Meticulous attention to detail is required for successful corneal transplant surgery. This starts with defining the geometric center of the cornea. Using instrumentation similar to that shown below, it is possible to accurately mark the center of the cornea.  Once this is accomplished, the Hanna Trephine System can be used.

The Hanna Trephine System is designed to remove a circular disc of diseased cornea, with a specified diameter, from the patient. The diameter is determined by the size of the patient's cornea.

 

 

Trephining the patient's cornea is facilitated with the use of a continuous, automated suctioning unit which aids in generating a uniform circular incision.

 

In addition, the suction unit is used to trephine the donor tissue as well.

Both components of the Hanna Trephine System (patient and donor trephination) use a special, finely finished circular blade.
 

The sighting mechanism for trephining the patient's cornea allows a "bulls-eye" of the center marking on the cornea.


 

After the donor has been transferred to the patient and secured with a continuous running 10-0 monofilament nylon suture, a critical adjustment of this suture is undertaken.  Without consideration of suture tension and the control of astigmatism, the patient may achieve a clear graft but no functional vision.  A qualitative keratometer which projects either a ring of light or a ring of dots is utilized to assist in achieving a spherical cornea.

If the ring of light, when projected on the cornea, is spherical, the corneal transplant is spherical. However, if the projection of the ring of light is oval, the suture must be adjusted until the projected light is spherical. Although every effort is made to achieve sphericality at the time of surgery, differential healing of the corneal tissue may induce some astigmatism. However, it is possible to adjust the suture in the office using the same equipment. The suture may be adjusted several times if necessary to achieve excellent functional acuity.

However, after the suture is removed, astigmatism may return because the stabilizing tension of the running suture has been released. Another technology can then be utilized to return the cornea to a more spherical surface.

Dr. Rubman has his own Hanna Trepine System and was the first surgeon in the NYC Metro area to use this system. He also owns the qualitative keratometers which he brings to the operating room when performing corneal transplant surgery.