Title: Corneal Correction Contact Lens
Technical field
[0001]
　The present invention relates to a cornea correction contact lens. And more particularly to a cornea correction contact lens having a structure for deforming the shape of the corneal surface.
BACKGROUND ART
[0002]
　As a means of correcting myopia, a treatment method (orthokeratology) in which contact lenses provided with multiple radius of curvature in multiple stages are worn overnight, the shape of the corneal surface is deformed, the focal length of the cornea itself is changed, Corneal correction contact lenses (orthokeratology lenses) to be used in the method are known (for example, Patent Document 1).
[0003]
　Explain the mechanism of vision correction using a cornea correction contact lens.
[0004]
　In the myopic state, as shown in FIG. 1, the surface of the cornea 2 has a convex curvature (an aspherical shape convex to the left side in FIG. 1) convex forward with respect to the retina. For this reason, the convergence of light occurs in front of the retina 6 without focusing on the retina 6.
[0005]
　In this cornea 2, as shown in FIG. 2, the cornea correction contact lens 1 is worn like a corset, and the shape of the corneal surface 7 shown in FIG. 1 is corrected.
[0006]
　As a result, even after removing the cornea correcting contact lens 1, the corneal surface 7 can be flattened as shown in FIG. 3.
[0007]
　Therefore, the refracting power of the light is adjusted, and the focal point is tied onto the retina 6, so that an improvement in visual acuity can be obtained for a certain period of time.
[0008]
　Regarding the cornea correction contact lens, it is common that the shape of the surface in contact with the corneal surface is divided into four parts. A base region disposed in the center of the corneal correction contact lens and being a concave spherical surface that presses the corneal surface and is responsible for correcting the surface curve, a circular region that is disposed around the base region and receives corneal tissue moving from the base region An annular alignment region arranged around the reverse region and the reverse region to adjust the corneal correction contact lens and cornea fitting and the corneal correction contact lens centering, forming an edge, removing the lens and corneal correction contact of the tear film It is an annular peripheral region that helps to flow into the lens.
Prior Art Document
Patent literature
[0009]
Patent Document 1: Japanese Patent No. 3881221
Summary of the invention
Problem to be Solved by Invention
[0010]
　In the conventional cornea correction contact lens described in Patent Document 1, the radius of curvature of the base region is determined from the average radius of curvature of the cornea before correction and the degree of correction to be corrected.
[0011]
　The radius of curvature of the alignment region is close to the average radius of curvature of the cornea before correction and also the radius of curvature of the base region is R B and the radius of curvature of the reverse region is R R in order to enhance fitting to the cornea ,
R R = R B + 11.00 D to 15.00 D (D: diopter)
.
[0012]
　However, since the shape derived from the conventional design concept based on the above formula is derived from a medical approach aimed at securing a region for receiving the moving corneal tissue, the cornea The lens depth in the region to be corrected by the correction is different.
[0013]
　As a result, according to the conventional deriving means based on the above formula, when the frequency to be corrected is small, since the lens depth in the region applied to the correction of the cornea is deepened, the amount by which the cornea is pressed in the axial direction of the eye May become shallow or may not be in contact with each other, it is impossible to press the central portion of the cornea sufficiently, it is impossible to obtain the expected correction power, or it takes time to obtain the corrected visual acuity, and the correction effect varies In some cases.
In addition, when the amount by which the cornea is pressed in the axial direction of the eye increases, there is a possibility that the cornea is scratched due to strongly pressing the surface of the cornea, the possibility of causing complications due to a decrease in intraocular pressure, There was a possibility of roughening. That is, according to the conventional method of deriving the value of the radius of curvature of the reverse region only from the radius of curvature of the base region to be corrected, there is a possibility of scattering the correction effect or damaging the cornea.
[0014]
　Therefore, in the present invention, it was found that it is preferable to derive the radius of curvature of the reverse region from the radius of curvature of the base region and the radius of curvature of the alignment region.
[0015]
　In the present invention, by changing the radius of curvature of the reverse region even when the number of degrees to be corrected is different, under the curvature radius of the same alignment region, correction of the cornea in which the depth of the cornea correction region is constant Provide a contact lens.
Means for solving the problem
[0016]
　In order to solve the above problem, the present invention has the following configuration.
[0017]
　(1) A cornea correcting contact lens for correcting visual acuity by changing the shape of a cornea, wherein the lens surface in contact with the cornea comprises a central portion called a base region which is disposed at the center and presses the cornea, An annular portion which is disposed in the periphery and is called a reverse area, an annular portion which is arranged around the reverse area and is called an alignment area, and an annular portion which is arranged around the alignment area and is called a peripheral area , Changing the radius of curvature of the reverse region even if the radius of curvature and width of the base region, the width of the reverse region, the radius of curvature and width of the alignment region, the radius of curvature and width of the peripheral region, and the frequency to be corrected change , Wherein the depth of the lens required for correcting the cornea is constant,
　(2) a cornea correcting contact lens, In the cornea correction contact lens, the corneal correction contact lens described in (1), wherein the depth of the lens necessary for correcting the cornea is constant under the curvature radius of the same alignment region in the cornea correction contact lens,
　(3) in the cornea correction contact lens (1) or (2), wherein the radius of curvature of the reverse region is derived according to the radius of curvature and width of the base region, the width of the reverse region, the radius of curvature and width of the alignment region and the radius of curvature and width of the peripheral region orthokeratology contact lens according to 2),
　(4) width W of the base region B , the width of the reverse area W R , the radius of curvature of the base region R B , the radius of curvature of the reverse region R R , the alignment region If the radius of curvature is R A, The lens depth of the base region is T B , the lens depth of the reverse region is T R , the point where the curve of the base region intersects the contact lens central axis, and the extension line of the curve of the alignment region and the contact lens central axis intersection point, the linear distance between the S P when the lens depth T of the reverse region R is derived by the following formula (1), the radius of curvature R of the reverse region R is, T R the following equation using the ( 2), the corneal correction contact lens according to (3)
[0018]
[Expression 1]

[0019]
(In the formula (1), E = W B / 2, F = W B / 2 + W R )
[0020]
[Expression 2]

[0021]
(In the formula (2), E = W B / 2, F = W B / 2 + W R represents
　a.) (5) Lens depth T R and the curvature radius R R is, the lens depth T derived respectively R and (4) wherein the 　radius of curvature and the width of the alignment region are within the range of ± 10% with reference to the radius of curvature R R ;
(6) the cornea correcting contact lens described in (4) orthokeratology contact lens according to a different (1) in the direction,
　according to (7) the maximum value of the radius of curvature of the alignment region in the same under a constant depth of the lens required for correction of the cornea (6) orthokeratology contact lens,
　(8) the radius of curvature of the reverse area, the radius of curvature and width of the base region, the width of the reverse area, the maximum value of the maximum value and the width of the radius of curvature of the alignment region, and the curvature of the peripheral region Orthokeratology contact lens according to become be derived according to the diameter and width (6) or (7),
　(9) the width of the base region W B , the width of the reverse area W R , the radius of curvature of the base region R BThe radius of curvature of the reverse area is R R , the maximum value of the radius of curvature of the alignment area is R AV , the lens depth of the base area is T B , the lens depth of the reverse area is T R , a point where the axis intersects the point where the extension line and the contact lens center axis of the curve having a maximum value of the radius of curvature of the alignment regions intersect, the linear distance between S P when the lens of the reverse region depth T R (6) to (8), wherein the radius of curvature R R of the reverse region is derived by the following formula (2) using T R: lens,
[0022]
[Expression 3]

[0023]
(In the formula (3), E = W B / 2, F = W B / 2 + W R )
[0024]
[Expression 4]

[0025]
(E = W B / 2, F = W B / 2 + W R in Expression (2) )
　(10) Lens Depth T R and Curvature Radius R R are calculated from the derived lens depth T R and Is within a range of ± 10% with reference to the radius of curvature R R (9).
Effect of the invention
[0026]
　According to the present invention, even when the power to be corrected is different, by changing the radius of curvature of the reverse region, the lens depth in the region applied to the correction of the cornea is made constant under the curvature radius of the same alignment region Providing a cornea correction contact lens.
Brief Description of the Drawings
[0027]
FIG. 1 is a schematic view of a corneal shape eyeball in the state of myopia.
FIG. 2 is a schematic view of an eyeball when a cornea correction contact lens is worn.
FIG. 3 is a schematic view of the eyeball after removing the cornea correction contact lens.
FIG. 4 is a schematic view of a cornea correction contact lens of the present invention.
FIG. 5 is a schematic diagram illustrating the shape of a cornea correction contact lens of the present invention.
FIG. 6 is a schematic view of a cornea correction contact lens for a toric of the present invention.
FIG. 7 is a schematic diagram illustrating a shape of a cornea correction contact lens for a toric of the present invention.
MODE FOR CARRYING OUT THE INVENTION
[0028]
　The present invention provides a cornea correcting contact lens for correcting visual acuity by changing the shape of a cornea, wherein the lens surface in contact with the cornea comprises a central portion, which is located in the center and is referred to as a base region pressing the cornea, , An annular portion called a reverse area, an annular portion disposed around the reverse area and called an alignment area, and an annular portion arranged around the alignment area and called a peripheral area And the radius of curvature of the reverse region is changed even if the radius of curvature and width of the base region, the width of the reverse region, the radius of curvature and width of the alignment region, the radius of curvature and width of the peripheral region, and the frequency to be corrected change , The depth of the lens necessary for correcting the cornea is constant, and in more detail, the songs in the same alignment region Under radius is orthokeratology contact lens the depth of the lens required for correction of the cornea, characterized in that a constant.
[0029]
　Hereinafter, an example of a preferred embodiment of the present invention will be described.
[0030]
　First, the cornea correction contact lens of the present invention is preferably a hard contact lens having high oxygen permeability. As shown in FIG. 4, the cornea correction contact lens of the present invention has a surface shape in contact with the cornea 2 of 4 It is divided into two parts.
[0031]
　They are
arranged around the cornea 2 shown in FIG. 1 and around the base region B, the base spherical part which is the center spherical part which presses the corneal surface 7 and corrects the surface radius of curvature, and from the base region B annular reverse region R to accept the corneal tissue to be moved,
is disposed around the reverse range R, orthokeratology contact lens 1 and the cornea 2 and the fitting and orthokeratology contact lens 1 of the annular alignment region a to adjust the centering
edge And is a peripheral region P that helps to remove the lens and inflow the lacrimal fluid into the cornea correction contact lens 1.
[0032]
　The radius of curvature R of the base region B B is the cross-sectional shape including a contact lens center axis M, the center point C B is located on the contact lens center axis M, the radius of curvature as the corneal surface 7 is power to be corrected Is determined. Since the shape of the corneal surface 7 changes according to the radius of curvature, myopia can be corrected.
[0033]
　In the reverse region R, a space is formed between the cornea correcting contact lens 1 and the cornea 2, and plays a role of receiving corneal tissue which moves as a result of correction in the base region B.
[0034]
　The alignment region A contributes to the centering adjustment of the cornea correction contact lens 1 in a state of contact with the cornea 2 at a distance of several microns or close to the contact. The curvature radius R of the alignment region A A is also to enhance the fit to the cornea 2, the center point C A is located on the contact lens center axis M, a value close to the corneal surface curvature radius of the front orthodontic .
[0035]
　In the peripheral region P, it plays a role of helping inflow of tear fluid from the end of the cornea correction contact lens 1 to the cornea 2, and its sectional shape forms a rounded conical shape in order to reduce foreign body sensation during wearing Is preferable.
[0036]
　As shown in FIG. 4, all the curved surfaces have a curvature radius with the center axis M of the contact lens as the center, and have a concave bowl shape with respect to the cornea 2 shown in FIG. 1.
[0037]
　Further, with respect to the transition point J 1 of the base region and the reverse region where the curved surfaces are continuous, the transition point J 2 of the reverse region and the alignment region, and the transition point J 3 of the alignment region and the peripheral region, so as not to scratch the cornea 2 when wearing , It is preferable to be rounded, and its radius of curvature is preferably 0.02 to 4.00 mm.
[0038]
　An embodiment of the present invention will be described in detail with reference to FIG. 5. FIG. 5 is a schematic view of the cornea correction contact lens 1 of the present invention.
[0039]
　In FIG. 5, the width of the base region is W B , the width of the reverse region is W R , the width of the alignment region is W A , the width of the peripheral region is W P , the radius of curvature of the base region is R B , the radius of curvature of the reverse region Is R R , the radius of curvature of the alignment region is R A , the curvature radius of the peripheral region is R P , the lens depth of the base region is T B , the lens depth of the reverse region is T R , the depth of the lens is S K (= T B + T R ), and,
the linear distance between K1 point curve and the contact lens center axis of the base region intersect, the point extension and the contact lens center axis M of the curve in the alignment region intersects K2, and the S P and.
[0040]
　With respect to the radius of curvature R B of the base region, since the radius of curvature is determined so as to be the power to be corrected, the lens depth T B of the base region is derived from the following formula (4) according to the width W B of the base region .
[0041]
[Expression 5]

[0042]
The radius of curvature R A of the alignment region is preferably set to a value close to the average radius of curvature R K of the cornea before correction, in order to enhance the fitting to the cornea 2 .
[0043]
　In the present invention, even if the R B, W B , W R , R A , W A , R P , W P and the number of times to correct are changed in the cross section including the center axis M of the cornea correction contact lens , By changing the radius of curvature R R of the reverse area, the depth of the lens necessary for correcting the cornea is constant, and furthermore, under the curvature radius R A of the same alignment area , And the depth S K is constant.
[0044]
　Specifically, in the cross section including the center axis M of the cornea correction contact lens of the present invention, the lens depth T R of the reverse region is derived by specifying the value of the depth S K of the lens for correcting the cornea , By determining the radius of curvature R R of the reverse region so as to satisfy that value, it is possible to make the depth S K of the lens for correcting the cornea constant.
[0045]
　That is, in the section including the center axis M of orthokeratology contact lenses of the present invention, the R B , W B , S K , and, T B from the lens depth T of the reverse region R is, T R = S K - T B is determined by. As a result, the T B , R B , W B , T R , W R , R A , W A , R P , and, W P from the base region and the transition points J1 and reverse region and an alignment region of the reverse region The transition point J 2 can be determined.
[0046]
　If the curve of the reverse region R passes through the transition point J 1 between the base region and the reverse region and J 2 in the reverse region and the alignment region, the frequency to be corrected changes under the curvature radius R A of the same alignment region It is possible to make the depth S K of the lens which is required for correcting the cornea constant.
[0047]
　Here , if the center point C R of the curvature radius R R of the reverse region is located on the contact lens center axis M, it is possible to form a suitable space for receiving the moving corneal tissue by correction, Even more preferable.
[0048]
　Further, from the straight line distance S P between the point K 1 where the curve of the base region intersects the contact lens central axis M and the point K 2 where the extended line of the curve of the alignment region intersects the contact lens central axis M , the lens depth T R may be derived and the radius of curvature R R of the reverse region may be determined so as to satisfy that value so that the depth S K of the lens for correcting the cornea may be constant.
[0049]
　In the cross section including the center axis M of the cornea correction contact lens, the straight line distance of R B , W B , W R , R A , W A , R P , W P , T B , T R and K 1 and K 2 S P , in order to simplify the calculation formula, E = W B / 2, F = W B / 2 + W R when a lens depth T of the reverse region R is derived by the following formula (1).
[0050]
[Expression 6]

[0051]
　The radius of curvature R R of the reverse region using the lens depth T R of the reverse region is such that its center point C R is located on the contact lens center axis M,
[0052]
[Expression 7]

[0053]
. At this time, the lens depth S K of the region which is required to correct the cornea can be made constant through the transition point J 1 between the base region and the reverse region and the transition region J 2 between the reverse region and the alignment region . This is the cornea correction contact lens of the present invention.
[0054]
　Further, according to the present invention, when it is assumed that the average curvature radius R K of the cornea is the same curved surface as the curvature radius R A of the alignment region, the point where the curve of the base region and the contact lens central axis M intersect K 1 and the straight line distance S P at the point K 2 where the extended line of the curve of the alignment region and the contact lens central axis M intersect with each other can be replaced with the design value assuming the amount of pressing of the cornea in the eye axis direction.
[0055]
　Therefore, the cornea correction contact lens of the present invention also leads to a prescription based on a design value assuming an appropriate amount of pressing of the cornea according to the frequency to be corrected. This makes it possible to derive a shape capable of sufficiently pressing the central portion compared with the conventional cornea correction contact lens, which is preferable.
[0056]
　Even if they do not exactly match the expressions (1) and (2) and (4), even if they do not coincide with the expressions (1) and (2) and (4) as ± 10% If it is a curved surface passing through the range, it is possible to obtain a practically sufficient effect.
[0057]
　Also, there is a corneal correction contact lens for toric. This is because, as shown in FIG. 6, the curvature radius R A and the width W A of the alignment region are different in the longitudinal direction and the lateral direction when the cornea correction contact lens is viewed from the central axis direction .
[0058]
　In the cornea correcting contact lens for toric, the numerical value of the radius of curvature of the alignment region is the maximum, the radius of curvature in the lateral direction shown in FIG. 6 is R AV , the numerical value of the radius of curvature of the alignment region is the smallest in FIG. 6 Is formed so as to satisfy R AV = R AH + 0.50 D to 6.00 D (D: diopter), where R AH is the curvature radius in the vertical direction shown .
[0059]
　Further, the width W AV of the radius of curvature R AV of the alignment region is derived so as to satisfy W AV = (contact lens diameter D - (W B + 2 · W R +2 · W P )) / 2 and corneal correction When viewing the contact lens from the central axis direction, the shape of the alignment region is an elliptical shape having an aspect ratio of greater than 0.90 and less than 1.00.

[0060]
　The cornea correction contact lens aspect for toric of the present invention will be described in detail with reference to FIG. 7.
[0061]
　7 is a schematic view of the cornea correcting contact lens 1 for toric according to the present invention, in which the numerical value of the radius of curvature of the alignment region is the largest, passing through the center axis M of the cornea correction contact lens, Sectional direction.
[0062]
　In FIG. 7, the width of the base region is W B , the width of the reverse region is W R , the width of the alignment region is W AV , the width of the peripheral region is W P , the radius of curvature of the base region is R B , the radius of curvature of the reverse region R R , the radius of curvature at which the alignment region becomes maximum is R AV , the radius of curvature of the peripheral region is R P , the lens depth of the base region is T B , the lens depth of the reverse region is T R , the cornea is corrected lens depth S K (= T B + T R ), and,
with the K1 point curve and the contact lens center axis of the base region intersects extended line contact lens center axis of a curve curvature of the alignment region radius is the maximum value And the point K 3 where M intersects is S PT .
[0063]
　With respect to the radius of curvature R B of the base region, since the radius of curvature is determined so as to be the power to be corrected, the lens depth T B of the base region is derived from the following formula (4) according to the width W B of the base region .
[0064]
[Expression 8]

[0065]
　It is preferable that the radius of curvature R AV which is the maximum in the alignment region be close to the maximum curvature radius R KT of the cornea before correction, in order to enhance the fitting to the cornea 2 .
[0066]
　According to the present invention, in the cross section where the numerical value of the radius of curvature of the alignment region is the maximum, passing through the central axis M of the cornea correction contact lens, the values ​​of R B, W B , W R , R AV , W AV , R AH , W AH , R P and W P and the degree of correction are changed , the depth of the lens required for correcting the cornea is constant by changing the radius of curvature R R of the reverse region , and furthermore, Characterized in that the depth S K of the lens for correcting the cornea is constant under the maximum curvature radius R AV of the alignment region .
[0067]
　Specifically, in the cross section where the numerical value of the radius of curvature of the alignment region is the maximum, passing through the center axis M of the cornea correction contact lens of the present invention, the value of the depth S K of the lens for correcting the cornea is designated By deriving the lens depth T R of the reverse area and determining the radius of curvature R R of the reverse area so as to satisfy that value, it is possible to make the depth S K of the lens for correcting the cornea constant is there.
[0068]
　Here , if the center point C R of the curvature radius R R of the reverse region is located on the contact lens center axis M, it is possible to form a suitable space for receiving the moving corneal tissue by correction, Even more preferable.
[0069]
　Further, the K1 point curve and the contact lens center axis M of the base region intersect, the point extension and the contact lens center axis M of the curve of curvature of the alignment region radius is the maximum value intersect K3, linear distance S between PT from By deriving the lens depth T R of the reverse region and determining the curvature radius R R of the reverse region so as to satisfy that value, the depth S K of the lens for correcting the cornea may be made constant.
[0070]
　Passes through the center axis M of orthokeratology contact lenses, in a cross-sectional radius of curvature of the numerical value of the alignment region is maximized, the R B , W B , W R , R AV , W AV , R P , W P , T B , T R , and the straight line distance between K 1 and K 3 is S PT , and in order to simplify the calculation formula, E = W B / 2, F = W B / 2 + W R , the lens depth T R Is derived by the following equation (3).
[0071]
[Expression 9]

[0072]
　The radius of curvature R R of the reverse region using the lens depth T R of the reverse region is such that its center point C R is located on the contact lens center axis M,
[0073]
[Expression 10]

[0074]
. At this time, the lens depth S K of the region which is required to correct the cornea can be made constant through the transition point J 1 between the base region and the reverse region and the transition region J 2 between the reverse region and the alignment region . This is the cornea correcting contact lens for toric of the present invention.
[0075]
　Further, according to the present invention, when it is assumed that the maximum curvature radius R KT of the cornea is the same as the maximum curvature radius R AV of the alignment region, a point K 1 where the curve of the base region intersects the contact lens central axis M, The straight line distance S PT at the point K 3 where the extension line of the curve at which the radius of curvature of the alignment region has the maximum value and the contact lens central axis M intersect can be replaced with the design value assuming the amount of pressing of the cornea in the axial direction .
[0076]
　Therefore, the cornea correcting contact lens for toric of the present invention leads to a prescription based on design values ​​assuming an appropriate cornea holding amount according to the frequency to be corrected. This makes it possible to derive a shape capable of sufficiently pressing the central portion compared with the conventional cornea correction contact lens, which is preferable.
[0077]
　Even if it does not correspond exactly from Eq. (2) to Eq. (4), if the surface is a curved surface that passes within the range of ± 10% with the value of Equation (2) to Equation (4) as the center value, A sufficient effect can be obtained.
Example
[0078]
　Hereinafter, the present invention will be described with reference to examples. The value and the height of each radius of curvature were measured with a contact type contour shape measuring instrument (manufactured by Mitutoyo Corporation).
[0079]
　Example 1
　For a sample A, a cornea correction contact lens for an eye assumed that the refractive power of the cornea is 42.00 dioptre, the radius of curvature of the cornea is 8.04 mm, and the refractive error is -2.50 I made it. At this time, since the target correction power is set to +0.75 diopter, the radius of curvature R B of the base region of the cornea correction contact lens is 8.71 mm. The cornea correction contact lens diameter D is 10.6 mm, the base region width W B is 6.20 mm, the reverse region width W R is 0.40 mm, the alignment region curvature radius R A is 8.04 mm, the base region The straight line distance S P between the point where the curve crosses the contact lens central axis and the point where the extension line of the curve of the alignment region intersects with the contact lens central axis is 0.03 mm and in order to omit the calculation formula, E = W The lens depth T R in the reverse region is derived from the following equation (1) with B / 2, F = W B / 2 + W R ,
[0080]
[Expression 11]

[0081]
　Using the lens depth T R of the reverse region, the radius of curvature R R of the reverse region was determined from the following equation (2) .
[0082]
[Expression 12]

[0083]
　As a result, the lens depth T R in the reverse region and the curvature radius R R in the reverse region of the cornea correction contact lens of the sample A are 0.20 mm and 7.34 mm, respectively, and the depth S of the lens for correcting the cornea K was 0.77 mm.
[0084]
　Example 2
　Similarly, for sample B, for cornea correction targeted on an eye assumed that the refractive power of the cornea is 42.00 dioptre, the radius of curvature of the cornea is 8.04 mm, and the refractive error is -5.00 A contact lens was made. At this time, since the target correction power is set to +0.75 dioptre like the sample A, the curvature R B of the base region of the cornea correction contact lens is 9.31 mm. The cornea correction contact lens diameter D is 10.6 mm, the base region width W B is 6.20 mm, the reverse region width W R is 0.40 mm, the alignment region curvature radius R A is 8.04 mm, the base region The straight line distance S P between the point where the curve crosses the contact lens central axis and the point where the extension line of the curve of the alignment region intersects with the contact lens central axis is 0.03 mm and in order to omit the calculation formula, E = W The lens depth T R in the reverse region is derived from the following equation (1) with B / 2, F = W B / 2 + W R ,
[0085]
[Expression 13]

[0086]
　Using the lens depth T R of the reverse region, the radius of curvature R R of the reverse region was determined from the following equation (2) .
[0087]
[Expression 14]

[0088]
　As a result, the lens depth T R in the reverse region and the radius of curvature R R in the reverse region of the cornea correction contact lens of the sample B are 0.24 mm and 6.41 mm, respectively, and the depth S of the lens K was 0.77 mm.
[0089]
　Example 3 For
　sample C, the corneal refractive power was 42.00 dioptre, the horizontal corneal radius of curvature was 8.04 mm, the longitudinal corneal radius of curvature was 7.76 mm, and the refractive error was -2.50 Corneal correction contact lenses for toric were prepared for the eyes assumed to be a cornea. At this time, since the target correction power is set to +0.75 diopters, the curvature R B of the base region of the cornea correction contact lens is 8.71 mm. Further, the cornea correcting contact lens diameter D was 10.6 mm, the base region width W B was 6.20 mm, and the reverse region width W R was 0.40 mm. Here, the radius of curvature R AV at which the numerical value of the radius of curvature of the alignment region is maximum is 8.04 mm, the point where the curve of the base region intersects the contact lens central axis, the point where the extension line of the curve of the alignment region and the contact lens central axis From the following equation (3) where E = W B / 2, F = W B / 2 + W R , the straight distance S PT between the intersecting point and the intersecting point is 0.03 mm, Derive the depth T R ,
[0090]
[Expression 15]

[0091]
　Using the lens depth T R of the reverse region, the radius of curvature R R of the reverse region was determined from the following equation (2) .
[0092]
[Expression 16]

[0093]
　As a result, the lens depth T R in the reverse region and the radius of curvature R R in the reverse region of the cornea correction contact lens of sample C were 0.20 mm and 7.34 mm, respectively, and the depth S of the lens for correcting the cornea K was 0.77 mm.
[0094]
　Example 4 For
　sample D, the corneal refractive power is 42.00 dioptre, the horizontal corneal radius of curvature is 8.04 mm, the longitudinal corneal radius of curvature is 7.76 mm, and the refractive error is -5.00 Corneal correction contact lenses for toric were prepared for the eyes assumed to be a cornea. At this time, since the target correction power is set to +0.75 dioptre like the sample C, the curvature R B of the base region of the cornea correction contact lens is 9.31 mm. Further, the cornea correcting contact lens diameter D was 10.6 mm, the base region width W B was 6.20 mm, and the reverse region width W R was 0.40 mm. Here, the radius of curvature R AV at which the numerical value of the radius of curvature of the alignment region is maximum is 8.04 mm, the point where the curve of the base region intersects the contact lens central axis, the point where the extension line of the curve of the alignment region and the contact lens central axis From the following equation (3) where E = W B / 2, F = W B / 2 + W R , the straight distance S PT between the intersecting point and the intersecting point is 0.03 mm, Derive the depth T R ,
[0095]
[Expression 17]

[0096]
　Using the lens depth T R of the reverse region, the radius of curvature R R of the reverse region was determined from the following equation (2) .
[0097]
[Expression 18]

[0098]
　As a result, the lens depth T R in the reverse region and the radius of curvature R R in the reverse region of the cornea correction contact lens of the sample D are 0.24 mm and 6.41 mm, respectively, and the depth S of the lens for corneal correction K was 0.77 mm.
[0099]
　From these, the curvature radius of the reverse region is changed even under the curvature radius of the same alignment region and under the curvature radius of the alignment region where the toric is the target and the maximum is to be corrected , It was possible to obtain a cornea correction contact lens in which the lens depth in the area to be corrected for the cornea is constant.
Industrial applicability
[0100]
　The present invention can be applied as a contact lens for cornea correction.
Explanation of sign
[0101]
1: cornea correction contact lens
2: cornea
3: ocular axis
4: iris
5: crystalline lens
6: retina
7: corneal surface
D: corneal correction contact lens diameter
B: base region
R: reverse region
A: alignment region
P: peripheral region
J 1 : A transition point where the base region and the reverse region intersect
J2: a transition point where the reverse region and the alignment region intersect
J3: a transition point where the alignment region and the peripheral region intersect each other
K1: a point where the curve of the base region intersects the contact lens central axis
K2: A point where the extension line of the curve of the alignment region and the contact lens central axis intersect with each other
K3: a point where the extension line of the curve having the maximum curvature radius of the alignment region and the contact lens central axis M intersect
M: the contact lens central axis
C B : the base Center point of the curvature radius of the region
C R : Center point of the curvature radius of the reverse region
C A: The center point of the curvature radius of the alignment region
C AV the center point of the maximum curvature radius of the alignment region
C P the center point of the curvature radius of the peripheral region
R K the average curvature radius of the cornea
R KT the maximum radius of curvature of the cornea
R B : Radius of curvature of the base region
R R : Radius of curvature of the reverse region
R A : Radius of curvature of the alignment region
R AH : Minimum curvature radius of the alignment region at the corneal correction contact lens for toric
R AV in the corneal correction contact lens for toric Maximum radius of curvature of the alignment region
R P : Radius of curvature of the peripheral region
R PH: Alignment area in toric correcting contact lens area curvature radius of peripheral area in the direction having minimum radius of curvature
T B : lens depth of base area
T R : lens depth in reverse area
S K : area to be corrected cornea lens depth of
S P : a point where the curve and the contact lens center axis of the base region intersect, that the extension and the contact lens center axis of the curve of the alignment regions intersect, the linear distance between the
S PT : curve and the contact of the base region A straight line distance between a point where the lens central axis intersects with a point where the curvature radius of the alignment region has the maximum value and a point where the contact lens central axis intersects with the extension line of the curve
W B : the width of the base region
W R : the width
W of the reverse region a : the width of the alignment area
W AH : alignment area minimum in the cornea corrective contact lens for toric Direction of width with a rate radius
W AV : Alignment area in toric correcting contact lens Width in the direction having the maximum radius of curvature
W P : Width of the peripheral area
W PH : Alignment area in the corneal correction contact lens for toric alignment Peripheral area in the direction with minimum radius of curvature width
The scope of the claims
[Claim 1]
　A cornea correction contact lens for correcting visual acuity by changing the shape of a
cornea, the lens surface in contact
with the cornea has a central portion,
which is located in the center and is referred to as a base region, which presses the cornea, An annular portion called a reverse region, an annular portion
arranged around the reverse region, called an alignment region, and an annular part arranged around the alignment region and called
a peripheral region, and the
base region
By changing the radius of curvature of the reverse area even if the radius of curvature and width of the reverse area, the width of the reverse area, the radius and width of the alignment area and the radius and width of the peripheral area and the frequency to be corrected change Wherein the depth of the lens necessary for correcting the cornea is constant.
[Claim 2]
　2. The cornea correction contact lens according to claim 1, wherein the depth of the lens required for correcting the cornea is constant under a radius of curvature of the same alignment region.
[Claim 3]
　The radius
of curvature of the reverse region is
derived according to the radius of curvature and width of the base region, the width of the reverse region, the radius of curvature and width of the alignment region, and the radius of curvature and width of the peripheral region A corneal correction contact lens as described.
[Claim 4]
　The width of the base region is W B , the width of the reverse region is W R , the radius of curvature of the base region is R B , the radius of curvature of the reverse region is R R , the radius of curvature of the alignment region is R A , the lens depth of the base region is T B , the lens depth in the reverse region as T R , the point where the curve of the base region intersects with the contact lens central axis and the point where the extension line of the curve of the alignment region intersects the contact lens central axis S P when the,
lens depth T of the reverse region R is derived by the following formula (1),
the radius of curvature R of the reverse region R is, T R claims using derived by the following formula (2) The cornea correction contact lens according to any one of 1 to 3.
[

Expression 1] (In the expression (1), E = W B / 2, F = W B / 2 + W R )
[

Expression 2] (In the expression (2), E = W B / 2, F = W B / 2 + W R )
[Claim 5]
5. The cornea correcting contact lens according to claim 4, wherein the lens depth T R and the curvature radius R R are within ± 10% of the derived 　lens depth T R and curvature radius R R , respectively .
[Claim 6]
　2. The cornea correction contact lens according to claim 1, wherein a curvature radius and a width of the alignment region are different in a longitudinal direction and a lateral direction when viewed from the direction of the central axis of the contact lens.
[7]
　7. The cornea correction contact lens according to claim 6, wherein the depth of the lens necessary for correcting the cornea is constant under the same maximum value of the curvature radius of the alignment region.
[Claim 8]
　The radius
of curvature of the reverse region is
derived in accordance with the radius of curvature and width of the base region, the width of the reverse region, the maximum value and maximum width of the radius of curvature of the alignment region, and the radius of curvature and width of the peripheral region Wherein the cornea correcting contact lens according to claim 6 or 7.
[Claim 9]
　The width of the base region is W B , the width of the reverse region is W R , the radius of curvature of the base region is R B , the radius of curvature of the reverse region is R R , the maximum value of the radius of curvature of the alignment region is R AV , The depth is T B , the lens depth in the reverse region is T R , the point where the curve of the base region intersects with the contact lens central axis, the extension line of the curve having the maximum value of the curvature radius of the alignment region and the contact lens center axis DOO intersect point, a straight line distance between S P when the,
lens depth T of the reverse region R is derived by the following formula (3),
the radius of curvature R of the reverse region R is, T R using the following The cornea correction contact lens according to any one of claims 6 to 8, which is derived by the expression (2).
[

Expression 3] (E = W B / 2, F = W B / 2 + W R. )
(4)

(In the formula (2), E = W B / 2, F = W B / 2 + W R )
[Claim 10]
10. The cornea correction contact lens according to claim 9, wherein the lens depth T R and the curvature radius R R are within the range of ± 10% with reference to the derived 　lens depth T R and curvature radius R R , respectively .