Optic nerve sheath fenestrator

Abstract

A disposable ophthalmic device and a surgical training device for optic nerve sheath fenestration includes a handle, a depth guard, and at least two microblades. The handle has a distal end and a proximal end opposite the distal end. The depth guard extends from the proximal end of the handle for a length. The at least two microblades extend from the depth guard and are spaced apart for a distance relative to each other. The at least two microblades are configured to make simultaneous incisions for incising the optic nerve sheath while the depth guard mitigates or prevents contact of the blades with the underlying optic nerve.

Description

[0001] PCT / US25 / 55902 14 January 2026 (14.01.2026)

[0002] 2102463-000547

[0003] -1-

[0004] OPTIC NERVE SHEATH FENESTRATOR CROSS-REFERENCE TO RELATED APPLICATIONS

[0005] This application is related to and claims the benefit of priority of U.S. Provisional Application No. 63 / 721,730, entitled OPTIC NERVE SHEATH FENESTRATOR, filed on 18 5 November 2024, the contents of which are incorporated herein by reference in their entirety for all purposes.

[0006] FIELD OF THE INVENTION

[0007] [OO1] The subject matter disclosed herein relates to optic nerve sheath fenestration (ONSF).

[0008] 10 BACKGROUND OF THE INVENTION

[0009]

[0002] Optic nerve sheath fenestration (ONSF) is a surgery performed for vision-related medical conditions, including but not limited to vision-threatening papilledema in patients usually secondary to idiopathic intracranial hypertension (IIH). There are between 7,000-8,000 new cases of IIH every year in the US and the incidence of this condition is increasing with the obesity epidemic. IIH patients may have visual involvement leading to permanent blindness if not treated. Typically, the initial management of IIH consists of medication (oral carbonic anhydrase inhibitors) and risk factor modification (weight loss, cessation of high-risk medications), but not all cases respond favorably to medical management alone and can take a significant amount of time to see results from risk factor modifications. If uncorrected, papilledema from IIH can cause fulminant vision loss due to pressure exerted by cerebrospinal fluid on the delicate optic nerves. In cases that do not respond to first-line medical management or have already resulted in fulminant vision loss at the time of diagnosis, surgical management options include ONSF, ventricular shunt placement, and endovascular 25 stenting are available. ONSF is the least invasive of these options, and in cases with predominantly visual involvement, ONSF can provide visual acuity stabilization or improvement in 94% of patients.

[0010]

[0003] ONSF is a surgical procedure involving creation of a small window in the optic nerve sheath to relieve pressure on the optic nerve and reduce swelling, thereby allowing excess fluid to drain and be absorbed into the surrounding tissues. Surgical techniques for fenestration are heterogenous, both in location of initial approach and technique of sheath fenestration: medial transconjunctival, lateral orbital, and eyelid crease incision can be used, and fenestration ranges from a single linear incision to parallel dual incisions. However, ONSF surgery is challenging, at least because of the 35 difficulty of manipulating the optic nerve sheath after the initial incision and the risk of PCT / US25 / 55902 14 January 2026 (14.01.2026)

[0011] 2102463-000547

[0012] -2-

[0013] damage to the underlying optic nerve, which could result in permanent vision loss. Though the need for fenestration is increasing, very few surgeons perform the surgery.

[0014]

[0004] In a typical ONSF, a surgeon cuts into the optic nerve sheath typically two or more times (e.g., a dual incision) using a conventional blade such as microsurgical 5 scalpels, ophthalmic microsurgical scissors, or a retinal micro vitreoretinal (MVR) blade.

[0015] These currently available tools have significant limitations as they are not designed with the particular surgical considerations for ONSF in mind and as such pose undue clinical risk. Further, use of these conventional blades makes manipulating the optical nerve sheath tissue more difficult and time-consuming. Additionally, the longer the 10 duration of stretching and manipulating the optic nerve, the higher the risk of an ischemic event like central retinal artery occlusion which can result in permanent vision loss. Given difficult visualization deep in the orbit, the need for expediency, and low tactile feedback from incisional depth, the surgery can be challenging and stressful to teach to trainees. Minor complications can also occur, including atonic pupil, subconjunctival hemorrhage, chemosis, diplopia and muscle weakness, but the most severe complication is blindness if the optic nerve is incised / severed or there is prolonged ischemia due to manipulation.

[0016]

[0005] Thus, there remains a need for improved surgical tools (e.g., a surgical blade or scalpel) for efficient and safe use during ONSF surgery.

[0017] SUMMARY OF THE INVENTION

[0018]

[0006] In accordance with an aspect of the invention, a disposable ophthalmic device for optic nerve sheath fenestration is provided. The disposable ophthalmic device includes a handle having a distal end and a proximal end opposite the distal end. A 25 depth guard extends from the proximal end for a length and at least two microblades extend from the depth guard. The at least two microblades are spaced apart for a distance relative to each other. The at least two microblades configured to make simultaneous incisions for incising the optic nerve sheath while the depth guard mitigates or prevents contact of the microblades with the underlying optic nerve.

[0019]

[0007] In accordance with another aspect of the invention, a surgical training tool for optic nerve sheath fenestration is provided. The surgical training tool includes a handle having a distal end and a proximal end opposite the distal end. A depth guard extends from the proximal end for a length and at least two microblades extend from the depth guard. The at least two microblades are spaced apart for a distance relative to each 35 other. The at least two microblades are configured to make simultaneous incisions for incising the optic nerve sheath while the depth guard mitigates or prevents contact of the microblades with the underlying optic nerve. PCT / US25 / 55902 14 January 2026 (14.01.2026)

[0020] 2102463-000547

[0021] -3-

[0022] BRIEF DESCRIPTION OF THE FIGURES

[0023]

[0008] The invention is best understood from the following detailed description when read in connection with the accompanying drawings, with like elements having the same reference numerals. When a plurality of similar elements are present, a single 5 reference numeral may be assigned to the plurality of similar elements with a small letter designation referring to specific elements. When referring to the elements collectively or to a non-specific one or more of the elements, the small letter designation may be dropped. According to common practice, the various features of the drawings are not drawn to scale unless otherwise indicated. On the contrary, the 10 dimensions of the various features may be expanded or reduced for clarity.

[0024]

[0009] FIG. 1A is a perspective view of an exemplary embodiment of a disposable ophthalmic device or a surgical training tool in accordance with aspects of the invention;

[0025]

[0010] FIG. IB is a front view of the device or tool of FIG. 1A;

[0026] [Oil] FIG. 1C is a side view of the device or tool of FIG. 1A;

[0027]

[0012] FIG. ID is a magnified view of a portion of the device or tool of FIG. 1C;

[0028]

[0013] FIG. IE is a top view of a portion of the device or tool of FIG. 1A;

[0029]

[0014] FIG. IF is a magnified view of a portion of the device or tool of FIG. IE;

[0030]

[0015] FIG. 2A is a perspective view of another exemplary embodiment of a disposable ophthalmic device or a surgical training tool in accordance with aspects of the invention;

[0031]

[0016] FIG. 2B is a side view of the device or tool of FIG. 2A;

[0032]

[0017] FIG. 2C is a top view of the device or tool of FIG. 2A;

[0033]

[0018] FIG. 2D is a front view of the device or tool of FIG. 2A;

[0034] 25

[0019] FIG. 2E is a magnified view of a portion of the device or tool of FIG. 2D;

[0035]

[0020] FIG. 3 is an image of an assessment of a prior art tool for ONSF in accordance with evaluations performed in a laboratory setting;

[0036]

[0021] FIGS. 4A-4B are images of an assessment of the device or tool of FIG. 1A in accordance with evaluations performed in a laboratory setting;

[0037]

[0022] FIGS. 5A-5B are images of another assessment of the prior art tool of FIG. 3 in accordance with evaluations performed in a laboratory setting; and

[0038]

[0023] FIGS. 6A-6D are images of another assessment of the device or tool of FIG. 1A in accordance with evaluations performed in a laboratory setting.

[0039] 35 DETAILED DESCRIPTION OF THE INVENTION

[0040]

[0024] In the following detailed description, numerous specific details are set forth by way of examples to provide a thorough understanding of the relevant teachings. PCT / US25 / 55902 14 January 2026 (14.01.2026)

[0041] 2102463-000547

[0042] -4-

[0043] However, it should be apparent to those skilled in the art that the present teachings may be practiced without such details. In other instances, well known methods, procedures, components, and circuitry have been described at a relatively high-level, without detail, in order to avoid unnecessarily obscuring aspects of the present 5 teachings.

[0044]

[0025] Additionally, various forms and embodiments of the invention are illustrated in the figures. It will be appreciated that the combination and arrangement of some or all features of any of the embodiments with other embodiments is specifically contemplated herein. Accordingly, this detailed disclosure expressly includes the 10 specific embodiments illustrated herein, combinations and sub-combinations of features of the illustrated embodiments, and variations of the illustrated embodiments.

[0045]

[0026] It will be understood that the terms and expressions used herein have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study except where specific meanings have otherwise been set forth herein. The terms "comprises," "comprising," "includes," "including," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises or includes a list of elements or steps does not include only those elements or steps but may include other elements or steps not expressly listed or inherent to such process, method, article, or apparatus. An element preceded by "a" or "an" does not, without further constraints, preclude the existence of additional identical or non-identical elements in the process, method, article, or apparatus that comprises the element.

[0046]

[0027] U nless otherwise stated, any and all measurements, values, ratings, positions, magnitudes, sizes, and other specifications that are set forth in this specification, 25 including in the claims that follow, are approximate, not exact. Such amounts are intended to have a reasonable range that is consistent with the functions to which they relate and with what is customary in the art to which they pertain, and taking into account manufacturing tolerances and typical variations in functional parameters. For example, unless expressly stated otherwise, a parameter value or the like may vary by as much as ± 10% from the stated amount.

[0047]

[0028] As used herein and throughout the specification, users of the disposable ophthalmic device or surgical training tool is not limited to a specific medical personnel or health care professional, but is to be broadly construed to include any provider of care, management or treatment related to ophthalmology. The term may include 35 trainees and professionals in the field of medicine, particularly in the fields of ophthalmology, nursing, and emergency medical services, as well as non-health care professionals. Further, mentions of an optic nerve sheath, an optic nerve, and other PCT / US25 / 55902 14 January 2026 (14.01.2026)

[0048] 2102463-000547

[0049] -5-

[0050] segments of human anatomy may also include anatomical models simulating or emulating functions or responses of their biological counterparts (e.g., for surgical training purposes). Still further, the term "subject" includes a patient, but is not limited to a specific patient and can encompass any and all types of patients, regardless of 5 sex, age, and / or other physiological factors.

[0051]

[0029] Referring generally to the figures, the devices or tools described herein include a disposable and handhold apparatus for improving or increasing efficacy, efficiency, and safety in optic nerve sheath fenestration. This is achieved, at least in part, by a dualblade design adapted to execute effective and efficient fenestration in a single step, 10 thereby reducing or preventing the likelihood of damaging the optic nerve. One skilled in the art would understand from the description herein that surgical incisions require a high degree of technical precision, particularly in an optic nerve sheath fenestration (ONSF) surgery, since it involves a full thickness incision of the optic nerve sheath in order to allow egress of cerebrospinal fluid, while also avoiding any contact with the underlying optic nerve (which remains separated from the sheath by only a small cuff of cerebrospinal fluid). Certain advantages are also available in terms of increasing the consistency and teachability of the ONSF procedure, while increasing safety and decreasing its technical difficulty. In this way, the devices or tools described herein increase accessibility of the procedure as well as gain traction as the surgery of choice for conditions such as medication-refractory papilledema.

[0052]

[0030] Turning now specifically to FIGS. 1A-1F, an exemplary embodiment of a disposable ophthalmic device or surgical tool 100 is provided. The disposable ophthalmic device 100 is adapted for optic nerve sheath fenestration (ONSF) in which the optic nerve sheath is incised. Non-limiting examples of the disposable

[0053] 25 ophthalmic device or surgical tool 100 includes a scalpel or a microvitreoretinal (MVR) blade. The disposable ophthalmic device 100 includes a handle 110, a depth guard 120, and at least two microblades 130. Additionally or optionally, the at least two microblades 130 are configured to make simultaneous incisions for severing the optic nerve sheath while the depth guard 120 mitigates or prevents contact or damage of the underlying optic nerve. In this way, the disposable ophthalmic device 100 enables the user (e.g., surgeon) to have increased control during surgery, thereby preventing or restricting inadvertent injury of the optic nerve as well as minimizing duration of time manipulating the optic nerve during the surgery. In an exemplary embodiment, the at least two microblades 130 (e.g., a dual-blade design) facilitate fenestration in a single 35 pass, the depth guard 120 prevents inadvertent injury to the optic nerve during fenestration, and the handle 110 (particularly the gooseneck member 240 design PCT / US25 / 55902 14 January 2026 (14.01.2026)

[0054] 2102463-000547

[0055] -6-

[0056] discussed further below) increase visualization to the user despite the limited exposure in the orbit.

[0057]

[0031] As best shown in FIG. 1A-1D, the handle 110 has a distal end 112 and a proximal end 114 opposite the distal end 112. Although the handle 110 is illustrated as 5 being integrally formed as a single body of unitary construction, one of ordinary skill in the art would understand from the description herein that the handle 110 may be comprised of separate components, e.g. a distal end portion 112 and proximal end portion 114. In an exemplary embodiment, as illustrated in FIGS. 1A-1F, the handle 110 may have a body 116 having a generally rectangular geometry, but the geometry 10 may vary, as shown in FIGS. 2A-2E (discussed further below), for example. In an exemplary embodiment, as best shown in FIGS. 1E-1F, the depth guard 120 extends from the proximal end 114 of the handle for a length (L). Additionally or optionally, the at least two microblades 130 extend from the depth guard 120 for a distance D2 (FIG. ID) or extends from an end portion of the proximal end 114 for distance D2' (FIG. IE). The at least two microblades 130 are spaced apart for a distance (D) relative to each other. In an exemplary embodiment, the at least two microblades 130 are spaced apart for the distance of at least 3 mm, or in a range between 3 mm and 6 mm. In an exemplary embodiment, the simultaneous incisions comprise two parallel linear incisions made by the at least two microblades 130 in a single pass (e.g., along the targeted underlying optic nerve sheath / optic nerve of the subject).

[0058]

[0032] Turning now to FIGS. 2A-2E, another exemplary embodiment of the disposable ophthalmic device or surgical tool 200 is provided. The disposable ophthalmic device or surgical tool 200 is similar in most respects with the components and operation of the disposable ophthalmic device or surgical tool 100 as described above. For example, the 25 disposable ophthalmic device or surgical tool 200 includes a handle 210, a depth guard, and at least two microblades configured to make simultaneous incisions for severing the optic nerve sheath while the depth guard prevents transection of the underlying optic nerve. However, the disposable ophthalmic device or surgical tool 200 differs from the disposable ophthalmic device or surgical tool 100, at least in that the proximal end 214 of the handle 210 comprises a gooseneck member 240 fixedly attached to a body 216 of the handle 210. Additionally or optionally, the gooseneck member 240 performs a similar function as the depth guard 120 in preventing transection of the underlying optic nerve during ONSF surgery. As best shown in FIG. 2B, the body 216 of the disposable ophthalmic device or surgical tool 200 extends for a length (!_')• The body 35 216 is generally cylindrical and elongated, with the distal end 212 having a greater diameter than that of the proximal end 214. The gooseneck member 240 has a vertical PCT / US25 / 55902 14 January 2026 (14.01.2026)

[0059] 2102463-000547

[0060] -7-

[0061] height LI and a horizontal width Wl. In a non-limiting example, LI is at least 14.5 inches (or at least 36 cm).

[0062]

[0033] EXAMPLES

[0063]

[0034] The co-inventors assessed feasibility and functionality of the components of the 5 devices disclosed herein, as well as verified any updates or improvements made.

[0064]

[0035] Methods and Design Considerations

[0065]

[0036] To understand the challenges and further define the unmet need, a customer needs assessment was conducted by interviewing oculoplastic surgeons as well as a chart review of prior ONSF procedures conducted at certain institutions between 9 / 8 / 09 10 and 4 / 29 / 22. To characterize the market potential and landscape, a market analysis of optic nerve sheath fenestration as well as a preliminary prior art search was performed. A functional prototype of the fenestration device was designed and fabricated, and the prototype was tested using fluorescein filled balloons overlying a tube (as shown in FIGS. 4A-4B) and the tube (as shown in FIGS. 6A-6D).

[0066]

[0037] The average thickness of the optic nerve sheath is 1 mm and the average volumetric preoperative fluid cuff to optic nerve sheath ratio has been found to be 0.62mm ± 0.09. The prototype device 100 / 200 has three features: 1) A dual blade scalpel, to facilitate sheath fenestration in a single pass; 2) A depth guard, to prevent nerve injury, and 3) An offset "gooseneck" handle to increase surgeon visualization given the limited exposure in the orbit. To test these variables in isolation a two-stage process was devised in which the blades and the handle were tested as separate prototypes.

[0067]

[0038] The prototype device 100 / 200 includes two microblades that were spaced 3 mm apart to allow for two simultaneous parallel linear incisions (FIG. 6D). The two

[0068] 25 microblades were then placed in a 3D printed handle. The length of the exposed blade tip 130 and blade guard 120 allows the blades 130 to cut the sheath, but not the nerve below. The handle 110 / 210 design is offset to increase visibility from the surgeon's line of sight to the operative field where the incision will be made.

[0069]

[0039] Thus, the prototype device 100 / 200 design avoids or mitigates the challenge of the "second cut sheath contraction" effect and enables the user or surgeon to achieve the "gold standard" window with the 3rd and 4th cut, if desired. Conventional "gold standard" approach to this procedure is a "window" wherein a rectangular piece of sheath is removed to allow for fluid egress and minimize risk of postoperative reclosure. A "window" involves the total removal of an entire rectangular piece of 35 sheath to theoretically minimize risk of wound fibrosis and thus chance of re-operation;

[0070] however, some surgeons modify this approach by making two parallel incisions or connecting the incisions on one end to make a "flap." There is ambiguity surrounding PCT / US25 / 55902 14 January 2026 (14.01.2026)

[0071] 2102463-000547

[0072] -8-

[0073] the mechanism by which ONSF achieves durable visual improvement; initially it was thought to be due to the creation of a fistula to drain excess cerebrospinal fluid, but these findings were historically reported as inconsistent. However, it is well established that fibrosis of the sheath incision post-fenestration is observed histologically in re5 fenestration patients, supporting scar fibrosis and incisional closure as a probable means of surgical failure and thus indication for reoperation. As a result, surgeons favor multiple incisions or the removal of a "window" to minimize the chance of reoperation and maximize the durability of clinical result. Currently no prospective trials comparing incisional variations (i.e., window vs. slits) exist. Though surgeons ideally 10 make 2+ slits in the sheath, in many cases the manipulation of the sheath after the initial fenestration poses too high a risk to complete a modified or full window.

[0074]

[0040] Regarding the design of the handle, there are relatively low price-points for conventional tools ($95 / MVR blade, $145 / scissors), but the handle of the available tools is frequently not long enough to reach into the surgical field. Moreover, blades in these available tools are unguarded and require multiple passes, requiring caution to prevent transection or injury / damage of the underlying optic nerve, and thus limiting surgeons' ability to adequately manipulate the optic nerve sheath after initial incision to make a second slit or full window. This increases the time the surgeon spends manipulating the nerve, especially after the initial incision, which increases the risk of nerve ischemia. For example, in a dual-incision technique, the second incision is challenging because after the initial incision, the cuff of cerebrospinal fluid surrounding the nerve sheath egresses and the nerve sheath contracts against the nerve, making it difficult to manipulate. Minimizing nerve manipulation is critical to prevent nerve ischemia, which can be a permanently blinding surgical complication. As a result, it is 25 difficult to provide trainees with sufficient operative experience to feel comfortable and confident, and many surgeons do not perform this procedure after fellowship training.

[0075]

[0041] Discussion

[0076]

[0042] Testing of the prototype devices was performed with fluorescein filled gloves overlying a tube. In particular, the assessment evaluated the prototype device's ability to make two parallel incisions in a single pass and guard against contact, injury or transection of the underlying nerve. Referring to FIGS. 3, 5A, and 5B, it was observed that the fluid egress after the initial incision significantly increases the difficulty in the second incision, as there is no longer fluid to provide a counter force against the nerve sheath. In contrast, turning to FIGS. 4A-4B and 6A-6D, it was observed that the 35 prototype device was able to make two parallel incisions (FIG. 6D), therefore minimizing nerve manipulation, time under tension, and risk of nerve injury. Notably, comparing FIGS. 5B and 6B, it can be seen that the devices or tools described herein PCT / US25 / 55902 14 January 2026 (14.01.2026)

[0077] 2102463-000547

[0078] -9-

[0079] achieve the advantage of preventing or mitigating injury to the underlying optic never during ONSF surgery.

[0080]

[0043] While the foregoing has described what are considered to be the best mode and other examples, it is understood that various modifications may be made therein and 5 that the subject matter disclosed herein may be implemented in various forms and examples, and that they may be applied in numerous applications, only some of which have been described herein. It is intended by the following claims to claim any and all modifications and variations that fall within the true scope of the present concepts.

Claims

PCT / US25 / 55902 14 January 2026 (14.01.2026)2102463-000547-10-What is claimed:

1. A disposable ophthalmic device for optic nerve sheath fenestration comprising: a handle having a distal end and a proximal end opposite the distal end;a depth guard extending from the proximal end for a length;5 at least two microblades extending from the depth guard and being spaced apart for a distance relative to each other, the at least two microblades configured to make simultaneous incisions for incising the optic nerve sheath while the depth guard mitigates or prevents contact of the blades with the underlying optic nerve.

2. The disposable ophthalmic device of claim 1 comprising a scalpel or a10 microvitreoretinal (MVR) blade.

3. The disposable ophthalmic device of claim 1, wherein the at least two microblades are spaced apart for the distance of at least 3 mm.

4. The disposable ophthalmic device of claim 1, wherein the simultaneous incisions comprise two parallel linear incisions made by the at least two microblades in a single pass.

5. The disposable ophthalmic device of claim 1, wherein the proximal end of the handle comprises a gooseneck member fixedly attached to a body of the handle.

6. A surgical training device for optic nerve sheath fenestration, the surgical training device comprising:a handle having a distal end and a proximal end opposite the distal end;a depth guard extending from the proximal end for a length;at least two microblades extending from the depth guard and being spaced apart for a distance relative to each other, the at least two microblades configured to make simultaneous incisions for severing the optic nerve sheath while the depth guard 25 prevents transection of the optic nerve.

7. The disposable ophthalmic device of claim 1 comprising a scalpel or a microvitreoretinal (MVR) blade.

8. The disposable ophthalmic device of claim 1, wherein the at least two microblades are spaced apart for the distance of at least 3 mm.

9. The disposable ophthalmic device of claim 1, wherein the simultaneous incisions comprise two parallel linear incisions made by the at least two microblades in a single pass.

10. The disposable ophthalmic device of claim 1, wherein the proximal end of the handle comprises a gooseneck member fixedly attached to a body of the handle.35

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