CN117562707A - Aspheric diffraction type large focal depth artificial lens and design method thereof - Google Patents
Aspheric diffraction type large focal depth artificial lens and design method thereof Download PDFInfo
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- 238000013461 design Methods 0.000 title claims description 21
- 238000000034 method Methods 0.000 title claims description 18
- 230000003287 optical effect Effects 0.000 claims abstract description 55
- 239000013078 crystal Substances 0.000 claims abstract description 42
- 230000004075 alteration Effects 0.000 claims abstract description 27
- 239000000463 material Substances 0.000 claims abstract description 12
- 210000001525 retina Anatomy 0.000 claims description 10
- 238000005457 optimization Methods 0.000 claims description 9
- 230000004438 eyesight Effects 0.000 claims description 8
- 238000003384 imaging method Methods 0.000 claims description 7
- -1 acrylic ester Chemical class 0.000 claims description 6
- 210000001742 aqueous humor Anatomy 0.000 claims description 4
- 238000004364 calculation method Methods 0.000 claims description 4
- 102100029469 WD repeat and HMG-box DNA-binding protein 1 Human genes 0.000 claims description 3
- 101710097421 WD repeat and HMG-box DNA-binding protein 1 Proteins 0.000 claims description 3
- 239000002178 crystalline material Substances 0.000 claims description 3
- 238000004088 simulation Methods 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 3
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 abstract 1
- 238000002513 implantation Methods 0.000 description 7
- 208000002177 Cataract Diseases 0.000 description 6
- 238000010586 diagram Methods 0.000 description 3
- 230000002980 postoperative effect Effects 0.000 description 3
- 206010036346 Posterior capsule opacification Diseases 0.000 description 2
- 230000004308 accommodation Effects 0.000 description 2
- 210000004087 cornea Anatomy 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000003801 milling Methods 0.000 description 2
- 231100000956 nontoxicity Toxicity 0.000 description 2
- 230000000007 visual effect Effects 0.000 description 2
- 206010061218 Inflammation Diseases 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 201000009310 astigmatism Diseases 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 230000004313 glare Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 230000008595 infiltration Effects 0.000 description 1
- 238000001764 infiltration Methods 0.000 description 1
- 230000004054 inflammatory process Effects 0.000 description 1
- 208000001491 myopia Diseases 0.000 description 1
- 201000010041 presbyopia Diseases 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/02—Prostheses implantable into the body
- A61F2/14—Eye parts, e.g. lenses, corneal implants; Implanting instruments specially adapted therefor; Artificial eyes
- A61F2/16—Intraocular lenses
- A61F2/1613—Intraocular lenses having special lens configurations, e.g. multipart lenses; having particular optical properties, e.g. pseudo-accommodative lenses, lenses having aberration corrections, diffractive lenses, lenses for variably absorbing electromagnetic radiation, lenses having variable focus
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/02—Prostheses implantable into the body
- A61F2/14—Eye parts, e.g. lenses, corneal implants; Implanting instruments specially adapted therefor; Artificial eyes
- A61F2/16—Intraocular lenses
- A61F2/1613—Intraocular lenses having special lens configurations, e.g. multipart lenses; having particular optical properties, e.g. pseudo-accommodative lenses, lenses having aberration corrections, diffractive lenses, lenses for variably absorbing electromagnetic radiation, lenses having variable focus
- A61F2/1616—Pseudo-accommodative, e.g. multifocal or enabling monovision
- A61F2/1618—Multifocal lenses
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/02—Prostheses implantable into the body
- A61F2/14—Eye parts, e.g. lenses, corneal implants; Implanting instruments specially adapted therefor; Artificial eyes
- A61F2/16—Intraocular lenses
- A61F2/1613—Intraocular lenses having special lens configurations, e.g. multipart lenses; having particular optical properties, e.g. pseudo-accommodative lenses, lenses having aberration corrections, diffractive lenses, lenses for variably absorbing electromagnetic radiation, lenses having variable focus
- A61F2/1654—Diffractive lenses
- A61F2/1656—Fresnel lenses, prisms or plates
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/02—Prostheses implantable into the body
- A61F2/14—Eye parts, e.g. lenses, corneal implants; Implanting instruments specially adapted therefor; Artificial eyes
- A61F2/16—Intraocular lenses
- A61F2002/1681—Intraocular lenses having supporting structure for lens, e.g. haptics
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2210/00—Particular material properties of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2210/00—Particular material properties of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
- A61F2210/0061—Particular material properties of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof swellable
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2240/00—Manufacturing or designing of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
- A61F2240/001—Designing or manufacturing processes
Abstract
An artificial lens with large focal depth and aspheric diffraction type is composed of an optical area with binary diffraction surface and aspheric surface. The hydrophilic acrylate material for artificial crystal is prepared through introducing binary surface to one surface of artificial crystal and optimizing the phase coefficient of binary surface to form two or more focuses. And designing the other surface to be an aspheric surface, optimizing the curvature radius and the high-order aspheric coefficients of the aspheric surface, correcting the spherical aberration of the crystal, enabling each focus formed by the diffraction surface to have positive and negative different spherical aberration, providing large focal depth, obtaining the surface shape of the optical element after running the program, drawing a mechanical processing original image by utilizing AutoCAD according to the obtained data, designing the shape of a loop to be an improved C loop, and finally producing the hydrophilic diffraction type large focal depth artificial crystal meeting the requirements.
Description
Technical Field
The invention relates to an artificial lens and a design method thereof, in particular to an aspherical diffraction type large focal depth artificial lens and a design method thereof.
Background
The ECCE combined artificial lens implantation of the extracapsular cataract extraction has been recognized as a safe and effective rehabilitation operation, but the IOL clinically used at present is mostly a single-focus artificial lens, the eye has good vision after the operation, but the adjusting function is lost, most patients need to wear a near-purpose lens after the operation, and certain inconvenience is brought to life. The natural lens of the human eye, due to the accommodation mechanism, can change its shape, refractive index, radius and thickness over time, thereby changing its focal length, i.e. it has the ability to continue the viewing path. After the natural lens is removed by cataract surgery, the traditional single focus artificial lens is implanted, the original adjusting capability of the eye is lost, the eye can see the far object clearly, and the eye is needed to be worn when reading, so that the experience is poor.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides an aspherical diffraction type large focal depth artificial lens and a design method thereof, and solves the technical problems of single-focus artificial lenses in the prior art.
The technical scheme of the invention is as follows: an aspherical diffraction type large focal depth artificial lens comprises an optical zone, wherein one surface of the optical zone is a binary diffraction surface type, and the other surface of the optical zone is an aspherical surface type. The optical area is provided with a supporting tab, and the supporting tab and the optical area are of an integrated structure. The support tab comprises two C-shaped structures which are symmetrically arranged at the outer edge of the optical zone. The supporting loop is provided with a mountain-shaped long through hole. The artificial lens is made of hydrophilic acrylic ester materials.
The design method of the aspheric diffraction type large focal depth artificial lens comprises the following steps:
1) Calculating the center thickness and the curvature radius of the crystal when the focal power is +5.0D < -32.0D > according to the requirement;
the specific method comprises the following steps:
according to requirements, the diameter of an optical zone of which the expansion coefficient is 1.1201 after the hydrophilic artificial crystal absorbs water and expands is 5.75mm, the thickness of a crystal loop is 0.28mm, and the curvature radius R and the center thickness tc of the artificial crystal are determined according to the optical power calculation shape and the geometric shape, wherein F is the optical power of the artificial crystal, and the units are diopters (D) and F b ＝(n IOL -n med )/R b F is the front surface optical power f ＝(n IOL -n med )/R f N is the back surface optical power IOL The refractive index of the crystalline material is 1.4571, n med For the refractive index of the surrounding environment, 1.336 is typically taken as a simulation in the case of an intraocular lens. The hydrophilic intraocular lens is designed to be equally biconvex, so R f ＝R b R is given by
The center thickness and radius of curvature of the crystal at optical power +5.0D— +32.0D are calculated according to the above formula, and the optical power takes a point every 0.5D.
2) Design of binary diffraction surface type: according to the Huygens-Fresnel diffraction principle, the light energy is distributed on diffraction focuses with different distances by utilizing the diffraction principle of binary surfaces,
in ZEMAX optical design software, the phase expression of the binary plane is:
wherein A is i (i=1, 2, …) is the i-th order phase coefficient, ρ is the normalized radius, the phase coefficient of the binary plane is optimized such that the-1 order diffraction focus is on the retina when the object distance is infinity, or the +1 order diffraction focus is on the retina when the object distance is near the vision network, the power distribution is theoretically calculated, and the light intensity distribution characteristics;
setting the surface of an artificial lens as a spherical surface, introducing a binary diffraction surface type on one spherical surface, distributing light energy on diffraction focuses of different far and near levels, if each band is etched with 2 steps, the light energy is mainly distributed on +1 and-1 diffraction orders, the energy of each order accounts for 40.5% of the total energy, diopters of a far point and a near point are respectively set, the difference value of the two is +1D, introducing an optimization function, optimizing an optical system, and finally obtaining the diffraction multifocal artificial lens;
the height h of the slope ring is calculated, and the structural characteristics of the binary phase surfaces of the second order can know that the phase depth of each slope ring is pi, so that the method comprises the following steps:
λ 0 ＝546nm，n IOL the refractive index of the hydrophilic material is 1.4571, nmed is the refractive index of aqueous humor of human eyes is 1.336, and h is approximately equal to 2 mu m after the hydrophilic material is brought into a number; and the surface shape of the binary optical element is obtained after the above operation is optimized.
3) Design of an aspheric surface:
the front and rear surfaces of the artificial lens are set to be even-order aspheric surfaces, and the surface type of the aspheric artificial lens surface is described as follows:
c is the curvature; r is the radius; k is a conic coefficient;
the optimal aspheric surface is realized by optimizing the k value and the high-order aspheric surface coefficient, the high-order aspheric surface design adopts the high-order coefficient, and the more the high-order coefficient is, the more aberration types are corrected, the higher the imaging quality is.
4) According to the diffraction double focal points, different additional optical powers of the far focal point and the near focal point are adopted, spherical aberration is set, an optimization function is added, the far focal point is set to be positive spherical aberration, the near focal point is set to be negative spherical aberration, quadric surface coefficients and high-order aspheric coefficients are set to be variables, the crystal surface type is optimized, and large focal depth artificial crystal optical model data are obtained.
5) Inputting the obtained data into zemax software to obtain the large focal depth continuous view artificial lens, wherein the specific method comprises the following steps: and inputting the obtained data into zemax software, setting one surface as an aspheric surface, setting the other surface as a binary diffraction surface, setting an optimization function, wherein the basic focal power is 20D, the additional focal power is +1D, the bifocal is set, the far focal point is a positive spherical aberration, the near focal point is a negative spherical aberration, setting a quadric surface coefficient, a high-order aspheric surface coefficient as a variable, setting a phase coefficient of the binary surface as a variable, and optimizing the crystal surface type to obtain the large focal depth continuous view artificial crystal.
The beneficial effects of the invention are:
1) One surface of the large focal depth artificial lens optical part is in a binary diffraction surface type, the other surface is in an aspheric surface type, and the aspheric surface is matched with multiple focuses for use, so that the focal depth extension artificial lens can be designed, and continuous vision is realized.
2) The design of the C-loop artificial lens support loop is improved, and the phenomena of rotation, deflection, inclination and the like of the artificial lens in the eye due to instability after the artificial lens is implanted into a capsular bag are avoided. The design improves the mechanical property and reduces the risk of post-expansion of the patient after implantation.
3) The hydrophilic material is acrylic ester, so that minimally invasive cataract crystal implantation operation can be realized, and complications such as postoperative inflammation, postoperative astigmatism, after cataract and the like can be reduced. The characteristics of the material can avoid the turbidity of the crystals caused by the infiltration of intraocular tissue fluid after the implantation of the crystals, can be highly purified, and has stable properties and excellent transparency. The refractive index is higher and is 1.4571 at 37 ℃, so that the intraocular lens with the same diopter can be made thinner, and the hydrophilic material is more suitable for small incision implantation, and a large number of physicochemical and toxicological researches indicate that the acrylic ester has excellent stability and biocompatibility, no toxicity and safe implantation in eyes.
Drawings
FIG. 1 is a schematic diagram of a diffractive large depth of focus intraocular lens;
FIG. 2 is a schematic diagram of a zemax simulated diffraction type large depth of focus intraocular lens;
FIG. 3 is a defocus MTF profile;
FIG. 4 is a perspective view of an artificial crystal;
fig. 5 is an enlarged view of an artificial diffraction torus.
Detailed Description
In order that the present application may be understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. The following embodiments are illustrative of the present invention, but are not intended to limit the scope of the invention. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Theoretical basis:
1. multifocal intraocular lens: in the same way, when a person looks near, the near object point can still form two image points after passing through the multifocal intraocular lens, wherein the far image point is positioned behind the retina, the diffuse spots are formed at the retina, and the near image point can just fall onto the retina. The appearance of the multifocal intraocular lens (multi-focus intraocular lens) ends the history of no accommodation of the intraocular lens, has good far-near vision after operation, and most patients do not need to wear glasses at close distance, thus improving the visual effect and life quality of the patients. The dependence on spectacles is low.
2. Diffractive multifocal intraocular lens: the diffractive multifocal intraocular lens is designed according to the huygens-fresnel diffraction principle, the most typical structure being that one surface of the optic is a smooth sphere with the refractive power of a monofocal lens, and the other surface is arranged with a plurality of concentric annular microscopic ramp rings with the diffractive power, which can cause light entering the eye to form two or more foci simultaneously. The large focal depth artificial lens adopts a diffraction type multifocal artificial lens design mode, prolongs the focal point of eyes and provides continuous vision. The focal point is prolonged by diffraction of the height, width and contour of each slope ring and aspheric surface control spherical aberration, and the height and contour of the diffraction surface are optimized, namely the phase of light rays in each area is changed, so that the constructive interference of light rays in different areas leads to the prolongation of the focal point. Constructive interference occurs over a range of distances. The large focal depth artificial lens can correct cataract and presbyopia. Can provide middle and far high quality vision within a certain distance, realize continuous vision, enhance contrast and greatly reduce the occurrence probability of visual interference such as postoperative halation, glare and the like, especially at night. The dependence on spectacles is low.
3. Aspheric surface: the spherical aberration of the crystal can be well controlled by introducing the aspheric surface, the spherical aberration of the crystal is designed to be an expected value by controlling parameters such as the surface type, the high-order aspheric surface coefficient and the like, and the spherical aberration of the cornea is synthesized, so that the cataract patient has better functional vision after operation. The traditional spherical artificial lens has positive Zernike spherical aberration, has similar refractive behavior to the aged artificial lens, and can not compensate positive cornea spherical aberration, so that the imaging quality of the human eye after operation is not ideal. The appearance of wave front aberration technology makes it possible to raise the imaging quality of eye after cataract operation, and the application of the technology in artificial lens design and cataract operation provides new thought and method for aspheric surface development and clinical result verification. The design of the high-order aspheric surface enables the imaging quality to be more approximate to that of natural crystals.
The concrete structure is as follows:
fig. 4 is a perspective view of an intraocular lens, wherein the intraocular lens 1 comprises an optical zone 2 and a supporting tab 3, the optical zone 2 and the supporting tab 3 are in an integrated structure, the optical zone 2 is used for converging light on a retina, the optical zone 2 is divided into a binary diffraction surface type 2a and an aspheric surface type 2b, the binary diffraction surface type 2a and the aspheric surface type 2b can be used as binary diffraction surface type or aspheric surface type, and a diffraction ring 4 is arranged on the binary diffraction surface type. Fig. 5 shows an enlarged view of the diffraction ring on the binary diffraction surface type, the detailed surface type of which is as shown in fig. 5, and the action of the supporting loop 3 is to play a role of fixing and stabilizing after being implanted into the capsular bag, so that the artificial lens can be firmly fixed in the capsular bag. Specifically, the outer surface of the optical zone 2 is provided with a supporting tab 3, the supporting tab 3 comprises two C-shaped structures, and the two C-shaped structures are symmetrically arranged at the outer edge of the optical zone 2. The supporting loop 3 is provided with a mountain-shaped long through hole for increasing supporting force, so that the crystal is more stable after being implanted. The artificial lens 1 is made of hydrophilic acrylic ester material, and acrylic ester has excellent stability and biocompatibility, no toxicity and safe implantation in eyes.
The specific method comprises the following steps:
1. according to requirements, the diameter of the optical zone of the hydrophilic artificial crystal after water absorption expansion (expansion coefficient is 1.1201) is 5.75mm, the thickness of the crystal loop is 0.28mm, and the curvature radius R and the center thickness tc of the artificial crystal are determined according to the optical power calculation shape and the geometric shape, wherein F is the optical power of the artificial crystal, and the units are diopters (D) and F b ＝(n IOL -n med )/R b F is the front surface optical power f ＝(n IOL -n med )/R f N is the back surface optical power IOL The refractive index of the crystalline material is 1.4571, n med For the refractive index of the surrounding environment, 1.336 is typically taken as a simulation in the case of an intraocular lens. The hydrophilic intraocular lens is designed to be equally biconvex, so R f ＝R b ＝R。
Then there is
The center thickness and radius of curvature of the crystal at optical power +5.0D— +32.0D are calculated according to the above formula, and the optical power takes a point every 0.5D.
2. The binary diffraction surface type part specifically comprises: according to the Huygens-Fresnel diffraction principle, the light energy is distributed on diffraction focuses with different distances by utilizing the diffraction principle of a binary plane.
In ZEMAX optical design software, the phase expression of the binary plane is:
wherein A is i (i=1, 2, …) is the i-th order phase coefficient, this design choice a i ρ is the normalized radius. The phase coefficients of the binary surfaces are optimized such that the object distance is infinity (far focus), -the 1 st order diffraction focus is on the retina, or the object distance is near the optic network (nearFocal point), the +1st order diffraction focal point is on the retina. Theoretically calculating the focal power distribution and the light intensity distribution characteristic.
The surface of the artificial crystal is set as a spherical surface, a binary diffraction surface type is introduced on one spherical surface, light energy is distributed on diffraction focuses of different levels of far and near, if 2 steps are etched in each wave band, the light energy is mainly distributed on +1 and-1 diffraction orders, and the energy of each order accounts for 40.5% of the total energy. And respectively setting diopters of a far point and a near point, wherein the difference value of the diopters is +1D, (or +1.5D, +2D, +2.5D.) and the diopters are +1D, introducing an optimization function, optimizing an optical system and finally obtaining the diffraction multifocal intraocular lens.
The height h of the slope ring is calculated, and the structural characteristics of the binary phase surfaces of the second order can know that the phase depth of each slope ring is pi, so that the method comprises the following steps:
λ 0 ＝546nm，n IOL the refractive index of the hydrophilic material is 1.4571, n med The refractive index of aqueous humor of human eye is 1.336, and h is approximately equal to 2 mu m after the aqueous humor is taken into the figure.
And the surface shape of the binary optical element is obtained after the above operation is optimized. A diffraction effect as shown in fig. 1 can be reached.
3. The aspheric surface type part specifically comprises: the front and rear surfaces of the artificial lens are set to be even-order aspheric surfaces, and the surface type of the aspheric artificial lens surface is described as follows:
curvature (inverse of radius of curvature) r: conic coefficient (quadric coefficient).
The optimal aspheric surface is realized by optimizing the k value and the high-order aspheric surface coefficient, the high-order aspheric surface design adopts the high-order coefficient, and the more the high-order coefficient is, the more aberration types are corrected, the higher the imaging quality is.
4. According to the different additional powers of the far focus and the near focus of the diffraction bifocal, spherical aberration is set, an optimization function is added, the far focus is set to be positive spherical aberration, the near focus is set to be negative spherical aberration, quadric surface coefficients and high-order aspheric coefficients are set to be variables, the crystal surface type is optimized, and the large focal depth artificial crystal optical model is obtained. Fig. 2 is a schematic diagram of a diffractive large depth of focus intraocular lens simulated by zemax software.
In addition, the aspheric diffraction type large focal depth artificial lens can be not limited to double focuses, when the focal depth is required to be larger, the number of focuses can be increased, and correspondingly, the spherical difference value is increased by controlling the aspheric surface type, so that the larger focal depth and the optimal imaging quality are realized.
Example 1:
the radius of curvature of the front and back surfaces of the artificial lens and the center thickness are calculated according to a calculation formula, the radius of curvature of the front and back surfaces of the 20D spherical artificial lens is 12.1206 mm-12.1206 mm, and the center thickness is 0.9748mm. And inputting the obtained data into zemax software, setting one surface as an aspheric surface, setting the other surface as a binary diffraction surface, setting an optimization function, wherein the basic focal power is 20D, the additional focal power is +1D, the bifocal is set, the far focal point is a positive spherical aberration, the near focal point is a negative spherical aberration, setting a quadric surface coefficient, a high-order aspheric surface coefficient as a variable, setting a phase coefficient of the binary surface as a variable, and optimizing the crystal surface type to obtain the large focal depth continuous view artificial crystal.
The quadric coefficient K is: 2.116128, the higher order aspherical coefficient A2 is: 3.510750E-04, A4 is: 1.477036E-04, the height of the slope ring is: radius of slope ring of 2 μm
Surface data of a diffraction type large focal depth artificial lens are obtained, and a defocusing curve of 50lp/mm space frequency at a 3mm aperture is shown in FIG. 3.
And (3) guiding the obtained optical surface type data into a high-precision lathe, turning the high-precision lathe to obtain a large-focal-depth artificial lens, and milling the contour by a milling machine to produce the diffraction type large-focal-depth artificial lens.
Claims (8)
1. An aspherical diffraction type large focal depth artificial lens is characterized in that: the artificial lens (1) comprises an optical zone (2), wherein one surface of the optical zone (2) is a binary diffraction surface type (2 a), and the other surface is an aspheric surface type (2 b).
2. An aspherical diffractive large depth of focus intraocular lens according to claim 1, wherein: the optical area (2) is provided with the supporting loop (3), and the supporting loop (3) and the optical area (2) are of an integrated structure.
3. An aspherical diffractive large depth of focus intraocular lens according to claim 2, wherein: the support loop (3) comprises two C-shaped structures which are symmetrically arranged at the outer edge of the optical zone (2).
4. An aspherical diffractive large depth of focus intraocular lens according to claim 2, wherein: the supporting loop (3) is provided with a ridged long through hole.
5. An aspherical diffractive large depth of focus intraocular lens according to claim 1, wherein: the artificial lens (1) is made of hydrophilic acrylic ester materials.
6. A method for designing an aspherical diffractive large-depth-of-focus intraocular lens according to any one of claims 1 to 5, characterized by the steps of:
1) Calculating the center thickness and the curvature radius of the crystal when the focal power is +5.0D < -32.0D > according to the requirement;
2) Design of binary diffraction surface type: according to the Huygens-Fresnel diffraction principle, the light energy is distributed on diffraction focuses with different distances by utilizing the diffraction principle of binary surfaces,
in ZEMAX optical design software, the phase expression of the binary plane is:
wherein A is i (i=1, 2, …) is the i-th order phase coefficient, ρ is the normalized radius, the phase coefficient of the binary plane is optimized such that the-1 order diffraction focus is on the retina when the object distance is infinity, or the +1 order diffraction focus is on the retina when the object distance is near the vision network, the power distribution is theoretically calculated, and the light intensity distribution characteristics;
setting the surface of an artificial lens as a spherical surface, introducing a binary diffraction surface type on one spherical surface, distributing light energy on diffraction focuses of different far and near levels, if each band is etched with 2 steps, the light energy is mainly distributed on +1 and-1 diffraction orders, the energy of each order accounts for 40.5% of the total energy, diopters of a far point and a near point are respectively set, the difference value of the two is +1D, introducing an optimization function, optimizing an optical system, and finally obtaining the diffraction multifocal artificial lens;
the height h of the slope ring is calculated, and the structural characteristics of the binary phase surfaces of the second order can know that the phase depth of each slope ring is pi, so that the method comprises the following steps:
λ 0 ＝546nm，n IOL the refractive index of the hydrophilic material is 1.4571, nmed is the refractive index of aqueous humor of human eyes is 1.336, and h is approximately equal to 2 mu m after the hydrophilic material is brought into a number; and the surface shape of the binary optical element is obtained after the above operation is optimized.
3) Design of an aspheric surface:
the front and rear surfaces of the artificial lens are set to be even-order aspheric surfaces, and the surface type of the aspheric artificial lens surface is described as follows:
c is the curvature; r is the radius; k is a conic coefficient;
the optimal aspheric surface is realized by optimizing the k value and the high-order aspheric surface coefficient, the high-order aspheric surface design adopts the high-order coefficient, and the more the high-order coefficient is, the more aberration types are corrected, the higher the imaging quality is;
4) Setting spherical aberration according to different additional powers of far and near focuses of the diffraction bifocal, adding an optimization function, setting the far focus as positive spherical aberration, setting the near focus as negative spherical aberration, setting quadric surface coefficients and high-order aspheric coefficients as variables, and optimizing the crystal surface type to obtain large focal depth artificial crystal optical model data;
5) And inputting the obtained data into zemax software to obtain the large focal depth continuous view artificial lens.
7. The design method according to claim 6, wherein: in the step 1), the specific method comprises the following steps:
according to requirements, the diameter of an optical zone of which the expansion coefficient is 1.1201 after the hydrophilic artificial crystal absorbs water and expands is 5.75mm, the thickness of a crystal loop is 0.28mm, and the curvature radius R and the center thickness tc of the artificial crystal are determined according to the optical power calculation shape and the geometric shape, wherein F is the optical power of the artificial crystal, and the units are diopters (D) and F b ＝(n IOL -n med )/R b F is the front surface optical power f ＝(n IOL -n med )/R f N is the back surface optical power IOL The refractive index of the crystalline material is 1.4571, n med For the refractive index of the surrounding environment, 1.336 is typically taken as a simulation in the case of an intraocular lens. The hydrophilic intraocular lens is designed to be equally biconvex, so R f ＝R b R is given by
The center thickness and radius of curvature of the crystal at optical power +5.0D— +32.0D are calculated according to the above formula, and the optical power takes a point every 0.5D.
8. The design method according to claim 6, wherein: in the step 5), the specific method comprises the following steps: and inputting the obtained data into zemax software, setting one surface as an aspheric surface, setting the other surface as a binary diffraction surface, setting an optimization function, wherein the basic focal power is 20D, the additional focal power is +1D, the bifocal is set, the far focal point is a positive spherical aberration, the near focal point is a negative spherical aberration, setting a quadric surface coefficient, a high-order aspheric surface coefficient as a variable, setting a phase coefficient of the binary surface as a variable, and optimizing the crystal surface type to obtain the large focal depth continuous view artificial crystal.
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