Supporting component of corneal prosthesis

Abstract

FIELD: ophthalmology.SUBSTANCE: corneal prostheses intended for surgical treatment with the aim of restoring vision in patients with severe corneal leukomas of various etiologies. A supporting component of a corneal prosthesis in the form of a curved plate, containing in the central part a cylindrical sleeve with an internal thread, the height of the cylindrical sleeve exceeds the thickness of the plate, while the plate and the cylindrical sleeve are made of a polymer material and constitute a single unit, and the plate has a mesh structure formed by through holes.EFFECT: reduction in the risk of protrusion and extrusion of the supporting part of the corneal prosthesis, improvement in the results of surgical treatment and simplification of the production of the supporting part of the corneal prosthesis.4 cl, 7 dwg

Description

[0001] FIELD OF TECHNOLOGY

[0002] The present invention relates to ophthalmology, namely to corneal prostheses intended for surgical treatment with the aim of restoring the vision of patients with severe corneal leukomas of various etiologies.

[0003] Keratoprosthetics is the only treatment method in the world for patients with burn and terminal dystrophic leukomas. Penetrating keratoplasty in this case produces unstable visual results and is typically accompanied by graft decompensation due to severe limbal insufficiency syndrome. With careful preparation of the ocular surface for keratoprosthetics (including correction of symblepharon, lagophthalmos, and eyelid inversion / eversion); adequate hypotensive antiglaucoma therapy; adherence to the principles of keratoprosthetics staging and patient compliance, this type of surgical intervention ensures stable anatomical, clinical, and functional results in both the early and late postoperative periods and does not require keratoprosthesis replacement.

[0004] Keratoprosthetics is aimed at restoring vision in patients with burn-related and terminal degenerative leukomas, offering a chance to improve visual function in this cohort of patients. Visual rehabilitation depends on the associated pathologies of the retina, optic nerve, lens, and adnexa, but in any case, this treatment method significantly reduces patient disability.

[0005] All modern corneal prosthesis models, despite the diversity of their design features, share a common structure: they consist of a supporting and an optical part. The supporting part (support component, support plate) is the peripheral portion of the prosthesis, in which the optical part (optical component, optical cylinder) is fixed in the center. The primary function of the supporting part is to ensure secure fixation of the entire prosthesis structure within the pathologically altered corneal tissue. The optical component replaces the cloudy central layers of the cornea and allows images from surrounding objects to be focused on the retina. Corneal prostheses (or keratoprostheses) can be permanent or disassemblable. The optical component is typically attached to the supporting part via a threaded connection.

[0006] PRIOR ART

[0007] A corneal prosthesis (keratoprosthesis) is known from the prior art in accordance with registration certificate RZN 2020 / 9972, registration date 05 / 12 / 2020, including the Operating Manual GH.0300.00.00. RE "Fedorov-Zuev penetrating, sterile corneal prosthesis." This device is also described in patent SU 506954, IPC A 61F 2 / 14, published 11 / 23 / 1985.

[0008] This well-known corneal prosthesis is designed for two-stage implantation and is an optomechanical device consisting of three main components: a support component, a temporary plug, and an optical component. The support component includes a titanium alloy ring with oppositely positioned closed support loops extending from it, and a cylindrical sleeve made of inert polymethyl methacrylate (SO-95-K structural organic plasticized glass) with internal threads. This cylindrical sleeve with internal threads is permanently installed in the titanium ring. The temporary plug and optical component are designed to be positioned within the cylindrical sleeve at different stages of the surgical procedure. The temporary plug is pre-installed in the cylindrical sleeve of the support component and is removable. The support component and temporary plug are implanted during the first stage of keratoprosthesis implantation.During the second stage of implantation, after the supporting component has become established in the cornea (approximately six months), the temporary plug is removed from the cylindrical sleeve and replaced with the optical component, which is permanently implanted. Between the first and second stages, a connective tissue capsule forms, securing the supporting component within the corneal layers. The ends of the temporary plug and the optical component are threaded, congruent with the internal threads of the cylindrical sleeve. The temporary plug and optical component, like the cylindrical sleeve, are made of inert polymethyl methacrylate. The temporary plug and optical component can be screwed in and out of the cylindrical sleeve. A special tool is used for this procedure. This corneal prosthesis is designed for implantation into a vascular corneal leukoma or into a cryopreserved donor cornea.The supporting component is installed into the prepared intrastromal pocket (ISP).

[0009] The Fedorov-Zuev corneal prosthesis design embodies the principle of minimal separation of corneal layers, which plays a positive role in stabilizing the results of keratoprosthetic surgery for vascular cicatricial leukomas of categories 4-5. However, this corneal prosthesis model has several drawbacks.

[0010] The supporting component of a known corneal prosthesis includes a titanium portion. However, this material in most cases causes aseptic tissue necrosis, which increases the risk of protrusion and extrusion of the supporting portion, leading to prosthesis loss. Titanium also promotes nonspecific chronic inflammation, leading to the formation of a retroprosthetic membrane, which in turn reduces visual function and leads to a persistent increase in intraocular pressure. Furthermore, the support loops of the titanium portion of the supporting element are very thin, posing a risk of iatrogenic deformation during surgical procedures. Furthermore, the contact area of ​​the known prosthesis, provided by the titanium element, is too small to ensure stable retention in the cornea, increasing the risk of prosthesis loss in the postoperative period.Since titanium is an opaque material, the supporting component of the known device is in most cases visible in the cornea, which causes some discomfort to the patient.

[0011] The titanium element and cylindrical sleeve, which form the supporting component of the known device, are made of different materials and are connected by tightly pressing the polymethyl methacrylate cylindrical sleeve into the ring of the titanium element. This connection is technologically complex, requiring high-precision machining to ensure a minimal gap between the ring of the titanium element and the cylindrical sleeve, ensuring insertion and secure retention of the sleeve. It is known that connecting elements made of different materials in any design always carries the risk of separation, which is critical during ophthalmic surgery.

[0012] DISCLOSURE OF THE INVENTION

[0013] The purpose of the present invention is to eliminate the disadvantages of the closest analogue.

[0014] The technical result is a reduction in the risk of protrusion and extrusion of the supporting part of the corneal prosthesis, an improvement in the results of surgical treatment and a simplification of the production of the supporting part of the corneal prosthesis.

[0015] The technical result is achieved by proposing a supporting component of a corneal prosthesis in the form of a curved plate and containing in the central part a cylindrical sleeve with an internal thread, the height of the cylindrical sleeve exceeds the thickness of the plate, while the plate and the cylindrical sleeve are made of a polymer material and constitute a single whole, and the plate has a mesh structure formed by through holes.

[0016] The plate length is typically 5.5-8.0 mm, and the plate width is 4.0-6.0 mm. The outer edge of the supporting component of the corneal prosthesis is typically a circle symmetrically truncated on both sides, a round shape, a rectangle with rounded corners, or an oval shape.

[0017] The predominantly supporting component of the corneal prosthesis is made of a material based on oligomers and monomers of the methacrylic series.

[0018] BRIEF DESCRIPTION OF DRAWINGS

[0019] The proposed technical solution is explained by the following graphic material.

[0020] Fig. 1 - general view of the supporting component of the corneal prosthesis.

[0021] Fig. 2 - top view of the supporting component of the corneal prosthesis.

[0022] Fig. 3 - section of the supporting component of the corneal prosthesis (A-A).

[0023] Fig. 4 - view of the supporting component of the corneal prosthesis assembled with a temporary plug.

[0024] Fig. 5 - view of the supporting component of the corneal prosthesis assembled with an optical cylinder.

[0025] Fig. 6, 7 - photo of the proposed supporting component of the corneal prosthesis.

[0026] The proposed supporting component of the corneal prosthesis (1) has the shape of a curved plate (2) corresponding to the curvature of the cornea of ​​the eye. The central part of the curved plate (2) contains a cylindrical sleeve (3) with an internal thread (4). Unlike a close analogue, the cylindrical sleeve (3) and the plate (2) are made of the same material and constitute a single unit. The plate (2) contains numerous through holes (5) over its area, which form a mesh structure of the plate (2). Unlike a close analogue, where contact with the cornea is ensured by the area of ​​thin loops of the titanium element, the proposed device contacts over the entire area of ​​the plate (2). The holes (5) ensure uniform ingrowth of connective tissue over the entire area of ​​the plate (2) during the period between the first and second stages of the surgery, which subsequently allows for the secure retention of the corneal prosthesis with an optical component with large optics in the cornea.Also, the holes (5) make the structure of the plate (2) as light as possible, which reduces the load on the cornea of ​​the eye. The size of the holes is selected from the range of 0.15-0.25 mm and is preferably 0.20 mm. The pitch of the holes (the distance between the centers of adjacent holes) is selected from the range of 0.25-0.40 mm and is preferably 0.30 mm. The shape of the holes (5) can be square (as shown in Figs. 1-5), rectangular or round, or other. The thickness (h) of the plate (2) is selected from the range of 0.10-0.20 mm and is preferably 0.15 mm. The specified intervals for the holes (5) and the dimensions of the plate (2) allow for an optimal balance between sufficient strength of the structure for reliable retention of an optical component with large optics and the maximum live cross-section of the mesh structure of the plate (2) for effective ingrowth. The length (L1) of the plate (2) is selected from the range of 5.5 - 8.0 mm and the preferred option is 6.5 mm.The width (L2) of the plate (2) is selected from the range of 4.0 - 6.0 mm, with a preferred value of 5.5 mm. The specified ranges of plate (2) dimensions allow for operations to be performed in various clinical cases. The height (H) of the cylindrical sleeve (3) exceeds the thickness (h) of the plate (2) and is selected from the range of 0.50-0.60 mm, with a preferred value of 0.55 mm. The height (H) is selected to ensure the implementation of an internal thread (4) in it, ensuring reliable retention of the temporary plug (7) and the optical component (8) at different stages of implantation.

[0027] Preferably, the outer edge (6) of the supporting component of the corneal prosthesis has the shape of a circle symmetrically truncated on both sides, as shown in Fig. 1-5. However, the said shape of the outer edge of the supporting component does not exclude the use of other shapes, such as a round shape, a rectangle with rounded corners, or an oval shape. The outer shape (6) is selected depending on the implantation technique, the size of the donor cornea, or the shape of the intrastromal pocket (ISP).

[0028] A corneal prosthesis comprising the support component (1) proposed within the framework of the present invention comprises a temporary plug (7) and an optical component (8). A thread is formed on the end of the temporary plug (7) and the optical component (8), which is congruent with the internal thread (4) of the cylindrical sleeve (3) of the proposed support component (1). The temporary plug (7) and the optical component (8) are configured to be screwed in and out of the cylindrical sleeve (3). A special tool is used for this manipulation.

[0029] EMBODIMENT OF THE INVENTION

[0030] For the manufacture of the proposed supporting component (1) of the corneal prosthesis, materials for the manufacture of implantable medical devices are used, for example, liquid light-curing compositions disclosed in patents EP2644348A1 "A method of manufacturing an artificial elastic implant for restorative and reconstructive surgery", published 02.10.2013, in patent RU2309781 "Drainage for antiglaucoma operations", in patent RU2198630 "Method of manufacturing elastic artificial lenses of the eye", in patent US9724850B2 "Method of manufacturing an artificial elastic implant for restorative and reconstructive surgery", published 08.08.2017, in patent US9480777B2 "Multipurpose implant with modeled surface structure for soft tissue reconstruction", published 01.11.2016, RU2792525 "Material for the manufacture of ophthalmological implants by photopolymerization", published 22.03.2023, or improved versions of these compositions.The known materials are compositions based on methacrylate oligomers and monomers, which include methacrylates of various structures: methacrylates with a linear hydrocarbon side chain and methacrylates with a branched hydrocarbon side chain. Medical devices produced from these materials possess the required biocompatibility. The polymerization process of each curable composition according to these patents produces a spatially cross-linked polymer with the required physical and mechanical properties, namely, a biologically inert material. During manufacturing, using the curable compositions according to these patents, a high level of smoothness can be achieved (for example, a surface roughness of no more than 50 nanometers). The surface of the product must be inert to reduce the body's tissue response, so the cured polymer undergoes an additional free radical blocking procedure, for example, by treating the surface with isopropyl alcohol.The supporting part of the corneal prosthesis can be manufactured by curing the composition in a mold or by 3-D printing. Compared to a similar device, these materials and methods simplify the production of the proposed device, eliminating the manufacturing step of ensuring a minimum gap between the ring and the cylindrical sleeve and their connection. In the proposed device, the threads inside the cylindrical sleeve can be machined.

[0031] Products formed from the above materials are transparent, making the implanted support component (1) virtually invisible to the patient's eye. This enhances the aesthetic effect, which in turn improves surgical outcomes.

[0032] WORKING WITH THE PROPOSED DEVICE

[0033] Work with the proposed device is carried out according to the following method.

[0034] During the first stage of the surgery, markings are made on the cornea using a marker or spatula, which is pre-stained with dye. These markings correspond to the area of ​​the intrastromal pocket being created for implantation of the supporting component of the corneal prosthesis assembly with a temporary plug.

[0035] At the obtained mark, a non-piercing corneal incision is made to a depth of 2 / 3 using a corneal incision cutter. The depth of the incision depends on the corneal thickness. Using cutters of varying working surface areas, a rectangular stromal pocket is created. The supporting component assembly with a temporary plug is implanted into the created intrastromal pocket, and interrupted sutures are placed over the corneal incision area.

[0036] The second stage of the surgery is performed no less than 6 months after the first, after the support component has healed. Using a trephine, the anterior layers of the cornea are trephinated precisely above the temporary plug and unscrewed from the support component. Then, using a blade, a through trephine is made in the central sections of the cornea near the cylindrical sleeve of the support component, and the optical component is screwed into it.

Claims

1. A supporting component of a corneal prosthesis (1) in the form of a curved plate (2), containing in the central part a cylindrical sleeve (3) with an internal thread (4), the height of the cylindrical sleeve (3) exceeds the thickness of the plate (2), characterized in that the plate (2) and the cylindrical sleeve (3) are made of a polymer material and constitute a single whole, and the plate has a mesh structure formed by through holes (5).

2. The supporting component of the corneal prosthesis (1) according to claim 1, characterized in that the length of the plate (2) is 5.5–8.0 mm, the width of the plate (2) is 4.0–6.0 mm.

3. The supporting component of the corneal prosthesis (1) according to claim 1, characterized in that its outer edge (6) has the shape of a circle symmetrically truncated on both sides, or a round shape, or the shape of a rectangle with rounded corners, or the shape of an oval.

4. The supporting component of the corneal prosthesis (1) according to paragraph 1, characterized in that it is made from a material based on oligomers and monomers of the methacrylic series.

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