"Top hat"-shaped penetrating keratoplasty using the femtosecond laser.

Purpose: To determine the feasibility of using a modified femtosecond laser to perform penetrating corneal resections.

Design: Controlled laboratory study.

Methods: Fourteen corneoscleral rims were mounted on an artificial anterior chamber. Eight underwent traditional penetrating keratoplasty (PKP) and six underwent "top hat"-shaped PKP using a femtosecond laser. Wound leakage pressure and induced astigmatism were compared between the two groups.

Results: Deep corneal resection with the femtosecond laser was feasible. Wound leakage occurred at 38 +/- 11 mm Hg in the traditional PKP eyes and at 240 +/- 69 mm Hg in the laser-shaped PKP groups. Initial induced astigmatism was 3.76 +/- 0.82 diopters and 3.46 +/- 1.36 diopters in the traditional and shaped PKP groups, respectively.

Conclusions: Shaped PKP using the femtosecond laser is feasible and provides superior incision integrity compared to traditional PKP. Initial induced astigmatism is dominated by suture effects.