This invention relates to an instrument for performing eye surgery, more particularly to a template which enables the ophthalmic surgeon to carefully remove portions of the anterior capsule during surgical removal of a cataract through a small incision.
From time to time the lens of the eye becomes opacified to the extent that vision is impaired. Opacified lenses are termed cataracts.
There is no presently known technology or treatment which will reverse the opacification of the lens. Accordingly, the preferred method of treatment for cataracts has been to surgically remove the lens and then to compensate for that removal by the substitution of an artificial lens.
The lens comprises a capsule which includes anterior and posterior portions. The capsule contains a nucleus surrounded by a cortex. The nucleus is comprised of relatively hard material while the cortex is a jelly-like material.
There are several surgical methods for removing cataracts. They are described in my U.S. Pat. No. 5,217,459.
As explained in that patent, during cataract surgery, it is necessary to form a circular opening in the anterior capsule. This procedure is known as a "capsulorhexis".
Many surgeons have difficulty using this procedure since the capsulorhexis includes the step of tearing a circular opening in the anterior capsule that has a diameter of no greater than about five or six millimeters in diameter. Further, to reach the anterior capsule, an incision of about three millimeters in length must be cut in the eye. This is to enable a small tool to fit through the incision and then to tear the opening in the anterior capsule.
There is concern on the part of ophthalmic surgeons that the opening in the anterior capsule will not be correctly formed. Thus, it may be in the wrong place or be of irregular shape, over or under-sized, or have jagged edges.
If the opening in the anterior capsule is too small, it is more difficult to remove the cataract. Further, there is a possibility that the opening will further constrict at a later date making vision more difficult.
On the other hand, if the opening in the anterior capsule is too large, the tear may extend from the anterior capsule around to the posterior capsule. This may lead to complications during surgery such as loss of the nucleus into the posterior segment of the eye, or de-centering of the interocular lens implant at a later date.
It would be advantageous to have an instrument which would avoid these problems while at the same time being capable of fitting through the small incision necessary to enter the eye while at the same time providing a template which will permit the accurate making of an opening in the anterior capsule having a diameter of about five or six millimeters. Further, additional advantages would flow if the instrument were made of inexpensive materials so that it could be discarded after use.
With the foregoing in mind the invention relates generally to an ophthalmic template for use in making an opening in the anterior capsule of the eye that comprises a member that includes an edge that has a shape that corresponds to the shape of the opening that is to be made in the anterior capsule. It also includes means for selectively retaining the member on the anterior capsule.
In another aspect, the invention relates to a method for making an opening in the anterior capsule of the eye comprising the steps of placing a template on the anterior capsule in the place where the opening is to be made, retaining the template in place, and removing the portion of the anterior capsule adjacent the template.