JPH0521922U - Intraocular lens - Google Patents

Abstract

(57) [Abstract] [Purpose] An eye that has a lens surface that changes gently while maintaining the feature of an aspherical lens that allows near and far vision, and that is relatively thin and lightweight. Provide an inner lens. In an intraocular lens to be inserted into the eye instead of the crystalline lens of a human eye, at least a part of both the front surface and the rear surface of the intraocular lens is subjected to progressive or multifocal aspherical surface processing. It is characterized by that.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an intraocular lens that is inserted into the eye instead of the crystalline lens of the human eye.

[0002]

[Prior Art]

 An aphakic eye whose lens has been removed due to a cataract or the like becomes a strong hypermetropic eye, so an intraocular lens is inserted to compensate for this. At present, the majority of intraocular lenses to be inserted are monofocal lenses made of PMMA or the like. Recently, an intraocular lens having a progressive or multifocal aspherical surface has been proposed. These intraocular lenses are designed to have a focal point suitable for near vision and a focal point suitable for far vision. In these proposed intraocular lenses, either the front surface or the rear surface is aspherically processed.

[0003]

[Problems to be solved by the device]

 Since the former monofocal intraocular lens cannot exert accommodation power, there is an inconvenience that the patient who inserts this lens must prepare glasses for far vision or near vision. In addition, the latter intraocular lens overcomes the drawback of the former in that it allows near vision and far vision, but it is used for near vision to far vision for near vision. There is a drawback in that the change from one focus zone to the next is rapid and the change from one focus zone to the next is rapid. In addition, there is a drawback that the lens thickness in the near vision area becomes large.

The present invention has been devised in view of the above-described drawbacks, and maintains a gently changing lens surface while maintaining the feature of an aspherical lens that allows near vision and distance vision. A technical problem is to provide an intraocular lens that has a long lens thickness and is relatively thin.

[0005]

[Means for Solving the Problems]

 The intraocular lens of the present invention has the following features in order to achieve the above object. (1) In an intraocular lens that is inserted into the eye instead of the crystalline lens of the human eye, at least a part of both the front surface and the back surface of the intraocular lens has a progressive or multifocal aspherical surface. It is characterized by being applied.

(2) The intraocular lens of (1) is composed of a near vision portion for near vision in a central region of the lens and a far vision portion for far vision in a peripheral region. It is characterized in that the above-mentioned aspherical surface processing is applied to the portion.

[0007]

[Action]

 As described above, both the front and rear surfaces of the lens are subjected to progressive or multifocal aspherical surface processing, and the change in the refractive index is achieved by the change in the curvature of both the front surface and the rear surface. Compared to creating a change in the refractive index, the change in the surface curvature is more gradual, and the thickness of the lens can be reduced.

[0008]

Embodiment 1 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view including the optical axis of the intraocular lens of this embodiment, and also shows a ray diagram for explaining the optical properties. FIG. 2 is a front view thereof. The loop is omitted. The intraocular lens 1 includes a near vision portion 2 for near vision that spreads from the center of the lens, and a far vision portion 3 for far vision provided in the periphery thereof. The near portion 2 is rotationally symmetric, and is processed such that the front and rear surfaces have progressively larger radii of curvature with increasing distance from the optical axis a. This is to make the change in radius of curvature gradual, and it does not matter if it is optically opposite. The distance portion 3 is formed so that both the front surface and the rear surface of the lens have a constant radius of curvature. At the boundary 4 between the near portion 2 and the distance portion 3 of the biconvex lens, the lens curve changes most slowly when the front and rear curves are processed in the same manner (the boundary becomes an obtuse angle). , It is possible to make the whole thinner than one processed into a spherical surface.

[0009]

Second Embodiment Next, a second embodiment will be described. FIG. 3 is a sectional view of the intraocular lens of the second embodiment, and FIG. 4 is its front view. The feature of the second embodiment as compared with the first embodiment is that the near portion is not formed on the upper part of the intraocular lens, and the distance portion has a constant radius of curvature. As described above, when the near portion is not the object of rotation, the optical image is inferior to that of the first embodiment, but the image processing by the brain hardly causes any practical problems. It is easy to understand that the above embodiment can be modified in various ways and that other than the biconvex lens can be applied.

[0010]

[Effect of the device]

 According to the intraocular lens of the present invention, while maintaining the feature of an aspherical lens that allows near vision and distance vision, it has a gently changing lens surface, and the lens thickness is relatively thin and lightweight. It is possible to provide an intraocular lens that is

[Brief description of drawings]

FIG. 1 is a sectional view of an intraocular lens of Example 1.

2 is a front view of the intraocular lens of Example 1. FIG.

FIG. 3 is a sectional view of an intraocular lens of Example 2.

4 is a front view of the intraocular lens of Example 2. FIG.

[Explanation of symbols]

 1 intraocular lens 2 near part 3 far part 4 boundary

Claims (2)

[Scope of utility model registration request] 1. An intraocular lens which is inserted into the eye in place of the crystalline lens of the human eye, wherein progressive or multifocal aspherical surface processing is performed on at least a part of both the front surface and the rear surface of the intraocular lens. An intraocular lens characterized by being applied. 2. The intraocular lens according to claim 1, comprising a near vision portion for near vision in a central region of the lens and a far vision portion for far vision in a peripheral region. An intraocular lens characterized in that the aspherical surface treatment is applied to.