Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Eye prosthesis – Intraocular lens
Patent
1996-10-11
1998-10-20
Jones, Mary Beth
Prosthesis (i.e., artificial body members), parts thereof, or ai
Eye prosthesis
Intraocular lens
A61F 216
Patent
active
058240748
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
If a blurred eye lens is removed within the scope of cataract surgery, it is generally replaced with an implanted intra-ocular lens today. After first calculating the optical constants of the eyes, the intra-ocular lens can be designed so that it corrects the existing refraction error, such as shortsightedness, farsightedness, and also astigmatism. At the respective wish of the patient, the intra-ocular lens can be chosen in such a way that a particular postoperative defect in vision exists, such as a weak shortsightedness that would enable the patient to see close up without additional correction.
While a spherical defect in vision, i.e., shortsightedness or farsightedness, can easily be corrected, the correction of an astigmatism still remains a problem today. In that connection it is important to know not only that an astigmatism can exist before the operation is undertaken to implant an intra-ocular lens, but that an astigmatism can also be produced as a side-effect of the operation, especially as the result of an operation incision and the incision sutures that later heal. In the recent past it is true that they have succeeded in reducing the problem of an operation-produced astigmatism through improved incision techniques; but the elimination of a potential astigmatism is not possible. As a result, it is a fact that each cataract operation is per se an astigmatism-producing operation, which, if the occasion should arise, can also be drawn upon to reduce the natural astigmatism caused by the geometry of the eye. In so far as an operating surgeon induces a typical postoperative astigmatism with a technique chosen by him, the residual total astigmatism could be corrected at least theoretically after the operation by inserting an intra-ocular lens with a compensation section to correct the astigmatism in such a way that the postoperative residual total astigmatism is corrected. It is, however, the case that the techniques of cataract surgery are so variable that an exact prediction of the residual total astigmatism after the operation is not yet possible. For this reason, it is not yet possible today to guarantee the elimination of postoperative astigmatism.
An intra-ocular lens arrangement with several intra-ocular lenses arranged one behind the other along a common axis is already known from U.S. Pat. No. 5,222,981. The lens arrangement consists of a basic lens, a covering lens, and a sandwich lens lying between the two. Especially this sandwich lens can be provided with a section through which an astigmatism can be corrected. The total lens arrangement is implanted in the eye, whereby the sandwich and the covering lens do not, at this stage, need to be provided with a section that is suitable for correcting a defect in vision. Only after the surgical operation to implant the lens has healed are the covering lens and the sandwich lens removed and replaced by the new lenses correcting the defect in vision. These lenses are certainly smaller than the total lens arrangement, but the second surgical operation is almost as serious as the one necessary for the implantation, for an incision several millimeters long must be carried out.
An intra-ocular lens arrangement made of a basic lens and a covering lens, which is also suitable for correcting an astigmatism, is known from U.S. Pat. No. 5,133,747. When the implantation is made, at first only the basic lens is implanted, and then subsequently the covering lens is put on, e.g., stuck on, in a smaller surgical operation. This covering lens then serves to correct the defect in vision, including an astigmatism. In this case as well, a second surgical operation is necessary, even when the operative astigmatism caused by the first surgical operation is relatively well compensated by this procedure. The procedure of sticking on the additional covering lens, however, requires high operative skills.
An intra-ocular lens for correcting an astigmatism is known from U.S. Pat. No. 4,512,039, which consists solely of a single torically cut in
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