Guided Trephine System and Laser Trephination, Comparison of Technical Settings and Clinical Outcomes
Schöner P., Krumeich J. H., Knülle A., Theilen H.
Klinik Krumeich, Bochum
Purpose: Comparison of physical, clinical and economical parameter between Excimer Laser and mechanically cut perforating keratoplasties with the Guided Trephine. Intended to show advantages and disadvantages of the respective method.
Method: Dimensions of donor button and recipients opening, angle of undercut are examined with the shadow comparison method. Completeness of trephination, time and costs of instrumentation are compared. Visual recovery, astigmatism before and after suture removal with either method is evaluated on 50 consecutive keratoconus cases.
Results: Angle of undercut with the GTS is dependent on the obturator radius and equal on both donor and recipient. Laser undercut is dependent on the pre-existing corneal radii and may be different at the anterior chamber and recipient site. Trephination is perforating 360° with the GTS, about 15° with the laser. Completion of this cut is performed with Vannas scissors. Time for donor and recipient trephination is 8 min with the GTS, about 20 min with the laser. Costs of instrumentation is about 1:10. Visual recovery for the means of both procedures is after 1 month 20/50, 3 months 20/35, 6 months 20/25. Astigmatism is both after 3 months and 6 months 2,7 D for the GTS measured by K-readings and subjectively, about 3 D for the laser means. After suture removal 1 year postoperatively neither method shows significant increase of
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