JP2005055580A - Hard contact lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hard contact lens with which good visual acuity and good wearing feeling are obtained by securing the stable position of a lens and appropriately exchanging lacrimal fluid during wearing the lens in both cases of conical cornea eyes and ordinary astigmatic eyes. <P>SOLUTION: A lens inside surface 1 is constituted of a circular lens central region 2, 2nd and 1st annular intermediate regions 3 and 4 continuous with the outside of the region 2, and an annular peripheral region 5 in projection to a plane orthogonal to a center axis 6. The lens inside surface has a contour formed by a base curve 7 in the lens central region, the 2nd intermediate curves 8 and 8' of the 2nd intermediate region and the 1st intermediate curves 9 and 9' of the 1st intermediate region continuous with the outside of the curve 7, and a peripheral edge curve 10 of the peripheral region on a cross section in a perpendicular direction to the center axis 6 of the lens. The distances of the connection point of the 2nd and the 1st intermediate curves from the surfaces of corneas 11 and 11', that is, the curvatures of the 2nd and the 1st intermediate curves are changed in the circumferential direction of the lens. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an improvement of a hard contact lens.

  Since the cornea is an avascular tissue, and oxygen supply to the cornea is almost done through tear fluid, when a hard contact lens covers the cornea, oxygen supply to the cornea is caused by oxygen in the lens material. There are two types, one by permeation and the other by the exchange of tears interposed between the contact lens and the cornea when the contact lens moves on the cornea by blinking.

  The hard contact lens is particularly a lens that corrects astigmatism and corrects visual acuity, and is in direct contact with the cornea surface via tears, so that the latter is important for supplying oxygen to the cornea. This is because tear exchange not only supplies new oxygen but also excretes corneal metabolites to maintain the function of the cornea.

By the way, conventional spherical contact lenses have problems in the visual acuity correction effect and positional stability of intensity astigmatism and irregular astigmatism. A hard contact lens having a surface and a hard contact lens having an aspheric inner surface have been developed so far.
For example, a toric soft contact lens for correcting corneal astigmatism, wherein the front surface of the lens is substantially rotationally symmetric and the rear surface of the lens is toric in the optically effective central region; and A contact lens having an aspherical shape, particularly an elliptical shape in a peripheral region surrounding a central region is known (see Patent Document 1). However, in this contact lens, tear fluid is not exchanged smoothly when the lens is worn, and a comfortable wearing feeling cannot be obtained. Furthermore, this contact lens has a complicated structure and is disadvantageous in terms of manufacturing cost.
Further, for example, a hard contact lens for correcting corneal corneal vision, in which the curvature of the curved surface of the rear surface of the lens in contact with the cornea is changed stepwise at a specific ratio is known (Patent Document). 2). However, when this contact lens is applied to normal astigmatic eye correction, the lens position does not become stable when the lens is worn, and the lens position is not stable. Therefore, a comfortable wearing feeling and appropriate visual acuity cannot be obtained. .

Japanese Patent Laid-Open No. 6-18821 JP 2003-15094 A

  Therefore, even if the subject of the present invention is applied to either a keratoconic eye or a normal astigmatic eye, the lens position is stable and appropriate tear fluid exchange is performed during lens wearing, and good visual acuity and wearing feeling are obtained. It is an object of the present invention to provide a hard contact lens that can be manufactured at low cost.

  In order to solve the above-described problem, according to the present invention, in the projection onto a plane perpendicular to the central axis of the lens, the lens inner surface has a plurality of circular lens central regions and a plurality of consecutively continuous outer portions of the lens central region. A concave base curve of the central region of the lens when viewed from a cross section in a direction perpendicular to the central axis of the lens, and comprising an annular intermediate region and an annular peripheral region continuous to the outside of the plurality of intermediate regions Each having a concave intermediate curve of each of the plurality of intermediate regions sequentially continuing outside the base curve, and a contour formed by a concave peripheral curve of the peripheral region continuing outside the intermediate curve; The ridgeline of the boundary between adjacent intermediate regions has a cross-section at a portion surrounded by the boundary, and the projection onto a cylindrical surface whose central axis coincides with the central axis of the lens. In the hard contact lens is configured, characterized in that extends forms a concave curve between the mutually adjacent points of the at least two points located at intervals on the edge line of the boundary.

In this configuration, preferably, the ridgelines of the boundary between the adjacent intermediate regions are adjacent to each other among the four points positioned at equal intervals on the ridgeline of the boundary in the projection onto the cylindrical surface. A quadratic or cubic approximate curve extends between them, and when wearing the lens, two of the four points located in one diameter direction are two points located in the other diameter direction from the cornea surface. Two points that are different from the distance from the corneal surface and that are diametrically opposed are arranged at an equal distance from the corneal surface.
Alternatively, the boundary ridgelines of the adjacent intermediate regions are quadratic between adjacent points among the eight points located at equal intervals on the boundary ridgeline in the projection onto the cylindrical surface. Alternatively, it extends in a cubic approximation curve, and when the lens is worn, the eight points are preferably arranged at different distances from the corneal surface.

  Preferably, the plurality of intermediate regions include a first intermediate region continuous to the peripheral region, and a second intermediate region extending between the first intermediate region and the lens central region, and the lens. An inner surface of the second intermediate region that is continuous outside the base curve, a first intermediate curve of the first intermediate region that is continuous outside the second intermediate curve, 1 has a contour formed by the peripheral curve continuous outside the intermediate curve, and the base curve is in the center region of the lens and has a predetermined distance from the center of the lens in the radial direction of the lens when the lens is worn. The second intermediate curve is composed of a second-order or third-order approximate curve that passes through a pair of first points whose distance from the corneal surface is a predetermined maximum distance and a corneal apex. A second point that is within the intermediate region and is separated from the center of the lens by a predetermined distance along the radial direction of the lens when the lens is worn; and an outer end of the base curve on the side facing the second point; It consists of a quadratic or cubic approximate curve passing through the outer end of the base curve on the side away from the second point, and the first intermediate curve is in the first intermediate region, and when the lens is worn, A third point that is a predetermined distance away from the center of the lens along the radial direction of the lens and that is a predetermined maximum distance from the corneal surface, and an outer end of the second intermediate curve on the side facing the third point And a quadratic or cubic approximate curve that passes through the outer edge of the second intermediate curve on the side away from the third point, and the peripheral curve is in the peripheral region, and when the lens is worn, Lens radial direction from lens center A fourth point at a predetermined distance away from the corneal surface along a predetermined distance, an outer end of the first intermediate curve on the side facing the fourth point, and the fourth point. It consists of a quadratic or cubic approximate curve that passes through the outer edge of the first intermediate curve on the far side.

  According to the present invention, a plurality of intermediate curves are added between the base curve and the peripheral curve, and the distance from the corneal surface at the connection point of the adjacent intermediate curves is changed in the circumferential direction of the lens. By changing the curvature in the circumferential direction of the lens, the inner surface of the lens is well adapted to both the keratoconus and the normal astigmatic cornea, the lens position is stable when wearing the lens, good visual acuity and comfortable A feeling of wearing is obtained. Furthermore, as the lens moves up and down on the cornea due to blinking, a certain pumping action is exerted in the gap between the intermediate curve and the corneal surface, and between the tear fluid around the lens and the intermediate curve and the corneal surface. Can efficiently exchange the lacrimal fluid stored in the gap of the cornea, thus supplying new oxygen to the corneal surface covered by the lens and excreting corneal metabolites to the peripheral region of the lens, Can maintain the function.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a plan view showing the projection of the inner surface of a hard contact lens according to the present invention onto a plane perpendicular to the central axis of the lens. As shown in FIG. 1, in the hard contact lens of the present invention, the lens inner surface 1 is projected onto a plane perpendicular to the central axis 6 of the lens, and a circular lens central region 2 and an outer side of the lens central region 2. In this embodiment, two annular intermediate regions 3, 4 of the second intermediate region 3 and the first intermediate region 4, and continuous outside these intermediate regions 3, 4. An annular peripheral region 5 is formed.

In addition, in this embodiment, the ridgeline of the boundary between the adjacent intermediate regions, in this embodiment, the ridgeline 12 of the boundary between the second intermediate region 3 and the first intermediate region 4 has a section surrounded by the boundary and the central axis is a lens. In the projection onto the cylindrical surface that coincides with the central axis 6, a concave curve extends between adjacent points of at least two points that are spaced apart on the boundary ridge line 12.
In this embodiment, the ridge line 12 at the boundary between the second intermediate region 3 and the first intermediate region 4 is located at four points (point c, point d, point g, FIG. Between the points h) adjacent to each other, a concave quadratic or cubic approximate curve extends. FIG. 3 shows how the edge 12 of the boundary between the second intermediate region 3 and the first intermediate region 4 is formed between the adjacent points d and g in FIG.
Furthermore, of the four points (point c, point d, point g, point h) when wearing the lens, two points (point d, point h) located in one diametric direction are from the corneal surface to the other diameter. Two points (point d and point h, and point c and point g) that are arranged at a distance different from the distance from the corneal surface of the two points (point c and point g) positioned in the direction and that face each other in the diameter direction Are arranged at an equal distance from the corneal surface.

  FIG. 2 shows a cross section along the diameter direction (X1-X1 line) connecting the points d and h and the cross section along the diameter direction (X2-X2 line) connecting the points c and g in FIG. In FIG. 2, the solid line indicates a common part in two cross sections, the alternate long and short dash line indicates a specific part in the cross section along the X1-X1 line, and the broken line indicates a specific part in the cross section along the X2-X2 line. Each part is shown. Reference numeral 11 denotes the corneal surface in the cross section along the X1-X1 line, and 11 'denotes the corneal surface in the cross section along the X2-X2 line.

Referring to FIG. 2, the lens inner surface 1 has a concave base curve 7 in the lens central region 2 and a plurality of intermediate regions sequentially continuing to the outside of the base curve 7 in a cross section taken along the line X <b> 1-X <b> 1 in FIG. Each of the concave intermediate curves, in this embodiment, the second intermediate curve 8 of the second intermediate region 3 and the first intermediate curve 9 of the first intermediate region 4 are continuous to the outside of these intermediate curves 8, 9. It has a contour formed by a concave peripheral curve 10 in the peripheral region 5.
Further, the base curve 7 is located in the lens central region 2 and is a pair of distances away from the lens center k in the radial direction of the lens when the lens is worn and the distance from the corneal surface 11 is a predetermined maximum distance. And a quadratic or cubic approximate curve passing through the first point e and the point f and the corneal apex 13.
The second intermediate curve 8 is located in the second intermediate region 3, and when the lens is worn, the second points d and h, which are separated from the lens center k by a predetermined distance along the radial direction of the lens, It consists of a quadratic or cubic approximate curve that passes through the outer ends e, f of the base curve 7 on the side facing the point 2 and the outer ends f, e of the base curve 7 on the side far from the second point.

The first intermediate curve 9 is located in the first intermediate region 4 and is separated from the lens center k by a predetermined distance along the radial direction of the lens and the distance from the cornea surface is a predetermined maximum distance when the lens is worn. A third point b, i, an outer end d, h of the second intermediate curve 8 on the side facing the third point, and an outer end h, d of the second intermediate curve 8 on the side farther from the third point It consists of a quadratic or cubic approximation curve passing through.
Further, the peripheral curve 10 is in the peripheral region 5, and when the lens is worn, the peripheral curve 10 is a fourth distance that is a predetermined distance away from the lens center k along the radial direction of the lens and the distance from the cornea surface is a predetermined maximum distance. The points a and j, the outer ends b and i of the first intermediate curve 9 on the side facing the fourth point, and the outer ends i and b of the first intermediate curve 9 on the side away from the fourth point. It consists of a quadratic or cubic approximate curve.

  In FIG. 2, the cross-sectional structure of the lens inner surface 1 along the line X2-X2 of FIG. 1 is from the corneal surface 11 ′ of the connection points c and g of the second intermediate region 3 and the first intermediate region 4 when the lens is worn. The distance and thus the curvature of the second intermediate curve 8 ′ and the first intermediate curve 9 ′ only differ from the case of the cross section along the line X1-X1 in FIG. Therefore, description of the cross-sectional structure of the lens inner surface along the line X2-X2 in FIG. 1 is omitted.

For manufacturing the hard contact lens shown in FIGS. 1 to 3, a custom-made system for manufacturing the lens after designing the lens structure after grasping the entire shape of the cornea of the lens wearer is applied. Is preferred.
In this system, first, in order to design a lens structure, a platid image projected onto the cornea of a lens wearer is analyzed using a computer, and shape data of the entire cornea is obtained. The corneal shape data is obtained by using a keratometry system, in this example, for example, PKS1000, SK2000, PR-7000, manufactured by Sun Contact Lens Co., but the model is particularly limited as long as it is an equivalent corneal shape analysis system. It is not something.
Since all the image data of the platide image projected on the cornea is converted into coordinates by using a computer, not only the entire cornea shape and curvature distribution but also a corneal curvature in an arbitrary range can be obtained.

Next, an actual lens design example using a keratometry system PR7000 manufactured by Sun Contact Lens Co. will be described. First, using the keratometry system PR7000, the lens wearer's corneal diameter, corneal weak main meridian, corneal strong main meridian, etc. are measured, and curvature distribution data of the entire cornea is obtained.
Based on the obtained data, the diameter of the hard contact lens is designed to be 8.5 to 10.5 mm, and the lens central region 2 is 3.25 to 3 from the lens center k along the radial direction of the lens. The second intermediate region 3 extends from the lens center k to a distance of 3.75 to 4.45 mm along the radial direction of the lens, and the first intermediate region 4 extends from the lens center k to the lens center. The peripheral region 5 is designed to extend from the lens center k to a distance of 4.25 to 5.25 mm along the radial direction of the lens, extending to a distance of 4.15 to 5.15 mm along the radial direction.

  Then, in the projection onto the cylindrical surface in which the ridgeline 12 at the boundary between the second intermediate region 3 and the first intermediate region 4 has a section surrounded by the boundary and the central axis coincides with the central axis 6 of the lens, Between the adjacent points among four points (point c, point d, point g, point h) located at equal intervals on the ridgeline 12 of the boundary, a concave shape is formed by forming a quadratic or cubic approximate curve. It is formed to spread. Furthermore, of the four points (point c, point d, point g, point h) when wearing the lens, two points (point d, point h) located in one diametric direction are from the corneal surface to the other diameter. Two points (point d and point h, and point c and point g) that are arranged at a distance different from the distance from the corneal surface of the two points (point c and point g) positioned in the direction and that face each other in the diameter direction Are arranged at equal distances from the corneal surface.

Also, for example, in the cross section along the line X1-X1 in FIG. 1, the base curve 7 is in the lens central region 2 and 3.25 along the radial direction of the lens from the lens center k when the lens is worn. Formed by a quadratic or cubic approximation curve passing through a pair of first points e and f and a corneal apex 13 that are separated by .about.3.65 mm and a distance from the corneal surface 11 of 0.01 to 1.5 mm. The
The second intermediate curve 8 is located in the second intermediate region 3, and when the lens is worn, the second points d and h separated from the lens center k by 3.75 to 4.45 mm along the radial direction of the lens. , Formed by a quadratic or cubic approximation curve that passes through the outer ends e, f of the base curve 7 facing the second point and the outer ends f, e of the base curve 7 away from the second point. The

The first intermediate curve 9 is in the first intermediate region 4, and is 4.15 to 5.15 mm away from the lens center k along the radial direction of the lens and the distance from the corneal surface 11 is 0 when the lens is worn. Of the third point b, i, which is .01 to 1.5 mm, the outer ends d, h of the second intermediate curve on the side facing the third point, and the second intermediate curve on the side away from the third point It is formed by a quadratic or cubic approximation curve that passes through the outer edges h and d.
The peripheral curve 10 is located in the peripheral region 5 and is 4.25 to 5.25 mm away from the lens center k along the radial direction of the lens and a distance from the corneal surface 11 is 0.01 to 1 when the lens is worn. A fourth point a, j of 5 mm, an outer end b, i of the first intermediate curve on the side facing the fourth point, and an outer end i of the first intermediate curve on the side farther from the fourth point, formed from a quadratic or cubic approximation curve through b.

Similarly, the base curve 7, the first intermediate curve 8 ′, the second intermediate curve 9 ′, and the peripheral curve 10 are formed on the cross section along the line X 2 -X 2 in FIG. The same applies to the other radial sections of the lens.
In addition, the distance from the cornea surface of each of the points a to j in this embodiment is as follows.
(1) Point a, point j: 0.01 to 1.5 mm
(2) Point b, Point i: 0.01 to 1.5 mm
(3) Point c, Point g: 0.01 to 0.8 mm
(4) Point d, Point h: 0 to 0.8 mm
(5) Point e, point f: 0.01 to 1.5 mm

When the design of the contact lens is completed, the lens is manufactured based on it. In manufacturing this lens, a cutting and polishing method is generally used, but other mold casting methods and the like may be used. The contact lens material is not particularly limited, and any material that can be processed into a contact lens may be used.
Further, when the contact lens is manufactured, the connecting portion of each curve on the inner surface of the lens is polished as necessary.

Thus, in the hard contact lens of the present invention, a plurality of intermediate curves are added between the base curve and the peripheral curve, and the distance from the corneal surface at the connection point of the adjacent intermediate curve changes in the circumferential direction of the lens. Since the curvature of the intermediate curve is changed in the circumferential direction of the lens, the inner surface of the lens is well adapted to both the keratoconus and the normal astigmatic cornea, and the lens position is stable when wearing the lens. Visual acuity and comfortable wearing feeling can be obtained.
In addition, when the lens is worn, more tears are stored in the gap between the intermediate curve and the corneal surface in addition to the conventional tears interposed between the lens inner surface and the corneal surface. And with the up and down movement of the lens on the cornea due to blinking, the gap between the intermediate curve and the corneal surface exerts some kind of pumping action, thereby through the peripheral curve of the lens and the gap between the corneal surface, The tear fluid around the lens is efficiently exchanged with the tear fluid stored in the gap between the intermediate curve and the corneal surface. By this tear exchange, new oxygen is supplied to the corneal surface covered with the lens, and corneal metabolites are excreted in the peripheral region of the lens, thereby maintaining the function of the cornea.

  FIG. 4 is a plan view showing a projection of the inner surface of a hard contact lens according to another embodiment of the present invention onto a plane perpendicular to the central axis of the lens. As shown in FIG. 4, the hard contact lens according to this embodiment is similar to the above-described embodiment in that the lens inner surface 20 has a circular lens central region 21 in the projection onto a plane perpendicular to the central axis of the lens. Two annular intermediate regions that are successively continuous outside the lens central region 21, that is, a second intermediate region 22 and a first intermediate region 23, and an annular peripheral region 24 that is continuous outside these intermediate regions 22, 23. It is made up of.

In addition, in the projection onto the cylindrical surface in which the ridge line 35 of the boundary between the second intermediate region 22 and the first intermediate region 23 has a section surrounded by the boundary and the central axis coincides with the central axis 25 of the lens, Points adjacent to each other among eight points (point P3, point P6, point P9, point P10, point P11, point P12, point P13, point P14 in FIG. 4) located on the ridgeline 35 of the boundary at equal intervals In the meantime, a quadratic or cubic approximate curve extends in a concave shape.
When the lens is worn, eight points (point P3, point P6, point P9, point P10, point P11, point P12, point P13, point P14) are arranged at different distances from the corneal surface.

  FIG. 5 shows a cross section along the diameter direction (Y1-Y1 line) connecting the points P3 and P6 and a cross section along the diameter direction (Y2-Y2 line) connecting the points P9 and P10 in FIG. In FIG. 5, the solid line indicates a common part in two cross sections, the alternate long and short dash line indicates a specific part in the cross section along the Y1-Y1 line, and a broken line indicates a specific part in the cross section in the Y2-Y2 line. Each part is shown. Reference numeral 32 denotes a corneal surface in a cross section along the Y1-Y1 line, and 32 'denotes a corneal surface in a cross section along the Y2-Y2 line. FIG. 6 shows a cross section along the diameter direction (Y3-Y3 line) connecting the points P11 and P12 and a cross section along the diameter direction (Y4-Y4 line) connecting the points P13 and P14 in FIG. In FIG. 6, the solid line indicates a common part in the two cross sections, the alternate long and short dash line indicates a specific part in the cross section along the Y3-Y3 line, and a broken line indicates a specific part in the cross section in the Y4-Y4 line. Each part is shown. Reference numeral 34 denotes the corneal surface in the cross section along the Y3-Y3 line, and 34 'denotes the corneal surface in the cross section along the Y4-Y4 line.

Referring to FIG. 5, the lens inner surface 20 includes a concave base curve 26 in the lens central region 21 and a second intermediate region that sequentially continues to the outside of the base curve 26 in a cross section taken along line Y1-Y1 in FIG. 4. 22 concave second intermediate curves 27, 36, a first intermediate region 23, a concave first intermediate curve 28, 37, and a peripheral peripheral curve 29 of a peripheral region 24 continuous outside these intermediate curves. Has a contour.
Furthermore, the base curve 26 is located in the lens central region 21 and is a pair of distances away from the lens center P15 in the radial direction of the lens and a distance from the corneal surface 32 being a predetermined maximum distance when the lens is worn. It consists of a quadratic or cubic approximate curve passing through the first point P4 and the point P5 and the corneal apex 33.
The second intermediate curves 27 and 36 are located in the second intermediate region 22 and are second points P3 and P6 separated from the lens center P15 by a predetermined distance along the radial direction of the lens when the lens is worn. The second or third approximation curve passes through the outer ends P4, P5 of the base curve 26 facing the second point and the outer ends P5, P4 of the base curve 26 away from the second point. Yes.

The first intermediate curves 28 and 37 are in the first intermediate region 23, and when the lens is worn, they are separated from the lens center P15 by a predetermined distance along the radial direction of the lens and the distance from the corneal surface is a predetermined maximum distance. Of the second intermediate curves 27, 36 on the side away from the third point P2, P7, the outer ends P3, P6 of the second intermediate curves 27, 36 on the side facing the third point It consists of a quadratic or cubic approximation curve passing through the outer ends P6 and P3.
Further, the peripheral curve 29 is in the peripheral region 24, and when the lens is worn, the peripheral curve 29 is a fourth distance that is a predetermined distance away from the lens center P15 along the radial direction of the lens and the distance from the cornea surface is a predetermined maximum distance. Points P1, P8, outer ends P2, P7 of the first intermediate curves 28, 37 on the side facing the fourth point, and outer ends P7 of the first intermediate curves 28, 37 on the side farther from the fourth point, It consists of a quadratic or cubic approximation curve that passes through P2.

  5, the cross-sectional structure of the lens inner surface 20 along the Y2-Y2 line of FIG. 4, and the cross-sectional structure of the lens inner surface 20 along the Y3-Y3 line of FIG. 4 in FIG. The cross-sectional structure of the inner surface 20 of the lens is from the corneal surfaces 32 ', 34, 34' of the connection points P9, P10, P11, P12, P13, P14 of the second intermediate region 22 and the first intermediate region 23 when the lens is worn. The distances, and hence the curvatures of the second intermediate curves 27 ', 30, 30', 36 ', 38, 38' and the first intermediate curves 28 ', 31, 31', 37 ', 39, 39' are shown in FIG. The only difference is the case of the cross section along the line Y1-Y1. Therefore, description of the cross-sectional structure of the lens inner surface along the Y2-Y2 line, the Y3-Y3 line, and the Y4-Y4 line in FIG. 4 is omitted.

  The contact lens according to this embodiment is also designed in the same manner as in the above-described embodiment. That is, first, based on the data obtained by the keratometry system PR7000, the diameter of the hard contact lens is designed to be 8.5 to 10.5 mm, and the lens central region 21 is formed from the lens center P15 to the lens center. The second intermediate region 22 extends from the lens center P15 to a distance of 3.75 to 4.45 mm along the radial direction of the lens, extending from a distance of 3.25 to 3.65 mm along the radial direction. The region 23 extends from the lens center P15 to a distance of 4.15 to 5.15 mm along the radial direction of the lens, and the peripheral region 24 extends from the lens center P15 to 4.25 to 5.25 mm along the radial direction of the lens. Designed to extend up to a distance.

Then, in the projection onto the cylindrical surface in which the ridge line 35 of the boundary between the second intermediate region 22 and the first intermediate region 23 has a section surrounded by the boundary and the central axis coincides with the central axis 25 of the lens, Between adjacent points among eight points (point P3, point P6, point P9, point P10, point P11, point P12, point P13, point P14) located at equal intervals on the ridge 35 of the boundary A quadratic or cubic approximate curve is formed to extend in a concave shape. Further, when the lens is worn, the eight points (point P3, point P6, point P9, point P10, point P11, point P12, point P13, point P14) are arranged at different distances from the corneal surface. It is formed.
Further, for example, in the cross section along the line Y1-Y1 in FIG. 4, the base curve 26 is in the lens central region 21, and 3.25 along the radial direction of the lens from the lens center P15 when the lens is worn. Formed by a quadratic or cubic approximate curve passing through a pair of first points P4 and P5 that are separated by .about.3.65 mm and a distance of 0.01 to 1.5 mm from the corneal surface 32, and the corneal apex 33. The
The second intermediate curves 27 and 36 are located in the second intermediate region 22 and are second points P3 separated from the lens center P15 by 3.75 to 4.45 mm along the radial direction of the lens when the lens is worn. A quadratic or cubic approximate curve that passes through P6, outer ends P4 and P5 of the base curve 26 facing the second point, and outer ends P5 and P4 of the base curve 7 away from the second point. Formed by.

The first intermediate curves 28 and 37 are located in the first intermediate region 23, and are distanced from the lens center P15 by 4.15 to 5.15 mm along the lens radial direction and from the corneal surface 32 when the lens is worn. Is the third point P2, P7 having a diameter of 0.01 to 1.5 mm, the outer ends P3, P6 of the second intermediate curve on the side facing the third point, and the second intermediate on the side away from the third point It is formed by a quadratic or cubic approximation curve that passes through the outer edges P6, P3 of the curve.
The peripheral curve 29 is in the peripheral region 24, and is 4.25 to 5.25 mm away from the lens center P15 along the radial direction of the lens and the distance from the corneal surface 32 is 0.01 to 1 when the lens is worn. A fourth point P1, P8 of .5 mm, an outer end P2, P7 of the first intermediate curve on the side facing the fourth point, and an outer end P7 of the first intermediate curve on the side farther from the fourth point, Formed from a quadratic or cubic approximation curve through P2.

Similarly, for the cross sections along the Y2-Y2 line, the Y3-Y3 line, and the Y4-Y4 line in FIG. 4, the base curve 26, the second intermediate curves 27 ′, 30, 30 ′, 36 ′, 38, 38 'And first intermediate curves 28', 31, 31 ', 37', 39, 39 'and a peripheral curve 29 are formed. The same applies to the other radial sections of the lens.
In addition, the distance from each corneal surface of the point P1-point P14 in this Example is as follows.
(1) Point P1, Point P8: 0.01 to 1.5 mm
(2) Point P2, Point P7: 0.01 to 1.5 mm
(3) Point P3, point P6: 0 to 1 mm
(4) Point P9, Point P10, Point P14: 0.02 to 1.2 mm
(5) Point P11, Point P12, Point P13: 0.01 to 1.5 mm
(6) Point P4, Point P5: 0.01 to 1.5 mm
In the case of this embodiment, the same effect as that of the embodiment shown in FIGS.

It is a top view which shows the projection on the plane orthogonal to the central axis of a lens of the inner surface of the hard contact lens by one Example of this invention. FIG. 2 is a diagram simultaneously showing a cross section along a diameter direction (X1-X1 line) connecting points d and h and a cross section along a diameter direction (X2-X2 line) connecting points c and g in FIG. 1. . It is the partial perspective view seen from the inner surface side of the hard contact lens shown in FIG. It is a top view which shows the projection on the plane orthogonal to the central axis of a lens by the inner surface of the hard contact lens by another Example of this invention. 5 is a diagram simultaneously showing a cross section along a diameter direction (Y1-Y1 line) connecting points P3 and P6 and a cross section along a diameter direction (Y2-Y2 line) connecting points P9 and P10 in FIG. , FIG. 5 is a diagram simultaneously showing a cross section along the diameter direction (Y3-Y3 line) connecting the points P11 and P12 and a cross section along the diameter direction (Y4-Y4 line) connecting the points P13 and P14 in FIG. .

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens inner surface 2 Lens center area | region 3 2nd intermediate area 4 1st intermediate area 5 Peripheral area 6 Center axis of lens 7 Base curve 8, 8 '2nd intermediate curve 9, 9' 1st intermediate curve 10 Perimeter curve 11, 11 '' Corneal surface 13 Apex of cornea

Claims (4)

In the projection onto a plane orthogonal to the central axis of the lens, the lens inner surface has a circular lens central region, a plurality of annular intermediate regions sequentially continuing to the outside of the lens central region, and an outer side of the plurality of intermediate regions. And a plurality of intermediate regions that are successively continuous with the concave base curve of the lens central region and the outside of the base curve when viewed in a cross section in a direction perpendicular to the central axis of the lens. Each of the regions has a contour formed by a concave intermediate curve, and a concave peripheral curve of the peripheral region continuous outside the intermediate curve, and a ridge line of a boundary between the adjacent intermediate regions is the boundary In a projection onto a cylindrical surface having a section surrounded by a cross section and having a central axis coinciding with the central axis of the lens, an interval is provided on the edge of the boundary. Hard contact lens characterized by extending forms a concave curve between the mutually adjacent points of the at least two points located. In the projection onto the cylindrical surface, the boundary ridgelines of the adjacent intermediate regions are quadratic or 3rd between adjacent points among four points located at equal intervals on the boundary ridgeline. The following approximate curve extends, and when the lens is worn, of the four points, two points located in one diameter direction are distances from the cornea surface and two points located in the other diameter direction from the cornea surface. 2. The hard contact lens according to claim 1, wherein two points that are arranged at different distances from each other and that are diametrically opposed are arranged at an equal distance from the corneal surface. In the projection onto the cylindrical surface, the ridgeline of the boundary between the adjacent intermediate regions is quadratic or 3rd between adjacent points among the eight points located at equal intervals on the ridgeline of the boundary. 2. The hard contact lens according to claim 1, wherein the hard contact lens extends in a next approximate curve, and the eight points are arranged at different distances from the corneal surface when the lens is worn. The plurality of intermediate regions include a first intermediate region that is continuous with the peripheral region, and a second intermediate region that extends between the first intermediate region and the lens central region. A base curve, a second intermediate curve of the second intermediate region continuous outside the base curve, a first intermediate curve of the first intermediate region continuous outside the second intermediate curve, and the outside of the first intermediate curve Having a contour formed by the peripheral curve continuous to
The base curve is in the lens center region, and when the lens is worn, the base curve is separated from the lens center by a predetermined distance in the radial direction of the lens, and the distance from the cornea surface is a predetermined maximum distance. Consists of a quadratic or cubic approximation curve passing through a point and the corneal apex,
The second intermediate curve is located in the second intermediate region, and faces the second point when the lens is worn, and a second point separated from the center of the lens by a predetermined distance along the radial direction of the lens. A quadratic or cubic approximate curve that passes through the outer edge of the base curve on the side and the outer edge of the base curve on the side away from the second point,
The first intermediate curve is in the first intermediate region, and when the lens is worn, the first intermediate curve is a predetermined distance away from the lens center along the radial direction of the lens and the distance from the cornea surface is a predetermined maximum distance. A quadratic or cubic approximation that passes through the third point, the outer end of the second intermediate curve on the side facing the third point, and the outer end of the second intermediate curve on the side away from the third point. Consist of curves,
The peripheral curve is in the peripheral region, and when the lens is worn, a fourth point that is a predetermined distance away from the lens center along the radial direction of the lens and a distance from the cornea surface is a predetermined maximum distance; And a quadratic or cubic approximate curve passing through the outer end of the first intermediate curve on the side facing the fourth point and the outer end of the first intermediate curve on the side away from the fourth point. The hard contact lens according to claim 1, wherein the hard contact lens is a hard contact lens.

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