A standard full thickness transplant involves the surgical removal of the central two-thirds of the damaged cornea as seen in the photo to the right. This area is replaced with clear, healthy donor tissue, which is held in place by many sutures.
The first successful human corneal transplant was performed in 1905 in the present day Czech Republic. Since then cornea transplants have become the most common and most successful form of solid tissue transplant.
In penetrating keratoplasty surgery, there is some variation to the techniques. Broadly, a trephine (a special surgical circular blade) is used to cut out a circular portion of the patient’s central cornea. A donor cornea of the same size is cut into a circle of the same dimensions, and is carefully aligned with the patient’s cornea. The donor cornea is then secured in place with sutures. There are some variations in technique, in how the sutures are placed attaching the donor cornea to the patient’s eye. In general, the sutures must ensure a secure, and stable fit of the donor cornea and the patient’s eye. Placing the sutures in a corneal transplant is a very delicate, skill-dependent task. Ideally, the sutures have equal tension along the graft, evenly distributing the tension attaching the donor cornea to the host. Unequal tension amongst the sutures will result in astigmatism, and irregular astigmatism cannot be corrected with glasses or soft contact lenses. The two main techniques involve either an interrupted suture technique, or a running suture technique.
