Trephination Case Study

PROCEDURE
Trephination and excision of donor tissue should always precede that of host cornea. Donor tissue is prepared by trephining a previously excised corneoscleral button. This button is usually trephined to be about 0.25 mm larger in diameter than the planned diameter of the host opening to facilitate watertight closure, minimize postoperative flattening and reduce the possibility of postoperative glaucoma. Mechanical trephination is the standard method although newer non-mechanical laser techniques are more accurate and are preferred by some surgeons when available (Gaster et al., 2012).
After donor tissue preparation is done, excision of the diseased host tissue is performed taking care not to damage other ocular structures like the iris and the lens. Different methods for recipient trephination are available. It can be done simply by freehand or with suction trephine systems such as the Hessburg-Barron system. These suction trephine systems stabilize the globe and ensure that the angle of trephination is perpendicular to the surface. Motorized and laser systems are also available. Then fixation of the donor tissue to the recipient bed is done using 10-0 monofilament nylon sutures (Bahar et al., 2009).
The depth of the sutures must typically involve about 90% of the corneal tissue

Currently, DSEK is the most popular form of endothelial keratoplasty among corneal surgeons because the procedure is relatively easy to learn and replicate and has good outcomes (Lee et al., 2009). A compromise between the two procedures is the ultra-thin DSAEK which involves creation of thinner donor lenticule by the microkeratome in order to improve the visual outcome (Taravella et al.,