Aspheric keratoprosthesis column, keratoprosthesis and application method thereof

Abstract

The invention discloses an aspheric keratoprosthesis lens column, a keratoprosthesis and an application method of the aspheric keratoprosthesis lens column, the whole lens column is cylindrical, the front surface of the lens column is a convex surface, the rear surface of the lens column is a concave surface, the rear surface of the lens column is a surface close to the retina, the front surface of the lens column is a surface far away from the retina, and the front surface and the rear surface of the lens column are both curved surfaces. And the spherical surfaces are rotationally symmetrical aspheric surfaces. The artificial cornea comprises a lens column and a support, and the lens column is installed on the support. The fixed position of the lens column is that the distance between the vertex of the rear surface of the lens column and the retina is 10-120mm, the focal plane is perpendicular to the optical axis, and the inclination angle of the focal plane is 0 degree. According to the lens column, spherical aberration and coma can be effectively corrected, and the imaging quality is improved; light scattering is reduced, the visual contrast at night and in a low-light environment is improved, and the visual experience of a patient is improved; the deviation tolerance of the implantation position is higher, and the operation difficulty and the risk of postoperative complications are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices. More specifically, the present invention relates to an aspherical artificial corneal lens cylinder, an artificial cornea and an application method thereof. Background Art

[0002] An artificial cornea refers to a product similar to the human cornea made of artificial synthetic materials. The artificial cornea includes two parts: an optical lens cylinder and a stent. The optical lens cylinder is made of a transparent material with excellent optical properties and stable physical and chemical properties, and is used to replace the cloudy cornea that obstructs the optical path of the eyeball after the disease. The stent is equivalent to a bridge connecting the optical lens cylinder and the surrounding tissues.

[0003] Existing artificial corneal lens cylinders are all spherical structures. However, as patients' requirements for visual quality continue to increase, especially in scenarios such as high definition, wide field of view, and night driving, the optical performance of spherical lens cylinders has become difficult to meet modern needs.

[0004] Spherical lens cylinders have inherent optical defects in design, which are mainly reflected in several aspects: (1) High-order aberration problem. Spherical lens cylinders are prone to spherical aberration and coma under large aperture and wide field of view conditions, resulting in blurred imaging and decreased contrast; (2) Glare and halo effects. Spherical structures are prone to cause light scattering. Especially at night or in strong light environments, patients may experience glare and halo phenomena, affecting visual comfort; (3) Narrow surgical tolerance. Spherical lens cylinders are more sensitive to deviations in the implantation position. Slight eccentricity or tilt may lead to a significant decrease in visual quality. Summary of the Invention

[0005] The present invention innovatively provides an aspherical artificial corneal lens cylinder, an artificial cornea and an application method thereof, which can solve at least some of the above problems.

[0006] To achieve the above technical objectives, the first aspect of the present invention discloses an aspherical artificial corneal lens cylinder. The lens cylinder is cylindrical as a whole. The front surface of the lens cylinder is a convex surface, and the rear surface of the lens cylinder is a concave surface. The rear surface of the lens cylinder is the surface close to the retina, and the front surface of the lens cylinder is the surface far from the retina. Both the front surface and the rear surface of the lens cylinder are curved surfaces and are both rotationally symmetric aspheres.

[0007] Further, the range of the conic constant k of the front surface and the rear surface of the lens cylinder is |k| < 30 and k ≠ 0.

[0008] Further, the design formulas for the front surface and the rear surface of the lens cylinder are:

[0009] Wherein, Let \(h\) be the radial height, the \(z\)-axis represents the optical axis of the lens cylinder. Along the optical axis of the lens cylinder, the positive direction of the \(z\)-axis is from the object side to the imaging side. Let \(r\) be the radial distance of any point on the curved surface from the \(z\)-axis, and \(R\) be the radius of curvature of the vertex of the curved surface. For the front surface of the lens cylinder, \(R>0\), and for the rear surface of the lens cylinder, \(R < 0\). Let \(k\) be the conic constant. The range of the conic constant of the front surface of the lens cylinder is \(|k|<30\) and \(k\neq0\). The range of the conic constant of the rear surface of the lens cylinder is \(|k|<30\) and \(k\neq0\). \(A_4\), \(A_6\), and \(A_8\) are the coefficients of the higher-order terms.

[0010] Further, the range of the radius of curvature \(R\) of the vertex of the front surface of the lens cylinder is \(2 - 10\) -3 mm -3 and the range of \(A_4\) is \(0 - 10\) -5 ~0mm -5 and the range of \(A_6\) is \(-10\) -7 mm -7 , and the range of \(A_8\) is \(0 - 10\) - 4 mm -3 For the rear surface of the lens cylinder, the range of the radius of curvature \(R\) of the vertex is \(-0.5 - (-30)\) -5 ~0mm -5 and the range of \(A_8\) is \(0 - 10\) -8 mm -7 .

[0011] Further, the range of the conic constant \(k\) of the front surface of the lens cylinder is \(-1 < k < 0\), and the range of the conic constant \(k\) of the rear surface of the lens cylinder is \(-20 < k < -1\) or \(2 < k < 20\).

[0012] Further, the material of the lens cylinder is allyl diglycol carbonate, polycarbonate, acrylic resin, or optical glass.

[0013] To achieve the above technical objectives, the second aspect of the present invention discloses an artificial cornea, which includes the aspherical artificial corneal lens cylinder described in the first aspect and a stent, and the aspherical artificial corneal lens cylinder is installed on the stent.

[0014] To achieve the above technical objectives, the third aspect of the present invention discloses an application method of the aspherical artificial corneal lens cylinder described in the first aspect. The fixed position of the lens cylinder is: the vertex of the rear surface of the lens cylinder is \(10 - 120\) mm away from the retina, the focal plane is perpendicular to the optical axis, and the inclination angle of the focal plane is \(0^{\circ}\).

[0015] The beneficial effects of the present invention are: The aspherical artificial corneal lenticule of the present invention has rotationally symmetric aspherical front and rear surfaces, which can effectively correct spherical aberration and coma, and improve the imaging quality; the aspherical design helps to reduce light scattering, enhance the visual contrast in nighttime and low-light environments, and improve the patient's visual experience; the aspherical lenticule has a higher tolerance to implantation position deviation, enhances the surgical tolerance, and reduces the surgical difficulty and the risk of postoperative complications. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a side view of the aspherical artificial corneal lenticule according to an embodiment of the present invention.

[0017] Figure 2 is a schematic diagram of the front surface of the aspherical artificial corneal lenticule according to an embodiment of the present invention.

[0018] Figure 3 is a schematic diagram of the rear surface of the aspherical artificial corneal lenticule according to an embodiment of the present invention.

[0019] Figure 4 is a schematic diagram of the shape of the front and rear surfaces of the aspherical artificial corneal lenticule gradually changing from the center to the edge according to an embodiment of the present invention.

[0020] Figure 5 is an imaging schematic diagram of a spherical lenticule.

[0021] Figure 6 is an imaging schematic diagram of the aspherical artificial corneal lenticule according to an embodiment of the present application.

[0022] Figure 7 is a schematic structural diagram of the artificial cornea according to an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The following will explain and illustrate in detail the aspherical artificial corneal lenticule, artificial cornea and their application methods provided by the present invention with reference to the accompanying drawings of the specification.

[0024] This embodiment specifically discloses an aspherical artificial corneal lenticule, as Figure 1 shown, the lenticule is cylindrical as a whole, the front surface of the lenticule is convex, the rear surface of the lenticule is concave, the rear surface of the lenticule is the surface close to the retina, the front surface of the lenticule is the surface far from the retina, and both the front surface and the rear surface of the lenticule are curved surfaces and are both rotationally symmetric aspherical surfaces.

[0025] The design formula of the rotationally symmetric aspherical surface is:

[0026] wherein, Let the radial height be \(h\), the \(z\)-axis represents the optical axis of the lens cylinder. Along the optical axis of the lens cylinder, the positive direction of the \(z\)-axis is from the object side to the imaging side. The retina is the imaging side, and the side in front of the lens cylinder, opposite to the imaging side, is the object side. Let \(r\) be the radial distance of any point on the surface from the \(z\)-axis (optical axis), \(R\) be the radius of curvature of the vertex of the surface. For the front surface of the lens cylinder in this embodiment, \(R>0\), and for the rear surface of the lens cylinder, \(R < 0\). Let \(k\) be the conic constant, and for the front and rear surfaces of the lens cylinder in this application, the conic constant \(k\neq0\). \(A_4\), \(A_6\), \(A_8\) are the coefficients of the higher-order terms, and \(N\) is an integer multiple of 2.

[0027] Taking a lens cylinder with an effective aperture of 2.60 mm as an example, as Figure 2 and Figure 4 shown, the radial height of the convex surface of the front surface of the lens cylinder in this application gradually increases from the center of the surface to the edge. As Figure 2 and Figure 3 shown, the radial height of the concave surface of the rear surface of the lens cylinder in this application gradually decreases from the center of the surface to the edge.

[0028] Both the front and rear surfaces of the lens cylinder in this application are aspherical surfaces, with strong aberration correction ability. By adjusting the conic constant \(k\) and the higher-order terms coefficients (\(A_4\), \(A_6\), \(A_8\) ), spherical aberration and coma can be effectively corrected, improving the imaging quality; the aspherical design of the front and rear surfaces helps to reduce light scattering, improving the visual contrast in night and low-light environments, enhancing the patient's visual experience and visual comfort; enhancing surgical tolerance, the aspherical lens cylinder has a higher tolerance for deviations in the implantation position, and the rotationally symmetric aspherical design can geometrically avoid asymmetric aberrations introduced by tilting or decentration, reducing the surgical difficulty and the risk of postoperative complications.

[0029] The artificial cornea optical system usually works under narrow field of view (object-side viewing angle is about ±5°) conditions and requires high-quality imaging to meet the visual requirements of the human eye. To improve the imaging quality, several main aberrations that need to be concerned about include: spherical aberration (axial imaging blur), astigmatism (inconsistent focal points in different meridional / sagittal directions off-axis), field curvature (curvature of the imaging surface), and coma (off-axis coma-shaped blur). A single spherical surface is difficult to correct various aberrations. Both the front and rear surfaces of the lens cylinder in this application adopt aspherical designs, and the surface shape is jointly determined by the parameters \(R\), \(k\), \(r\) and the higher-order terms coefficients. The parameters can be adjusted according to the patient's situation, and these aberrations can be significantly reduced through the design of the aspherical optical surface, thereby improving the imaging quality.

[0030] Further, the range of the conic constant k of the front surface and the rear surface of the lens cylinder is |k| < 30, and k ≠ 0. When the conic constant k of the surface < -1, the surface is a hyperboloid; when k = -1, the surface is a paraboloid; when -1 < k < 0, the surface is an oblate ellipsoid; when k > 0, the surface is a prolate ellipsoid. That is, the front surface of the lens cylinder is a hyperboloid, a paraboloid, an oblate ellipsoid or a prolate ellipsoid, and the rear surface of the lens cylinder is a hyperboloid, a paraboloid, an oblate ellipsoid or a prolate ellipsoid. The specific value of k can be adjusted within the above range according to the evaluation of the patient's vision, corneal damage, etc. By adjusting the value of k, the curvature distribution of the surface from the center to the edge can be changed, thereby controlling the aberration outside the Gaussian. For example, a negative value of k (especially close to -1) makes the surface develop into a parabolic shape, and the edge curvature decreases relative to the center, which helps to focus the peripheral light more accurately to the focus, thereby correcting spherical aberration. At the same time, appropriately selecting the value of k can also partially satisfy the Abbe sine condition, making the magnification of the light rays at different aperture heights equal, thereby reducing coma aberration. The adjustment of k largely determines the primary and tertiary aberration correction capabilities of the aspheric surface, that is, it simultaneously affects the preliminary compensation of spherical aberration and coma aberration. Clinically proven, limiting the value of k within the above range in this application can maximize the aberration correction ability.

[0031] Further, the design formulas for the front surface and the rear surface of the lens cylinder of this application are:

[0032] Wherein, is the radial height, the z-axis represents the optical axis of the lens cylinder, and the positive direction of the z-axis is along the object side to the imaging side on the optical axis line of the lens cylinder. r is the radial distance of any point on the surface from the z-axis, R is the vertex curvature radius of the surface. For the front surface of the lens cylinder, R > 0, and for the rear surface of the lens cylinder, R < 0. k is the conic constant. The range of the conic constant of the front surface of the lens cylinder is |k| < 30 and k ≠ 0, and the range of the conic constant of the rear surface of the lens cylinder is |k| < 30 and k ≠ 0. A4, A6, and A8 are the coefficients of the higher-order terms.

[0033] This application limits the coefficients of the higher-order terms to A4, A6, and A8, enabling the aspheric shape to go beyond the simple conic surface to finely correct the residual aberration. Each higher-order term corresponds to a higher-order radial curvature change: A4 is used to correct the primary spherical aberration and part of the higher-order spherical aberration; A6 and A8 are used to correct the higher-order spherical aberration (fifth-order and seventh-order spherical aberration) and the aberration compensation for large-aperture and high-image-height light rays. When there is still residual aberration only by adjusting k, these higher-order terms allow further fine-tuning of the curvature of the peripheral region, making the optical path of the marginal light more consistent with the on-axis light.

[0034] Further, the range of the vertex curvature radius R of the front surface of the lens cylinder is 2 - 10 mm, and the range of A4 is 0 - 10 -3 mm-3 、 The range of A6 is -10 -5 ~0 mm -5 、 The range of A8 is 0~10 -7 mm -7 , the range of the curvature radius R of the vertex of the curved surface on the rear surface of the lens column is -0.5~-30 mm, and the range of A4 is 0~10 -4 mm -3 、 The range of A6 is -10 -5 ~0 mm -5 、 The range of A8 is 0~10 -8 mm -7 。

[0035] A4 of the front surface and the rear surface of the lens column is positive. A positive A4 makes the edge of the mirror surface flatter or slightly bulged relative to the spherical surface (different combinations may result in different forms), thus delaying the convergence of the marginal rays and offsetting the positive spherical aberration; the negative A6 provides correction with the opposite trend in the more peripheral area, so that the extreme marginal rays do not deviate excessively from the focus. The combination of these higher-order terms A4, A6 and A8 adjusts the position of the light focus in different aperture regions respectively, so as to optimize the combined aberration under the conditions of multi-field of view and multi-aperture.

[0036] The curvature radius R of the vertex of the curved surface determines the curvature and the refractive power at the center of the curved surface, and is a parameter for controlling the basic refractive power of the optical system. A smaller R means a steeper surface and a stronger optical power, but at the same time it will introduce more significant spherical aberration (in the case of uncorrected) and a more curved image plane. On the contrary, a larger R means a flatter surface and a weaker optical power, and the spherical aberration and field curvature are relatively small. Therefore, in this application, the range of the curvature radius R of the vertex of the curved surface of the front surface of the lens column is set to 2~10 mm, and the range of the curvature radius R of the vertex of the curved surface of the rear surface of the lens column is -0.5~-30 mm, which can be adjusted within this range according to the specific situation of the patient, achieving a balance among the optical power, spherical aberration and field curvature, and achieving the optimal performance.

[0037] The following explains the influence mechanism of the above parameters on the aberration: (1) Influence of each parameter on spherical aberration Spherical aberration is the on-axis imaging blur caused by inconsistent focal points due to different heights of the light aperture. In the artificial cornea system, spherical aberration is one of the key factors affecting the image quality of the human eye. The optimization of spherical aberration is mainly achieved through R, k and A4.

[0038] The influence of the curvature radius R of the surface vertex on spherical aberration: When other conditions remain unchanged, a smaller R (steeper curvature) will focus the edge entrance pupil light closer to the mirror surface, resulting in positive spherical aberration (edge light is over-refracted, and the focus is further forward than the axial light); increasing R will alleviate this phenomenon. However, R must also meet the refractive power requirements of the system and cannot be increased infinitely. Therefore, in the design, R is usually used to roughly adjust the focal length to obtain the required optical power, and then the resulting spherical aberration is corrected through k and higher-order terms.

[0039] The influence of the quadratic constant k on spherical aberration: Adjusting k is one of the most effective means of correcting spherical aberration. When k decreases from 0 (spherical surface) to a negative value, the surface of the lens cylinder gradually changes to an elongated ellipsoid (oblate ellipsoid) or even a parabola. A parabola (k = –1) can focus parallel light precisely to the focal point without spherical aberration (this is the ideal situation in reflection); for refraction, a suitable negative value of k can also greatly reduce spherical aberration. Negative k makes the edge of the lens cylinder surface gradually flatten, thereby delaying the convergence position of the edge light and making it closer to the focus of the axial light. By selecting k, the peripheral light and the central light can be focused almost synchronously, thereby greatly reducing the first-order spherical aberration. The actual human cornea exhibits a mild negative spherical aberration characteristic: the average corneal anterior surface k≈–0.2 (mild ellipse), and the positive spherical aberration formed in this way is significantly reduced compared to the spherical surface.

[0040] The influence of high-order coefficients on spherical aberration: Even with the optimal k value, high-order spherical aberration may still remain, especially in the case of nonlinear deviations caused by large apertures or material refractive index. A4 can correct the residual third-order spherical aberration and further unify the focus; A6 and A8 are used to correct fifth-order and seventh-order spherical aberrations. For example, after the parabolic shape reduces most of the spherical aberration, there may still be "coma"-like high-order tails or focus tailing. At this time, by introducing A4 or A6 with appropriate amplitudes, the marginal light can be fine-tuned again to completely compress the on-axis spot size. It should be noted that the use of high-order terms should be moderate: excessively large high-order coefficients may cause drastic changes in the local curvature of the surface, leading to new aberration sources or manufacturing difficulties. Therefore, in actual design, k is often used to correct the main spherical aberration, and then A4, A6 and A8 with smaller amplitudes are used to converge the aberration to obtain on-axis imaging quality close to the diffraction limit.

[0041] (2) Effects of various parameters on coma Coma is a typical off-axis aberration, which is manifested as an elongated comet-like image of a point light source. The generation of coma is closely related to the incident height of the light and the position of the aperture stop. When the aperture is not on the surface of the optical element or the system does not meet the sine condition, the light in different aperture areas has different magnifications for the off-axis object point image, forming a comet tail.

[0042] Basic Influence of Diaphragm Position and Structure on Coma: In the human eye, the iris (diaphragm) is located behind the cornea and in front of the lens. This layout makes it impossible to simply cancel out the coma of the cornea through symmetry. Therefore, in the design of artificial corneas, it is necessary to actively correct the coma on the corneal surface. By precisely aligning the optical center of the lens column surface with the diaphragm center and adopting a rotationally symmetric lens column structure, asymmetric aberrations introduced due to tilt or eccentricity can be geometrically avoided, thereby suppressing coma. Simply put, maintaining the accuracy of system assembly and symmetry is a prerequisite for reducing coma.

[0043] Influence of Conic Constant k on Coma: The sine condition states that if the inclination angles of the exit pupil rays at different aperture heights in an optical system satisfy a constant ratio, spherical aberration and coma can be corrected simultaneously, and the system is called an aplanatic system. The selection of k plays a crucial role in achieving an approximate sine condition. When the value of k is appropriate, the aspheric surface not only eliminates spherical aberration but also makes the effective focal lengths of the rays at different apertures consistent, which is equivalent to eliminating coma. For example, the posterior surface of the lens is considered approximately parabolic, that is, the conic constant k is close to -1 to control off-axis aberrations. Similarly, in the design of the double surfaces of an artificial cornea, usually one surface (usually the posterior surface) is made close to a parabolic or hyperbolic shape (k≈-1 or lower) to satisfy the approximate sine imaging condition in the presence of a subsequent diaphragm. In this way, for off-axis rays with a small field of view within 5°, the image magnifications generated by each aperture part are basically the same after passing through the corneal refraction, thereby significantly reducing the coma tail.

[0044] Influence of Higher-Order Term Coefficients on Coma: Rotationally symmetric higher-order terms mainly act directly on axisymmetric aberrations (such as spherical aberration), but they can also indirectly affect the magnitude of coma. Specifically, by adjusting the refractive index distribution in the peripheral region through A4, A6, and A8, etc., the refraction angles of the rays at different heights can be finely tuned to make the focusing of off-axis rays more uniform. For example, if it is found in the optimization that there is still a residual coma "tail" at the 5° field of view, the magnitudes of A4 or A6 can be adjusted to slightly over-correct or under-correct the marginal rays, thereby canceling out the coma on the off-axis image plane. In practice, through the cooperation of higher-order terms and k, the coma within the range of ±5° can be significantly reduced, making the imaging of off-axis points close to a symmetric circular spot.

[0045] (3) Influence of Each Parameter on Astigmatism and Field Curvature Both astigmatism and field curvature are important indicators for describing off-axis imaging quality. Among them, astigmatism means that an off-axis object point forms images on two mutually perpendicular principal sections at different focal planes (the meridional plane and the sagittal plane foci do not coincide) after passing through an optical system, resulting in the elongation of the off-axis light spot; field curvature means that the positions of the best foci of all image points are not on the same plane but on a curved surface, and for the human eye, the ideal situation should match the curvature of the retina.

[0046] The influence of the surface vertex curvature radius R on field curvature: Field curvature is mainly determined by the distribution of the total refractive power of the system. The image surface curvature (Petzval curvature, Pittsburgh curvature) generated by a single surface is approximately proportional to its refractive power: (image surface curvature radius) ≈ (image space refractive index / refractive power). Therefore, a smaller R (higher refractive power) will result in a steeper image surface curvature, i.e., stronger field curvature; increasing R weakens the field curvature. However, in an artificial cornea, field curvature itself is not necessarily a harmful aberration because the human retina is curved. If the optical image surface curvature is close to the retina curvature, the image points can fall on the retina for clear imaging. Therefore, in design, we do not pursue completely eliminating field curvature but rather matching it. By adjusting the refractive power distribution of the front and rear surfaces (i.e., the combination of R of the front and rear surfaces), the effective Petzval curvature can be changed. For example, making the front surface bear the main refractive power and the rear surface be flatter can reduce the total field curvature; vice versa. In an artificial cornea, due to different material refractive indices, the surface vertex curvature radii of the front and rear surfaces need to cooperate with each other to reduce the total field curvature to match the retina curvature.

[0047] The influence of the conic constant k and higher-order terms on astigmatism: Astigmatism belongs to the third-order off-axis aberration, and its magnitude is affected by the effective refractive power of the lens and the distance from the aperture stop to the lens. A single rotationally symmetric optical surface cannot completely eliminate astigmatism, but reasonable shape design can slow down the growth of astigmatism. For example, a hyperbola (k < –1) will produce different refractive characteristics in the meridian / sagittal directions compared to a sphere, which may, to a certain extent, reduce the difference in focal distances in the two directions, thereby reducing astigmatism. In addition, higher-order terms (A4, A6, etc.) can indirectly affect the astigmatic focus error by changing the refraction of marginal rays. For example, when weighing coma and astigmatism in design, slightly adjusting A6 may act on both simultaneously: because it changes the incident angle dependence of peripheral rays, thereby affecting the focusing positions of off-axis rays in two cross-sections. The optimization of the conic constant k also helps in astigmatism control: because k determines the "curvature degree" of the lens, for a thin lens with a given focal power, different front and rear curvature distributions will affect its astigmatism correction ability - this is similar to the principle of the best-form lens in traditional optics. Therefore, in the optimization of an artificial cornea, the k values of the front and rear surfaces are usually adjusted simultaneously to minimize astigmatism. At the same time, since astigmatism is inseparable from field curvature (field curvature is the average curvature of the meridian and sagittal image surfaces), optimizing k and A6, A8 to reduce astigmatism will also make the field curvature flatter or more consistent with the retina curvature.

[0048] Considering the influence of the above factors on aberrations comprehensively, the parameter ranges of the lens cylinder in this application are designed as follows: the range of the surface vertex curvature radius R of the front surface of the lens cylinder is 2 - 10 mm, the range of A4 is 0 - 10 -3 mm -3 and the range of A6 is -10 -5~0 mm -5 、The range of A8 is 0 to 10 -7 mm -7 , the range of the curvature radius R of the vertex of the curved surface on the rear surface of the lens cylinder is -0.5 to -30 mm, and the range of A4 is 0 to 10 -4 mm -3 、The range of A6 is -10 -5 ~0 mm -5 、The range of A8 is 0 to 10 -8 mm -7 , the range of the conic constant of the front surface and the rear surface is ∣k∣ < 30 and k ≠ 0. According to the retinal conditions of the patient, each parameter is adjusted comprehensively within the corresponding range above, significantly reducing the aberration and thus improving the imaging quality.

[0049] Preferably, the central thickness d of the rear surface of the lens cylinder ranges from 2.2 to 4.5 mm, and the curvature radius R of the vertex of the curved surface ranges from -11.8 to -14.2 mm. The rear surface is relatively flatter than the front surface to weaken the field curvature and spherical aberration.

[0050] Preferably, the range of the conic constant k of the front surface of the lens cylinder is -1 < k < 0, and the front surface is an oblate ellipsoid surface, so that the positive spherical aberration formed is significantly reduced compared with the spherical surface. The range of the conic constant k of the rear surface of the lens cylinder is -20 < k < -1 or 2 < k < 20, and the rear surface is a hyperboloid or a prolate ellipsoid surface, satisfying the approximate sine imaging condition in the presence of a subsequent diaphragm to eliminate coma. Designed in this way, the front surface and the rear surface correct each other synergistically to compensate for the spherical aberration caused by the material and structure, achieving a high correction of spherical aberration, coma and astigmatism, and balancing between eliminating spherical aberration, eliminating coma and reducing astigmatism.

[0051] This application comprehensively considers the influence of each parameter on the aberration, limits each parameter within the above range. R controls the basic optical power and field curvature, k dominates the primary spherical aberration and a certain degree of coma and astigmatism, and A4, A6 and A8 finely correct the spherical aberration margin and take into account the off-axis aberration. Through the reasonable combination of each parameter, the on-axis and off-axis imaging quality is balanced in the narrow-field artificial cornea system.

[0052] In the practical application of an artificial cornea, biomechanical factors also affect field curvature and astigmatism. The cornea needs to bear the intraocular pressure. If the design is improper, the edge stress may cause the lens to deform, thereby introducing additional astigmatism or changes in field curvature. It is necessary to ensure that the artificial cornea can still maintain the designed curved surface shape under stress - this involves giving the structure a certain thickness and shape margin during optical design so that the deformation under intraocular pressure is minimized. The optimization of this bionic adaptation belongs to the combined consideration of mechanics and optics, which goes beyond the scope of pure optical parameter adjustment, but cannot be ignored in the optimization of higher - order aberrations. During actual design, the deformation under simulated stress can be fed back into the optical model, and the surface curvature can be iteratively optimized to compensate for potential deformation, so as to still maintain good optical performance during actual wearing.

[0053] Based on this, the central thickness d of the lens cylinder of this application is 0.5 - 5.0 mm, and the effective aperture of the lens cylinder is 1.5 - 5.0 mm, ensuring that the artificial cornea can still maintain the designed curved surface shape under stress, reducing the deformation caused by edge stress to suppress field curvature. The central thickness d and the effective aperture of the lens cylinder are adjusted within the above range according to the specific conditions of the patient's eyes.

[0054] Optionally, the material of the lens cylinder is allyl diglycol carbonate, polycarbonate, acrylic resin or optical glass, which is safe and reliable and has excellent optical and mechanical properties.

[0055] Taking the lens cylinder with an effective aperture of 2.6 mm and a material of acrylic resin (refractive index of 1.489) of this application as an example, the imaging quality of the artificial cornea lens cylinder of this application is tested by adjusting various parameters for optical simulation: Example 1 The central thickness d of the lens cylinder is 3.00 mm, and the parameters of the front and rear surfaces of the lens cylinder are shown in the following table:

[0056] Using a spherical lens cylinder with the same central thickness d, effective aperture and material as a comparison, when the light wave wavelength λ = 587.6 nm, on the optical product design and simulation software Zemax, the final RMS spot (0°, ±5°) (radius of the blur circle) of the lens cylinder in Example 1 is approximately 2.36 µm, which is significantly lower than the blur circle radius of 8.4 µm of the spherical lens cylinder, and the blur circle radius is reduced by about 3.6 times; when the spatial frequency is 50 lp / mm, the modulation transfer function (MTF) of Example 1 is 0.50, and the MFT of the spherical lens cylinder is 0.26, which is increased by about 1.9 times. The design of this application can make the MTF curve decay smoothly in the full field of view, avoiding low - frequency collapse.

[0057] As Figure 5The imaging of a spherical mirror cylinder is shown as follows, Figure 6 which is the imaging of the mirror cylinder of Example 1. By comparison, it can be clearly seen that the imaging quality of the mirror cylinder of the present application is significantly better than that of the spherical mirror cylinder.

[0058] Example 2 The central thickness d of the mirror cylinder is 4.5 mm, and the parameters of the front and rear surfaces of the mirror cylinder are shown in the following table:

[0059] When the light wave wavelength λ = 587.6 nm, the radius of the blur spot of the mirror cylinder of Example 2 is approximately 8.0 µm on the optical product design and simulation software Zemax; when the spatial frequency is 50 lp / mm, the MTF of Example 2 is 0.27.

[0060] Compared with the aforementioned spherical mirror cylinder, the radius of the blur spot of Example 2 is reduced, and the MTF is increased.

[0061] Example 3 The central thickness d of the mirror cylinder is 3.1 mm, and the parameters of the front and rear surfaces of the mirror cylinder are shown in the following table:

[0062] When the light wave wavelength λ = 587.6 nm, the radius of the blur spot of the mirror cylinder of Example 3 is approximately 7.0 µm on the optical product design and simulation software Zemax; when the spatial frequency is 50 lp / mm, the MTF of Example 3 is 0.30.

[0063] Compared with the aforementioned spherical mirror cylinder, the radius of the blur spot of Example 3 is reduced, and the MTF is increased.

[0064] Example 4 The central thickness d of the mirror cylinder is 2.9 mm, and the parameters of the front and rear surfaces of the mirror cylinder are shown in the following table:

[0065] When the light wave wavelength λ = 587.6 nm, the radius of the blur spot of the mirror cylinder of Example 3 is approximately 7.5 µm on the optical product design and simulation software Zemax; when the spatial frequency is 50 lp / mm, the MTF of Example 4 is 0.28.

[0066] Compared with the aforementioned spherical mirror cylinder, the radius of the blur spot of Example 4 is reduced, and the MTF is increased.

[0067] Example 5 The central thickness d of the mirror cylinder is 2.2 mm, and the parameters of the front and rear surfaces of the mirror cylinder are shown in the following table:

[0068] When the wavelength of the light wave λ = 587.6 nm, the radius of the blur spot of the lens cylinder of Example 3 on the optical product design and simulation software Zemax is approximately 7.65 µm; when the spatial frequency is 50 lp / mm, the MTF of Example 5 is 0.29.

[0069] Compared with the aforementioned spherical lens cylinder, the radius of the blur spot of Example 5 has decreased, and the MTF has increased.

[0070] Comparing Examples 1 - 5, it can be seen that by comprehensively adjusting the numerical values of each parameter, the final imaging quality can be adjusted; comparing Examples 2 - 4, it can be seen that only by adjusting the k value and the curvature radius of the surface vertex, the final imaging quality can also be adjusted. The adjustment of each parameter on the front surface is based on the same principle. Therefore, the parameters of the lens cylinder can be adjusted according to the specific eye conditions of the patient to adjust the imaging quality, and when adjusted within the parameter range of the present application, the imaging quality of the lens cylinder of the present application is better than that of the spherical lens cylinder.

[0071] The lens cylinder of the present application can achieve complex surface processing through ultra-precision molding technologies (such as nanoimprinting and ion beam polishing). When nanoimprinting is combined with ion beam polishing treatment, the comprehensive roughness Ra of the lens cylinder can be optimized to 0.04 - 0.06 μm. This process avoids the "dead zone" limitation of traditional cold processing, thereby improving the optical freedom without increasing the thickness.

[0072] The embodiment of the present application also discloses an artificial cornea, such as Figure 7 shown, including the aspherical artificial cornea lens cylinder 1 and the bracket 2 described in the above embodiments. The aspherical artificial cornea lens cylinder 1 is installed on the bracket 2. The center of the bracket 2 is provided with an installation hole, the installation hole is provided with internal threads, the outer wall of the lens cylinder 1 is processed with external threads, and the lens cylinder 1 is in threaded cooperation with the installation hole of the bracket 2 through the external threads on the outer wall. As Figure 7 shown, the bracket 2 includes a first support ring 21 sleeved outside the lens cylinder 1 and a second support ring 22 arranged outside the first support ring 21. The installation hole is arranged on the first support ring 21 and is located at the center of the first support ring 21. There are several connecting rods 23 evenly arranged and connecting the two between the first support ring 21 and the second support ring 22. Through this bracket 1, the support medium and environment required for tissue cell growth can be provided, ensuring the implantation effect of the artificial cornea. The embodiment of the present application also discloses an application method of the aspherical artificial cornea lens cylinder described in the above embodiments. The fixed position of the lens cylinder is: the vertex of the rear surface of the lens cylinder is 10 - 120 mm away from the retina, the focal plane is perpendicular to the optical axis, and the focal plane inclination angle is 0°. The distance between the vertex of the rear surface of the lens cylinder and the retina can be adjusted according to the specific eye conditions of the patient.

[0073] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention.

[0074] In the present invention, unless otherwise clearly specified and defined, the terms "mounted", "connected", "connected to", "fixed", etc. shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0075] In the description of this specification, the descriptions with reference to the terms "this embodiment", "one embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any at least one embodiment or example. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0076] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" can explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0077] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and simple improvements made to the substantial content of the present invention shall be included in the protection scope of the present invention.

Claims

1. An aspherical artificial corneal lens cylinder, characterized in that, The overall shape of the lens column is cylindrical. The front surface of the lens column is convex, and the rear surface is concave. The rear surface of the lens column is the surface close to the retina, and the front surface of the lens column is the surface far from the retina. Both the front surface and the rear surface of the lens column are curved surfaces and are rotationally symmetric aspherical surfaces.

2. The aspherical artificial corneal lens cylinder according to claim 1, wherein, The range of the conic constant k of the front surface and the rear surface of the lens column is |k| < 30, and k ≠ 0.

3. The aspherical artificial corneal lens cylinder according to claim 1, wherein, The design formula of the front surface and the rear surface of the lens column is: Among them, is the radial height, the z-axis represents the optical axis of the lens barrel, the positive direction of the z-axis is along the object side to the imaging side on the optical axis of the lens barrel, r is the radial distance of any point on the curved surface from the z-axis, R is the curvature radius of the vertex of the curved surface, R>0 for the front surface of the lens barrel, R<0 for the rear surface of the lens barrel, k is the conic constant, the range of the conic constant of the front surface of the lens barrel is |k|<30 and k≠0, the range of the conic constant of the rear surface of the lens barrel is |k|<30 and k≠0, and A4, A6, and A8 are the coefficients of the higher-order terms.

4. The aspherical artificial corneal lens column according to claim 3, characterized in that, The range of the curvature radius R of the curved surface vertex on the front surface of the mirror column is 2 to 10 mm, the range of A4 is 0 to 10 -3 mm -3 , the range of A6 is -10 -5 to 0 mm -5 , the range of A8 is 0 to 10 -7 mm -7 , The range of the curvature radius R of the vertex of the curved surface on the rear surface of the lens column is -0.5 to -30 mm, the range of A4 is 0 to 10 -4 mm -3 , the range of A6 is -10 -5 to 0 mm -5 , the range of A8 is 0 to 10 -8 mm -7 .

5. The aspherical artificial corneal lens cylinder according to claim 4, wherein The range of the conic constant k of the front surface of the lens column is -1 < k < 0, and the range of the conic constant k of the rear surface of the lens column is -20 < k < -1 or 2 < k < 20.

6. The aspherical artificial corneal lens cylinder according to any one of claims 1-5, characterized in that, The material of the lens column is allyl diglycol carbonate, polycarbonate, acrylic resin or optical glass.

7. An artificial cornea, characterized in that, It includes the aspherical artificial cornea lens column according to any one of claims 1-6 and a stent, and the aspherical artificial cornea lens column is installed on the stent.

8. A method for applying the aspherical artificial corneal lens cylinder according to any one of claims 1-6, characterized in that, The fixed position of the lens column is: the vertex of the rear surface of the lens column is 10-120 mm away from the retina, the focal plane is perpendicular to the optical axis, and the focal plane inclination angle is 0°.

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