The influence of the cutting procedure on the loss of corneal endothelial cells of the recipient eye in mechanically guided trephination.
BACKGROUND
Excessive damage to the endothelial monolayer during corneal trephination may contribute to transplant failure. For this reason, we performed several trephining experiments to determine the influence of various cutting conditions (sharpness, rotation rate, and cutting power) on the endothelial damage in the recipient bed.


METHODS
A mechanically guided motor trephine (Mikro-Keratron) was used for cutting experiments in fresh, enucleated porcine eyes. Eight different, reproducible combinations of cutting conditions were applied, and ten epithelial, full-thickness trephinations were performed for each combination. The endothelial defect was measured with a light microscope (60 x). In addition, the bend radii of the porcine cornea were measured.


RESULTS
The mechanically guided Mikro-Keratron used with a sharp blade, high rotation rate (840 rev/min), and moderate cutting power (49 mN) caused a 31-micron-wide band of damaged endothelium in the recipient bed. Decrease of the rotation rate to 30 rev/min resulted in an increase of the endothelial defect to 168%. A cutting power of 392 mN combined with a rotation rate of 840 rev/min increased the defect to 126%. The system allowed full-thickness 360 degrees trephination. The corneal bend radii in porcine eyes measured 8.28 mm horizontally and 8.20 mm vertically.


CONCLUSIONS
Our preliminary results indicate that the mechanically guided motor trephine, used under optimal conditions, is a suitable cutting device and may improve the outcome of penetrating keratoplasty; however, further investigation of this new approach is necessary.
Daniel
J
J
Augenklinik, Klinikum Berlin-Buch, Germany.
Huebscher
H J
HJ
D000818:Animals; D002452:Cell Count; D002470:Cell Survival; D004728:Endothelium, Corneal / Q000473:pathology* / Q000601:surgery; D015948:Keratoplasty, Penetrating / Q000295:instrumentation / Q000379:methods*; D013552:Swine