JP2008112121A - Multi-reverse zone ortho-k lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a contact lens of a new structure for orthokeratology therapy in which the effect of orthokeratological effects appear early during the wearing, the exchange of stepwise lenses is omitted, and a sufficient orthodontic effect of a single lens, or by readjustment of fewer number of times of the lenses is realized. <P>SOLUTION: As the regions of the lens, one set or a plurality of sets of tissues 5 (intermediate zone), 6 (secondly reverse zone) are constituted in addition to 3 (base zone) bearing plastic surgery of the cornea, 4 (reverse zone) receiving the cornea tissue that moves from the portions of the 3 (base zone), 7 (alignment zone ) contributing the fitting, and 8 (peripheral zone) constituting the portion of the edge. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a contact lens having an effect of deforming the shape of the cornea, and eliminates the trouble of adjusting the size of the contact lens in accordance with the change in the shape of the cornea, so that the wearing of a single lens or the number of times of lens readjustment is smaller than before. It is related with the technique which continues an effect by.

A treatment method (generally orthokeratology or ortho-K) that improves the myopia of the patient by deforming the shape of the cornea by wearing a certain contact lens at night and changing the focal length of the cornea itself, and this treatment method A corneal correction lens (generally an ortho-K lens) is known.

FIG. 3 shows the structure of a corneal correction lens described in Patent Document 1.

As for FIG. 3, the inside of the lens is mainly divided into three parts. The central spherical portion is the center zone, the next annular portion is the tier zone, and the annular portion at the end is the peripheral zone.

A spherical surface having a radius of curvature longer than the radius of curvature of the cornea is applied to the center zone, so that the cornea has an effect of being deformed more flatly. The corneal tissue in the center zone moves to the space formed by the tier zone.

In the peripheral zone, the distance between the cornea and the lens is increased, making it easy to remove the lens and taking in tears covering the cornea so that tears can be exchanged when blinking occurs. There is.
US Pat. No. 5,349,395

In the lens shown in FIG. 3 or a lens intended to change the shape of the cornea based on similar logic, it is known that the effect of the change in the shape of the cornea is likely to occur more quickly when the tier zone space is narrowed. .

However, when the shape of the cornea starts to change, the corneal tissue flows into the space between the center zone and the tier zone, so that the free space between the cornea and the lens decreases. In particular, when the tier zone is configured to be narrow, the decrease is significant. In the reduced state, the lens fitting becomes tight, and various diseases and disorders due to lack of tears between the lens and the cornea, and a peak phenomenon of the effect of shape change tend to occur. For this reason, it is necessary to replace the lens whose size has been readjusted and wear it again.

In view of this, the present invention provides a plurality of stages where the corneal tissue flows in, thereby narrowing the portion corresponding to the tier zone so that the effect of the shape change can be brought out quickly and the phenomenon that the lens fitting becomes tight is alleviated. Thus, an object of the present invention is to provide a technique for maintaining the effect by wearing a single lens.

A lens having the characteristics described below is constructed.

The rear surface of the lens is connected to the substantially circular central portion called the base zone, the annular portion called the reverse zone, which is connected to the base zone, the annular portion called the intermediate zone which is connected to the reverse zone, and is connected to the intermediate zone. , One or more sets of annular portions called second reverse zones, a plurality of sets, an annular portion called an alignment zone connected to the outermost set of second reverse zones, a portion called peripheral zones located around the alignment zone Contact lens formed by more.

A contact lens that provides a shaping effect that makes the cornea flatter, that is, has a larger curvature radius, by making the curvature radius of the base zone larger than the curvature radius of the central portion of the cornea.

The contact lens which makes the space which receives the movement of a corneal cell tissue of a center part between a base zone and a reverse zone by making the curvature radius of the said reverse zone smaller than the curvature radius of a cornea center part.

The intermediate zone has a larger radius of curvature and the second reverse zone has a smaller radius of curvature than the corneal portion behind, so that the space between the intermediate zone and the second reverse zone can accept the movement of the corneal cell tissue in the center. Contact lens that creates.

A contact lens that fits the lens along the corneal surface by making the curvature radius of the alignment zone equal to the curvature radius of the corneal portion behind the alignment zone.

A contact lens having a radius of curvature of the peripheral zone larger than that of the alignment zone.

Table of contents Applicable object (1) Applicable object 2. Configuration of lens (1) Name of each part (2) Size 3. Lens effect (1) Base zone effect (2) Reverse zone effect (3) Intermediate zone, second reverse zone effect (5) Alignment zone effect Difference in corneal shape change from conventional lens (1) Conventional lens (2) Lens according to the present invention (3) Comparison by graph

1. Applicable object (1) Applicable object The object to which the lens according to the present invention is applied is preferably a person having a mild or moderate myopic symptom with a correction value of visual acuity of about 3 to 6 diopters. By increasing the radius of curvature of the base zone, it can be applied to myopia of 6 diopters or more.

2. Lens Configuration (1) Name of Each Part FIG. 1 shows the configuration of the cornea and the lens.
Reference numeral 1 denotes a corneal surface, and 2 denotes a lens surface.
Reference numerals 3 to 8 denote parts on the back surface of the lens.
3 indicates a base zone.
4 indicates a reverse zone.
Reference numeral 5 denotes an intermediate zone.
6 indicates a second reverse zone.
7 alignment zones are shown.
Reference numeral 8 denotes a peripheral zone.

(2) The radius of the entire size lens is about 5 mm to 5.5 mm.
In the cornea, since it is not desirable to make the shape unevenness at the part where light actually passes, the base zone preferably has a radius of 3 mm or more. It is desirable to make the reverse zone and the second reverse zone as narrow as possible.

3. Effect of lens (1) Effect of base zone The base zone calculates the focal length from the radius of curvature of the cornea of the lens user and the refractive index of the cornea, and reverses the focal length by adding the degree of correction to the focal length. The radius of curvature is determined in accordance with the calculated value of the radius of curvature of the cornea assumed after forcing.
By changing the shape of the cornea according to the base zone, there is an effect of correcting myopia.

(2) Effect of reverse zone In the reverse zone, a space between the cornea and the lens is created to transfer the corneal cellular tissue corrected in the base zone.

(3) Effects of the intermediate zone and the second reverse zone As with the reverse zone, the intermediate zone and the second reverse zone create a space between the cornea and the lens, and the corneal cell tissue corrected in the base zone is transferred. Is done.

(4) Effect of alignment zone The alignment zone is in contact with the cornea, or at a distance of several microns at most and is almost in contact with the cornea, thereby contributing to lens fitting.

(5) Effect of peripheral zone When the lens is separated from the cornea to form an edge, it has an effect of assisting removal of the lens and inflow of tears into the lens.

4). Difference in corneal shape change from conventional lens (1) Conventional lens The corneal shape change in the conventional lens is shown below. For the sake of simplicity, for the sake of simplicity, a diagram having only three parts corresponding to the base zone, the reverse zone, and the peripheral zone is shown. The situation is the same even if the number of parts is increased by the lens.
Indicates the initial wearing state. There is room in the space between the lens and the cornea, and the effect of cornea correction begins to appear.
Indicates the state of middle wear. Due to the movement of the corneal tissue, there is no room in the space between the lens and the cornea. The fitting at this time becomes tight, and the effect of corneal correction reaches a peak.
Indicates a state in which the lens is subsequently replaced. In this way, it is necessary to readjust the lens size every time the correction effect is partially achieved.

(2) Lens in the present invention The state of corneal shape change in the lens in the present invention is shown below.
Indicates the initial wearing state. There is room in the space between the lens and the cornea, and the effect of cornea correction begins to appear.
Indicates the state of middle wear. Although corneal tissue movement occurs, there is still room for the space created by the intermediate zone and the second reverse zone between the cornea.
Indicates the state of late wearing. Furthermore, movement of the corneal tissue occurs, and a sufficient correction effect is obtained.

(3) Comparison by graph FIGS. 0 and 3 are graphs in which the distance between the lens and the cornea surface is plotted against the diameter from the center of the cornea. The former assumes a conventional lens, and the latter assumes a lens in the present invention.
As a typical example, the curvature radius of the cornea is 7.8 mm and the correction value is 3 diopters.
As is apparent from this graph, the lens according to the present invention achieves a larger margin between the lens and the cornea together with a narrow reverse zone.

It is a figure which shows the whole structure of a cornea and a lens in this invention. It is a figure which shows the structure when the lens in this invention is seen from the side surface and the back side. It is a figure which shows the whole structure of a cornea and a lens in patent document 1. FIG. It is a figure which shows a cornea and a lens in the initial state which wore the conventional type lens. It is a figure which shows a cornea and a lens in the middle-stage state which wore the conventional type lens. It is a figure which shows the lens which readjusted the cornea and size in the intermediate | middle state wearing a conventional lens. It is a figure which shows a cornea and a lens in the initial state which mounted | wore with the lens in this invention. It is a figure which shows the cornea and the lens in the intermediate state which equipped with the lens in this invention. It is a figure which shows the cornea and a lens in the latter-stage state which wears the lens in this invention. The distance between the lens and the corneal surface assumed when the lens is worn (because it is the thickness of the tear film, it is referred to as Tear Layer Thickness and abbreviated as TLT) is plotted against the diameter from the center of the cornea It is a graph and is referred to as “Tear Layer Profile”. It is an assumption graph in the case of a conventional lens. The distance between the lens and the corneal surface assumed when the lens is worn (because it is the thickness of the tear film, it is referred to as Tear Layer Thickness and abbreviated as TLT) is plotted against the diameter from the center of the cornea It is a graph and is referred to as “Tear Layer Profile”. It is an assumption graph in the case of the lens in the present invention.

Explanation of symbols

1. 1. Represents the corneal surface 2. Represents the curved surface on the front side of the lens. 3. represents the base zone 4. represents reverse zone 5. Represents the intermediate zone Represents the second reverse zone. Represents the alignment zone 8. Represents the peripheral zone Represents the curved surface on the front side of the lens. 10. Represents the interior sandwiched between the front and back curved surfaces of the lens. Represents the center zone 12. Represents the tier zone Represents a peripheral zone

Claims (6)

The rear surface of the lens is connected to the substantially circular central portion called the base zone, the annular portion called the reverse zone, which is connected to the base zone, the annular portion called the intermediate zone which is connected to the reverse zone, and is connected to the intermediate zone. , One or more sets of annular portions called second reverse zones, a plurality of sets, an annular portion called an alignment zone connected to the outermost set of second reverse zones, a portion called peripheral zones located around the alignment zone Contact lens formed by more. 2. The contact lens according to claim 1, wherein the curvature radius of the base zone is made larger than the curvature radius of the central portion of the cornea, thereby providing a shaping effect that makes the cornea flatter, that is, has a larger curvature radius. 2. The contact lens according to claim 1, wherein a space for receiving movement of corneal cell tissue in the central portion is created between the base zone and the reverse zone by making the curvature radius of the reverse zone smaller than the curvature radius of the central portion of the cornea. . The intermediate zone has a larger radius of curvature and the second reverse zone has a smaller radius of curvature than the corneal portion behind, so that the space between the intermediate zone and the second reverse zone can accept the movement of the corneal cell tissue in the center. The contact lens of claim 1, wherein: The contact lens according to claim 1, wherein the lens is fitted along the corneal surface by making the curvature radius of the alignment zone equal to the curvature radius of the corneal portion behind it. The contact lens according to claim 1, wherein a radius of curvature of the peripheral zone is larger than that of the alignment zone.

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