FI79619C - Intraocular lens - Google Patents

Description

1 79619

Intraokulaarilineei

The invention relates to an intraocular lens which can be fitted into the eye and which is multifocal, i.e. consists of at least two parts with different refractive forces.

In cataract surgery, the lens is most often removed. In this case, replace the lens with, for example, glasses or contact lenses. However, the glasses are then very strong and therefore thick and heavy. Contact lenses are also often difficult to use and are not suitable for all cataract surgery patients due to the irritation they cause.

Therefore, in recent years, an intraocular lens, the so-called intraocular lens, has been used in cataract surgery to replace the lens. The lenses are divided into groups based on, for example, the location of the lens, in which case we speak of ventricular-angle-based, iris-based, and posterior-chamber lenses. In this case, the fastening member arranged in connection with the lens rests on a corresponding chamber. The optical part of the lens is usually made of polymethyl methacrylate (perspex) either by turning or casting. Lenses can also be classified based on the material and design of the heel lugs. The heel plaster lug may be made of polypropylene, either clear or colored, usually blue.

All previously known lenses are characterized by spherical optics realized by the convexity of the front and back surfaces of the lens. These spherical intraocular1 inserts have the disadvantage that they form an accurate image from only one distance. Thus, if the lens is preoperatively designed to correct the patient's farsightedness, the patient must wear reading glasses for close-up work. Similarly, the lens can be designed to correct a patient's near vision if the patient spends most of his or her time reading, writing, or similar close-up work, for example.

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It is an object of the invention to provide an intraocular line that corrects a patient's visual acuity both near and far. Such a multifocal intraocular line <B10L> is provided according to the invention in such a way that the different refractive parts of the lens are fixed relative to each other and are concentric or divided into symmetrical areas.

If, according to the invention, the lens is divided into two parts, a first part and a second part, the second part can be located e.g. in the central part of the lens, on its main axis, whereby the first part is formed by the peripheral part of the lens.

The diameter of the lens is about 6 mm. In the above case, the central part is 1.8-2.3 mm. This arrangement provides two images to the retina, of which, depending on the situation, the brain emphasizes more importance. According to the invention, it is also possible to fit several parts into the lens, whereby more precise images are obtained on the retina, respectively.

According to the invention, the first part of the lens is a first substance and the second part of the lens is a second substance, the second substance having a different refractive index than the first substance. According to the invention, the second part of the lens is then preferably a hole, cavity or recess formed in the middle of the lens. The hole can extend through the lens, creating a so-called needle hole. It is not necessary to have a hole in the middle of the lens, but a sleeve parallel to the main axis of the lens, which forms said needle hole, can be fitted to it.

The central part folds close to the light and the peripheral part far or vice versa. By resizing the central part, an optimal balance can be achieved between the remote and close-up images displayed simultaneously.

It is also possible according to the invention to emphasize one eye for near vision and the other for farsightedness.

According to the invention, the lens can also be made aspherical, in which case the first part of the lens has a different refractive power than the second part thereof.

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The invention will now be described in more detail with reference to the accompanying figures, in which Figure 1 shows an eye with a conventional intraocular lens, Figure 2 shows an eye with a bifocal intraocular lens, Figures 3-11 show bifocal or multifocal intraocular lenses divided into two or more. into several parts which produce different refractive power.

Figure 1 shows a conventional intraocular lens 2 fitted to the eye 1, adapted for farsightedness. In this case, the light rays 6 and 6 'coming from afar are exactly refracted at one point 3 on the retina of the eye. In contrast, the nearby light rays 7 and 7 'refract at point 4 and form a blurred image in the area 5 of the retina of the eye.

Figure 2 shows how an intraocular lens 2 divided into two parts 8 and 9 refracts both distal rays 6 and 6 'and near rays 7 and 7' in the lens regions 8 and 9, respectively, to one and the same point 3 on the retina of the eye 1. In this case, the brain can emphasize either a close-up image or a long-distance image, so that both are displayed accurately.

Figures 3 and 4 show a bifocal intraocular lens which is aspherical, the peripheral part 8 of the lens having a certain focal length, and the central part 9 of the lens having a different focal length. This also gives two images for the retina.

Figure 5 shows a lens with a body in the central region 9 of a material having a higher refractive power than the peripheral part 8. Thus, with a lens of uniform curvature, two different images are obtained on the retina.

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Figure 6 shows a lens with a so-called needle hole fitted in the central region. This can be accomplished either simply by making a small hole through the lens, whereby this acts as a lens in a manner familiar from a pinhole camera. The peripheral part 8 then forms a second part of the lens with a second focal length. The needle hole can also be provided by a tube 10 placed in the middle of the lens, which delimits the needle hole area 9.

The lens of Figure 7 is divided into a plurality of parts located concentrically about the axis of the lens. In this case, every other part 11 has the same focal length, and every other part 12 has the same focal length. In this case, for example, the parts 11 may be adapted for near vision and the parts 12 for far vision.

The lens of Figure 8 is also divided into several areas, these areas being located radially alternately. In this case, the area 11 can be adapted for far vision and the area 12 for near vision.

Figure 9 shows a lens in which the curvature of the lens is constantly changing. This provides continuous focusing accuracy at different distances.

Figure 10 shows a diffraction type lens. This lens is formed with concentric rings, the thickness of which is reduced by an amount corresponding to the optical distance of half a wavelength. Thus, the half-wave regions 13 and the full-wave regions 14 provide two different images on the retina of the eye.

By using the so-called "Fresnel" lens according to Fig. 11, the thickness of the lens, and thus the weight, can be reduced. Here, concentric Fresnel prisms 15 are used, the prism power of which increases as it goes outward in the lens.

Claims (10)

5,79619 An intraocular lens which is multifocal, i.e. consists of at least two parts with different refractive forces, characterized in that the different refractive parts of the lens are fixed relative to each other and are concentric or divided into symmetrical areas. An intraocular lens according to claim 1, characterized in that the lens (2) consists of two parts, a first (Θ) and a second (9) part. An intraocular lens according to claim 2, characterized in that the second part (9) of the lens is located in the central part of the lens, its main axis, and in that the first part (8) of the lens is located peripherally around the second part (9). An intraocular lens according to any one of the preceding claims, characterized in that the first part (8) of the lens is a first substance and in that the second part (9) of the lens is a second substance having a different refractive index than the first substance. An intraocular lens according to any one of the preceding claims, characterized in that the second, central part (9) of the lens is a hole (9), a cavity or a recess formed in the lens, or a body of another substance embedded in it. An intraocular lens according to any one of the preceding claims, characterized in that the second, central part (9) is a hole extending through the lens, a so-called needle hole. Intraocular lens according to one of Claims 1 to 3, characterized in that the lens is aspherical, the first part (6) of the lens having a different refractive power than the second part (9) thereof. 6,79619 Intraocular line according to Claim 1, characterized in that the lens is designed as Fresnel prisms <15). An intraocular line according to claim 1 or 2, characterized in that the lens is divided into a plurality of sector portions, each other portion (11 res. 12) having the same focal length. An intraocular line according to claim 1 or 2, characterized in that when the lens is divided into substantially concentric parts, these are formed by regions in each of which <11 'resp. 12 ') have the same focal length. PfttentKrftY