A continuous vision artificial lens for wavefront modulation

Abstract

The present invention provides a continuous vision artificial lens for wavefront regulation, which deeply adjusts the wavefront aberration of the artificial lens through Zernike polynomials. By controlling the aberration of different regions of the optical surface of the artificial lens, the distribution of the wavefront is regulated, so that the focus is no longer concentrated on a certain point, but continuously distributed within a certain depth of focus (1.5D to 3.5D), extending the depth of field and providing continuous and seamless switching of vision from far to near without the need to switch the focus between different distances. Through Zernike wavefront regulation, the connection between the foci is smoother, there is no fixed focus, a fully continuous visual range is provided and the light energy utilization rate is high. Therefore, patients can obtain higher low-light vision after surgery.

Description

Technical Field

[0001] This application relates to an intraocular lens in the field of medical devices, and specifically to a continuous vision intraocular lens with wavefront regulation. Background Art

[0002] An intraocular lens is an implantable medical device made of a polymer material, used to replace the aging natural lens of the human eye, and placed in the anterior chamber or posterior chamber of the human eye to treat cataracts or refractive errors.

[0003] The optical design of multifocal intraocular lenses is generally divided into diffractive and refractive types. They focus light into multiple concentrated foci in different ways, which can increase the viewing distance of patients to a certain extent. However, due to the relatively high light concentration at different foci, glare, halos or starburst phenomena occur in low-light or dark environments at night, affecting visual comfort. At the same time, since multifocal intraocular lenses provide at least two or more foci, it may be difficult for the brain to adapt to focus switching, resulting in visual confusion or blurring. For example, the patent with publication number CN110062899A titled "Intraocular Lens with Zone-by-Zone Step Height Control" constructs a Fresnel zone by manufacturing a serrated optical step structure on the front surface or the back surface of the lens. When parallel light enters the human eye and passes through the Fresnel zone, it is diffracted and focused onto several different diffraction orders. Different diffraction orders have different refractive powers and different light energy distribution ratios. At the same time, a large part of the light is diffracted to useless foci, forming stray light and causing visual effects. Therefore, low light energy utilization is also a major problem of diffractive intraocular lenses.

[0004] All of the above reasons have caused various difficulties in the clinical use of multifocal intraocular lenses. Therefore, the intraocular lens with extended depth of field has emerged. However, there are also several common problems with the existing intraocular lenses with extended depth of field. For example, the patent with the publication number CN104755012A and the title of "Multi-ring lenses, systems, and methods for extending the depth of focus" uses the Echelette diffraction grating technology. Through a special diffraction grating design, the light is dispersed to different focal points to extend the depth of field, enabling patients to obtain clear vision at different distances. It uses two small-step diffraction steps to design a small additional optical power diffraction crystal. Coupled with the natural depth of field of the human eye, the effect of depth of field delay can be achieved. However, it is still based on diffraction technology, and the problem of stray light cannot be avoided, and the light energy utilization rate is lower than 85%. For example, the patent with the publication number CN115778631A and the title of "Ophthalmic lens" discloses that by adjusting the high-order term coefficient of the aspheric surface, the concentration of the main focus is adjusted to make its light spot spread, achieving the effect of extended depth of field. However, the depth of field obtained by only adjusting the aspheric coefficient is very limited, and the range of its depth of focus is relatively small, making it difficult to achieve the effect of continuous visual range. The patent with the publication number CN 110711050 A and the title of "An intraocular lens" discloses a technology that uses Zernike polynomials to characterize the optical surface to improve traditional aspheric intraocular lenses and astigmatic intraocular lenses. By making one of the surfaces an asymmetric structure, the aberration caused by the cornea can be reduced, and a better effect of distant vision can be achieved to a certain extent. However, it cannot achieve continuous visual range, and good vision cannot be obtained at medium and short distances, and at the same time, the continuity of the visual range is lost. Summary of the Invention

[0005] In view of the problem of discontinuous visual range of the existing intraocular lens in the prior art, the present invention provides an intraocular lens. By separately using Zernike polynomials in different regions to deeply adjust the wavefront aberration of the intraocular lens, and by controlling the aberration of different regions of the optical surface of the intraocular lens, the distribution of the wavefront is regulated, so that the focus is no longer concentrated on a certain point, but continuously distributed within a certain depth of focus (1.5D to 3.5D), thereby extending the depth of field and providing continuous and seamless switching vision from far to near without the need to switch the focus between different distances. The specific technical solutions are as follows:

[0006] An intraocular lens for extending the depth of field through wavefront regulation, the intraocular lens comprising an optical part and a mechanical part, one surface of the optical part being set as a free surface formed by Zernike wavefront regulation, and the corresponding other surface being a spherical or aspherical surface; the mechanical part being a supporting loop;

[0007] The free surface is successively divided into two or more continuous regions from the center outwards, and the aberration type of each region is selected and set according to Zernike polynomials to determine the aberration value , adjacent regions are set to different types of aberrations; the relational expression of the surface curve of the freeform surface in polar coordinates is as follows:

[0008] (1)

[0009] Wherein, is the working wavelength, n2 is the refractive index of the intraocular lens, n1 is the refractive index of the aqueous humor, is the polar coordinate form of the wavefront function of the surface of the intraocular lens, is adjusted and deduced and confirmed by formulas (2)-(4),

[0010] (2)

[0011] (3)

[0012] (4)

[0013] Where: n is the radial order (n≥0), m is the angular frequency (∣m∣≤n, and n−∣m∣ is an even number), ρ is the normalized radial coordinate (0≤ρ≤1), θ is the angular coordinate (0≤θ<2π); is the adjustment coefficient, representing the weight of the corresponding aberration, with a value range of -5 to 10; k is the integer index variable in the summation formula, starting from 0 and gradually increasing until reaching the upper limit .

[0014] The polar coordinate relational expression (1) of the present invention can be transformed into the Cartesian coordinate relational expression of the sag Zf(r) of the freeform surface and the radial coordinate r, the distance from the center point of the lens on the optical axis, through r = r0 , Zf(r) = r0 .

[0015] Furthermore, the supporting loop is an L-shaped, C-shaped or plate-shaped loop.

[0016] Furthermore, the diameter range of the freeform surface is 5.5 mm to 7.5 mm, and it is successively divided into 2-5 regions from the center outwards, with the diameter of each region increasing by 1-1.5 mm.

[0017] Furthermore, the Zernike polynomial can be selected from 0 to multiple orders, and the aberration types of each region are translation, defocus, astigmatism, spherical aberration, tilt or coma, etc.

[0018] Furthermore, the aspherical optical surface expression is as follows:

[0019] (5)

[0020] Among them, Z(r) is the aspheric surface function, r is the radial coordinate, which is the distance from the center point of the lens on the optical axis, R is the curvature radius of the basic spherical surface, K is the conic coefficient, is the aspheric high-order term coefficient, i = 1, 2, …, n, where n is a natural number not less than 1; when K = 0 and all the aspheric high-order term coefficients are 0, the surface is a spherical surface.

[0021] Among them, 0 - multi-order Zernike polynomials can be used in the present invention. The following Table 1 symbolically lists the first 4 orders, and the wavefront diagrams of the corresponding aberration patterns are as Figure 1 shown.

[0022] Table 1

[0023]

[0024] In the present invention, by adjusting the corresponding weights of different aberrations, an adjusted optical surface is obtained according to Equations (2)-(4). Specifically, during the adjustment and confirmation, computer calculation is used, and the setting ratio of the aberration weights of different types is confirmed by referring to the focus focusing situation after ray tracing. After placing the lens in the theoretical eye model and modifying the aberration weights of different regions, real-time optimization adjustment is carried out until the optimal solution is obtained, that is, the best weight value that extends the focus without generating breakpoints.

[0025] The intraocular lens of the present invention that performs wavefront regulation through Zernike polynomials in regions has the following advantages: it can achieve no stray light, and the light energy utilization rate is 100%. All incident light rays will become part of the effective focus, thus avoiding phenomena such as glare; the Zernike polynomial has a high degree of wavefront regulation, avoiding limitations between regions, freely controlling the aberrations of different regions, directly controlling the imaging result, and then converting it into the elevation of the free-form surface for processing the surface type, enabling the formation of a highly liberalized free-form surface on the optical surface of the intraocular lens. Compared with the high-order aspheric surface, it can achieve a higher depth of field range; through Zernike wavefront regulation, by controlling the adjustment coefficients of different regions, the connection between foci is smoother, there is no fixed focus, and compared with the focus formed by diffraction, it will not be concentrated and has useless diffraction orders, avoiding the formation of stray light, thereby reducing visual interference; because it provides a full continuous visual range and has a high light energy utilization rate, patients can obtain a higher dark vision after surgery. Description of the Drawings

[0026] Figure 1 is the wavefront diagram of the aberration pattern;

[0027] Figure 2 is the schematic structural diagram of the intraocular lens;

[0028] Figure 3It is the wavefront curve of the freeform surface in Example 1;

[0029] Figure 4 It is the schematic diagram of the sagittal height distribution in Example 1;

[0030] Figure 5 It is the comparison diagram of the intraocular lens in Example 1 with the single - focus and multi - focus intraocular lenses in the prior art;

[0031] Figure 6 It is the wavefront curve of the freeform surface in Example 2;

[0032] Figure 7 It is the schematic diagram of the sagittal height distribution in Example 2;

[0033] Figure 8 It is the comparison diagram of the intraocular lens in Example 2 with the single - focus and multi - focus intraocular lenses in the prior art. Detailed implementation manners

[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0035] Example 1

[0036] In this embodiment, the structure of the intraocular lens is as Figure 2 shown. The diameter of the optical part of its freeform surface is 6 mm. The freeform surface is divided into 4 regions. In the first region, the zero aberration is adjusted through the Zernike polynomial to achieve good distant vision; in the second region, the surface range is adjusted to positive spherical aberration through the Zernike polynomial, and its weight is set to 0.42 to shift the distant vision to the middle distance. However, through the setting of the aberration coefficients, the formation of visual breakpoints is avoided, and the depth of focus is made continuous; in the third region, while increasing the defocus aberration, negative spherical aberration is increased, and its weight distribution is set to 0.27 and - 0.09, so that the vision shifts to the near distance while being continuous with the middle vision. In this way, a continuous visual range can be formed at three viewing distances of far, middle, and near; in the fourth region, it is set as a zero - aberration region to enhance the vision in the dark environment. The wavefront curve of the freeform surface set in this way is as Figure 3 shown. After substituting the basic optical power, the wavefront is transformed into the sagittal height distribution and added to the Cartesian coordinate system. Then the sagittal height distribution of this embodiment is as Figure 4 shown.

[0037] Another surface in this embodiment is set as a high-order aspherical surface, and the detailed setting parameters of the two different optical surfaces are shown in Table II and Table III below. In this way, patients implanted with this intraocular lens can see clearly at far, medium, and near distances simultaneously, and visual interference is greatly reduced; this embodiment is placed in the model eye required by "ISO 11979-2:2024, 5th Edition, Ophthalmic Implants - Intraocular Lenses" to test the response curve of its modulation transfer function (MTF) with defocus. Compared with the single-focus and multi-focus intraocular lenses of the prior art, the results are as Figure 5 shown. Among the response curves of its MTF with defocus, the value of MTF does not continuously drop below 0.1, and the defocus depth range where MTF is greater than 0.1 is greater than 2.5D, with good continuous visual range, and the continuity of its visual range is much better than that of the prior art.

[0038] Table II:

[0039]

[0040] Table III:

[0041]

[0042] Example 2

[0043] In this embodiment, the diameter of the optical part of the freeform surface is 6.5 mm. The freeform surface is divided into 3 regions. In the first region, it is adjusted to positive spherical aberration through Zernike polynomials, and the far focus is directly displaced towards the middle distance, with its weight distribution set to 0.33; in the second region, while setting defocus aberration for this surface through Zernike polynomials, negative spherical aberration is added to set the near focus, with its weight distribution set to 0.56 and -0.12; the third region is set as a region where the spherical aberration gradually increases with the radial distance, and its weight value is 0.11r (r is the radial distance from the surface to the center), enhancing vision in the dark environment while increasing the continuity between near vision and intermediate vision. The wavefront curve of the freeform surface set in this way is as Figure 6 shown. After substituting the basic optical power, adding a few drops to the wavefront conversion sagittal height distribution, the sagittal height distribution of this embodiment is as Figure 7 shown.

[0044] Another surface in this embodiment is set as a high-order aspherical surface, and the detailed setting parameters of the two different optical surfaces are shown in the following table. At this time, the surface shapes of the front and rear surfaces of the intraocular lens of this embodiment of the present invention are obtained. This embodiment is placed in the model eye required by "ISO11979-2:2024, 5th Edition, Ophthalmic Implants - Intraocular Lenses" to test the response curve of its modulation transfer function (MTF) with defocus. Compared with the single-focus and multi-focus intraocular lenses of the prior art, the results are as Figure 8As shown, in the MTF response curve with respect to defocus, the value of MTF does not continuously fall below 0.1, and the depth of focus range where MTF is greater than 0.1 is greater than 3D, with good continuous visual range. It can be seen that the continuity of its visual range is much better than that of the prior art, and it also has good vision at various viewing distances, achieving the effect of full visual range continuity.

[0045] Table 4:

[0046]

[0047] Table 5:

[0048]

[0049] The above has described in detail the preferred embodiments of this patent. However, this patent is not limited to the above embodiments. Within the scope of knowledge possessed by ordinary technicians in the art, various changes can be made without departing from the gist of this patent.

Claims

1. A continuous vision artificial lens for wavefront modulation, characterized in that: The intraocular lens comprises an optical part and a mechanical part. One surface of the optical part is set as a free-form surface formed by Zernike wavefront modulation, and the corresponding other surface is a spherical surface or an aspherical surface; the mechanical part is a supporting loop. The diameter range of the freeform surface is 5.5 mm to 7.5 mm, which is successively divided into 2 to 5 regions from the center outwards, with the diameter of each region increasing by 1 - 1.5 mm. The aberration type of each region is selected and set according to the Zernike polynomial, and the aberration value W(ρ,θ) is determined. Adjacent regions are set with different types of aberrations; Zf(ρ,θ) is the polar coordinate function of the surface curve of the freeform surface, and its relationship with the wavefront polar coordinate function of the intraocular lens surface is as follows: where λ is the working wavelength, n2 is the refractive index of the intraocular lens, and n1 is the refractive index of the aqueous humor. Adjust and derive for confirmation through equations (2)-(4): where: n is the radial order, n≥0; m is the angular frequency, ∣m∣≤n, and n - ∣m∣ is an even number; is the radial function of the Zernike polynomial; ρ is the normalized radial coordinate, 0≤ρ≤1; θ is the angular coordinate, 0≤θ<2π; is the adjustment coefficient, representing the weight of the corresponding aberration, with a value range of -5 to 10; k is the integer index variable in the summation formula, starting from 0 and gradually increasing until reaching the upper limit 2. The continuous vision artificial lens for wavefront regulation according to claim 1, wherein: The supporting loop is an L-shaped loop, a C-shaped loop or a plate-shaped loop.

3. The continuous vision artificial lens for wavefront modulation according to claim 1, wherein: The Zernike polynomial adopts 0 - multiple orders, and the aberration types in each region are translation, defocus, astigmatism, spherical aberration, tilt or coma.

4. The continuous vision artificial lens for wavefront regulation according to claim 1, characterized in that: The surface type expression of the aspherical optical surface is as follows: Wherein, Z(r) is the aspherical surface type function, r is the radial coordinate, the distance from the center point of the lens on the optical axis, R is the curvature radius of the basic spherical surface, K is the conic coefficient, αi is the aspherical high-order term coefficient, i = 1, 2,..., n, and n is a natural number not less than 1; when K = 0 and all the aspherical high-order term coefficients αi are 0, the surface type is a spherical surface.

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