JP2604645B2 - Near-to-medium range distortion-free presbyopic lens - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a near-medium-range distortion-free presbyopic lens for correcting vision of presbyopia.

[0002]

2. Description of the Related Art In general, the accommodation power of the crystalline lens in the eyeball is weakened, and in the case of presbyopia in which the near point is far away, the accommodation (accommodation) necessary for viewing a nearby object becomes impossible. It is advisable to make up for the lack of accommodation power with spectacles wearing convex lenses.

Conventionally, such presbyopic lenses include:
For example, there is a convex lens having a structure as shown in FIG. That is, it is a presbyopic lens in which the radius of curvature r (1) of the front surface 50F of the lens 50 is set smaller than the radius of curvature r (2) of the rear surface 50R of the lens 50.

Specifically, in the case of taking a 2 degree (diopter) lens as an example, r (1) = 116.754 mm, r
(2) = Presbyopia lens with 218.667 mm and r (1) <r (2).

In the case of this conventional presbyopic lens, the lens 5
Since the curvature radii r (1) and r (2) are both set to be constant from the geometric center 51 to the outside in the radial direction, the size of the object and the size of the virtual image viewed through the lens 50 are determined. Since the ratio (lateral magnification) changes depending on the position of the object, distortion occurs, and this phenomenon has a problem that the higher the power of the lens is, the more significant it becomes.

[0006] In addition, as shown by hatching in FIG.
For example, in the case of a patient wearing a lens of degree, the corrected near point on the optical axis a is 300 mm (however, the numerical value is the distance from the angle of the eyeball 52), and the far point of the patient with the naked eye is Assuming infinity, the corrected far point
) Is 504 mm (focal length of the lens) and the angles θ1 and θ2 between the optical axis a and the line of sight b of the eyeball are set to 30 degrees, the near point is 300 mm, the far point is 504 mm, and clear vision is achieved. There is a problem that the area is narrow, and this phenomenon becomes more pronounced as the lens power increases.

Therefore, when the lens 50 having such a conventional structure is worn, the clear vision range is limited to a short distance, and at the same time, an image is deformed due to distortion and comfortable vision cannot be obtained. In this case, there is a problem that eye fatigue becomes great.

[0008]

According to the present invention, there is no distortion (no distortion) , the clear vision region can be greatly expanded, and the image is not deformed when worn. It is an object of the present invention to provide a short-range, medium-range, distortion-free presbyopia lens (hereinafter simply abbreviated as a presbyopia lens) which is obtained and has little eye fatigue even when worn for a long time.

[0009]

SUMMARY OF THE INVENTION The present invention, in the lens front surface of the small radius of curvature presbyopia correction lens with respect to the radius of curvature of the lens rear surface, the lens moves away towards geometry in mind either et radially outer lens At least one of the front and back
It is a presbyopic lens in which the refractive power of each of the lenses is sequentially corrected, and the refractive power is sequentially set to be small so that the lateral magnification for all principal rays becomes equal to the lateral magnification in the paraxial region. .

[0010]

According to the present invention, the refractive power of the lens surface is sequentially changed so as to be equal to the lateral magnification in the paraxial region, and this lens surface is created in a unique aspherical structure. There is no effect, and the clear visual range can be greatly expanded, and there is no deformation of the image when worn, comfortable vision is obtained, and eyestrain is reduced even when worn for a long time.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings, taking as an example a case where the refractive power of the front surface of a lens is corrected.

The drawing shows a presbyopia lens. In FIG. 1, the presbyopia lens 11 has a radius of curvature of a front surface 11F of the lens 11 set to be smaller than a radius of curvature r (2) of a rear surface 11R of the lens 11. At the same time, the curvature radius r ′ (1) of the front surface 11F of the lens 11 is sequentially corrected as the distance from the vicinity of the geometric center 12 of the lens 11 to the outside in the radial direction increases, so that the lateral magnification for all principal rays is in the paraxial region. The radius of curvature r '(1) is sequentially set to be large so as to be equal to the lateral magnification.

That is, with respect to the curvature radius r (1) before correction indicated by the imaginary line in FIGS. 1 and 2, the front surface 11F of the lens 11 is corrected radially outward from the geometric center 12 of the lens 11. The subsequent radius of curvature r '(1) is shown in FIGS.
As shown by the solid line, the correction is made so as to become sequentially larger (r '(1)> r (1)).

The specific configuration of the second presbyopia lens 11 will be described below as an example. Now, as shown in FIG. 1, when the lens 11 is worn, the separation distance E 'on the optical axis a between the front surface of the cornea of the eyeball 13 and the rear surface 11R of the lens.
P ′ is set to 18 mm and the thickness d (1) of the lens 11 on the optical axis a
To 3 mm, the optical axis a between the front surface 11F of the lens and the object 14
The upper distance d (0) is 300 mm, the radius of curvature r (2) of the rear surface 11R of the lens is 218.667 mm, and the radius of curvature r (1) of the front surface 11F of the lens on the optical axis a is 116.75.
4 mm, the refractive index of air N '(0) = 1,
Refractive index N ′ (1) of transparent acrylic resin lens 11 =
When the lateral magnification β in the paraxial region is obtained from 1.492, β = 2.
44136. The lens rear surface 11R and the virtual image 15
The distance d (2) on the optical axis a between the two is -731.11 mm.

Next, when the height y (0) of the object 14 is set to 10 mm, the radius of curvature r 'of the lens front surface 11F is set so that the height y' (3) of the virtual image 15 becomes equal to the above-mentioned lateral magnification β.
(1) is converted from r (1) = 116.754 mm to r ′ (1).
= 116.8539962768555 mm, and the height y (3) of the virtual image 15 before correction is the height y after correction.
If the configuration is such that '(3) = 24.413 mm, the lateral magnification β = y' (3) / y (0) = 2.444134.

That is, as shown in FIG. 2, the horizontal length x (1) and the vertical length y (1) of the coordinates of the intersection of the principal ray and the curved surface before correction are shown in FIG. 3 , respectively . The horizontal length x ′ of the coordinates of the intersection of the curved surface and the principal ray after correction
The radius of curvature of the front surface 11F of the lens is increased from r (1) to r '(1) in order to correct (1) and the vertical length y' (1). Next, when the height y (0) of the object 14 is set to 20 mm, the radius of curvature r ′ (1) of the lens front surface 11F is set so that the height y ′ (3) of the virtual image 15 becomes equal to the above-described lateral magnification β.
R ′ (1) = 116.9539947575076
If the height is corrected to 6 mm and the height y (3) of the virtual image 15 before the correction is equal to the height y ′ (3) = 48.8331 mm after the correction, the lateral magnification β = y ′ (3) / y. (0) =
2.444166.

Next, when the height y (0) of the object 14 is set to 30 mm, the radius of curvature r '() of the lens front surface 11F is set so that the height y' (3) of the virtual image 15 becomes equal to the above-mentioned lateral magnification β. 1)
Is r ′ (1) = 117.4533987121582 mm
And the height y (3) of the virtual image 15 before the correction is equal to the height y ′ (3) = 73.2479 mm after the correction, the lateral magnification β = y ′ (3) / y ( 0) = 2.4
416.

Hereinafter, the height y (0) of the object 14 is increased by 10 mm and the radius of curvature r '(1) of the lens front surface 11F is increased in the same manner as described above until y (0) = 170 mm.
For convenience of explanation, only numerical values are shown. When y (0) = 40 mm, r '(1) = 118.1539764404297 mm y' (3) = 97.60202 mm β = 2.4415 When y (0) = 50 mm r '(1) = 118.9539643233984 mm y' (3) = 122.0077 mm β = 2.444154 When y (0) = 60 mm r ′ (1) = 120.0539474487305 mm y ′ (3) = 146.481 mm β = 2.444136 y (0) = 70 mm When r '(1) = 121.153930664625 mm y' (3) = 170.903 mm β = 2.444147 When y (0) = 80 mm r '(1) = 122.5390930175578 mm y' (3) = 195.306 mm β = 2.444133 When y (0) = 90 mm r ′ (1) = 123.9538879394531 mm y ′ (3) = 219.731 mm β = 2.4 When 145 y (0) = 100 mm r '(1) = 125.65386999117 mm y' (3) = 244.129 mm β = 2.444129 When y (0) = 110 mm r '(1) = 127.353383595703 mm y R (3) = 268.551 mm β = 2.444137 When y (0) = 120 mm r ′ (1) = 129.225390625 mm y ′ (3) = 292.957 mm β = 2.44311 y (0) = 130 mm When r '(1) = 131.154022167969 mm y' (3) = 317.386 mm β = 2.444143 When y (0) = 140 mm r '(1) = 133.254150390625 mm y' (3) = 341. 793 mm β = 2.444138 When y (0) = 150 mm r ′ (1) = 135.454286667968 mm y ′ (3) = 366.194 mm β = 2.4413 y (0) = 160 mm r '(1) = 1377.6544189453125 mm y' (3) = 390.615 mm β = 2.444134 y (0) = 170 mm r '(1) = 139 .954555932719 mm y ′ (3) = 415.024 mm β = 2.44132 Thus, the radius of curvature r ′ (1) of the front surface 11F of the lens is set such that the lateral magnification for all principal rays is equal to the lateral magnification β in the paraxial region. ) Are sequentially set to be large, and this lens front face 11F
Is created in a unique aspherical structure, so that there is an effect that distortion is completely eliminated, and there is an effect that a complete distortion-free lens (a lens with no distortion) can be formed. What
The above-mentioned generated aspheric surface is calculated by the algorithm of the computer.
Calculation, created.

In addition, as shown by hatching in FIG. 4, there is an effect that the clear visual range can be greatly expanded. As an example of the above-mentioned two-degree lens 11, the near point on the optical axis a is 300 mm, the far point is 504 mm, and the optical axis a and the principal ray b
In the position where the angles θ1 and θ2 are set to 30 degrees, the near point is about 373 mm and the far point is about 780 mm, and the clear visual range is greatly expanded as compared with the conventional lens shown in FIG. This effect becomes more pronounced as the power of the lens increases.

Therefore, when the lens 11 having the above structure is worn, there is no shaking (fracture) of the image due to the movement of the eyeball, and a clear viewing zone is obtained from a short range to a middle range, and comfortable vision is secured. In addition, there is an effect that eye fatigue is reduced even when worn for a long time.

Further, as described above, the curvature radius of the lens front surface 11F is sequentially set to be large (the refractive power of the lens is set to be small), so that the projection amount of the lens front surface 11F, that is, the swelling becomes small. Since the thickness of the lens 11 can be reduced, the thinner lens has an effect that a brighter visual field can be obtained and the weight of the lens 11 can be reduced.

In the above embodiment, the refractive power of the lens is gradually reduced by sequentially increasing the radius of curvature of the front surface of the lens. However, the present invention is not limited to the correction of only the front surface of the lens. Of course, only the rear surface or the front and rear surfaces may be corrected.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a presbyopic lens of the present invention.

FIG. 2 is an explanatory diagram showing a state before correction of a front surface of a lens.

FIG. 3 is an explanatory diagram showing a state after correction of a front surface of a lens.

FIG. 4 is an explanatory diagram showing a clear visual region of the lens of the present invention.

FIG. 5 is an explanatory diagram showing a clear viewing area of a lens having a conventional structure.

[Explanation of symbols]

 11: Lens 11F: Lens front surface 11R: Lens rear surface 12: Lens geometric center r (1): Curvature radius of lens front surface before correction r '(1) ... Curvature radius of lens front surface after correction r' (2) … The radius of curvature of the rear surface of the lens

Claims (1)

(57) [Claims] 1. The rear surface of a lens(11R)For the radius of curvature of
Lens front(11F)Lens with small radius of curvature
At, LesLens(11)Geometric center of(12)From half
As you move radially outwardLens front (11F),
At least one of the rear surface (11R)The refractive power of the lens surface
Sequential correctionTherefore, the lateral magnification for all chief rays (b) is always
Set to be equal to the lateral magnification in the paraxial region  A short-range, medium-range distortion-free presbyopic lens.