Attomev Docket No. 00170-0031-00304 may be treated. It has not been previously contemplated that treatment of lesions with less than 50% stenosis, including stenosis as low as about 15%, would be meaningful.

[0040] Table 1 lists examples of OAs, including specific diameters, cross-sectional areas, percentage decrease in cross-sectional areas, and percentage stenosis based on the percentage decrease in cross-sectional areas. In particular, in example OA number 2 (row 2), a decrease of about 17% in luminal blood flow (specifically, a 16.67% stenosis of the OA) to the retina manifests as a cross-sectional area reduction of blood flow of about 30% (specifically. 30.56%). This correlates directly to a major reduction in oxygen and nutrients to the retina. The demand for improved blood flow is driven by the metabolic requirements of the retina, which begins to experience dysfunction at levels of stenosis at or below about 30% in the OA. This dysfunction materially contributes to the advancement of retinal disease in a variety of biological symptoms (dysfunction in the mitochondria of the retinal pigment epithelium (RPE), upregulation of Hypoxia-Inducible Factor 1-Alpha (HIF-la) and vascular endothelial growth factor (VEGf) and other issues).

[0041] In addition. Table 1 shows, in example OA number 4 (row 4), a 50% stenosis has cross-sectional blood flow area reduction equivalent of 75%. This example demonstrates how even a seemingly small level of stenosis, as measured conventionally, can have a significant impact in terms of reducing the blood supply to the photoreceptors. The column entitled “% stenosis’" represents a percentage difference in the diameter of a healthy vessel (row 1) as compared to a stenosed vessel (rows 2-7) in a single plane only (that is, in two dimensions, or 2D), based on a single diametric measurement from that plane, and does not reflect the effect of stenosis on the total cross-sectional, three-dimensional area of a vessel. The column entitled “% decrease mm2” represents a percentage difference in cross-sectional area between a healthy vessel (row 1) and stenosed vessels (rows 2-7). the cross-sectional area being a sum of a plurality of diametric measurements of the vessel in three dimensions, that is, in 3D. This comparison of 3D measurements is more representative of the reduction in blood flow, as it describes an entirety7of the reduction of cross-sectional area of the vessel caused by luminal stenosis.TABLE 1Attorney Docket No. 00170-0031-00304

[0042] In addition to not appreciating lower levels (that is, lower percentages) of stenosis having a significant effect on blood flow through small diameter blood vessels, such as arteries, there is also a lack of appreciation for the complexity of the OA anatomy and the degree of difficulty required to access the OA and treat diseases using conventional tools. One of the most challenging aspects of this treatment is accessing the desired treatment location within the OA. Current neuro microcatheter devices are not designed for use within the OA, and do not address this unique anatomy, which is smaller in caliber, has multiple angulations, and is significantly more tortuous as compared to ty pical neuro vessels or other endovascular targets, such as cardiovascular or peripheral vessels. Due to these characteristics, current microcatheters do not provide adequate shape, positioning capabilities or support to establish purchase in the OA with a guidewire. As an example, FIG. 6A is a digital image that shows a device 600 A, having a guidewire, prolapsing as it is advanced into the OA 605 A. Arrow A points to the tip of a typical (non-optimized) microcatheter 610A, arrow B points the distal tip of the guidewire, and arrow C points to the desired target for guidewire placement in order to provide the needed support for the advancement of an interventional device. FIG. 6B is a digital image that shows the desired placement of the guidewire of the device 600A within the OA 605B, with arrow D pointing to the distal tip of the guidewire, successfully navigated past the central retina artery (CRA) (not shown) using a microcatheter according to one or more embodiments of the present disclosure. Placement of the guidewire in the OA 605B, dow n to and past the CRA allows the device 600A to have proper purchase in the OA 605B, so a physician can easily manipulate other devices, such as angioplasty balloons and other devices, over the guidewire of the device 600A, to provide therapy or treatment.SYSTEMS AND DEVICES

[0043] The microcatheters and related systems and devices of the present disclosure are configured to navigate, access, and facilitate placement of intravascular devices, such as guidewires, within the OA behind an eye of a subject. Successful placement of theAttomev Docket No. 00170-0031-00304 microcatheter, as part of the system, is accomplished by use of a specialized tip segment shape (that is. a shape of a distal tip portion of the microcatheter), and optimization of flexibility, torqueability, pushability, and cross-sectional properties along an overall length of the microcatheter or at least portions thereof, and with the use of radiopaque markers with fluoroscopy and a guidewire. Collective optimization of these characteristics and use of the radiopaque markers and fluoroscopy contributes directly to the ability of the microcatheter to access, properly locate, and aid in the delivery of therapy to the OA where other microcatheters fail. The microcatheter must perform in a challenging anatomical environment as defined by several limiting characteristics. These include the following:

[0044] 1. Aortic arch (AA) - difficulty' of navigation of devices, such as microcatheters, through an AA of a subject increases with age due to changes in arch elongation, branch vessel origin configuration, calcification, and vessel origin. FIG. 7 is a digital image of the AA 700.

[0045] 2. Internal Carotid Artery' (ICA) - the ICA has several serpentine curves in a 3D space, and tortuosity of the ICA typically increases with age. FIG. 8 is a digital image of two ICAs 800 A and 800B of a subject.

[0046] 3. OA tortuosity - the OA takeoff angle of the SL from the ICA may range from 45° to 140°, and may contain total occlusions, concentric lesions, or non-concentric calcified lesions. The takeoff angle and level of calcification may contribute to difficulty and access of the OA. The adjoining angle "a’ may range from 90° to 135° in the opposite direction of the SL and may contribute to difficulty in device placement. All of this tortuosity' occurs in a 3D space. FIG. 9 is a digital image of an OA 900 branching from an ICA 905, and in particular, shows the relative directions in which the SL 910 of the OA 900 branches from the ICA 905, and the angleca’ between the SL 910 and the LL 915 of the OA 900.

[0047] 4. OA takeoff placement on ICA - further compounding OA tortuosity is the placement of the OA takeoff. The OA may originate on the C6 segment of the ICA, proximal to the C6 segment, distal to the C6 segment, or anywhere in between. In addition, there may also be variation on the circumferential location on the C6 segment. FIG. 10A is a digital image showing one example of a placement of the OA takeoff 1000 A on the ICA 1005 A, and FIG. 10B is a digital image showing another example of a placement of the OA takeoff lOOOB on the ICA 1005B.

[0048] 5. OA diameter and length - diameters of the OA may range from about 1.2 mm to about 2 mm (in a healthy person). The OA typically reduces in caliber (or diameter) as it nears the eye (retina), with diameters of about 1 mm along the segments from the origin ofAttomev Docket No. 00170-0031-00304 the OA to the branch of the CRA. In the embodiments of microcatheters, and related systems and methods for treatment of the ophthalmic artery, a total length of the OA, from the origin thereof to the branch of the CRA, may be in the range of about 1 mm to about 15 mm.

[0049] FIG. 11 is a digital image showing an example of an SL 1100 and a LL 1105 of an OA 1110, and the corresponding lengths LSL and LLL, respectively, in a patient to be treated for AMD. In this example, the length LSL is about 2.47 mm and the length LLL is about 10.6 mm. In some cases, as part of a method of treatment using the microcatheter described herein, it may be desirable to place the microcatheter in the SL 1100, while in other cases, it may be desirable to place the microcatheter in the LL 1105. As noted above, positioning of the microcatheter in the SL 1100 and the LL 1105 may be guided by the use of radiopaque markers and fluoroscopy. Microcatheter placement in either of the SL 1100 or the LL 1105 is intended to allow for optimal positioning of the guidewire. Optimal positioning is determined by cannulating the OA ostium with the microcatheter so that the guidewire can be advanced into and down the OA 1110. The radiopaque markers of the microcatheter may include, for example, a radiopaque platinum- tungsten (Pt-W) coil, which may be integrated into the guidewire using, for example, solder. In addition, a radiopaque marker or a radiopaque braid may be used for visualization for optimal positioning. Such a radiopaque marker or radiopaque braid may be placed at one or more locations on the guidewire, and more specifically, for example, may encompass a distal tip and some distance or length of the guidewire toward a proximal section. That is, the radiopaque marker or radiopaque braid may define a distal segment of the guidewire. As another specific example, radiopaque markers or radiopaque braids may be placed at discrete locations along the length of the guidew ire to allow for measuring capability (that is, the capability' of measuring parts of vasculature through which the guidewire extends) under fluoroscopy. Further, placement may be assessed based on positional response of the microcatheter to the guidew ire. If the microcatheter moves w ith movement of the guidewire, the microcatheter may be repositioned.

[0050] The microcatheters of the present disclosure may be configured for use as part of a system for treatment of obstructions (e.g., stenosis, lesions, plaques) within neurovascular anatomy for the purpose of increasing perfusion to the retina in the treatment of eye diseases. In one or more embodiments, the microcatheter is used as part of a system to provide access to the OA for the treatment of AMD. It should be noted that fabrication and use of an AMC for treatment of the OA to address eye disease has not been previously contemplated. Existing devices do not address the unique anatomy for this application.Attomev Docket No. 00170-0031-00304

[0051] The microcatheters of present disclosure may also be configured for use as a part of a system for accessing the OA and enabling subsequent therapy or treatment. The following features may facilitate use of the microcatheters for this purpose.

[0052] 1. Application-specific tip shape - a shape of a distal tip portion of the microcatheter (approximately 3 cm of the distal-most end of the microcatheter) has been optimized to work within the target anatomy so as to provide the ability to access the OA and provide support using therapeutic devices. Access is accomplished by incorporating specific shapes to reach desired locations within the OA. This distal tip portion may be planar or two-dimensional (2D) in shape or non-planar or three-dimensional (3D) in shape, such as two concentric circles, and may be designed to contact specific portions of the anatomy (for example, ICA segment C6) to facilitate navigation and placement. FIGs. 13A to 16C and 18A to 18C depict exemplary shapes and dimensions of the distal tip of the microcatheter according to several embodiments. For example, the shape of the distal tip portion may be designed to deflect off of the apex of the ICA segment C6 to preferentially place the distal-most tip of the microcatheter into the OA ostium.

[0053] FIGs. 13 A, 13B, 13C and 18B are schematics showing a primary shape (or a first shape) of the distal tip portion of the microcatheter, according to one embodiment, w hich is optimized for placement into the SL and up to angle ‘a’ of the OA. FIGs. 14A, 14B, 14C, and 18C are schematics showing a secondary shape (or a second shape) of the distal tip portion of the microcatheter, according to another embodiment, which is optimized for placement into the LL and up to angle ‘b’, which may be in a range of about 90° to 210°, of the OA. FIGs. 15 A, 15B, and 15C are schematics showing a third shape of the distal tip portion of the microcatheter, according to still another embodiment, and FIGs. 16 A, 16B, and 16C are schematics showing a fourth shape of the distal tip portion of the microcatheter, according to other embodiments. These embodiments are described in more detail, below.

[0054] 2. Flexibility - fl exi bi 1 i ty varies along the length of the microcatheter to allow the distal tip portion to be straightened via insertion and manipulation of a guidewire, so that the microcatheter may be delivered to the OA ostium via conventional means (e.g., with a guide sheath or a guide catheter, with or without an intermediate catheter, and using a guidewire that is 0.014 inch (about 0.365 mm) in diameter or less). With reference to FIG. 13C, as an example, the varied flexibility allow s for the portion in Zone 1 of the distal tip portion of the microcatheter to be atraumatic, while allowing the portions in Zones 1 and 2 of the distal tip portion of the microcatheter to deform in a straight fashion (that is, to deform into a straight shape) for delivery of the microcatheter to a desired location, and w hile allowing the distal tipAttomev Docket No. 00170-0031-00304 portion to regain the initial tip shape when the guidewire is removed, to provide access to the OA. This flexibility is accomplished via a combination of use of one or more types and one or more layers of polymers with particular characteristics (for example, polymers having a durometer value in a predetermined range, or polymers having a thickness in a predetermined range, among others), as well as with layers and patterns of braid, bonding techniques, and application of lubricious coatings, in forming the microcatheter.

[0055] 3. Torqueability - the microcatheter is designed to be torqueable, so that the user may steer the microcatheter to the desired destination. Torqueability is also determined by the combination of characteristics mentioned in number 1 above.

[0056] 4. Pushability - the microcatheter is designed to be pushable, so that the user may advance the microcatheter to the desired destination. Pushability is also determined by the combination of characteristics mentioned in number 1 above.

[0057] 5. Cross section - the microcatheter is designed with a cross section that facilitates entry into an OA that may have a luminal reduction, such as stenosis. This cross section mayor may not be concentric. The cross-sectional inner diameter (ID) of the microcatheter allows for injection of contrast, pharmaceuticals, or other matenals that may be compatible with the ID

[0058] 6. Radiopacity - the microcatheter has a radiopacity profile that facilitates recognition under fluoroscopy to aid in manipulation during use.

[0059] Embodiments of the microcatheter and related systems and methods for treatment of obstructions within vasculature behind an eye of a subject will be described with reference to FIGs. 12A to 18C. FIGs. 12A and 12B are schematics of a system 1200 including a microcatheter 1205 and a guidewire 1210, according to one embodiment of the present disclosure. As shown in FIG. 12 A, the microcatheter 1205 has a proximal portion 1215 and a distal tip portion 1220, extending from the proximal portion 1215. The microcatheter 1205 has an overall length LMC (depicted in FIG. 12B, when the microcatheter is in a straightened state), which may be in a range of about 135 cm to about 175 cm. In addition, the microcatheter 1205 may have an inner diameter ID in a range of about 0.203 mm to about 0.559 mm and an outer diameter OD in a range of about 0.432 mm to about 1.346 mm. Additional ranges of these values are listed in the tables below. Although the microcatheter 1205 is shown as having a constant ID and OD along its length LMC, one or both of the ID and the OD may vary- along one or more portions of the microcatheter 1205.

[0060] As noted above, the distal tip portion 1220 may be approximately 3 cm of the distal- most end of the microcatheter 1205. The distal tip portion 1220 may have a preformed shape,Attomev Docket No. 00170-0031-00304 shown in FIG. 12A, including at least a first curved portion 1225 and a second curved portion 1230. In one or more embodiments, a radius of curvature ri225 of the first curved portion 1225 may be greater than a radius of curvature ri23o of the second curved portion 1230. In other embodiments, the preformed shape may be one of the shapes shown and described with respect to FIGs. 13A to 18C.

[0061] With reference to FIG. 12B, the guidewire 1210 may be configured to be advanced through an inner lumen 1235 of the microcatheter 1205 for positioning of a distal end 1240 of the guidewire 1210 within the vasculature behind the eye of the subject, and to be withdrawn, at least partially, or removed from the microcatheter 1205 during or after placement of the microcatheter 1205 at a desired location within the vasculature behind the eye.

[0062] FIGs. 13 A. 13B, and 13C show an embodiment of a microcatheter 1300, positioned within an ICA 1305 and an ostium 1310 of an OA 1315. A distal tip portion 1320 of the microcatheter 1300 has a primary shape or a first shape. As noted above, the first shape of the distal tip portion 1320 is optimized for placement into the SL 1325 and up to angle ‘a’ 1330 of the OA 1315. The first shape is defined by a first curved portion 1335 and a second curved portion 1340, as well as a bend 1345 located between a proximal portion 1350 and the distal tip portion 1320 of the microcatheter 1300. The distal tip portion 1320 also has a distal tip 1355 of the microcatheter 1300 at a distal-most end. An angle a of the bend 1345, shown in FIG. 13B, may be in a range of about 70° to about 120°. The first curved portion 1335 and the bend 1345 may correspond to Zone 1 of the microcatheter 1300, shown in FIG. 13C. and the second curved portion 1340, which may be atraumatic, may correspond to Zone 2 of the microcatheter 1300, shown in FIG. 13C. Both Zones 1 and 2 are configured to deform into a straight shape when a guidew ire is inserted through an inner lumen of the microcatheter 1300, and to return to the first shape when the guidewire is removed from the inner lumen of the microcatheter 1300. That is, the distal tip portion 1320 of the microcatheter 1300 is configured to deform from the first shape to a straight shape when a guidewire is inserted through the distal tip portion 1320 of the microcatheter 1300, and the distal tip portion 1320 is configured to return (or is biased to return) from the straight shape to the first shape when the guidewire is removed from the distal tip portion 1320.

[0063] Table 2 includes dimensional characteristics for the first shape, including a maximum width E of the distal tip portion 1320, a radius of curvature F of the first curved portion 1335, a radius of curvature G of the second curved portion 1340, the angle H (marked in FIG. 13B as a) of the bend 1345. an inner diameter ID of the microcatheter 1300. an outer diameter OD of the microcatheter 1300, and an overall length of the microcatheter 1300. The ranges of theAttomev Docket No. 00170-0031-00304 listed dimensions were determined by using anatomical models, such that distal tip portion 1320 of the 1300 interacts with the walls of the ICA 1305 to place the distal tip 1355 of the microcatheter 1300 into the OA ostium 1310. In addition, the ranges may be approximate (that is, the values listed may be understood as approximate, such that each value could be “about” the stated value). Once the distal tip portion 1320 of the microcatheter 1300 is in place in one of the ICA 1305, the ostium 1310, or the OA 1315, the guidewire may be advanced distally into the OA 1315 to gain purchase, so that other instruments (for example, a balloon catheter) can be advanced over the guidewire. That is, the first shape of the distal tip portion 1320 of the microcatheter 1300 may facilitate positioning of the distal tip portion 1320 of the microcatheter 1300 in the OA anatomy, including OA anatomy having a variety of ICA shapes and OA takeoff positions.TABLE 2

[0064] FIGs. 14A. 14B, and 14C show an embodiment of a microcatheter 1400, positioned within an ICA 1405 and an ostium 1410 of an OA 1415. A distal tip portion 1420 of the microcatheter 1400 has a secondary shape or a second shape. As noted above, the secondAttomev Docket No. 00170-0031-00304 shape of the distal tip portion 1420 is optimized for placement into a LL 1425 and up to angle ‘b’ 1430. which may be in a range of about 90° to 210°. of the OA 1415. The second shape is defined by a first curved portion 1435 and a second curved portion 1440. The distal tip portion 1420 also has a distal tip 1445. The first curved portion 1435 may correspond to Zone 1 of the microcatheter 1400, shown in FIG. 14C, and the second curved portion 1440 may correspond to Zone 2 of the microcatheter 1400, shown in FIG. 14C. Both Zones 1 and 2 are configured to deform into a straight shape when a guidewire is inserted through an inner lumen of the microcatheter 1400, and to return to the second shape when the guidewire is removed from the inner lumen of the microcatheter 1400. That is, the distal tip portion 1420 of the microcatheter 1400 is configured to deform from the second shape to a straight shape when a guidewire is inserted through the distal tip portion 1420 of the microcatheter 1400. and the distal tip portion 1420 is configured to return from the straight shape to the second shape when the guidewire is removed from the distal tip portion 1420.

[0065] Table 3 includes dimensional characteristics for the second shape, including a maximum width I of the distal tip portion 1420, a radius of curv ature J of the first curved portion 1435, a radius of curvature K of the second curv ed portion 1440, an inner diameter ID of the microcatheter 1400, an outer diameter of the microcatheter 1400, and an overall length of the microcatheter 1400. The ranges of the listed dimensions for this embodiment were also determined by using anatomical models, such that the distal tip portion 1420 interacts with the walls of the ICA 1405 to place the distal tip 1445 into the OA ostium 1410. In addition, the ranges may be approximate (that is, the values listed may be understood as approximate, such that each value could be “about” the stated value). Once the distal tip portion 1420 is in place in one of the ICA 1405, the ostium 1410, or the OA 1415, the guidewire may be advanced distally into the OA 1415 to gain purchase, so that other instruments (for example, a balloon catheter) can be advanced over the guidewire. That is, the second shape of the distal tip portion 1420 of the microcatheter 1400 may facilitate positioning of the distal tip portion 1420 in the OA anatomy, including OA anatomy having a variety of ICA shapes and OA takeoff positions.TABLE 3Attomev Docket No. 00170-0031-00304

[0066] FIGs. 15 A. 15B, and 15C show an embodiment of a microcatheter 1500, positioned within an ICA 1505 and an ostium 1510 of an OA 1515. A distal tip portion 1520 of the microcatheter 1500 has a third shape, which may be referred to as a loop shape. The third shape is defined by a first curved portion 1525 and a second curved portion 1530. The distal tip portion 1520 also has a distal tip 1535. The first curv ed portion 1525 may correspond to Zone 1 of the microcatheter 1500. shown in FIG. 15C, and the second curved portion 1530 may correspond to Zone 2 of the microcatheter 1500, shown in FIG. 15C. In addition, the third shape is a loop, formed in part by the first curved portion 1525 and the second curved portion 1530, as shown in FIGs. 15A, 15B, and 15C. Both Zones 1 and 2 are configured to deform into a straight shape when a guidewire is inserted through an inner lumen of the microcatheter 1500, and to return to the third shape when the guidewire is removed from the inner lumen of the microcatheter 1500. That is, the distal tip portion 1520 of the microcatheter 1500 is configured to deform from the third shape to a straight shape when a guidewire is inserted through the distal tip portion 1520 of the microcatheter 1500. and the distal tip portion 1520 is configured to return from the straight shape to the third shape when the guidewire is removed from the distal tip portion 1520.

[0067] Table 4 includes dimensional characteristics for the third shape, including a maximum width L of the distal tip portion 1520, a radius of curvature M of the first curved portion 1525, a radius of curvature N of the second curved portion 1530, an inner diameter ID of the microcatheter 1500, an outer diameter of the microcatheter 1500, and an overall length of theAttorney Docket No. 00170-0031-00304 microcatheter 1500. The ranges of the listed dimensions for this embodiment were also determined by using anatomical models, such that the distal tip portion 1520 interacts with the walls of the ICA 1505 to place the distal tip portion 1520 into the OA ostium 1510. In addition, the ranges may be approximate (that is, the values listed may be understood as approximate, such that each value could be “about” the stated value). Once the distal tip portion 1520 is in place in the ICA 1505, the ostium 1510, or the OA 1515. a guidewire may be advanced distally through the microcatheter 1500 and into the OA 1515 to gain purchase, so that other instruments (for example, a balloon catheter) can be advanced over the guidewire. That is, the third shape of the distal tip portion 1520 of the microcatheter 1500 may facilitate positioning of the distal tip portion 1520 in the OA anatomy, including OA anatomy having a variety of ICA shapes and OA takeoff positions.TABLE 4

[0068] FIGs. 16A, 16B, and 16C show an embodiment of a microcatheter 1600, positioned within an ICA 1605 and an ostium 1610 of an OA 1615. A distal tip portion 1620 of the microcatheter 1600 of this embodiment has a fourth shape, defined by a first curved portion 1625, a second curved portion 1630, a third curved portion 1635, and a fourth curved portionAttorney Docket No. 00170-0031-003041640. The first curved portion 1625, the second curved portion 1630, and the third curved portion 1635 may correspond to Zone 1 of the microcatheter 1600, shown in FIG. 16C, and the fourth curved portion 1640 may correspond to Zone 2 of the microcatheter 1600, shown in FIG. 16C. Both Zones 1 and 2 are configured to deform into a straight shape when a guidewire is inserted through an inner lumen of the microcatheter 1600, and to return to the fourth shape when the guidewire is removed from the inner lumen of the microcatheter 1600. That is. the distal tip portion 1620 of the microcatheter 1600 is configured to deform from the fourth shape to a straight shape when a guidewire is inserted through the distal tip portion 1620 of the microcatheter 1600, and the distal tip portion 1620 is configured to return from the straight shape to the fourth shape when the guidewire is removed from the distal tip portion 1620.

[0069] Table 5 includes dimensional characteristics for the fourth shape, including a maximum width of the distal tip portion 1620, a radius of curvature of the first curved portion 1625, a radius of curvature of the second curved portion 1630, a radius of curvature of the third curved portion 1635, a radius of curvature of the fourth curved portion 1640, an inner diameter ID of the microcatheter 1600, an outer diameter OD of the microcatheter 1600, and an overall length of the microcatheter 1600. The ranges of the listed dimensions for this embodiment were also determined by using anatomical models, such that the distal tip portion 1620 of the microcatheter 1600 interacts with the walls of the ICA 1605 to place the distal tip portion 1620 of the microcatheter 1600 into the OA ostium 1610. In addition, the ranges may be approximate (that is, the values listed may be understood as approximate, such that each value could be “about’’ the stated value). Once the distal tip portion 1620 of the microcatheter 1600 is in place in the ICA 1605, the ostium 1610, or the OA 1615, a guidewire may be advanced distally through the microcatheter 1600 into the OA 1615 to gain purchase, so that other instruments (for example, a balloon catheter) can be advanced over the guidewire. That is, the fourth shape of the distal tip portion 1620 may facilitate positioning of the distal tip portion 1620 in the OA anatomy, including OA anatomy having a variety of ICA shapes and OA takeoff positions.TABLE 5Attomev Docket No. 00170-0031-00304METHODS OF USE

[0070] FIG. 17 is a flowchart of a method 1700 for accessing an OA of a subject for treatment of an obstruction or obstructions within vasculature behind an eye of the subject. The method 1700 may include a step 1705 of placing a microcatheter within the vasculature behind the eye, until a distal tip of the microcatheter is within an ostium of the OA of the subject. The microcatheter may have a proximal portion, a distal tip portion extending from the proximal portion, and an inner lumen. The distal tip portion may have a preformed shape, including one of the first shape, the second shape, the third shape, or the fourth shape, described above and shown in FIGs. 13A to 16C. The shape includes at least a first curved portion and a second curved portion. The method 1700 may also include a step 1710 of placing a guidewire within the vasculature behind the eye, until a distal tip of the guidewire is positioned within the 1CA of the subject.

[0071] The step 1705 of placing a microcatheter, such as one of the microcatheters described above, within the vasculature behind the eye of the subject, until a distal end of the microcatheter is positioned within the ostium of the OA, may include using the following steps (other permutations may be possible):

[0072] 1. An intermediate catheter (size 6F or smaller, for example) may be delivered over a guidewire (0.035 inch (about 0.889 mm) in diameter, for example) may be navigated through a catheter sheath introducer that has been placed within the vasculature of the subject. TheAttomev Docket No. 00170-0031-00304 guidewire may be navigated such that a distal end of the guidewire does not pass the base of the skull or the petrous segment (C2) of the ICA, unless specialized wires are used, due to the risk of perforation of the ICA. Then, after delivery of the intermediate catheter, the guidewire may be removed, and a smaller guidewire (0.014 inch (about 0.356 mm) in diameter or smaller, for example) and the microcatheter (such as one of the microcatheters described above) may be delivered for navigation through the intermediate catheter, until a distal end of one or both of the smaller guidewire and the microcatheter is positioned beyond the petrous segment of the ICA, for OA cannulation.

[0073] 2. In some embodiments, the microcatheter and the smaller guidewire may be preloaded into the intermediate catheter, as a system (that is, the system may include at least the microcatheter, the smaller guidewire, and the intermediate catheter, according to some embodiments). The system may be delivered to the ICA through the catheter sheath introducer, for OA cannulation.

[0074] Further, step 1705 of placing the microcatheter within the vasculature behind the eye of the subject may include advancing the microcatheter so that a distal tip portion of the microcatheter is within the ICA and near the ostium of the OA, and is in a straight shape, and retracting the guidewire within the microcatheter so that the guidewire is not within the distal tip portion, and the distal tip portion changes from the straight shape to a preformed shape (e.g., the first shape, the second shape, the third shape, or the fourth shape described above), so that a distal tip of the microcatheter is positioned within one of the ostium or the OA.

[0075] The step 1705 of placing the microcatheter within the vasculature behind the eye may include determining whether the microcatheter is correctly positioned based on a positional response of the microcatheter and the guidewire upon movement of the guidewire. If the microcatheter does not move with movement of the guidewire, it is determined that the microcatheter is correctly positioned within the OA. And, if the microcatheter does move with movement of the guidewire, it is determined that the microcatheter is not correctly positioned within the OA. If it is determined that the microcatheter is not correctly positioned within the OA, the method 1700 may further comprise repositioning the microcatheter.

[0076] To ensure the guidewire has the material properties (flexibility, torqueability, pushability, or cross-sectional properties, for example) for the guidewire to navigate from a femoral access point of a subject to the OA, a diameter of the guidewire may be within the range of about 0.013 inch (about 0.330 mm) to about 0.014 inch (about 0.356 mm). A relatively smaller diameter guidewire (that is, a guidewire having a diameter that is less than about 0.013 inch (0.330 mm)) may not have the material properties needed to manipulate theAttomev Docket No. 00170-0031-00304 guidewire for successful navigation from the femoral access point to the OA. The method 1700 may further include a step of placing another guidewire within the microcatheter, and advancing the other guidewire until a distal end of the other guidewire is within one of the SL and the LL of the OA.

[0077] By these steps, the OA may be cannulated by a microcatheter and a guidewire. Then, the microcatheter may be advanced to a desired position within the OA (that is, a distal end of microcatheter may be advanced to a location within the OA), to allow for positioning of a guidewire within the OA (that is, positioning of a distal end of the guidewire at another location within the OA). Once the guidewire is in the desired location within the OA, the microcatheter may be removed, and one or more additional therapeutic devices may be loaded over the guidewire and advanced into the OA (that is, the device(s) may be advanced into the OA over the guidewire).

[0078] Although the method 1700 is described as including steps 1705 and 1710 above, the method 1700 may include additional steps. For example, in one embodiment, the method 1700 may also include a step of placing a catheter sheath introducer (or a guide sheath or guide catheter) radially or femorally within the vasculature behind the eye of the subject, so that a distal end of the catheter sheath introducer is placed at a desired position, within one of the CCA or the ICA. The desired position for the distal end of the catheter sheath introducer may be a location as far distally into the CCA or the ICA into which the catheter sheath introducer can be placed.

[0079] The step of placing the catheter sheath introducer may include one of the following methods:

[0080] 1. Exchange Method: a diagnostic catheter may be first used to direct a guidewire (0.035 inch (about 0.889 mm) or about 0.038 inch (about 0.965 mm) in diameter) into the left or right CCA or the ICA. The diagnostic catheter may then be removed, while leaving the guidewire in place. The catheter sheath introducer with a dilator or a tracking catheter may then be delivered over the guidewire to the CCA or ICA, and placed at the first position, as noted above. The guidewire and dilator or tracking catheter can then be removed, leaving the catheter sheath introducer in place.

[0081] 2. Telescoping Method: a diagnostic catheter may be preloaded into the catheter sheath introducer, and the diagnostic catheter and catheter sheath introducer may be advanced to the aortic arch over a guidewire (about 0.035 inch (about 0.889 mm) or about 0.038 inch (about 0.965 mm) in diameter). The diagnostic catheter may be used to direct the guidewire to the left or right CCA or the ICA. The diagnostic catheter and the catheter sheath introducerAttomev Docket No. 00170-0031-00304 may then be tracked over the guidewire to the CCA or ICA. and then the guidewire and the diagnostic catheter may be removed.

[0082] As another example, the method 1700 may further include a step of advancing a guidewire through the microcatheter until a distal tip of the guidewire is positioned within the OA, a step of removing the microcatheter while keeping the guidewire in position, and placing a treatment device over the guidewire, until a distal end or a distal tip of the treatment device is positioned within the OA, at a desired location (e.g., at a location of an obstruction). The method 1700 may also include a step of performing a treatment using the treatment device.

[0083] FIG. 18A shows a microcatheter 1800A and a guidewire 1805 A, positioned within an ICA 1810A. The guidewire 1805 A extends through a distal tip portion 1820 A of the microcatheter 1800 A, so that the distal tip portion 1820A is in a straight configuration. FIG. 18B shows the distal tip portion 1820B of the microcatheter 1800B, having the first shape, as described above with reference to FIGs. 13 A, 13B, and 13C. From the position of the microcatheter 1800A and guidewire 1805 A shown in FIG. 18 A, in which the distal tip portion 1820A of the microcatheter 1800A is in a straight shape (or an approximate straight shape), the guidewire 1805B may be retracted into the microcatheter 1800B by a predetermined amount or distance, so that the microcatheter 1800B returns to its preformed shape, here, the first shape, including a first curved portion 1825B, a second curved portion 1830B. and a bend 1835B. Then, a distal tip 1840B of the distal tip portion 1820B may be positioned or placed within the O A 1815B, as shown in FIG. 18B. Next, the guidewire 1805B that had been retracted within the microcatheter 1800B may be advanced distally through the microcatheter 1800B, until a distal end of the guidewire 1805B is at a desired location. In the example shown in FIG. 18B, a distal tip 1845B of the guidewire 1805B is positioned beyond the distal tip 1840B of the microcatheter 1800B.

[0084] FIG. 18C show-s another embodiment the microcatheter 1800C shown in FIG. 18A returns to its preformed shape, which is the second shape, described above with reference to FIGs. 14A. 14B, and 14C. From the position of the microcatheter 1800A and guidewire 1805 A shown in FIG. 18 A, in which the distal tip portion 1820A of the microcatheter 1800A is in a straight shape (or an approximate straight shape), the guidewire 1805C may be retracted into the microcatheter 1800C by a predetermined amount of distance, so that the microcatheter 1800C returns to its preformed shape, including a first curved portion 1825C and a second curved portion 1830C. Then, a distal tip 1840C of the distal tip portion 1820C of the microcatheter 1800C may be positioned or placed within the OA 1815C, as shown inAttomev Docket No. 00170-0031-00304FIG. 18C. Next, the guidewire 1805C that had been retracted within the 1800C may be advanced distally through the 1800C, until a distal tip 1845C of the guidewire 1805C is at a desired location. In the example shown in FIG. 18C, the distal tip 1845C of the guidewire 1805C is positioned beyond the distal tip 1840C of the microcatheter 1800C.RESULTS

[0085] In clinical trials of the treatment including use of the microcatheters and the method described herein, a mean stenosis of subjects was about 40%, with a range of stenosis from about 17% to about 67%. These patients w ere symptomatic for AMD and all experienced improvements in visual metrics post treatment. Treating stenosis in a range of, for example, less than 50% or. more specifically, about 30%. is counterintuitive considering the range of stenosis treated for atypical stroke patient (e g., 70% stenosis or greater). However, for patients having relatively less percentage stenosis (e.g., less than 50%, or about 30%), treatment in accordance with the method described herein, and using the system as described herein, reduced flow restriction and improved flow. Details and results of the abovereferenced clinical trials are published in Lylyk et al., Ophthalmic artery angioplasty in a cohort of patients with geographic atrophy secondary to non-exudative age-related macular degeneration,” J. NeuroIntervent Surg., August 19, 2025. The system and method described herein are, therefore, useful for treatment of retinal diseases, such as AMD.

[0086] Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

Claims

Attorney Docket No. 00170-0031-00304CLAIMSWe claim:

1. A system for treatment of one or more obstructions within vasculature behind an eye of a subject, the system comprising: a microcatheter having a proximal portion, a distal tip portion, extending from the proximal portion, and the distal tip portion having a preformed shape, including at least a first curved portion and a second curved portion, and the microcatheter further having an inner lumen; and a guidewire configured to be advanced through the inner lumen of the microcatheter for positioning of a distal end of the guidewire within the vasculature behind the eye of the subject, wherein, when the guidewire extends through the distal tip portion of the microcatheter, the distal tip portion has a generally straight shape, and, when the guidewire does not extend through the distal tip portion of the microcatheter, the distal tip portion is in the preformed shape.

2. The system of claim 1. wherein the microcatheter further has a bend between the proximal portion and the distal tip portion, and an angle of the bend is in a range of about 70° to about 120°.

3. The system of claim 1, wherein a radius of curvature of the first curved portion is in a range of about 1.5 mm to about 3.8 mm. and a radius of curvature of the second curved portion is in a range of about 0.25 mm to about 2.5 mm.

4. The system of claim 1, wherein an inner diameter of the inner lumen of the microcatheter is in a range of about 0.203 mm to about 0.559 mm, and an outer diameter of the microcatheter is in a range of about 0.432 mm to about 1.346 mm.

5. The sy stem of claim 1, wherein an overall length of the microcatheter is in a range of about 135 cm to about 175 cm.

6. The system of claim 1, wherein a radius of curvature of the first curved portion is in a range of about 1.5 mm to about 3.8 mm, and a radius of curvature of the second curved portion is in a range of about 0.5 mm to about 1.5 mm.

7. The system of claim 1, wherein a radius of curvature of the first curved portion is in a range of about 0.25 mm to about 1.5 mm, and a radius curvature of the second curved portion is in a range of about 1.5 mm to about 3.8 mm.Attorney Docket No. 00170-0031-003048. The system of claim 1, wherein the distal tip portion forms a loop shape.

9. The system of claim 1, wherein the distal tip portion further includes a third curved portion and a fourth curved portion.

10. The system of claim 9, wherein a radius of curvature of the first curved portion is in a range of about 0.25 mm to about 1.5 mm, a radius of curvature of the second curved portion is in a range of about 2.0 mm to about 4.0 mm, a radius of curvature of the third curved portion is in a range of about 1.5 mm to about 3.8 mm, and a radius of curvature of the fourth curved portion is in a range of about 2.0 mm to about 4.0 mm.

11. The system of claim 1. wherein a length of the distal tip portion is about 3 cm.

12. The system of claim 1, wherein the distal tip portion is planar in shape.

13. The system of claim 1, wherein the distal tip portion has a three-dimensional non- planar shape.

14. The system of claim 1, wherein a cross-sectional shape of the distal tip portion includes at least two concentric circles.

15. A method for accessing an ophthalmic artery (OA) of a subject for treatment of obstructions within vasculature behind an eye of the subject, the method comprising: placing a microcathctcr within the vasculature behind the eye, rmtil a distal tip of the microcatheter is within an ostium of an ophthalmic artery (OA) of the subject, the microcatheter having a proximal portion, a distal tip portion, extending from the proximal portion, and the distal tip portion having a preformed shape, including at least a first curved portion and a second curved portion, and the microcatheter further having an inner lumen; and placing a guidewire within the vasculature behind the eye, until a distal end of the guidewire is positioned within an internal carotid artery (ICA) of the subject.

16. The method of claim 15, further comprising: placing a catheter, before placing the microcatheter, within the vasculature behind the eye. wherein placing the guidewire within the vasculature behind the eye is performed before placing the microcatheter within the vasculature behind the eye, and includes advancing the guidewireAtorney Docket No. 00170-0031-00304 through the catheter, until a distal tip of the guidewire reaches a desired location within an internal carotid artery of the subject, and wherein placing the microcatheter within the vasculature behind the eye includes advancing the microcatheter over the guidewire, so that tire distal tip portion of the microcatheter is in a generally straight shape, until the distal tip of the microcatheter is near the ostium of the OA, and retracting the guidewire into the microcatheter, so that the guidewire does not extend through at least the distal tip portion of the microcatheter, the distal tip portion returns to the preformed shape, and a distal tip of the microcatheter is positioned within the ostium of the OA.

17. The method of claim 16, further comprising: advancing the guidewire through the microcatheter until a distal tip of the guidewire is positioned within the OA; removing the microcatheter, while keeping the guidewire in position; placing a treatment device over the guidewire, until a distal end of the treatment device is positioned within the OA; and performing a treatment, using the treatment device.

18. The method of claim 16, wherein placing the microcatheter further includes determining whether the microcatheter is correctly positioned based on positional response of the microcatheter, wherein, if the microcatheter does not move with movement of the guidewire, the microcatheter is correctly positioned within the OA, and. if the microcatheter does move with movement of the guidewire, the microcatheter is not correctly positioned within the OA.

19. The method of claim 18, further comprising repositioning the microcatheter if it is determined that the microcatheter is not correctly positioned within the OA.

20. The method of claim 15, wherein a radius of curvature of the first curved portion is in a range of about 1.5 mm to about 3.8 mm, and a radius of curvature of the second curved portion is in a range of about 0.25 mm to about 2.5 mm, and wherein the microcatheter further has a bend between the proximal portion and the distal tip portion, and an angle of the bend is in a range of about 70° to about 120°.

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