DE2814810A1 - CONTACT LENS - Google Patents

Description

SPOFA spojene podniky pro zdravotnickou vyrobu Prague (CSSR)

Contact lens

The invention relates to a contact lens with an inner and an outer boundary surface.

For all aids that are used to correct refractive errors of the eye, the basic principle is so far an optically functional region that is as homogeneous as possible. This applies to both glasses and lenses for contact lenses. In this sense, such designs are also used in the manufacture of contact lenses Surfaces obtained that have a constant refractive power over the entire optical surface and consequently also the purest Secure the image on the retina, e.g. B. Lenses in which by turning or grinding both on the inner as well as exactly spherical surfaces are formed on the outer side, their interaction by only relatively small spherical aberration is characterized. It goes without saying that the contact lenses manufactured in this way visual acuity through the ability to accommodate

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of the carrier is conditional. Is this ability missing (e.g. in the aphakic core) or is it severely limited (e.g. in the presbyopic nucleus) j then image sharpness can only be achieved for objects at a certain distance, and the lens must therefore be prescribed either for seeing from distant or for seeing objects in the vicinity.

The invention is based on the object of a contact lens to create sufficient visual acuity for close objects and distant objects at the same time can guarantee even with limited or even completely absent accommodation ability of the eye.

The object set is achieved according to the invention by a contact lens as specified in claim 1, and advantageous developments of the invention are characterized in the subclaims.

According to the invention, visual acuity can be achieved simultaneously for both distant and near objects, even in patients with limited or no accommodation, by deliberately designing the optics of the contact lens in such a way that it becomes highly inhomogeneous in the region of the optic zone. Surprisingly, it has been found that when some aspherical optical surfaces are used, which cause the refraction of the contact lens in the center in the direction towards the edge of the pupil to change continuously by 2 to 5 diopters, these surfaces do not give the patient the feeling of a Image distortion and to a large extent replace his lack of accommodation as effectively as if he were able to accommodate up to h diopters and therefore both distant objects

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stand as well as objects at a distance of 25 cm.

In these cases, from the point of view of conventional principles of optics, it is a very imperfect one Illustration of how one can prove by calculation or experimentally that one can only use image sharpness in near the optical axis, while in the direction towards the edges the image gradually becomes blurred dissolves. However, this disadvantage does not have any negative consequences for visual acuity because it is in the foveal region of the retina of the eye, which is only able to perceive the sharp image and which is completely in the range of a very narrow Viewing angle (5 - 10 °), the sharpness of the image due to the optically inhomogeneous lenses mentioned is so good that the ability to differentiate, which is limited anyway by the diffraction of light and the mutual removal of the retinal leaves is not deteriorated further by the inhomogeneity of the contact lens.

The invention thus results in a contact lens whose dioptric value in the optical zone, ie within a diameter of up to 6 mm, is produced in such a way that the refraction changes fluently or in small jumps from its individual sections in the range of 2 to 5 dioptres which is achieved in that its central part up to a diameter of 6 mm is formed by inner and outer surfaces, the normals of which intersect the optical axis, the ratio of the normal distances from the axis to points lying on the inner and outer Area at the same distance from the axis, this distance from the axis is in the range of 5 to 15 % different.

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Advantageously, the middle part of the lens can be achieved by combining an outer spherical or elliptical, parabolic or hyperbolic surface formed with an inner elliptical, parabolic or hyperbolic surface will.

The invention also relates to a contact lens of otherwise conventional shape with homogeneous optics (the inner and outer surface of which is spherical in rough cracks), the outer surface of which is machined in such a way that there are unevennesses on it, which continuously increase the refractive power in the individual sections Change the range from 2 to 5 diopters, i.e. areas whose normals intersect the optical axis and whose normal distances from the axis differ from the radius of the original outer surface in a range of - 2.5 to 7.5 % .

Signs of a similar reprocessing have already been seen in the case of soft contact lenses that have been centrifugally cast established. Their inhomogeneity has so far been considered to be their disadvantage because of the assessment of the optical quality of contact lenses have unlawfully transferred the criteria applicable to spectacle lenses. The surprising finding that one achieves an extraordinarily beneficial effect if one uses their apparent Deliberately increased disadvantage, broadens the area of application very considerably, because the on such Wisely made lenses provide sharp near and far vision for a large group of patients with refraction failure. At the same time, however, the effort to create a completely homogeneous look for patients remains full accommodation capacity further entitled to those who

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perfectly correspond to optically homogeneous lenses that can be obtained by conventional methods (i.e. with two spherical surfaces) and preparation of the casting technology according to the CS-PS 96I.

In the drawing, the invention is illustrated by means of examples; show it:

Pig. I a schematic section through a part of an inventively designed Contact lens on a greatly enlarged scale and with normal distances entered,

2 to 5 corresponding sections through contact lenses, in which the optical inhomogeneity desired according to the invention is achieved through combination of various second-order surfaces of revolution, i.e. surfaces of revolution with meridians in the form of conic sections is and

6 shows a section through a contact lens, the outer surface of which is strong in the drawing exaggerated - has bumps.

The central zone Z with a diameter of up to 6 mm is delimited in the contact lens of FIG. 1 by an inner surface 1 and an outer surface 2, the normals and H of which intersect the optical axis O. The ratio of the normal ^{distances AA '/ BB 1} from the axis O changes as a function of the perpendicular distance χ of the points A and B from the axis O in the range from 5 to 15 %.

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In Fig. 2, an outer surface 2 is in the form of a flat ellipsoid combined with an inner surface 1 in the form of a steep ellipsoid.

In FIG. 3, an outer spherical surface 2 is combined with an inner paraboloidal surface 1.

In FIG. K , an inner surface 1 in the form of a steep ellipsoid is combined with an outer hyperboloid-shaped surface 2.

In FIG. 5, an inner parabolic surface 1 is combined with an outer hyperbolic surface 2.

The optical inhomogeneity in all cases just mentioned is such that the deviation of the dioptric Value of each part of the contact lens from the mean axis to the square of the perpendicular distance of that part the contact lens from the axis is proportional. In the examples illustrated in Figures 2 and 3, the value is this deviation positive; in those illustrated in Figs Cases this deviation is negative.

In Fig. 6, a contact lens, the inner surface 1 and the outer surface 2 of which are spherical in rough lines, is illustrated. However, this lens has bumps 5 on the outer surface 2, the normal lines of which intersect the optical axis 0 and the normal distances 6 of which from the axis 0 differ from the radius R of the original outer surface 2 in the range of - 2.5 to 7.5 % differentiate.

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Claims (2)

Expectations 1. Contact lens with an inner and an outer boundary surface , characterized in that in order to generate inhomogeneous refractive power, the inner boundary surface (1) and the outer boundary surface (2) are designed in a central zone (Z) around the optical axis (0), which is limited by a maximum diameter of 6 mm, so that the Ratio AAVBB ^{1 of} the distances AA ¹ and BB ¹ between one of two points A and B at the same distance χ from the optical axis (0) on the inner boundary surface (1) or on the outer boundary surface (2) on the one hand and the Intersection point A ¹ or B ^{1 of} the normal {3 or 4) through these points A and B with the optical axis (0) on the other hand depending on the distance χ from the optical axis (0) in a range of 5 to 15 % varies. 2. Contact lens according to claim 1,
characterized, that in the central zone (Z) an outer boundary surface (2) of spherical, elliptical, parabolic or hyperbolic shape with an inner boundary surface (1) of elliptical, parabolic or hyperbolic shape Shape is combined. 233- (S 9312) -DfE 809842/0826 ORIGINAL WSPECTED Contact lens according to Claim 1, characterized in that that with a spherical design both the inner boundary surface (1) and the outer boundary surface (2), the outer boundary surface (2) has unevenness (5) whose normals intersect the optical axis (O) and their normal distances (6) from the optical axis (0) differ from the radius (R) of the original spherical shape of the outer boundary surface (2) in a range from 2.5 to 7> 5 % . 8038 4 2/0826