JP2846811B2 - Presbyopia contact lenses - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a presbyopia contact lens having a near vision correction area and a distance vision correction area, and more particularly to a presbyopia contact lens in which the power changes exist concentrically.

[0002]

2. Description of the Related Art Conventionally, a multifocal lens has been used as an ophthalmic lens for supplementing visual acuity, which has been applied to an eye having poor visual acuity adjusting ability such as presbyopia, and has a large number of powers in one lens. Ophthalmic lenses have been proposed.

[0003] Such multifocal ophthalmic lenses can be broadly classified into two types. The near vision correction area and the distance vision correction area set for the lens are separately used as necessary and separately provided. Observing the near vision correction area and the distance vision correction area at the same time, and by observing the brain of the wearer (observer), selecting and observing those at the desired distance. Although there is a thing, the former type of ophthalmic lens requires a high level of prescription technology, and in the field of ophthalmic lenses, it is difficult to properly use and observe a plurality of correction regions. In addition, the latter type (simultaneous observation type) of observing each correction area at the same time is becoming mainstream.

The simultaneous observation type ophthalmic lens is disclosed in Japanese Patent Application Laid-Open Nos. 57-105717 and 60-913.
No. 27, JP-A-61-272717, JP-A-62-1
Japanese Patent No. 21419 proposes various contact lenses for presbyopia in which the near vision correction region and the far vision correction region are provided concentrically by changing the power concentrically.
However, these conventional contact lenses for presbyopia cannot always sufficiently perform vision correction in both the distance vision correction region and the near vision correction region.

[0005] In order to clarify the cause, the present inventors prototyped various presbyopia contact lenses that have been conventionally proposed, conducted a wearing test, and conducted detailed studies. As a result, most of the contact lenses were found to shift toward the ear when worn, and the tendency was found to be due to the shape of the general human cornea. That is, since the shape of the human cornea has a larger curvature on the ear side than on the nose side, the contact lens is more likely to be moved to the one with the larger curvature.

On the other hand, in the general shape of the human eye,
It is known that the pupil center is displaced from the cornea center by about 0.2 to 0.6 mm to the nose side.

As described above, in general, the contact lens shifts to the ear side when worn, while the pupil shifts to the nose side. Assuming that the center (the geometric center of the lens) is located at the center of the pupil, the power is changed concentrically around the geometric center of the lens. For this reason, at the time of actual wearing, the positional relationship between each correction area of the contact lens and the pupil is not kept at a preset positional relationship. As a result, in the conventional contact lens, both the near and far vision are used. It was difficult to make clear observations in the correction region.

[0008] Further, the present inventors proceed with research on the positional relationship between each correction area of the contact lens and the pupil of the eye, and as a result, the near vision correction area (or the distance vision correction area) is reduced. They found that it was possible to observe something near (or far away) without covering all or most of the pupil.

[0009]

The present invention has been made in view of the above-mentioned circumstances, and a problem to be solved is that the power is concentrically changed so that the near vision correction area is far from the near vision correction area. An object of the present invention is to provide a presbyopic contact lens having a visual acuity correction area formed therein so that a clear observation can be performed by any of these near / far vision correction areas.

[0010]

In order to solve the above problems, the present invention is characterized in that a substantially circular central vision correction area that forms one of a near vision correction area and a distance vision correction area is provided. , Is provided in an annular shape surrounding the central vision correction area,
In a presbyopic contact lens having a peripheral vision correction region that forms one of the near vision correction region and the distance vision correction region, the central vision correction region is defined as the center of a circle that forms the outer shape of the contact lens ( It is formed at a diameter of 0.8 mm to 3.5 mm around a position shifted by 0.2 mm to 2.4 mm to the nose side with respect to a vertical meridian passing through the geometric center of the lens), and has a size of 0.8 to 3.5 mm. The vision correction area is
The optical center is formed in the same area with respect to the force correction area .

The central vision correction area can be formed as either a near vision correction area or a distance vision correction area. In particular, such a central vision correction area is defined as a near vision correction area, and a peripheral vision correction area is used. If the area is a distance vision correction area,
The diameter of the central vision correction area is preferably 0.8 mm to 2.8.
mm, more preferably 1.0 mm to 2.0 mm.

Further, when the central vision correction area is a distance vision correction area and the peripheral vision correction area is a near vision correction area,
The diameter of the central vision correction area is preferably 1.2 mm to 3.5.
mm, more preferably 1.5 mm to 3.5 mm.

Further, in such a presbyopic contact lens, a rotation preventing means for positioning at the time of wearing may be employed, if necessary.

When ballast means is employed as the rotation preventing means, slab-off processing on the peripheral portion of the lens can be appropriately employed.

Furthermore, in the presbyopic contact lens according to the present invention, the center of the central vision correction area can be set so as to be deviated from a horizontal parallel passing through the geometric center of the lens. .

[0016]

[Effects and Effects] In short, in the presbyopic contact lens according to the present invention, the pupil is shifted from the center of the cornea to the nose side, and the contact lens is shifted to the ear side when worn. Considering this, the center of the change in the power of the contact lens is set at a position shifted to the nose side from the center of the circle forming the outer shape of the contact lens.
In other words, the change in the power is made to exist according to the actual shape of the eye and the wearing state of the lens.

Thus, in the contact lens for presbyopia according to the present invention, when worn, the central vision correction area exists in the pupil, and the center of the correction area exists near the center of the pupil. In other words, the contact lens can be advantageously arranged so that the visual axis (here, the center of the pupil substantially matches the visual axis) and the optical axis of the contact lens substantially match.

Therefore, when the presbyopic contact lens is worn, the positional relationship between each correction area of the lens and the pupil of the eye can be correctly maintained at a preset positional relationship. Thus, clear observation can be performed in both the near vision correction area and the distance vision correction area.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the presbyopic contact lens according to the present invention, as shown in FIG. 1, either one of a near vision correction area and a distance vision correction area (2).
Is provided near the center (center) of the lens, while the other (4)
Is provided in an annular shape so as to surround it. The two correction areas (2, 4) are formed and positioned on the same optical center P. In addition, each correction area (2,
4) does not have to be a perfect circular shape or a perfect annular shape, but may be an elliptical shape, an elliptical annular shape, or the like. In addition, the correction regions (2, 4) need only have the optical center: P substantially coincident with each other, and may be mutually deviated in terms of area or outer shape. That is, the central visual acuity correction area 2 has a substantially circular shape with the optical center P substantially coincident with the outer shape center, but the peripheral visual acuity correction area 4 does not necessarily have the optical center as a geometrical geometric center. is not.

The central vision correction area 2 is formed so as to satisfy any of the following conditions. (A) The center of a circle forming the outer shape of the contact lens 6 (the geometric center of the lens): a vertical meridian passing through O: m,
In other words, at the time of wearing the lens, with respect to the vertical line passing through the geometric center O, the distance from the nose side (the right side in FIG. 1) is set to 0.
The center is a position shifted in the range of 2 mm to 2.4 mm. (B) The size is from 0.8 mm to 3.5 mm in diameter.

That is, when the deviation amount A of the center of the central vision correction area 2 is smaller than 0.2 mm, the effect of shifting the central vision correction area 2 to the nose side cannot be sufficiently expected, and the contact lens 6 cannot be moved. When worn, the positional relationship between each of the correction regions 2 and 4 of the lens and the pupil 8 of the eye deviates from a preset positional relationship, and it is difficult to perform good observation in both the correction regions 2 and 4. Because it becomes. Note that, more effectively, the deviation amount A of the center (P) of the central vision correction area 2 is desirably 0.3 mm to 2.0 mm,
More preferably, it is set to 0.3 mm to 1.0 mm.

Further, if the central visual acuity correction area 2 itself is too small, the amount of light required for the visual acuity correction cannot be obtained, so that observation in the near or far vision correction area arranged as the central visual acuity correction area 2 is difficult. It becomes difficult. On the other hand, if the central visual acuity correction area 2 is too large, there may be a case where an area required for observation and located on the pupil 8 of the peripheral visual acuity correction area 4 cannot be ensured. Observation in the eyesight correction area becomes difficult.

Experience has shown that when the central vision correction area 2 is used as the near vision correction area, if the near vision correction area covers 40% or more of the pupil area, distant observation is hindered. Fear arises. This is because more light is required for distant observation than for near observation,
In addition, at the time of distant observation, it is highly likely that discomfort is caused when a near object appears to overlap with a distant object. On the other hand, when the central vision correction area 2 is a distance vision correction area, when such a distance vision correction area covers most of the pupil area, the contrast is reduced due to a lack of light from the peripheral vision correction area. Intense, which may hinder near-field observation.

From the above, it is desirable that the diameter D of the central visual acuity correction area 2 is effectively set to 0.8 mm to 2.8 mm when it is the near vision correction area. Preferably, it is 1.0 to 2.0 mm. When the central vision correction area 2 is used as a distance vision correction area, the diameter is desirably 1.2 mm to 3.5 mm, and more preferably 1.5 mm to 3.5 mm.

Thus, the central vision correction area 2 that satisfies the above conditions A and B is formed, and the peripheral vision correction area 4 surrounds the central vision correction area 2 so as to be present in a ring shape. . Thus, the central vision correction area 2 and the peripheral vision correction area 4 have substantially the same optical center: P
Thus, the intended presbyopia contact lens 6 having the power change formed concentrically thereon can be obtained. That is, in such a contact lens 6, the center (P) of the central visual acuity correction area 2 is advantageously positioned near the center of the pupil 8 when the lens is worn, and the central visual acuity correction area 2 is located within the pupil 8. The optical centers P of the central vision correction area 2 and the peripheral vision correction area 4 are advantageously located on the visual axis and both are located on the pupil 8. The areas of the visual acuity correction areas can be advantageously secured, and observation can be favorably performed using the two visual acuity correction areas 2 and 4. In addition,
In FIG. 1, reference numeral 10 denotes a cornea, and a point Q is a geometric center of the cornea 10.

In the presbyopic contact lens 6 having the central vision correction area 2 and the peripheral vision correction area 4 satisfying the above conditions A and B, there is an individual difference in the corneal shape and pupil position of the wearer. Even if there is, the optical center of the vision correction areas 2 and 4: P
Does not greatly deviate from the visual axis, and the sharpness at the time of observation can be sufficiently ensured by any of the vision correction regions 2 and 4. However, more effectively, the conditions A and B (particularly,
It is desirable to set specific setting values within the range of the condition A) according to the wearer.

The setting operation according to the wearer can be carried out, for example, by first mounting the test contact lens having the same inner surface shape as the presbyopic contact lens to be worn by the wearer on the wearer, which is most stable. At the position, the amount of displacement between the geometric center of the test contact lens and the center of the pupil of the wearer is measured using an anterior ocular segment observation device or the like, and based on the measured value of the amount of displacement, only the amount of the displacement, This can be achieved by setting the optical center of the vision correction area to be shifted from the geometric center of the lens. Note that the inner surface standard of the test contact lens can be determined by measuring the shape (curvature) of the cornea using a corneal shape measuring device (keratometer) or the like, similarly to the case of a general contact lens. In general, a test contact lens is used in which some mark is given in advance so that the examiner can visually recognize the geometric center.

In the presbyopic contact lens 6 according to the present invention, if necessary, the optical center P of the central vision correction area 2 is moved upward or downward with respect to the latitude line passing through the lens geometric center O. It is also possible to set a bias (see specific examples shown in FIGS. 5 and 7). And, by such a vertical deviation processing, the alignment of the optical center point in the vision correction area with the pupil of the wearer may be more advantageously performed.

Further, the presbyopia contact lens according to the present invention can be formed by using various known lens materials.
For example, it can be manufactured by employing a manufacturing method by a conventionally known molding method. Further, as shown in FIG. 2, by using a special jig 12 provided at an angle with respect to the lens main axis b, a cutting method using a predetermined cutting tool 14 is applied to the lens material 15. By cutting, a contact lens for presbyopia can be produced.

In the presbyopic contact lens 6 according to the present invention, since the optical centers of the vision correction areas 2 and 4 must be arranged so as to be located on the nose side of the wearer, generally,
The contact lens 6 is provided with anti-rotation means for positioning during wearing, so that the optical center of the vision correction area 2.4 more advantageously and stably coincides with the visual axis. You can be impatient. Specifically, various ballast means including a prism ballast means for decentering the center of gravity below the lens by shifting the center of the inner surface and the outer surface of the contact lens 6 are provided for the contact lens. At this time, since the thickness usually increases at the peripheral portion of the lens which is not related to the optical area, a cutting process called slab-off is performed so as to reduce the thickness of the peripheral portion of the lens, as shown in FIG. , A slab-off region 16 is formed. Alternatively, as shown in FIG. 4, means for reducing the thickness of the upper part and the lower part of the contact lens 6 is provided, and the lens is stabilized by the relationship between the upper and lower thin portions 18, 18 and the upper and lower eyelids. It is done as follows.

FIGS. 5 to 7 show specific examples 22, 30, and 32 of presbyopia contact lenses designed to satisfy the above conditions. FIG.
And presbyopia contact lenses 22, 30 shown in FIG.
Is a specific example in the case where the central vision correction area is a near vision correction area, and the contact lens 32 for presbyopia shown in FIG. 7 has a central vision correction area as a distance vision correction area. This is a specific example in the case of performing. In these figures, reference numerals 24 and 25 denote a near vision correction area, reference numerals 26 and 27 denote a distance vision correction area, reference numeral 28 denotes a slab-off area as a rotation preventing means, and reference numeral 34 denotes a thin part as a rotation preventing means.

More specifically, in the presbyopia contact lens 22 (diameter: 14.0 mm) shown in FIG.
(A) The optical center P of the near vision correction area 24 as the central vision correction area is the nose side (right side in the figure) with respect to the vertical meridian: m passing through the geometric center O of the lens. 1.
It is shifted by 0 mm. Further, in this specific example, the optical center P of the near vision correction area 24 is shifted downward by 0.18 mm from the horizontal parallel line n passing through the geometric center O of the lens. (B) The near vision correction area 24 has a diameter D =
It is formed in a 1.8 mm circle. As a result, the pupil diameter of the eye changes depending on the illuminance (the pupil diameter is about 2.5 mm to 4.0 mm under the illuminance of a normal room or the like), but when the presbyopia contact lens 22 is worn on the eye. Can be advantageously positioned such that the optical center P of the vision correction areas 24, 26 is located near the center of the pupil, and the central vision correction area 24 is only within the pupil. In addition, the distance vision correction area 26 is formed with a diameter of 8.0 mm.

In the presbyopia contact lens 30 (diameter: 14.0 mm) shown in FIG. 6, (A) the optical center of the near vision correction area 24 as the central vision correction area: P
Is shifted A = 0.3 mm to the nose side (right side in the figure) with respect to the vertical meridian: m passing through the geometric center O of the lens. (B) The near vision correction area 24 has a diameter D = 1.
It is formed in a circular shape of 2 mm. Further, a distance vision correction area 26 as a peripheral vision correction area is formed around the near vision correction area 24. However, the distance vision correction area 26
A part of the peripheral portion is cut off by slab-off processing as rotation preventing means. Even in such a presbyopic contact lens 30, when worn on the eye, the optical center P of the vision correction areas 24 and 26 is positioned near the center of the pupil, and the central vision correction area 24 is located at the center. It can be advantageously arranged to be only in the pupil.

Further, in the presbyopia contact lens 32 (diameter: 14.0 mm) shown in FIG. 7, (A) the optical center of the far vision correction area 27 as the central vision correction area: P
Is shifted A = 1.5 mm to the nose side (right side in the figure) with respect to the vertical meridian: m passing through the geometric center O of the lens. Further, in this embodiment, such a distance vision correction area 27 is used.
Is shifted 0.5 mm downward with respect to the horizontal latitude line: n passing through the geometric center O of the lens. Also,
(B) The distance vision correction area 27 is formed in a circular shape having a diameter D of 2.0 mm. Further, a near vision correction area 25 is formed around the distance vision correction area 27 as a peripheral vision correction area. Thus, even when the presbyopic contact lens 32 is worn on the eye, the optical center P of the vision correction areas 25 and 27 is positioned near the center of the pupil, and the central vision correction area 27 is used. Can be advantageously arranged to be present only in the pupil. The near vision correction area 25 has a substantially elliptical shape because the thin portions 34 are formed at the upper part and the lower part of the contact lens 32, respectively.

Therefore, the above presbyopia contact lens 2
In any of 2, 30, 32, near vision correction area 2
Good observations can be made in both the 4,25 and the distance vision correction areas 26,27.

Although the specific configuration and examples of the presbyopia contact lens according to the present invention have been described in detail above, it goes without saying that the present invention is not subject to any restrictions due to such description. It is a place. Further, in addition to the above-described specific description, various changes, modifications, improvements and the like can be made to the present invention based on the knowledge of those skilled in the art without departing from the spirit of the present invention. It should be understood.

For example, in the above description, a contact lens having two focal points, a near vision correction area and a distance vision correction area, has been described. However, the present invention is not particularly limited to a bifocal contact lens. Absent. For example, it is possible to provide a transition portion between the near vision correction region and the distance vision correction region, and provide the transition portion with a correction region in which the power continuously changes from near to far.

It goes without saying that the present invention can be advantageously applied to various types of presbyopia contact lenses, regardless of whether they are hard contact lenses or soft contact lenses.

[Brief description of the drawings]

FIG. 1 is an explanatory plan view illustrating a specific configuration of a contact lens for presbyopia according to the present invention.

FIG. 2 is an explanatory diagram for explaining a cutting method of a contact lens.

FIG. 3 is a plan view and a longitudinal sectional view showing an example of a rotation preventing unit provided in a contact lens.

FIG. 4 is a plan view and a vertical sectional view showing another example of the rotation preventing means provided in the contact lens.

FIG. 5 is an explanatory plan view showing an example of a presbyopic contact lens according to the present invention.

FIG. 6 is an explanatory plan view showing another example of the contact lens for presbyopia according to the present invention.

FIG. 7 is an explanatory plan view showing still another example of the contact lens for presbyopia according to the present invention.

[Explanation of symbols]

 2 Central vision correction area 4 Peripheral vision correction area 6 Presbyopia contact lens 8 Pupil 10 Cornea 16 Slab-off area 18 Thin portion 22, 30, 32 Presbyopia contact lens 24, 25 Near vision correction area 26, 27 Far vision Correction area 28 Slab-off area 34 Thin part

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor, Kazuwa Miura 3 Shinsama, Seki City, Gifu Prefecture Inside Menicon Seki Plant (72) Inventor Tadashi Sawano, 3-4-15 Sakae Naka-ku, Nagoya City, Aichi Prefecture Sakae Building Menicon Corporation Clinical Center (72) Inventor Kenichi Ishihara 3-12-7 Biwajima, Nishi-ku, Nagoya-shi, Aichi Prefecture Menicon Corporation Biwajima Research Laboratories (72) Inventor Hiroyuki Oyama 3 Shinshinma, Seki City, Gifu Prefecture (56) References JP-A-6-289329 (JP, A) JP-A-2-293819 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G02C 7 / 04 G02C 7/06

Claims (4)

(57) [Claims] 1. A presbyopic contact lens having a substantially circular central vision correction area and a peripheral vision correction area provided in an annular shape surrounding the central vision correction area , wherein the central vision correction area is far-sighted. In front of the eyesight correction area
The peripheral vision correction area is a near vision correction area, and the central vision correction area is located on the nasal side with respect to a vertical meridian passing through the center of the circle (the geometric center of the lens) forming the outer shape of the contact lens. The diameter is 1.2 mm to 3.5 mm centered on a position shifted by 0.2 mm to 2.4 mm from the center, and the peripheral vision correction area is located between the central vision correction area and the optical center. A contact lens for presbyopia, which is formed in the same manner as above. 2. The presbyopia contact lens according to claim 1 , further comprising a rotation preventing means for positioning during wearing. 3. The contact lens for presbyopia according to claim 2 , wherein ballast means is employed as said rotation preventing means, and slab-off processing is applied to a peripheral portion of the lens. Wherein a center of said central vision correction region is presbyopia correction contact lens according to any one of claims 1 to 3 are allowed biased with respect to the horizontal direction of the parallels passing through the geometric center of the lens.