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
can be used.
The Hanna Trephine System
is designed to remove a circular
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
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
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.
After the suture is removed, however, astigmatism may return
because the stabilizing tension of the running suture has been released. Other
here, can then be utilized to return the cornea to a more spherical
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. The Informed Consent for Corneal
Transplant can be found