KR0129588B1 - Contact lens - Google Patents

Abstract

The central part of contact lens for correcting the feebleness of eyesight caused by age is non-spherical lens with 2mm~4mm diameter and the perimetrical part of contact lens is composed of single-focused spherical lens with about 6.0~13.5mm diameter. Therefore in this contact lens the radiation from long distance penetrates a spherical face(2) to be formed in retina while the radiation from short range penetrates a non-spherical face to be formed exactly in retina. Consequently, the dim situation is clearly solved.

Description

Presbyopia contact lens and its manufacturing method

1 is an enlarged cross-sectional view of a contact lens of the present invention.

2 is an enlarged cross-sectional view of an eye wearing the contact lens of the present invention.

3 is a cross-sectional view showing a state appearing when the eye wearing the contact lens of the present invention exposed to light.

* Explanation of symbols for the main parts of the drawings

1: aspherical lens, 2: spherical lens,

10: lens of the eye, 15: anterior chamber,

16: iris, 17: ciliary body,

L: contact lens, NP: near-beam,

DP: far-field light, P: the point where the light beam enters the retina of the eye through the contact lens of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact lens for presbyopia correction, and in particular, to form an aspherical lens for correcting near vision and intermediate distance vision at the center of the lens using a soft hydrophilic material, and a spherical lens for correcting the distance vision at the peripheral portion The formed presbyopia correction contact lens.

Presbyopia patients are people who are unable to pull 100% of the ciliary body that is pulling the lens in the eye as they get older.If the ciliary body fails to pull the lens properly, the lens is unable to act as a convex lens and blurs the object at a short distance. Looks like. Accordingly, when a presbyopia patient looks at a distance of about 30-40 cm (13-16 inches), a lens that can adjust to normal vision is needed.

In addition, as elderly people drive more and more, they need sufficient long-distance vision at night so that they can drive at night. Multifocal lenses have been developed for this purpose, but no fully satisfactory lenses have been developed.

Accordingly, the development of a multifocal lens capable of correcting presbyopia vision has been urgently required. It would be more effective if such a multifocal lens could correct astigmatism such as paranoia and abnormal eyes.

Here, the multifocal lens is used to correct the long distance or the reading distance regardless of the distance by forming different focal points according to the part of the lens, and can mainly correct presbyopia or prepresbyopic ametropia. Mostly, bifocal lenses have been used.

Conventional bifocal contact lenses include those described in US Pat. Nos. 4199231 and 5125729.

U.S. Patent No. 4,99,231 relates to presbyopia contact lenses manufactured with a spherical rear surface and an aspherical front surface, and attempted to correct both near vision and far vision with aspherical lenses, but both near and far vision corrections are sharp. In addition, we tried to minimize the blurring that occurs when the lens is spherical when the images of objects near and far form on the retina of the eye, but the success rate is 50%. It's just about to the extent that it has a flaw that causes dizziness.

U.S. Patent No. 5,257,529 is a multifocal contact lens made of a spherical lens in which the center of the lens corrects the distance vision, an aspherical lens in which the peripheral portion corrects the near vision, and a spherical lens in which the outer periphery of the peripheral portion corrects the distance. As to the lens, the lens has a disadvantage in that the focus is properly obtained only by adjusting the brightness of the light as the distance vision correction center is located at the center. That is, at night, the pupil of the eye becomes large, and the near vision part of the lens enters the pupil so that the vision of the distance is not correct. As a result, when driving at night, which requires long vision, a very dangerous situation may occur. On the contrary, in the bright place, the pupil becomes small, so when the reading light that requires near vision has a problem that the distance vision part enters the pupil and the letters are blurred and difficult to see.

In addition, in the conventional bifocal lens, vision correction is hardly possible, such as when the vision is not necessary for the long-range vision category and the frequency is necessary only for the near vision category.

An object of the present invention, in order to solve the above problems, the center is made of an aspherical surface to correct the near vision, mid-range vision and far vision regardless of the dark or bright, the peripheral portion surrounding it is spherical It is manufactured to provide a contact lens for presbyopia correction that can correct the vision in the near and middle distance as well as in the long range.

It is still another object of the present invention to precisely manufacture even the small aspherical surface which is difficult to manufacture precisely by the manufacturing method (lathe-cutting) using manual or lathe cutting by drawing the contact lens of the present invention by a mold casting method. It is to provide a manufacturing method that can be.

In order to achieve the above object, the presbyopia contact lens of the present invention is an aspherical lens for correcting near vision and intermediate distance vision at the center of the lens and its peripheral portion is a contact lens made of a single focal spherical lens for correcting far vision. The diameter of the aspherical lens of the center portion is formed to about 2mm-4mm, and the diameter of the spherical lens of the peripheral portion is formed to about 6.0-13.5mm. The aspherical lens is a single focal lens or a multifocal lens.

In addition, the contact lens of the present invention is manufactured by a mode casting method.

The present invention has the advantage of correcting the eyes with astigmatism added to the presbyopia. That is, the conventional astigmatism lens has astigmatism of about 50% due to instability of the astigmatism axis, and in order to correct the astigmatism axis, a prism having a poor fit when worn should be added to the lens, but the contact lens of the present invention has astigmatism. It is not necessary to add a prism to the lens to correct it, so the fit can be corrected while having a fit.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a front view showing the front surface of the contact lens of the present invention, in which a boundary line is not actually displayed, but is circled to show the aspherical surface and the spherical surface separately. Here, the circle 1 at the center represents an aspheric surface having a diameter of about 2.0 mm -4.0 mm and represents a center aspheric near power (hereinafter referred to as CANP).

The lens is a hydrophilic soft lens (L), and is usually made of a flexible material such as hydroxyethyl methacrylate, acrylic monomer, vinylpyrrolidone (N-vinyl 2-pyrrolidone), epoxy, or the like.

The aspherical surface at the center of the front of the lens is about 2.0mm-4.0mm in diameter, and its periphery is made of spherical surface of about 6.0mm-13.5mm in diameter, and the back of the lens is made of spherical surface suitable for corneal shape. The spherical boundary lines are smoothed and show little distinction.

2 is a side view showing a state in which the contact lens of the present invention is worn on the eye.

3 shows a case where the eye is exposed to light when the object is viewed after wearing the contact lens of the present invention on the eye. Here, the light beam DP from a long distance passes through the spherical surface 2 and is formed in the retina, and the light beam NP from the short distance passes through the aspherical surface 1 and is accurately formed in the retina. The biur circle is completely solved.

In the present invention, the pupil is enlarged in a dark place and can not be read, so that only the circular single focus lens can be used to see the far field, and in the bright place the pupil is reduced, so that the near, middle and far distances can be determined through the aspherical lens. All can be seen.

Contact lenses have been made of hard lenses for the past 25 years, but have been made of soft lenses since about 10-15 years ago. The contact lens of the present invention can be manufactured with a hard lens or a soft lens, but when manufactured with a conventional hard lens size, the lens moves well in the eye, and thus the near vision correction site is not located at the center of the eye, which makes it difficult to correct the vision. . Soft lenses are also superior to hard lenses in terms of the ability to blink after wearing and return the lens to the center of the eye.

Hereinafter, embodiments of the present invention will be described in detail.

Example 1

The following results were obtained when a 59-year-old man wore the presbyopia contact lens of the present invention.

This person does not need vision correction in both the left and right eyes when looking at a distance, but when reading near, he needs + 0.50D correction in both the left and right eyes. Available, denoted K reading.) Is 7.85mm × 180 ° / 7.72mm × 90 ° in both left and right sides. The lens was mainly made of 2HEMA material, and the water content was 38%, the linear expansion coefficient was 1.18, the refractive index was 1.44, the center thickness of the lens was 0.06, the curve radius of the lens was 8.4mm, and the diameter of the lens was 14.0mm.

The frequency of the contact lens provided to said person is as follows. Near Field Calibration (CANP): + 1.50D

Long Range Calibration (PSDP): Plano (no calibration required)

The visual acuity was measured by using the contact lens manufactured by the above-described lens assistant, and the visual acuity of long distance and near was 1.2 (a sight correction value used in the USA: 24/20). Therefore, it was proved that vision correction was assured even when the distance was difficult to correct with the existing bifocal contact lens and the frequency was needed only at close range.

Example 2

The following results were obtained when a 50-year-old man wore the presbyopia contact lens of the present invention.

This person has an astigmatism added to myopia, and the left and right eyes have a myopia of -5.00D, and the left eye has an astigmatism of -1.00D (180 ° of astigmatism axis). Both left and right eyes need a correction of + 1.00D, and the corneal curve of this human eye (measured by Keratometer and indicated by K reading) has a radius of 7.80mm × 180 ° / 7.59mm × 90 °. The right side is 7.80 mm x 180 ° / 7.67 mm x 90 °, and the same material as that of Example 1 was used as the lens.

The frequency of the contact lens provided to said person is as follows.

Near field calibration degree (CANP): -4.00D

Long Range Calibration (PSDP): -5.00D

After wearing the lens, both eyes had corrected visual acuity of 1.2 (corrected for visual acuity: 24/20). The right eye of the presbyopia patient is myopia with presbyopia and the left eye is myopia and astigmatism with presbyopia.

In general, in the case of theft (90 °) and the astigmatism of the oblique axis, the astigmatism correction success rate was only about 50% due to the instability of the astigmatism axis. In order to solve the instability of the astigmatism axis, a prism was put into the contact lens, but there was a disadvantage in that the lens was inconvenient to wear. However, the contact lens of the present invention has a merit that it is possible to obtain a corrective effect even without putting a prism in the lens, thereby providing excellent fit and perfect vision correction.

However, in the present invention, the degree of astigmatism of 1.00D is perfectly corrected, but it is difficult to correct astigmatism of more than 1.00D, but since about 50% of patients with astigmatism have a weak degree of vision less than 1.00D, the effect of the present invention is Big.

Example 3

The following results were obtained when a 65-year-old man wore the presbyopia contact lens of the present invention.

This person needs correction of + 0.50D for both left and right eyes, and + 2.00D for near vision when reading.

The corneal curve of this human eye (measured by Keratometer and denoted by Kreading) has a radius of 7.50mm × 180 ° / 7.38mm × 90 ° in both left and right sides, and the same material as that used in Example 1 was used as the lens. .

The frequency of the contact lens provided to the said person is as follows.

Near field calibration degree (CANP): + 2.50D

Long Range Calibration (PSDP): + 0.50D

Visual acuity was measured by using the contact lens manufactured with the lens power, and the visual acuity of the far and near was 1.2 (a sight correction value used in the USA: 24/20).

As shown in the above embodiment, it can be seen that the contact lens of the present invention exhibits excellent effects in all cases in which myopia or astigmatism is added to the presbyopia as well as the presbyopia.

Accordingly, the present invention can correct near vision and distant vision regardless of the size of the pupil that changes according to the brightness of the light, no boundary line between the near vision and distant vision, and the north side of the center itself is the By doing so, the near focus is clearly formed on the retina, and it is effective to correct both vision, not selective vision correction at the near or near vision site.

In addition, since the presbyopia correction lens of the present invention is manufactured by a mold casting method, even a small aspherical surface which is difficult to manufacture precisely by a manual method or a lathe cutting using lathe cutting can be manufactured accurately. As a result, manufacturing costs and processes can be reduced, resulting in mass production at a low cost.

Claims (4)

A presbyopia corrective contact lens, comprising: an aspheric lens for correcting near vision at the center of a lens and a spherical single focus lens for correcting far vision at a periphery thereof. The contact lens of claim 1, wherein said aspherical lens is a single focus lens. The contact lens of claim 1, wherein the aspheric lens is a multifocal lens. The lens of claim 1, wherein the diameter of the aspherical lens in the center of the lens is about 2 mm to 4 mm, and the diameter of the single focus lens around the lens is about 6.0 mm to 13.5 mm.