JP6190133B2 - Ophthalmic lens design method and ophthalmic lens manufacturing method - Google Patents

Description

  The present invention relates to an ophthalmic lens, an ophthalmic lens design method, and an ophthalmic lens manufacturing method.

  As the ophthalmic lens, a contact lens, an intraocular lens, and the like are known, and are used as a lens after visual acuity correction and cataract surgery.

  An intraocular lens as an example of an ophthalmic lens is inserted into the eye in order to replace the function of the lens after the lens that has become cloudy due to the progression of cataracts is removed by surgery. There are various functions required for an intraocular lens. For example, it is possible to see an object more clearly (increase the contrast), widen a visible range (clear vision area), and the like. In response to such demands, various optical designs for the lens unit have been proposed.

  As a technique for increasing the contrast, for example, techniques described in Patent Documents 1 to 3 are known. These techniques improve contrast by reducing the spherical aberration of the lens. However, if the spherical aberration is reduced, the depth of focus of the lens becomes shallow, and there is a problem that the visible range becomes narrower than that of the spherical lens.

  On the other hand, a multifocal intraocular lens is known as a technique for widening the visible range. For example, Patent Document 4 describes an intraocular lens in which a near portion and a far portion are arranged according to a desired appearance. However, the amount of light entering each of the near portion and the far portion is smaller than that of a spherical lens that captures light in the entire lens, and as a result, there is a problem that the contrast is lowered. Patent Document 5 describes an intraocular lens in which the visible range is wider than that of a spherical lens by increasing the depth of focus. However, the contrast of this intraocular lens is lower than that of a spherical lens, as in Patent Document 4.

  As described above, the function of increasing the contrast and the function of widening the visible range are generally contradictory functions, and thus a technique that appropriately balances these functions is known. For example, Patent Documents 6 and 7 describe an annular mask lens having an optical part designed so that the transmittance gradually changes in the radial direction from the center of the lens.

U.S. Pat. No. 4,450,982 Special table 2003-534565 gazette Japanese Patent Laid-Open No. 2006-14818 JP 60-85744 A Special table 2000-511439 gazette US Pat. No. 5,662,706 US Pat. No. 5,905,561

  In the annular mask lens having the above-described optical portion, the contrast is improved to some extent, and the visible range is relatively wide. On the other hand, in Patent Documents 6 and 7, when manufacturing this annular mask lens, a light-transmitting region (annular mask) is formed by irradiating the lens that is the material with light and exposing the photosensitive material on the lens. It is described to form. At this time, a rotating mask having a “petal” shape is arranged between the lens and the light source and is rotated. By doing so, the “petal” -shaped portion of the rotating mask partially transmits the light emitted from the light source, so that the photosensitive material on the lens is partially exposed. As a result, a region where the transmittance gradually changes is formed.

  However, in order to form a region where the transmittance gradually changes, it is necessary to precisely control the number of rotations of the rotary mask, the exposure intensity, etc. In addition, the lens on which the mask is formed is small. It has been extremely difficult to manufacture a lens having such a region.

  The present invention has been made in view of the above problems, and mainly provides an ophthalmic lens having a relatively wide visible range, improved contrast, and easily manufacturable, and an ophthalmic lens design method and manufacturing method. Objective.

  In order to solve the above problem, the present inventor does not form a region that is difficult to manufacture, such as a region where the transmittance changes, but is an area equivalent to the region where the transmittance changes while being easy to manufacture. As a result, it was found that the above-mentioned problems can be solved, and the present invention has been completed.

That is, the aspect of the present invention is
An ophthalmic lens comprising a transmission region through which light is transmitted and a non-transmission region through which light is not transmitted,
A region in which the light transmittance is continuous from the center of the lens in the radial direction, and includes a continuous region including at least the center of the lens, and a change in which the light transmittance changes in the radial direction in the continuous region. Assuming a lens with a region,
In the ophthalmic lens, the presence ratio of the transmission region and the non-transmission region in the circumferential direction from the center of the ophthalmic lens in the radial direction is equivalent to a change in transmittance in the change region of the assumed lens. The ophthalmic lens is characterized in that the transmissive region and the non-transmissive region are arranged.

  ADVANTAGE OF THE INVENTION According to this invention, the range which can be seen is comparatively wide, contrast is improved, and the ophthalmic lens which can be manufactured easily, the design method and manufacturing method of an ophthalmic lens can be provided.

FIG. 1 is a plan view of an intraocular lens according to the present embodiment. FIG. 2 is a plan view of an intraocular lens having a region where the transmittance changes in the radial direction. FIG. 3 is a plan view of a pinhole lens having a circular opening. FIG. 4 is a schematic diagram for explaining a method of binarizing a region where the transmittance varies in the radial direction and distributing the region to a transmissive region and a non-transmissive region in the lens. FIG. 5 is a plan view showing a modification of the intraocular lens according to the present embodiment. 6A is a plan view of a lens to which apodization is applied, and FIG. 6B is a transmittance distribution in the radial direction of a lens to which apodization is applied and a lens to which apodization is not applied. FIG. 7 shows a two-dimensional plot of a point spread function (PSF) for a lens to which apodization is applied and a lens to which apodization is not applied, and a cross-sectional view of the PSF. In FIG. 7A, the pupil diameter is 2.0 mm, in FIG. 7B, the pupil diameter is 3.0 mm, and in FIG. 7C, the pupil diameter is 4.0 mm. FIG. 8 shows a modulation transfer function (MTF) obtained by Fourier transforming a PSF of a lens to which apodization is applied and a lens to which apodization is not applied, and a spatial frequency (SF). It is a graph which shows the relationship. In FIG. 8A, the pupil diameter is 2.0 mm, in FIG. 8B, the pupil diameter is 3.0 mm, and in FIG. 8C, the pupil diameter is 4.0 mm. FIG. 9 is a graph showing the relationship between defocus and MTF in a specific SF. 9 (a) and 9 (d), the pupil diameter is 2.0 mm, in FIGS. 9 (b) and 9 (e), the pupil diameter is 3.0 mm, and in FIGS. 9 (c) and 9 (f), the pupil is The diameter was 4.0 mm. FIG. 10 is an image of the Landolt ring that would be seen when using a lens to which apodization was applied and a lens to which apodization was not applied. In FIG. 10A, the pupil diameter is 2.0 mm, in FIG. 10B, the pupil diameter is 3.0 mm, and in FIG. 10C, the pupil diameter is 4.0 mm. FIG. 11 is a plan view of the intraocular lens of Example 1 obtained by binarizing the region where the transmittance changes in the radial direction. 12A is a PSF of the intraocular lens of Example 1, FIG. 12B is a cross-sectional view of the PSF, and FIG. 12C is an intraocular lens of Example 1 and apodization. This is an image of the Landolt ring that would be seen when using a lens to which the lens is applied and a lens to which the apodization is not applied. 13A is a plan view of a lens to which apodization is applied, and FIG. 13B is a transmittance distribution in the radial direction of a lens to which apodization is applied and a lens to which apodization is not applied. FIG. 14 shows a two-dimensional plot of a point spread function (PSF) for a lens with and without apodization, and a cross-sectional view of the PSF. In FIG. 14A, the pupil diameter is 2.0 mm, in FIG. 14B, the pupil diameter is 3.0 mm, and in FIG. 14C, the pupil diameter is 4.0 mm. FIG. 15 is a plan view of an intraocular lens of Example 2 obtained by binarizing a region where the transmittance changes in the radial direction. 16A is a PSF of the intraocular lens of Example 2, FIG. 16B is a cross-sectional view of the PSF, and FIG. 16C is an intraocular lens of Example 2 and apodization. This is an image of the Landolt ring that would be seen when using a lens to which the lens is applied and a lens to which the apodization is not applied.

Hereinafter, the present invention will be described in detail in the following order with respect to an intraocular lens as an example of an ophthalmic lens based on the embodiments shown in the drawings.
1. 1. Configuration of intraocular lens 2. Intraocular lens design method Effects of the embodiment 4. Modified example

(1. Configuration of intraocular lens)
FIG. 1 is a plan view of an intraocular lens according to the present embodiment. The intraocular lens 1 has a substantially circular convex lens shape. The intraocular lens 1 is made of a soft material such as soft acrylic, silicon, or hydrogel, or a hard material such as polymethyl methacrylate (PMMA). The diameter of the intraocular lens 1 is not particularly limited as long as it is a diameter that can function as an intraocular lens. In the present embodiment, the diameter of the intraocular lens 1 is set to 6.0 mm. Moreover, what is necessary is just to set the thickness of the intraocular lens 1 according to a desired refractive index.

  Although not shown in FIG. 1, a support arm or the like may be attached to the outer peripheral portion of the intraocular lens 1 as necessary. The support arm has a role of holding and fixing the intraocular lens in the eye.

  The intraocular lens 1 has a transmission region 2 that is a region through which light incident on the lens is transmitted, and a non-transmission region 3 that is a region through which light is not transmitted. That is, the intraocular lens 1 according to the present embodiment is binarized into a transmissive region 2 and a non-transmissive region 3. The opaque region 3 is formed, for example, by applying a mask to the lens. The transmission region 2 and the non-transmission region 3 are arranged so as to be equivalent to a change in transmittance in the change region when a lens having a region (change region) in which the transmittance changes in the radial direction is assumed. Has been.

(2. Intraocular lens design method)
In the following, a method of arranging the transmissive region 2 and the non-transmissive region 3 so as to be equivalent to the region where the transmittance of the assumed lens changes in the radial direction will be described. First, the transmittance is increased in the radial direction. The optical characteristics of a lens having a changing region (change region) will be described in detail.

  FIG. 2 is a plan view of a lens (hereinafter also referred to as gradation lens 11) having a region where the transmittance varies in the radial direction. The gradation lens 11 includes, in order from the optical center O of the lens toward the outer periphery of the lens, a circular region 12 having a radius r1, an annular region 14 having an inner diameter r1 and an outer diameter r2, and an inner diameter r2 and an outer diameter. And an annular region 13 in which r3. The circular region 12 is a region that transmits light (transmittance 100%), and the annular region 13 is a region 13 that does not transmit light (transmittance 0%). The annular region 14 is a region where the circular region 11 and the annular region 13 are connected, and the transmittance is gradually decreased toward the outer periphery of the lens. Therefore, in the present embodiment, the gradation lens 11 has a region (continuous region) where the transmittance shows a continuous value from the center O to r3, and the change region (annular region 14) is included in the continuous region. .

  A method for obtaining such a gradation lens 11 is not particularly limited, and is a region (annular region 14) in which the transmittance is continuously changed according to desired optical characteristics and the circular region 12 and the annular region 13 are connected. ) May be used. In the case of an intraocular lens, as shown in FIG. 2, the annular region 14 preferably has a distribution that changes so that the transmittance gradually decreases in the direction from the center of the lens toward the outer periphery. In the present embodiment, the gradation lens 11 is obtained by applying apodization to a pinhole lens having an opening with a predetermined diameter.

  As shown in FIG. 3, the pinhole lens 21 has an opening 22 that transmits light and an annular region 23 that does not transmit light. In the pinhole lens 21, the transmittance is discontinuous at the end of the opening 22, that is, at a point at a distance rc from the center O. Since such a pinhole lens 21 has a diffraction limit, the light transmitted through the opening 22 is diffracted, and concentric fringes are observed. That is, the PSF of the light transmitted through the opening 22 generally includes a side lobe and a side ring. Due to such side lobes and the like, the contrast is lowered in the pinhole lens.

  Therefore, amplitude apodization is applied to the pinhole lens in order to reduce side lobes and the like. In the present embodiment, “apodization” means that discontinuity is removed or smoothed using a mathematical function with respect to the discontinuous transmittance distribution. Specifically, by applying apodization to the pinhole lens 21 shown in FIG. 3, a region where the transmittance gradually decreases from the vicinity of the end of the opening (at the end of the opening) is formed. By softening the sharp change in the transmittance), the transmittance is made continuous in the range from the opening to the outer periphery of the lens. By doing so, a gradation lens 11 as shown in FIG. 2 can be obtained. The gradation lens 11 has a region where the transmittance shows a continuous value (continuous region) and a region where the transmittance gradually changes in the radial direction (change region).

  In the present specification, “the transmittance shows a continuous value in the radial direction” means that the transmittance is expressed by a function f (r) of the diameter r, or can be approximated to f (r). When approaching from the diameter (r−α) smaller than the certain diameter r toward the diameter r, and approaching from the diameter (r + α) larger than the certain diameter r toward the diameter r, both f ( r) means the same value, and “transmissivity is discontinuous in the radial direction” means approaching from the diameter (r−α) to the diameter r and moving from the diameter (r + α) to the diameter r. This means that f (r) does not become the same value when approaching. Specific examples are shown below.

  In the graph showing the relationship between the radial distance and the transmittance shown in FIG. 2, when paying attention to the diameter r1, the transmittance is 1 when approaching r1 from a value smaller than r1, and from the value larger than r1, r1 The transmittance is also 1 when approaching toward. Focusing on the diameter r2, similarly to r1, the transmittance is 0 both when approaching r2 from a value smaller than r2 and when approaching r2 from a value larger than r2. Become. Therefore, in the graph shown in FIG. 2, the transmittance shows a continuous value from 0 to r3.

  On the other hand, in the graph showing the relationship between the radial distance and the transmittance shown in FIG. 3, when paying attention to the diameter rc, the transmittance becomes 1 when approaching rc from a value smaller than rc, and a value larger than rc. When approaching from rc to rc, the transmittance is zero. Therefore, in the graph shown in FIG. 3, the transmittance is discontinuous at rc.

  The mathematical function used when applying the apodization is not particularly limited. A function may be selected from known functions according to optical characteristics required for the lens, and examples thereof include a Gaussian function, a sine function, and a cosine function.

  The obtained gradation lens 11 is a lens having a relatively wide viewable range and improved contrast as compared with the pinhole lens 21. However, as described above, it is very difficult to manufacture a gradation lens. For example, Patent Documents 6 and 7 employ a method of forming a mask by applying a photosensitive material on a lens and exposing it to light. In this method, a rotating mask having a petal shape is disposed between a lens and a light source, and a photosensitive material on the lens is partially exposed to form a region where the transmittance varies in the radial direction. However, in order to accurately reproduce the gradation, it is necessary to precisely control the number of rotations of the rotating mask, the exposure intensity, etc. In addition, the lens on which the mask is formed is small and it is extremely difficult to obtain a desired gradation. In addition, the obtained gradation may vary from lens to lens.

  Therefore, in this embodiment, a lens having optical characteristics equivalent to those of the gradation lens is proposed from a viewpoint completely different from the technical idea of manufacturing the lens by reproducing the transmittance distribution in the gradation lens as it is. In other words, by binarizing the region where the transmittance in the gradation lens changes in the radial direction, the lens can be configured only from the transmission region and the non-transmission region. Therefore, it is not necessary to form a gradation that is extremely difficult to reproduce in the lens, and a lens having optical characteristics equivalent to that of the gradation lens can be easily manufactured by simply forming an opaque region on the lens.

  Examples of the method for binarizing the region where the transmittance changes in the radial direction include the following methods. First, a substantially circular lens in plan view is divided into n pieces in the circumferential direction, and divided into n fan-shaped regions. The number (n) to be divided is 2 or more, and preferably 4 or more. In FIG. 4, the lens is divided into four equal parts. The sector-shaped region C1 is configured from a region where the transmittance shows a continuous value from the optical center O toward the radial direction, and includes a region 14 (change region) where the transmittance changes in the radial direction. Since the transmittance distribution in each sector region is equal, the transmittance at a point where the distance from the optical center O is r is equal in each sector region.

  As shown in FIG. 4, in the fan-shaped region C1, if the transmittance is 75% (0.75) at a point where the distance r from the center O is ra, of the set (arc) of points where the diameter is ra It is assumed that a 3/4 number of points is a point where the transmittance is 100%, and a ¼ number of points is a point where the transmittance is 0%. Then, these points are arranged on an arc so as to form a transmission line segment 51 that is a set of points having a transmittance of 100% and an opaque line segment 52 that is a set of points having a transmittance of 0%. Can be allocated.

  Specifically, in FIG. 4, a transmission line segment 51 is formed when the angle θa of the fan-shaped region is 0 to 3π / 8 [rad], and not when θa is 3π / 8 to π / 2 [rad]. A transmission line segment 52 is formed. If the transmittance is 20% (0.20) at a point where the distance r from the center O is rb, a transmission line segment 51 is formed until the angle θb is 0 to π / 10 [rad]. The opaque line segment 52 is formed until θb reaches π / 10 to π / 2 [rad].

  That is, when binarization is performed, a line segment (arc) having a length rθ is converted into a transmission line segment 51 and a non-transmission line segment 52 so as to be equivalent to the transmittance at the diameter r in the change region 14. Allocation. Therefore, in the intraocular lens 1, the transmittance on the circumference having the diameter r is determined by the length ratio of the transmission line segment 51 and the non-transmission line segment 52 in the circumferential direction. By performing such an operation in the radial direction from the center O to the outer periphery r3 of the lens, as shown in FIG. 4, the ratio between the length of the transmission line segment and the length of the non-transmission line segment in the circumferential direction is the radial direction. Thus, regions (14a and 14b) continuously changing are obtained. Since only the region 14a having a transmittance of 100% and the region 14b having a transmittance of 0% exist in this region, this region is binarized.

  In other words, assuming a gradation lens 11 having a region where the transmittance varies in the radial direction (change region), the intraocular lens 1 has a transmittance of 100% and a transmittance of 0 at a certain diameter. By expressing as a ratio divided into%, it can be binarized so as to be equivalent to a change in transmittance in the change region 14. Therefore, the radial change of the transmittance in the change region 14 of the gradation lens 11 is a change in the radial direction of the length ratio of the transmission line segment 51 and the non-transmission line segment 52 in the circumferential direction in the intraocular lens 1. It corresponds.

  As described above, the binarized intraocular lens 1 having optical characteristics equivalent to those of the gradation lens 11 can be obtained.

  If the number (n) for dividing the lens is too large, the central angle θ of the sector-shaped region is small, so that the arc length rθ is small, and the length of the transmitted line segment and the non-transparent line segment are distributed. The length of will also be shortened. As a result, the distribution of transmission line segments and non-transmission line segments in the entire lens becomes close to gradation. In this case, it is not preferable because it is difficult to manufacture the lens. Therefore, in the present embodiment, from the viewpoint of manufacturing, the upper limit of the number (n) to be divided is preferably 32 or less.

  The method for producing a binarized intraocular lens in this way is not particularly limited, and may be produced using a known method. For example, the above-mentioned non-transparent region is obtained by applying a photosensitive substance to the surface of a lens material obtained by putting a predetermined polymer material into a mold and heat-polymerizing it, and masking and exposing the above-described transmissive region. Can be formed.

(3. Effects of the present embodiment)
According to this embodiment, when assuming a lens (gradation lens) having a region (change region) in which the transmittance varies in the radial direction, binarization is performed so as to be equivalent to a change in transmittance in the region. The obtained lens (with the transmissive region and the non-transmissive region formed) is obtained. Unlike a gradation lens, such a lens can be easily manufactured because the optical surface of the lens is composed only of a transmissive region and a non-transmissive region. Moreover, since the lens according to the present embodiment is binarized so as to be equivalent to the change in transmittance in the change region, the lens has optical characteristics equivalent to those of the gradation lens. Therefore, it is possible to obtain an ophthalmic lens having a relatively wide visible range and improved contrast.

(4. Modifications)
In the above embodiment, when the change region is binarized, the change region is divided into a region where the transmittance is 100% and a region where the transmittance is 0%. However, the transmittance value is not limited to 100% and 0%, and a region indicating the maximum value of the transmittance required for the lens and a region indicating the minimum value may be formed.

  In the above embodiment, the line segment (arc) is divided and distributed to the transmission line segment and the non-transmission line segment. However, a minute region is set along the circumferential direction, and the region having the transmittance of 100% is set. You may allocate the area of a micro area | region so that an area and the area of the area | region of the transmittance | permeability 0% may become equivalent to the change of the transmittance | permeability. At this time, the area of the minute region to be set may be changed according to the radial distance r.

  In the above-described embodiment, the gradation lens has a continuous transmittance when moving from the center O of the lens toward the outer periphery. That is, the entire lens is composed of a continuous region where the transmittance shows a continuous value.

  However, as long as the portion of the lens does not significantly affect the visual acuity characteristics, a region where the transmittance is discontinuous may be binarized. For example, as shown in FIG. 5, a region where the transmittance is discontinuous may be binarized in the vicinity 70 of the boundary between the region 2 where the transmittance changes and the non-transmissive region 3. When a sharp portion near the boundary is rounded, the lens can be manufactured more easily. Even in this case, the region from the center O to the boundary vicinity 70 is a continuous region in which the transmittance shows a continuous value, and the above-described effect can be obtained.

  Hereinafter, although this invention is demonstrated based on a more detailed Example, this invention is not limited to these Examples.

Example 1
In Example 1, a lens was designed using a virtual model having optical characteristics similar to those of an average human eye, and the optical characteristics of the lens were simulated. A Liou-Brennan eye model having the parameters shown in Table 1 was used as a virtual model. In this embodiment, a model in which a 20.0D spherical intraocular lens is inserted instead of the crystalline lens of the human eye is used. The diameter of the intraocular lens was 6.0 mm, and the pupil diameter was 3.0 mm.

  The simulation was evaluated using a ZEMAX (registered trademark) optical design program manufactured by ZEMAX Development Corporation. Calculations relating to apodization and binarization were carried out by sending necessary data such as wavefront data from ZEMAX to MATLAB (registered trademark).

First, a simulation was performed in which apodization using a sine function was applied to an intraocular lens in which the diameter of the opening was 3 mm and the outer side was an opaque region. The function I _S (r) used for apodization is a function of the lens diameter r, and in this embodiment, a sine function represented by the following formula 1 was used.

  “A” and “b” in Equation 1 indicate the positions of the apodization start point and end point, respectively. In this embodiment, a is 0.5 mm and b is 1.5 mm. FIG. 6A shows a plan view of a lens (Apodized) to which apodization is applied. FIG. 6B shows the transmittance distribution in the radial direction of the lens to which apodization obtained by simulation is applied, together with the transmittance distribution of a lens to which apodization is not applied (Unapodized).

  As shown in FIG. 6B, the lens to which the apodization was not applied naturally had the same transmittance distribution as that of the pinhole lens having an aperture diameter of 3 mm. On the other hand, in a lens to which apodization is applied, the transmittance is 1 (100%) up to a point where the distance r from the center O is 0.5 mm, and when the distance exceeds 0.5 mm, the transmittance starts to gradually decrease. It was confirmed that the transmittance was 0 (0%) at a point of 1.5 mm, and thereafter the transmittance distribution was 0%. In other words, a lens to which apodization is applied is composed of a continuous region where the transmittance is a continuous value, and the continuous region includes a region where the transmittance changes in the radial direction (change region). It was.

  In this example, the above simulation was also performed when the pupil diameters shown in Table 1 were 2.0 mm and 4.0 mm. In the following, the results when the pupil diameter is 2.0 mm, 3.0 mm, and 4.0 mm are shown.

  7A to 7C show a two-dimensional plot of a point spread function (PSF) and a cross-sectional view of the PSF regarding a lens to which apodization is applied and a lens to which apodization is not applied. FIG. 7A shows the result when the pupil diameter is 2.0 mm, FIG. 7B shows the result when the pupil diameter is 3.0 mm, and FIG. 7C shows the pupil. This is the result when the diameter is 4.0 mm.

  As is apparent from FIGS. 7A to 7C, it was confirmed that the side lobe was reduced as the normalized radius was increased by applying apodization. It was also confirmed that the side lobe tends to decrease as the pupil diameter increases. Therefore, it was confirmed that the contrast was lowered in the lens to which the apodization was not applied, whereas the contrast was increased in the lens to which the apodization was applied.

  Subsequently, the MTF was calculated by Fourier transforming each PSF with respect to the lens to which the apodization was applied and the lens to which the apodization was not applied. The results are shown in FIG. 8A shows the result when the pupil diameter is 2.0 mm, FIG. 8B shows the result when the pupil diameter is 3.0 mm, and FIG. 8C shows the pupil. This is the result when the diameter is 4.0 mm.

  MTF is expressed as a function of SF, is an index of image transfer characteristics (resolution), and changes according to the change of SF. A large MTF indicates a high contrast. SF indicates the number of repeated white and black stripes included in the unit length. Here, the visual acuity indicates a minimum visual angle at which a white part and a black part of a visual target can be recognized separately, and is an index of eye resolution. Therefore, it can be said that SF and visual acuity correspond.

  From FIGS. 8A to 8C, it was confirmed that by applying apodization, the MTF on the lower SF side was strengthened and the MTF on the higher SF side was weakened. The range of human visual acuity corresponds to the low frequency side SF, and in order to increase the contrast of the image in the range of human visual acuity, the MTF on the lower SF side is higher than the MTF on the higher SF side. Is required to be high. For example, when SF is 100 cycles / mm (corresponding to a visual acuity of 1.0 (20/20)), from FIGS. 8A to 8C, a lens to which apodization is applied has an MTF higher than that of an unapplied lens. It was confirmed that the contrast was improved in the range of human vision. It was also confirmed that the contrast tends to be improved as the pupil diameter increases.

  FIG. 9 shows defocusing when the horizontal axis is defocused and the vertical axis is MSF at a specific SF (50 cycles / mm for (a) to (c) and 100 cycle / mm for (d) to (f)). The characteristic (Through Focus Response: TFR) is shown. 9A and 9D show the results when the pupil diameter was 2.0 mm, and FIGS. 9B and 9E show the results when the pupil diameter was 3.0 mm. FIG. ) And (f) are the results of setting the pupil diameter to 4.0 mm.

  As is clear from FIG. 9, the lens to which the apodization is applied has a higher contrast and a wider width than the lens to which the apodization is not applied. The wide width means that the depth of focus is deep, and that contrast can be obtained even when the focus is deviated to some extent. This width is an indicator of the visible range. Therefore, it can be confirmed that a lens to which apodization is applied has a wider visible range than an unapplied lens.

  7 to 9, it was confirmed that application of apodization improved various optical characteristics such as suppression of aberration and depth of focus compared to an unapplied lens. To visually show these results, FIG. 10 shows an image of the Landolt ring that would be seen when using a lens with and without an apodization applied. 10A shows the result of setting the pupil diameter to 2.0 mm, FIG. 10B shows the result of setting the pupil diameter to 3.0 mm, and FIG. The result is 0 mm.

  As is clear from FIG. 10, it was confirmed that the lens (gradation lens) to which the apodization was applied had a wider focus range and a higher contrast range than the unapplied lens, that is, the visible range was wide. .

Subsequently, the change region of the lens (gradation lens) to which apodization was applied was binarized to obtain a lens according to Example 1. The pupil diameter was 4.0 mm. Specifically, the gradation lens is equally divided into n along the circumferential direction, and the transmittance I (x, y) at an arbitrary point (x, y) in the gradation lens is binarized. Convert to I _DS (x, y). In this embodiment, _IDS is calculated using Equation 2 below.

In Equation 2, “mod (a, b)” indicates a modulo operation and indicates the remainder of “a / b”. Further, n is a discretization number represented by a positive integer, and in the present embodiment, indicates the number by which the lens area is divided. In this embodiment, n is 8. If the angle of the central angle of the sector area obtained by dividing the lens is θ, x and y can be expressed as x = r cos θ and y = rsin θ. Further, tan ⁻¹ (y / x) represents the angle θ of the point (x, y). The results are shown in FIG.

  From FIG. 11, it was confirmed that the region where the transmittance varies in the radial direction (change region) was binarized, and the lens according to Example 1 was composed of only the transmission region and the non-transmission region. In this example, binarization was performed so that the transmission region was line-symmetric.

  Next, FIG. 12A shows a PSF of the binarized lens shown in FIG. 11, and FIG. 12B shows a cross-sectional view of the PSF. In the cross-sectional view of FIG. 12B, for reference, the cross-section of the PSF of the lens to which the apodization shown in FIG. 7C is not applied is also shown. As is clear from FIGS. 12A and 12B, even in the case of binarization, the lens according to Example 1 has a reduced side lobe than the PSF of the lens to which apodization is not applied. It was confirmed that

  FIG. 12 (c) shows the Landolt ring that would be visible when using the binarized lens according to Example 1, a lens to which apodization was applied, and a lens to which apodization was not applied. Show the image. As is clear from FIG. 12C, the lens according to Example 1 shows better visual acuity characteristics than a lens to which apodization is not applied, and has almost the same visual acuity characteristics as a lens to which apodization is applied. I was able to confirm.

(Example 2)
In Example 2, when applying apodization, a Gaussian function I _G (r) shown in the following Expression 3 was used instead of the sine function of Example 1. This Gaussian function I _G (r) is a function of the radius r, and is a function obtained by convolution of the rectangular function (x) shown in Expression 4 and the Gaussian function G (r) shown in Expression 5.

  In Equation 3, “c” is a radius value at which the transmittance is 0.5 (50%). In this embodiment, c is 1.0 mm. In addition, the standard deviation σ of the Gaussian function in Equation (5) was set to 0.32. FIG. 13A shows a plan view of a lens (Apodized) to which apodization is applied. Further, FIG. 13B shows the transmittance distribution in the radial direction of the lens to which the apodization is applied, together with the transmittance distribution of the lens (Unapodized) to which the apodization is not applied.

  Furthermore, a two-dimensional plot of a point spread function (PSF) for a lens to which apodization is applied and a lens to which apodization is not applied, and cross-sectional views of the PSF are shown in FIGS. 14A shows the result when the pupil diameter is 2.0 mm, FIG. 14B shows the result when the pupil diameter is 3.0 mm, and FIG. 14C shows the result when the pupil diameter is 4. mm. The result is 0 mm.

  As is clear from FIGS. 13 and 14, it was confirmed that the same result as in Example 1 was obtained even when the function used when applying the apodization was changed.

Subsequently, the change region of the lens (gradation lens) to which apodization was applied was binarized using the equations shown in Equations 3 to 5 above, and the lens according to Example 2 was obtained. Binarization was performed in the same manner as in Example 1 except that the following Equation 6 was used when binarizing. That is, the pupil diameter was set to 4.0 mm. The results are shown in FIG.

  From FIG. 15, as in Example 1, it was confirmed that the region where the transmittance varies in the radial direction was binarized, and the lens according to Example 2 was composed of a transmissive region and a non-transmissive region. . In Example 2 of FIG. 15, binarization was performed so that the transmission region was asymmetric.

  Next, FIG. 16A shows a point spread function (PSF) of the binarized lens shown in FIG. 15, and FIG. 16B shows a cross-sectional view of the PSF. In the cross-sectional view of FIG. 16B, for reference, the cross-section of the PSF of the lens to which the apodization shown in FIG. 7C is not applied is also shown. Similar to Example 1, even when binarized, it was confirmed that the side lobe of the lens according to Example 2 was reduced more than the PSF of the lens to which apodization was not applied.

  FIG. 16 (c) shows the Landolt ring that would be seen when using a binarized lens according to Example 2, a lens to which apodization was applied, and a lens to which apodization was not applied. Show the image. As in Example 1, it can be confirmed that the lens according to Example 2 shows better visual acuity characteristics than a lens to which apodization is not applied, and has almost the same visual acuity characteristics as a lens to which apodization is applied. It was.

DESCRIPTION OF SYMBOLS 1 ... Intraocular lens 2 ... Transmission area 3 ... Impermeable area

Claims (4)

Assuming a gradation lens having a change region in which the light transmittance continuously changes in the radial direction of the lens,
The ratio of the length of a line segment that forms an arc having a radius r from the center of the ophthalmic lens and that transmits light and a non-transparent line segment that does not transmit light is a radius from the center of the gradation lens. By determining the ratio of the length of the transmission line segment and the non-transmission line segment so as to correspond to the transmittance of light on the circumference of r, the transmission region through which light is transmitted and the non-transmission of light. A setting step for setting the transmission region to the ophthalmic lens;
A method for designing an ophthalmic lens, comprising: In the assumed process,
A gradation lens having the change region is assumed by applying apodization to a discontinuous transmittance distribution obtained when light is transmitted through a pinhole lens having an opening.
The method for designing an ophthalmic lens according to claim 1. Assuming a gradation lens having a change region in which the light transmittance continuously changes in the radial direction of the lens,
The ratio of the length of a line segment that forms an arc having a radius r from the center of the ophthalmic lens and that transmits light and a non-transparent line segment that does not transmit light is a radius from the center of the gradation lens. By determining the ratio of the length of the transmission line segment and the non-transmission line segment so as to correspond to the transmittance of light on the circumference of r, the transmission region through which light is transmitted and the non-transmission of light. A setting step for setting the transmission region to the ophthalmic lens;
Manufacturing the set ophthalmic lens;
A method for producing an ophthalmic lens, comprising: In the assumed process,
A gradation lens having the change region is assumed by applying apodization to a discontinuous transmittance distribution obtained when light is transmitted through a pinhole lens having an opening.
The method for manufacturing an ophthalmic lens according to claim 3.