Diffractive eye implant with extended myopic vision

Abstract

The invention relates to a diffractive ocular implant with correction of far vision and magnification of near vision, characterized in particular in that it has a phase transfer curve as a function of the viewing distance (abbreviation PTF-TF) in which there is no discontinuity in the corneal plane of at least 1.3 D, advantageously greater than 1.45 D, on a depth of field between intermediate vision and near vision, i.e. between 0.5 D and 4 D for spatial frequencies from 0 to 100 cycles / mm for a pupil of at least 3 mm in diameter.

Description

Technical Field

[0001] This invention belongs to the field of ocular implants.

[0002] More particularly, the present invention relates to a diffractive eye implant with enhanced near vision. Background Technology

[0003] Cataracts are the natural loss of the lens's transparency. The natural lens contributes to the convergence of one-third of the eye's light. Cataract surgery involves removing the natural lens to restore sharp vision. In the 1950s, Mr. Ridley implanted the first artificial lens in the ciliary sulcus to correct aphakia, restoring the lost one-third of the optical power at once. The artificial lens is now implanted in a capsular bag.

[0004] Without accommodation (at rest), distant objects are focused (sharply) on the retina of a normal eye (neither nearsighted, farsighted, nor astigmatic).

[0005] In order to see objects clearly at close range (from intermediate to near distance), the young natural lens has the ability to change its shape. Therefore, through the action of the ciliary muscles (which contract and relax the small band fibers), the anterior and posterior radii of curvature of the natural lens increase its optical power by several diopters.

[0006] This loss of accommodation occurs with age and in all cases occurs after cataract surgery, during which the natural lens is replaced by an artificial lens, which does not have the ability to change its focal length according to the desired viewing distance.

[0007] Some so-called conditioning implants (deformable polymers, mobile optics) attempt to restore conditioning, but so far the results have been unsatisfactory (partly due to fibrosis of the capsule, which limits the possibility of changing shape over time).

[0008] To mitigate this loss of accommodation, numerous multifocal implants have been developed. These are based on dividing light energy across several visual regions. In the early 2000s, diffractive optics demonstrated their superiority over refractive optics in both distance and near vision.

[0009] Diffractive optics allow for a variety of choices in the distribution of diffraction energy depending on the selected viewing distance. The optical quality produced by the chosen profile is limited by its MTF (modulation transfer function).

[0010] MTF is a number between 0 and 1 (or 0% and 100%) that represents image contrast (an image can be non-contrast-enhanced because it is out of focus, or because energy is shared between several focal points). "Through-focus" MTF (abbreviated as MTF-TF) expresses MTF as a function of defocus (which is expressed as a function of viewing distance or added light (1D = 1 / 1m)), making it possible to determine depth of field.

[0011] Literature has shown that, regardless of optical profile or technique, visual outcomes are related to the MTF profile of the implanted intraocular lens (IOL) or implant. Therefore, on average, binocular visual acuity is better than the following:

[0012] • 0LogMAR(10 / 10) when MTF is 0.40;

[0013] • For an MTF of 0.20, the values ​​are between 0 and 0.05 LogMAR (9 / 10).

[0014] For an MTF of 0.15, 0.1 LogMAR(8 / 10),

[0015] When the MTF is 3mm and the cycle count is 50 / mm, MAR means "minimum angular resolution".

[0016] The first type of diffractive optics is a bifocal optics, with one MTF peak for hyperopia (additional 0D) and another peak for myopia (additional +3D or +4D). These implants allow for sharp vision for reading (approximately 40cm), but patients must wear corrective glasses to achieve moderate vision (40 to 90cm).

[0017] Several solutions have been developed to achieve near-ideal vision (without the need for glasses) and sharp, continuous vision across all myopic distances (from 40 to 90 cm):

[0018] -mash up;

[0019] - "EDOF";

[0020] - Trifocal implant

[0021] -mash up:

[0022] The hybrid approach involves using two bifocal implants with different light inputs for each eye (one eye for near vision and the other for intermediate vision).

[0023] The goal is to provide contrast-enhanced images at intermediate vision, which is not the case with trifocal implants. Combinations of +1.75D / +4D and +1.5D / +3D (IOL-plane refraction) have yielded interesting defocus curves (i.e., visual acuity as a function of viewing distance). However, a limitation of this solution is binocular visual comfort for the patient. To maintain binocular balance, a 0.5D refraction difference has been proposed, and combinations of +2.5D / +3D (IOL-plane refraction) have shown results similar to trifocal implants, except in the 1D and 1.5D zones (in the corneal plane).

[0024] EDOF (an abbreviation for extended depth of field):

[0025] Extended depth-of-field implants are bifocal (or sometimes trifocal) implants that provide good intermediate vision with lower illumination. Note that the lower the illumination, the greater the depth of field at distance, because illumination is a function of "1 / x" of distance. These implants provide comfort for computer vision (intermediate vision) but require corrective glasses for near vision.

[0026] Triple Enzyme Implant

[0027] Trifocal implants are diffractive IOLs whose energy is distributed across three visual peaks (i.e., far, intermediate, and near). Therefore, they allow for sharp and intermediate vision, whereas bifocal implants only provide sharp near vision. Currently, trifocal implants are the most advanced "top-tier" solution for achieving sharp vision from infinity to near.

[0028] However, trifocal implants exhibit three distinct visual peaks, with a contrast discontinuity in the MTF-TF between near and intermediate visual acuity. In some trifocal implants, this discontinuity is visible on the MTF-TF at 50 cycles / mm, representing the size of the intermediate letter. Therefore, visual acuity is sharp at 40 and 80 cm, but not at 60 cm.

[0029] In other implants, this MTF-TF discontinuity was found at 100 cycles / mm, meaning it was more pronounced for smaller letter sizes.

[0030] Prior art related to this invention includes documents FR 3 072 020, US2007 / 182921 and WO 03 / 107076.

[0031] The purpose of this invention is to mitigate the disadvantages of the above-mentioned indications and to provide an intraocular implant that enables sharp and continuous vision throughout the entire useful near vision zone and requires the recognition of the smallest characters (reading a book set at 40cm from the reader, a mobile phone, a tablet computer, a laptop computer placed at 60cm from the user, a stationary computer placed at 80cm, etc.). Summary of the Invention

[0032] Therefore, the present invention relates to a diffractive ocular implant having corrected distance vision and magnified near vision, characterized by the fact that it has a phase transfer curve (abbreviated as PTF-TF) as a function of viewing distance, with no discontinuity at a depth of at least 1.3D in the corneal plane, i.e., at least 1.3D of the area of ​​light accumulation in the corneal plane, where the light accumulation in the corneal plane is understood as the reciprocal of the distance between the viewed object and the cornea, advantageously greater than 1.45D. This lack of discontinuity lies between intermediate and near vision, i.e., at least 3mm in diameter. The pupil has a spatial frequency between 0.5D and 4D for the range of 0 to 100 cycles / mm, and the diffractive eye implant includes a body having at least one optical surface having an optical axis and a plurality of diffraction zones concentrically arranged around the optical axis. Each of these concentric zones has at least one radius r and is distributed between a central region and a peripheral region. Notably, at least one central or peripheral region of the diffraction zone has the outline of N consecutive small step-grate gratings, the consecutive radii of which conform to the following relationship when moved away from the optical axis:

[0033]

[0034] In this relation:

[0035] N is an integer greater than 1;

[0036] λ is the conceptual wavelength;

[0037] fp is the focal length corresponding to the light applied for near vision;

[0038] Δf is the focal length change, which is non-zero, positive or negative, and its absolute value is less than 10000;

[0039] F2(N) is a polynomial of at least order 3 for variable N, preferably of order 3 to 5, and is expressed as follows:

[0040] F2(N)=cte+a*N+b*N^2+c*N^3+d*N^4+…,

[0041] Alternatively, it can be a function whose finite expansion or Taylor expansion is equivalent to a function of the polynomial represented above.

[0042] The height of the continuous small step gratings (diffraction steps) is given by the following formula:

[0043]

[0044] In this relation:

[0045] Δn is the refractive index change, which is the difference between the refractive index of the implant material and the refractive index of the aqueous humor of the eye or the surrounding environment;

[0046] α is the height coefficient of the small step grating, which is between 0.25 and 1.75.

[0047] Thanks to this invention, near-vision depth of field is achieved while maintaining good distance vision, without the discontinuity of spatial frequencies up to 100 cycles / mm.

[0048] The expression "at least 3rd order" indicates the minimum order of the polynomial. Specifically limiting it to the maximum order is inappropriate. In practice, for example, one could consider an equation of order 10, but with a dominant order of 3 and negligible coefficients with respect to order 10.

[0049] According to other non-limiting and advantageous features of the invention, individually or according to any combination of at least two of the following:

[0050] -cte is a real number between -5 and +5.

[0051] -a, b, c, d, etc. are real numbers contained between -5 and +5.

[0052] -The diffraction region has a circular shape;

[0053] - The diffraction region has an elliptical shape, r N It is its small radius;

[0054] The diffraction region consists of alternating full regions and empty regions, which are in particular composed of slits or holes, or formed by local variations in refractive index.

[0055] - The curve has no discontinuities starting from 0.8D in the corneal plane;

[0056] -The curve has no discontinuities starting from 2D in the corneal plane;

[0057] - The region is a central region having a radius of at least 1 mm and being surrounded by an outer region that is refractive or diffractive, monofocal or multifocal, for example, having a bifocal equation:

[0058]

[0059] - The region is the peripheral region surrounding the central region, which has a radius of at least one millimeter and is refracting or diffracting, monofocal or multifocal, for example, having a bifocal equation:

[0060]

[0061] - The function F2(N) is a 3rd-order polynomial of variable N;

[0062] Implants are selected from the following groups: intracorneal implants, anterior chamber (phakic or intraocular lens), posterior chamber implants, or ciliary sulcus implants;

[0063] - It has a non-spherical surface;

[0064] - It has an apodization profile, meaning that the height of the small stepped grating decreases as it moves away from the optical axis in order to limit halo phenomena in night vision.

[0065] Throughout this application, the term "corrected distance vision" refers to visual acuity with an MTF greater than 20% in a 3mm pupil at 50 cycles / mm.

[0066] The expression “enhanced near vision” is defined by the fact that it has a phase transfer curve (abbreviated as PTF-TF) as a function of viewing distance, with no discontinuity in a depth of field of at least 1.3D in the corneal plane, i.e., in an area of ​​at least 1.3D of illumination in the corneal plane, where the illumination in the corneal plane is understood as the reciprocal of the distance between the viewed object and the cornea, advantageously greater than 1.45D. Attached Figure Description

[0067] Other features and advantages of the invention will become apparent after reading the following description of embodiments thereof. The description is made with reference to the accompanying drawings, in which:

[0068] - Figure 1 This is the MTF-TF curve of a commercially available trifocal implant;

[0069] - Figure 2 It is the MTF-TF curve of a commercially available bifocal implant;

[0070] - Figure 3 The MTF-TF curve of the implant according to the present invention;

[0071] - Figure 4 This is a half-outline view of the implant according to the invention. It should be understood that the variability of the small step grating shown in this figure is due to apodization.

[0072] - Figure 5 This is a half-outline view of the implant according to the invention. It should be understood that the variability of the small step grating shown in this figure is due to apodization.

[0073] - Figure 6 The MTF-TF curve of the implant according to the present invention;

[0074] - Figure 7 The MTF-TF curve of the implant according to the present invention;

[0075] - Figure 8 The MTF-TF curve of the implant according to the present invention is shown. Detailed Implementation

[0076] Unless otherwise stated, illumination will be indicated in the corneal plane in the following text.

[0077] The concept of phase transfer function (PTF):

[0078] Any optical system can be represented by its point spread function (PSF).

[0079] The PSF (Presentation Spectrum Fraction) is the spatial distribution of light intensity within the image plane of an optical system formed by a point source object. A more accurate PSF indicates better optical quality. This PSF in the spatial domain is crucial because, when transformed into the frequency domain, it becomes the optical transfer function (OTF), which allows for the simulation of images of any object seen through the lens of the system under study.

[0080] Its description is as follows:

[0081]

[0082] Where, ω x ,ω y Let represent the spatial frequency in Fourier space, x and y represent the spatial dimensions in real space, Re and Im represent the real and imaginary parts of the complex number, and i is the square root of -1 in the complex space.

[0083] The modulation transfer function is the modulus of the optical transfer function, which is the square root of the square of the power of its real and imaginary parts.

[0084] Its description is as follows:

[0085]

[0086] The phase transfer function (PTF) is the independent variable of the optical transfer function. It is expressed as follows:

[0087]

[0088] To achieve visual comfort without discontinuities across a wide depth of field, it's helpful to think in terms of "phase" and "phase reversal." In practice, when the MTF-TF drops to zero after a peak and then has a new peak, this typically corresponds to phase reversal. This means that for a given spatial frequency (100 / cycle / mm in the case of an MTF-TF curve at 100 / cycle / mm), the perceptible signal is reversed. Thus, for example, a black test pattern on a white background appears white on a black background.

[0089] In the case of IOL (Interfocal Lens), people can have phase reversal at high frequencies, but this also functions as defocusing. Therefore, for commercial trifocal implants, the implant is no longer sufficiently focused between intermediate and near vision, and phase reversal exists.

[0090] Figure 1 This is the situation, where commercial trifocal implants are being processed.

[0091] In this figure, the x-axis shows the added light (from 0 to 3D in the corneal plane), and the y-axis shows the MTF (left) and phase (right).

[0092] The following curves were plotted:

[0093] -Curve A: MTF curve;

[0094] -Curve B: The real part of the OTF curve;

[0095] -Curve C: The imaginary part of the OTF curve;

[0096] -Curve D: Phase transfer curve.

[0097] Unless otherwise stated, the same parameters are repeated in the following figures.

[0098] Phase reversal was actually observed near 1.5D of added light (within the corneal plane). Therefore, this implant does not allow for clear and continuous vision without phase reversal between intermediate and near vision.

[0099] The parameters involved in this invention are defined as follows:

[0100] MTF-TF (or TFMTF = "Transfer Function by Focus") represents the optical quality of the contrast of an image of a starting object with 100% contrast as a function of viewing distance (described by refraction in diopter form: 0D = distance vision / +1 to +2D = intermediate refraction / 3D = near refraction within the corneal plane).

[0101] These are curves simulated using optical simulation software, such as the simulation software known by the brand name Zemax for intraocular implants placed in a standard eye model.

[0102] MTF-TF curves were established for a given spatial frequency. Typically, for multifocal implants, we are interested in the MTF-TF at 50 cycles / mm. The MTF-TF at 25 cycles / mm (for larger objects) and 100 cycles / mm (for smaller objects) are also of interest.

[0103] The MTF-TF curve for a given optical profile at 50 cycles / mm (e.g.) depends on the pupil of the optical system and the wavelength of the light used.

[0104] Therefore, we are preferably interested in the green wavelength (546 nm), but we are also interested in plotting the photopic MTF-TF and scotopic MTF-TF (night vision) corresponding to the wavelength integral of sunlight.

[0105] Similarly, we are preferably interested in pupils with a diameter of 3 mm (corresponding to visual acuity in good lighting (daytime reading vision), but for pupils of 2 to 6 mm, the continuity of MTF-TF may be of interest.

[0106] An MTF value greater than 0.15 is considered to provide the wearer with satisfactory near vision.

[0107] Near vision NV is usually equal to +3D (in corneal plane illumination), but can be included between +2D and +4D.

[0108] Intermediate visual acuity (IV) is usually equal to +1.5D (in corneal plane illumination), but can be between +1D and +2D.

[0109] Implant according to the present invention:

[0110] The near vision-enhancing implant with a constant phase according to the present invention can be defined as follows:

[0111] These are diffractive implants with both far and near vision, whose optical transfer function phase is constant over an expanded intermediate to near vision zone, meaning there is no phase reversal at spatial frequencies up to 100 cycles / mm. This optical transfer function is constant over an illumination range at least 30% (and preferably 45%) larger than that of conventional bifocal implants (such as the ARtis PLM implant sold by the applicant).

[0112] Attached Figure 2 The phase transfer function of the illumination of a conventional bifocal implant based on illumination + 3D is shown at 100 cycles / mm.

[0113] Note that the phase is constant in the 1.35D to 2.35D zone / or at a depth of 1D in the corneal plane (curve D).

[0114] exist Figure 3 An example of an enlarged near vision profile under constant phase is shown in the figure.

[0115] Note that the phase is constant in the 0.6D to 2.05D ​​region or at a depth of 1.45D within the corneal plane.

[0116] This curve can be obtained from different diffractive optical implants, which will be described below.

[0117] It is understood that this type of implant comprises a body having at least one optical surface having an optical axis and a plurality of diffraction regions arranged concentrically around the optical axis, each of which has at least one radius r.

[0118] For bifocal implants, the radius of the continuous ring has a radius r. N Make:

[0119]

[0120] The relational expression includes:

[0121] -N is the ring number (counted from the center);

[0122] -f p It corresponds to the focal length for adding light for near vision.

[0123] -λ is the design wavelength (typically 546nm).

[0124] The height h of the diffraction steps (small step gratings) in these regions is equal to:

[0125]

[0126] The relational expression includes:

[0127] -Δn is the refractive index change (i.e., the difference between the refractive index of the implant material and the refractive index of the aqueous humor or surrounding environment of the eye when it is a problem with corneal implants);

[0128] -α is the height factor of the profile.

[0129] If α = 0.5, then the relative energy distribution is 50% for distance vision and 50% for near vision.

[0130] The shape of the diffraction edifice grating in each region is called a "phase diagram," and it is described by parabolas on each edifice grating, such that:

[0131]

[0132] Where x is the radial position.

[0133] According to the present invention, by utilizing a diffraction profile that provides extended depth of field, an implant with a continuous phase profile between near vision and intermediate vision is produced.

[0134] The central region of this implant is defined by a contour for which the radius r of the continuous ring is... N Determined by the following types of equations:

[0135]

[0136] Where F2(N) is the expression of the least third-order polynomial of variable N. F2(N) can be expressed as follows:

[0137] F2(N) = cte + a*N + b*N 2 +c*N 3 +d*N 4 +…

[0138] in:

[0139] -N is an integer greater than 1;

[0140] -λ is the conceptual wavelength;

[0141] -f p It corresponds to the focal length for adding light for near vision.

[0142] -Δ f This refers to changes in focal length;

[0143] -cte is a constant consisting of real numbers between -5 and +5.

[0144] -a, b, c, and d are real numbers contained between -5 and +5.

[0145] Note that F2(N) can be a function whose finite expansion or Taylor expansion is equivalent to the polynomial expressed above. The term "equivalent" means that the finite expansion or Taylor expansion of the function gives the same result as the F2(N) function expressed above.

[0146] For indication only, these implants may include a central region with extended depth of field (e.g., a diameter of 1.5 to 6 mm) and an optional “peripheral” region, which may be described as conventional (e.g., a diameter of 2 to 6 mm).

[0147] Figure 4 A “half” outline of the implant I1 according to the invention is shown.

[0148] The “half” profile refers to the fact that the y-axis (which reflects the height of the small step gratings of these implants in micrometers) coincides with their optical axis AO, and only the profile extending to one side of this axis is shown.

[0149] In this diagram, the central and peripheral regions are represented as RC and RP, respectively.

[0150] Note that, due to the start of the outer region RP, the outline of the fourth small step grating visible in this figure has been cut off.

[0151] Although it is a “phase diagram”, the small step grating can have different shapes (e.g., sine or cosine), and such different shapes will not significantly change the invention.

[0152] In the present case, the different refractive regions have a circular shape. However, according to an alternative embodiment not shown here, these diffraction regions have an r N It has an elliptical shape with a small radius.

[0153] Still according to the embodiment presented herein, the central region RC has an extended depth of field, has a radius of at least one millimeter, and is surrounded by a peripheral region RP, which is refractive or diffractive, monofocal or multifocal, for example having a bifocal equation:

[0154]

[0155] Conversely, this could be the opposite, such that it would be a central region RC with a radius of at least one millimeter, which would be refractive or diffractive, monofocal or multifocal, for example, having a bifocal equation:

[0156]

[0157] Figure 5 A “half-outline” of another implant I2 according to the invention is shown.

[0158] The main parameters of the implant according to the present invention are given below.

[0159] Example 1:

[0160] A 4th-order function F(N) (which corresponds to) Figure 5 The outline and Figure 6 (The curve):

[0161] Table 1

[0162]

[0163] ●Central Area:

[0164]

[0165]

[0166] ●Outer area:

[0167]

[0168] Therefore, the phase is Figure 6 It was observed that the depth was constant in the 0.5D to 2.05D ​​region or at a depth of 1.55D within the corneal plane.

[0169] Example 2 (which corresponds to) Figure 4 The outline and Figure 7 (The curve):

[0170] A 5th-order function F(N):

[0171] Table 2

[0172]

[0173] ●Central Area:

[0174]

[0175] ●Outer area:

[0176]

[0177]

[0178] Therefore, in Figure 7 It was observed that the phase was constant in the region from 0.5D to 2.14D or at a depth of 1.64D within the corneal plane.

[0179] Finally, Figure 8 In one embodiment, the phase is constant in the region from 1.1D to 3.3D or at a depth of 2.2D within the corneal plane.

[0180] As indicated above, the diffraction profile (also known as a step or small step grating) of the implant according to the invention can vary according to the radius (its constituent variable x) according to the following equation (i.e., we are dealing with the reduction of the step height between the center and the periphery):

[0181] Apodized Profile (x) = Profile (x) * Apodization (x)

[0182] The “apodization(x)” function is a decreasing function such that for 0 < abs(x) < r max (r max = maximum radius of the diffraction profile), then 0 < Apodization(x) ≤ 1.

[0183] For example, this function can take the following form: Apodization(x) = (1 - abs(a.x / b)^c), where a, b, and c consist of real numbers.

[0184] The diffraction profile can be composed of concentric steps, circular steps, or elliptical diffraction steps (mini - staircase grating). In other embodiments, the diffraction effect can be obtained by alternating full regions and empty regions (holes, slits), which modify the local refractive index by the regions and generate diffraction in the same way as the mini - staircase grating.

[0185] In other words, this diffraction profile is not defined by the geometry but by the refractive index change of the (multiple) materials that make it up, and this will produce the same effect. For example, the modification of the refractive index can be obtained by alternating full regions “n mat” and empty regions “n0” (formed by holes or slits), which modify the local refractive index by the regions and generate diffraction in the same way as the mini - staircase grating.

[0186] The implants according to the present invention make it possible to correct presbyopia. They can also correct other refractive errors (myopia, hyperopia, astigmatism).

[0187] These can be intracorneal implants (lenticules), anterior chamber (phakic or intraocular lenses), or posterior chamber or ciliary sulcus intraocular implants.

Claims

1. A diffractive ocular implant (I1, I2) having corrected distance vision and amplified near vision, wherein the distance vision is a visual acuity such that the modulation transfer function (MTF) of the implant is greater than 20% at 50 cycles / mm in a 3mm pupil, and the near vision is a visual acuity in which its phase transfer curve (abbreviated as PTF-TF) as a function of viewing distance has no discontinuities, wherein: - The diffractive ocular implant has a phase transfer factor (PTF-TF) as a function of viewing distance, with no discontinuities in a depth of field of at least 1.3D in the corneal plane, i.e., in an area of ​​at least 1.3D of illumination in the corneal plane, where the illumination in the corneal plane is understood as the reciprocal of the distance between the viewed object and the cornea. The absence of discontinuities lies between intermediate and near vision, i.e., for a pupil with a diameter of at least 3mm, the spatial frequency is between 0.5D and 4D for a range of 0 to 100 cycles / mm. The diffractive ocular implant includes a body having at least one optical surface, the at least one optical surface having an optical axis (AO) and a plurality of diffraction zones concentrically arranged around the optical axis (AO), each of the concentrically arranged plurality of diffraction zones having at least one radius r and distributed between a central region (RC) and a peripheral region (RP), at least one central region (RC) or peripheral region (RP) of the diffraction zone having the outline of Nmax consecutive small step-grate gratings, the consecutive radii r of the small step-grate gratings decreasing as the implant moves away from the optical axis (AO). N It meets the following relationship: In this relation: N is an integer greater than or equal to 1 and takes consecutive integer values, with a maximum value of Nmax; λ is the conceptual wavelength; f p This corresponds to the focal length used for adding light for near vision; Δ f The focal length variation is non-zero, positive, or negative, and its absolute value is less than 10000; F2(N) is a polynomial of order 3 to 5 for variable N. The maximum height of the difference between two consecutive small epoch gratings, i.e., diffraction steps, is given by the following relationship: In this relation: -Δn is the refractive index change, which is the difference between the refractive index of the implant material and the refractive index of the aqueous humor of the eye or the surrounding environment; -α is the height coefficient of the small grating, which is between 0.25 and 1.

75.

2. The implant (I1, I2) according to claim 1, wherein, The zero-degree coefficient (cte) of F2(N) is a real number between -5 and +5.

3. The implant (I1, I2) according to claim 1, wherein, The coefficients (cte, a, b, c, d) of F2(N) are real numbers contained between -5 and +5.

4. The implant (I1, I2) according to claim 1, wherein, The diffraction region has a circular shape.

5. The implant (I1, I2) according to claim 1, wherein, The diffraction region has an elliptical shape, r N It is its small radius.

6. The implant (I1, I2) according to claim 1, wherein, The diffraction region consists of alternating full regions with a refractive index of "nmat" and empty regions with a refractive index of "n0".

7. The implant (I1, I2) according to any one of claims 1 to 3, wherein, The curve has no discontinuities starting from 0.8D in the corneal plane.

8. The implant (I1, I2) according to any one of claims 1 to 3, wherein, The curve has no discontinuities starting from 2D in the corneal plane.

9. The implant (I1, I2) according to any one of claims 1 to 3, wherein, The central region has a radius of at least 1 mm and is surrounded by a peripheral region (RP), which is refractive or diffractive, monofocal or multifocal.

10. The implant (I1, I2) according to any one of claims 1 to 3, wherein, The central region (RC) is surrounded by the peripheral region (RP), the central region (RC) having a radius of at least one millimeter, and being refracting or diffracting, monofocal or multifocal.

11. The implant (I1, I2) according to any one of claims 1 to 3, wherein, The function F2(N) is a 3rd-order polynomial of the variable N.

12. The implant (I1, I2) according to any one of claims 1 to 3, wherein, The implants are selected from the following groups: intracorneal implants, phakic anterior chamber implants or intraocular lens anterior chamber implants, intraocular posterior chamber implants or ciliary sulcus implants.

13. The implant (I1, I2) according to any one of claims 1 to 3, wherein, The implant has a non-spherical surface.

14. The implant (I1, I2) according to any one of claims 1 to 3, wherein, The implant has an apodization profile, meaning that the height of the small step grating decreases as it moves away from the optical axis, in order to limit halo phenomena in night vision.

15. The implant (I1, I2) according to claim 6, wherein the void is composed of a slit or a hole.

Images