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R.F. Steinert, T. Ignacio, M. Sarayba, R. Kurtz; Shaped Penetrating Keratoplasty Using a Femtosecond Laser . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2690.
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Purpose: To demonstrate and compare mechanical stability and induced astigmatism between traditional penetrating keratoplasty (PKP), a top hat shaped keratoplasty performed using a femtosecond laser (FSTHPK), and other incisional configurations Methods: In studies to date, eight corneoscleral rims were mounted on an artificial anterior chamber. Four samples were assigned to the PKP group and underwent traditional blade trephination PKP surgery with 7.0 mm donor/recipient button sizes. Utilizing a modified IntraLase femtosecond laser, the other four corneas underwent FSTHPK by first performing a 9.0 mm cylindrical cut from the anterior chamber into the stroma, stopping at 2/3 corneal depth. The laser then performed a horizontal lamellar dissection at 2/3 corneal depth from the 9.0 mm diameter to a 7.0 mm diameter, followed by a 7.0 mm cylindrical cut from the lamellar plane into the anterior corneal surface. All corneal specimens were then removed and replaced, secured by four cardinal sutures. Wound integrity was evaluated by determining the IOP level at which fluid leakage from the wound occurred. A 12 bite running suture was then placed and the cardinal sutures were removed. Wound leakage was again determined using the same method. Pre–operative and post–operative topographies were compared. Results: After placement of the four cardinal sutures, wound leakage occurred at 19 ± 3.36 mmHg for FSTHPK corneas compared to 0 ± 0 mmHg for PKP corneas (p= 0.01). After placement of the running suture, leakage occurred at 86.25 ± 9.74 mmHg for FSTHPK corneas compared to 76.25 ± 20.98 mmHg for PKP corneas (p= 0.31). Both techniques induced similar steepening of the corneal curvature after the placement of the running suture, indicating similarity of the suture tension in the specimens. The modified wound group showed a mean change in average K of +3.43 ± 3.62 D while the traditional PK group showed a mean change in average K of +3.21 ± 6.67 D (p= 0.89). There was a trend toward less induced astigmatism with the FSTHPK eyes (3.88 ± 1.96 D) as compared to the PKP (9.1 ± 3.20 D) (p= 0.08). Further samples and different incision configurations are under current investigation with this methodology. Conclusions: FSTHPK is initially more stable and induces less astigmatism compared to PKP. This procedure and other configurations under current investigation could provide patients with more stable structural result and perhaps yield more rapid visual rehabilitation with less astigmatism compared to traditional PKP.
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