Intraocular lens surgical procedures, and specifically cataract surgery to which the present invention is directed primarily, have become more sophisticated, with less intraoperative complications occurring. Hence, ophthalmologists now are focusing more attention on the refinements, one of which is the correction and prevention of corneal astigmatism. In order for the surgeon to be able to properly evaluate the effects of their cataract incisions and closures, several requirements are necessary.
The incision must be as standardized and reproducible as possible, as should be the closure, including the number and type of sutures, the suture material and the placement of sutures and their corresponding knots. The suture tension should also be adjustable according to the individual surgical requirements. The sclera and/or limbal marker and method of using it in intraocular surgery according to the present invention are effective in refining the intraocular surgical techniques required in procedures such as cataract removal and intraocular lens implantation. The use herein of the terms "sclera and/or limbus" and "sclera and/or limbal area" with respect to procedures involving the use of the present invention relate to the personal preferences of surgeons as to the location of making incisions for this type of surgery as opposed to corneal surgery. Thus, in some procedures, a surgeon may wish to mark the sclera and in others, the limbus or limbal area which defines the boundary region between the cornea and the sclera.
Final astigmatism correction, at the time of closure, may be monitored by any one of a number of available hand-held or microscope-mounted surgical keratometers, or may merely be estimated by the surgeon.
Various types of instruments have been used to aid in standardizing incisions in the cornea during radial and non-radial keratotomy ophthalmosurgery for the control of astigmatism. However, prior to the present invention, no one has devised a sclera and/or limbal marker and method of using it for other types of ophthalmosurgery. One device comprises a case in the form of a bush having a central opening to accommodate a sight centering means, and a series of plates at right angles to the sight centering means. The plates are adapted to be brought into contact with the cornea to be marked out. The plates are provided with sharpened curvilinear edges corresponding to the curvature of the cornea. In use, the plates of the device are pressed into the eye to cause temporary elastic deformation or indentations of the cornea to mark areas for incising the cornea.
A similar marking device has the same basic structure as the prior art device described above, except that each plate is mounted on a separate holder for adjustable movement radially with respect to the bush. The sharp bladed tips of the plates cause corneal indentations when pressed against the eye. The eye may be prestained with brilliant green dye prior to pressing the plates of the blades onto the eye.
These devices, however, mark the cornea of a patient's eye and are used in radial keratotomy or corneal transplants. Their purpose is to make radial marks for radial incisions on the cornea in order to help reduce myopia. Non-radial incisions or combinations of non-radial and radial incisions on the cornea are used to reduce post-operative astigmatism and/or myopia associated with corneal surgery.
Other devices are known for use as blanks or templates against a patient's skin to define the proper incision pattern to promote proper handling with a hairline scar. One of these devices is a skin biopsy device which includes a plurality of short members extending outwardly from the template sides. The members act as markers to indicate the location of sutures when the device is pressed against the skin to make the skin red or discolored in the area of the marker members.
A problem encountered in using ophthalmosurgical or skin marking devices of the prior art is that they are not adapted for use in cataract surgery to mark the sclera and/or limbus of an eye to indicate the location of sutures instead of or in addition to incisions. Furthermore, due to their sharp edges, the ophthalmosurgical marker devices are designed to mark the cornea of an eye, prior to corneal surgery, by indenting the corneal surface. Cataract surgery on the other hand, requires the marking of the sclera and/or limbal area. The incision used in cataract and/or intraocular lens surgery is made perpendicular to the marking lines of the present invention and not parallel to the marking lines as described in the prior art. The marking lines are also used for suture placement after the incision is made. The skin marking devices are also not adapted for use in any way in cataract surgery.
Some surgeons presently use ink to mark the sclera prior to making the incision. They use ink-dipped dividers preset to the desired dimensions. Depending on the desired dimensions, this may require the use of more than one set of dividers, the dividers have to be carefully aligned in each instance, and, because of the extra care and manipulation required, the procedure is rather time consuming.
The present invention provides an incision and/or suture marking device having a plurality of precisely oriented, outwardly extending projections coated with a waterproof ink, such as gentian violet, which when pressed gently onto a patient's eye places ink markings on the sclera and/or limbal areas after the conjunctiva is "reflected" (cut and folded back, usually distally, to form a "fornix based flap"), indicating the length and location where incisions and sutures are to be placed during surgery. The inked projections make ink marks which will define the proper length bites for a suture needle on either side of an incision line during suture placement. By indicating the placement of sutures on the sclera and/or limbus, rather than merely the location of incisions on the cornea as in the ophthalmosurgical devices of the prior art, surgeon induced astigmatism often resulting from tangential displacement of tissue at the incision line caused by uneven or improper suture placement after cataract removal can be controlled or eliminated. Furthermore, where pre-existing astigmatism exists, the skilled cataract surgeon can reduce or even eliminate it by judicious placement of the cataract incision, and/or varying the suture tension.
The marking device, when pressed onto the sclera and/or limbus of any eye prior to surgery, among other things: defines the length and location of incisions and suture placement by making predetermined patterns of ink marks on the scleral and/or limbal areas of the eye; provides for proper, and preferably equal, spacing between sutures; defines uniform suture bites, for example 1 mm or other desired dimensions, on each side of the incision; and allows the surgeon to accurately reappose the proximal and distal sides of the incision without lateral displacement along the incision line. These in turn prevent misalignment of wound surfaces during suture placement, thus reducing or eliminating the possibility of post-operative astigmatism.