KR20210085583A - Contact Lenses with Spherical Aberration Control Design for Improved Visual Performance - Google Patents

Abstract

Disclosed is a contact lens to which a spherical aberration control design for improving visual performance is applied. The contact lens to which the spherical aberration control design for improving the visual performance according to the present invention is applied comprises: the inner surface of a lens having a predetermined inner curvature designed by a spherical design method; and the outer surface of the lens having a predetermined outer curvature designed by an aspherical design method. An object of the present invention is to provide the aspherical design method for compensating for spherical aberration, based on a spherical design.

Description

Contact Lenses with Spherical Aberration Control Design for Improved Visual Performance

The present invention relates to a contact lens, and more particularly, to a contact lens to which a spherical aberration control design for improving visual performance is applied.

Myopia, or myopia, is an optical or refractive defect in the eye in which light rays from an image are focused on a point before reaching the retina. Myopia usually occurs because the eyeball is longer than the focal point of the object or the cornea is too steep. A negative or negative powered lens may be used to correct myopia.

Hyperopia or hyperopia is also an optical or refractive defect in the eye where light rays from the image are focused on a point after or behind the retina after reaching the retina. Hyperopia usually occurs because the eyeball is shorter than the focal point of the object or the cornea is too flat. A plus or positive powered lens may be used to correct hyperopia.

Typically, contact lenses have a central optic that provides correction of myopia and farsightedness. The term “spherical contact lens” is often used to refer to a contact lens for correcting myopia or farsightedness that has a spherical or nearly spherical surface.

Prior art 1 discloses "a contact lens with improved visual performance and minimized halos using pupil apodization". Prior art 1 discloses a soft contact lens designed to improve visual performance, with reduced pupil edge wavefront aberration, reduced halo and reduced light scattering. Prior Art 1 discloses that soft contact lenses are designed using pupil apodization to modulate the lens amplitude transmission profile.

Prior art 2 discloses "a toric ophthalmic lens with selected spherical aberration properties". Prior art 2 has substantially zero spherical aberration for a first circular opening having a first diameter and substantially zero spherical aberration for a second circular opening having a second diameter, wherein the first diameter is at least 4 mm; The second diameter is 3mm or more, and the first diameter is 0.5mm or more larger than the second diameter The content is disclosed for a toric ophthalmic lens.

However, according to the method presented in Prior Art 1, if the lens power is set with an existing spherical design-based contact lens, if it is to be replaced with a natural log (exp) function, the problem of power matching arises. This can cause great confusion for consumers and optometrists. In addition, it can be made by applying a complex design to a single frequency, but it is difficult to design when the frequency is extended for several frequencies, and it is difficult to measure and verify these products, so it has great difficulties in mass production.

In addition, according to the method presented in Prior Art 2, an aspherical lens designed with zero spherical aberration does not fit the real human eye, so it does not form an image well, and has a big problem in power matching. And, it can be made by applying a complex design to a single frequency, but it is difficult to design when the frequency is extended for several frequencies, and it is difficult to measure and verify these products, so it has great difficulties in mass production.

As can be seen from the above-described prior art, spherical aberration may occur in the lens due to the geometric shape of the lens, even when the spherical front or rear surface provides satisfactory visual acuity. Such spherical aberration generates noise outside of normal focus in the retina, causing image blur and light blur, which causes fatigue or dizziness in the lens wearer.

In order to solve this problem, if only aspherical design is applied, there is a problem of visual acuity matching, which makes it difficult to find a lens with an appropriate power for myopia or hyperopia patients.

In particular, due to the characteristics of soft contact lenses provided to unspecified people by mass production, it is difficult to always guarantee proper performance for individual eyes. As a result, side effects such as image blur or light blur occur in people who do not match the performance of soft contact lenses, which often leads to complaints of fatigue or dizziness.

Patent Document 1: Patent Publication No. 10-2018-0020909 (2018.02.28) Patent Document 2: Patent Publication No. 10-2011-0067142 (June 21, 2011)

The present invention devised to solve the above problems provides an aspherical design method for compensating for spherical aberration, and provides an aspherical design method based on a spherical design for proper power matching.

That is, an object of the present invention is to provide a contact lens to which a spherical aberration control design for improving visual performance capable of reducing or improving image blur and light blur is universally applied.

In order to achieve the above object, according to an embodiment of the present invention, a contact lens to which a spherical aberration control design for improving visual performance is applied includes: an inner surface of a lens having a predetermined inner curvature designed by a spherical design method; and an outer surface of the lens having a predetermined outer curvature designed by an aspherical design method.

In this case, the outer surface of the lens, the contact lens, characterized in that the outer curvature is determined according to the following equation.

(where r is the radial distance from the vertex, C is 1/R, R is the radius of curvature of the spherical design, k is the shape factor (or -e ² , where e is the eccentricity)).

In this case, it has a first gradient change value between the lens power and the spherical aberration in the first power range of -5.00 to -10.00 diopters.

In this case, the second gradient change value between the lens power and the spherical aberration in the second diopter range of -10.00 diopters or more is designed to be smaller than the first gradient change value.

On the other hand, the power deviation within the pupil region of the contact lens is designed to be reduced compared to the power deviation of the spherically designed contact lens.

On the other hand, the spherical aberration amount has a value of 0.25 or less in all dioptric lenses.

According to various embodiments of the present invention, an aspherical design method for compensating for spherical aberration is adopted, but for proper power matching, an aspherical design technique is provided as a spherical design basis to reduce or improve image blur and light spread. perform

1 is a screen of power measurement results for a -7.5 diopter myopia lens;
2 is a view exemplarily explaining spherical aberration occurring in a spherical lens;
3 is a view showing a spherical aberration graph of a myopic lens;
4 is a power measurement result screen for explaining the causes of image blur and light blur in -7.5 diopter myopia lenses;
5 is a power measurement result screen in which the spherical aberration of the -7.5 diopter lens is removed;
6 is a view exemplarily explaining the inner curvature and the outer curvature for the lens design;
7 is a curve shape graph according to the conic constant (k);
8 is a view comparing the relationship between the lens power and spherical aberration for a contact lens (HD lens) and a spherical lens according to the present invention;
9 is a power measurement screen of a -7.5 diopter myopia lens, and,
10 is a screen showing the power measurement results of the -7.5 diopter myopia lens of the contact lens according to the present invention.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings. Preferred embodiments described below may be variously designed and changed within the scope of the technical spirit of the present invention.

Spherical Lenses and Spherical Aberration

1 is a screen showing the power measurement results for a -7.5 diopter myopia lens. Referring to FIG. 1 , the power of the lens according to the spherical lens design is -6.50 diopters from the center, and the power gradually increases from the center to the edges.

2 is a diagram exemplarily illustrating spherical aberration occurring in a spherical lens. Referring to FIG. 2 , the light passing through the spherical lens does not focus on a single point, but becomes further away from the focal point of the paraxial ray as it moves away from the optical side. Referring to FIG. 2( a ), the light is not clearly seen in the cross-shaped slit and the light is cloudy is a phenomenon due to spherical aberration. Referring to FIG. 2(b) , as the distance from the optical axis increases, the focus is focused on a point P_2 that is further away from the focal point P_1 of the paraxial ray. The spherical aberration becomes more severe as the lens power increases, and this will be described with reference to the drawings below.

3 is a diagram illustrating a spherical aberration graph of a myopic lens. Referring to FIG. 3 , it can be seen that the dioptric power and the slope of the spherical aberration of the myopic lens are upward sloping from 0.00 diopters to 0.5 diopters when viewed from the side. It can be seen that the slope of the trend line is 0.05 because the spherical aberration is 0 when the lens power is -1.5 diopters and the spherical aberration is 0.5 at -11.5 diopters. As such, the lens power and the spherical aberration have a positive correlation. Accordingly, the higher the power, the more severe the spherical aberration occurs.

Image blur and light blur

As the power of the lens increases, the spherical aberration increases. Therefore, image blur and light blur occur in the section where the power is rapidly increased. This will be described in detail with reference to the drawings.

4 is a screen showing the results of power measurement to explain the causes of image blur and light blur in a -7.5 diopter myopia lens. Referring to FIG. 4 , the power of the -7.5 diopter myopia lens is -6.5 at the center, and the power gradually increases toward the edge of the lens. At a point about 2.5mm away from the center, the power of the lens increases sharply, and at a point about 3.0mm away, it rises to -8.2 diopters. That is, it causes image blur or light blur in the ±2.5 ~ ±3.0mm section.

Although the spherical design myopia lens has a power of -7.5 degrees, the power in the center is -6.5 degrees, and at the end of the pupil size, a sharp change in power occurs to the level of -8.2 degrees, which causes image blur and image blur to the patient. It causes problems such as light scattering.

Since the conventional myopia lens is manufactured using a spherical manufacturing method, the spherical aberration becomes larger in the section where the dioptric power is increased, so that the phenomenon of image blur or light blur becomes conspicuous.

5 is a screen showing the power measurement result screen from which the spherical aberration of the -7.5 diopter lens is removed. Referring to FIG. 5 , if an aspherical surface is designed to improve the spherical aberration so that the spherical aberration is made '0' or a lens close to '0', it is difficult to perform power matching on the eyeball.

Because the human eye has a structure that selectively adjusts the muscles to the visual field of view, spherical aberration is 'spherical aberration' for patients who could see objects well even with slight image blur and light blur in the periphery in the past spherical design lenses. A lens that becomes 0' or is close to '0' causes a problem that the field of view does not match at all.

contact lens according to the invention

6 is a view exemplarily explaining an inner curvature and an outer curvature for a lens design. Referring to FIG. 6 , the dioptric power of the lens is determined according to the inner curvature (base curve) and the outer curvature (front curve) of the lens. The determination of the outer curvature in the spherical design is based on the lens manufacturer's formula as shown in Equation 1 below.

Here, 1/f = D (power, power), n is the refractive index in air, n1 is the refractive index of the lens material, and R1 and R2 are the curvatures of the lens surface (R1 is the outer curvature, R2 is the inner curvature).

In the present invention, in order to improve image blur and light blur, an aspherical design is designed using an aspherical equation as shown in Equation 2 below based on a front curve of a conventional spherical design.

In Equation 2, r denotes a radial distance from the vertex, C denotes 1/R, and R denotes a radius of curvature of the spherical design. k is the shape factor (or -e ² , where e is the eccentricity), and when k is 0, the cone is a sphere. If -1<k<0, the cone is an ellipse. If ∂>0, the cone is an ellipse with a steep surface due to negative eccentricity. The change in the shape of the curve according to the conic constant (k) will be described with reference to the following drawings.

The contact lens according to the present invention has aberration values for each of a series of lenses in the lens power range as shown in Table 1 below.

Referring to Table 1 above, aberration values for each of a series of diopter-corrected lenses are displayed over a range of 0.00 to -19.5 diopters. As recorded in the left column of Table 1, when it is formed in an elliptical curve on the front side, it can be seen that spherical aberration is significantly reduced compared to the existing spherical design (however, there is a large difference in the vicinity of 0.00 ~ -2.00 diopters) The sub-tables of Table 1 above show the shape coefficients and aberration values of the relevant optical areas that provide optimal visual acuity for each dioptric power of a series of contact lenses.

7 is a curve shape graph according to the conic constant (k). Referring to FIG. 7 , the conic constant (k) is -e ² , where e means the eccentricity. When k is 0, the cone is a sphere. If -1 < k < 0, the cone is an ellipse. If ∂>0, the cone is an ellipse with a steep surface due to negative eccentricity.

Comparison of contact lenses according to the invention and spherical lenses

8 is a diagram comparing the relationship between the lens power and spherical aberration for a contact lens (HD lens) and a spherical lens according to the present invention. A contact lens (hereinafter referred to as an HD lens) according to the present invention is composed of an inner surface of a lens having a predetermined inner curvature designed by a spherical design method and an outer surface of a lens having a predetermined outer curvature designed by an aspherical design method to be a technical feature. By using this outer curvature as an aspherical design method, image blur and light blur are reduced.

Referring to FIG. 8( a ), there is no significant difference compared to the spherical design in the 0.00 to -2.00 diopter section (the first section). At low powers, spherical aberration does not occur significantly, so even if there is no significant difference, there is no difference in effect. It can be seen that in the -2.00 to -8.00 diopter section (the second section), the lens according to the present invention exhibits a slope similar to the amount of reduction in the amount of spherical aberration in the first section. At a high power of -8.00 diopters or more, a change in the amount of spherical aberration similar to the slope in the second section is exhibited, so it can be understood that the spherical aberration is significantly reduced compared to the spherical lens.

Referring to FIG. 8(b) , it can be confirmed that image blur or light bleeding appears in the spherical lens, and in the case of the HD lens, the image is clear and there is no problem of light bleeding.

As described above, the HD lens according to the present invention exhibits a remarkable effect of reducing spherical aberration by 25 to 77% compared to a spherical lens.

9 is a power measurement screen of a -7.5 diopter myopia lens. Referring to FIG. 9 , in the case of a myopic lens of -7.5 diopters, since the power is rapidly increased below -7.5 diopters, image blurring or light blurring due to spherical aberration appears.

On the other hand, the contact lens according to the present invention exhibits a characteristic that spherical aberration is significantly reduced even when applied to a -7.5 diopter myopia lens. More specific details will be described below with reference to separate drawings.

10 is a screen showing the power measurement results of the -7.5 diopter myopia lens of the contact lens according to the present invention. Referring to FIG. 10 , there is no point at which the increase rate of the dioptric power is rapidly changed from the center to the edge compared to the spherical lens.

That is, referring to FIG. 10 , it can be seen that the spherical aberration is almost eliminated at -7.75 diopters. The contact lens according to the present invention 1) has an area that can be adjusted to an image that is easily seen by the eye (easy power matching compared to a fully aspherical design), 2) has a reduced dioptric power area in the pupil compared to a spherical design (image Blur improvement), 3) The sudden power change at the tip of the pupil is weak (improving light blur).

As described above, the contact lens according to the present invention exhibits remarkable effects of reducing spherical aberration and improving light blur or blur by adopting a design method that complements the disadvantages of spherical design and aspherical design.

Claims (6)

A contact lens to which a spherical aberration control design for improving visual performance is applied, the contact lens comprising:
an inner surface of the lens having a predetermined inner curvature designed by a spherical design method; and
A contact lens comprising: an outer surface of a lens having a predetermined outer curvature designed by an aspherical design method.
According to claim 1,
The outer surface of the lens, a contact lens, characterized in that the outer curvature is determined according to the following equation.

(where r is the radial distance from the vertex, C is 1/R, R is the radius of curvature of the spherical design, k is the shape factor (or -e ² , where e is the eccentricity)).
3. The method of claim 2,
A contact lens, characterized in that it has a first slope change value between the lens power and the spherical aberration in a first power range of -5.00 to -10.00 diopters.
4. The method of claim 3,
A second gradient change value between the lens power and the spherical aberration in a second diopter range of -10.00 diopters or more is smaller than the first gradient change value.
According to claim 1,
The contact lens, characterized in that the power deviation within the pupil region of the contact lens is designed to be reduced than the power deviation of the spherically designed contact lens.
According to claim 1,
A contact lens, characterized in that the spherical aberration amount has a value of 0.25 or less in all dioptric lenses.

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