Top Hat Wound Configuration for Penetrating Keratoplasty Using the Femtosecond Laser

Abstract

To evaluate the mechanical stability and induced astigmatism of a modified multiplanar "top hat" wound configuration for full-thickness penetrating keratoplasty (PK) using the femtosecond laser as compared with PK in a laboratory model. Eight human corneoscleral rims were mounted on an artificial anterior chamber. Four samples were assigned to the traditional PK group. Four samples underwent full-thickness keratoplasty with the femtosecond laser: a 9.0-mm cylindrical cut was made from the anterior chamber into the stroma, followed by a ring-shaped (outer diameter 9.0 mm, inner diameter 7.0 mm) horizontal lamellar resection at two-thirds corneal depth and a 7.0-mm cylindrical cut from the lamellae to the corneal surface. Mechanical stability was evaluated after placement of the cardinal sutures and the running sutures. In the "top hat" PK group, wound leakage occurred at 19 +/- 3.36 mm Hg after placement of the cardinal sutures and at 86.25 +/- 9.74 mm Hg after placement of the running sutures. In the traditional PK group, leakage occurred at 0 +/- 0 mm Hg and 76.25 +/- 20.98 mm Hg after placement of the cardinal sutures and running sutures, respectively. Both techniques induced steepening of the corneal curvature postop. The modified wound group showed a mean change in average K of 3.43 +/- 3.62 D, whereas the traditional PK group showed a mean change in average K of 3.21 +/- 6.67 D. The femtosecond laser-produced "top hat" wound configuration for PK was found to be more mechanically stable than that produced by the traditional method.