Experimental 193-nm excimer laser trephination with divergent cut angles in penetrating keratoplasty

Berthold Seitz, Ashley Behrens, Achim Langenbucher, Murat M. Kus, Gottfried O.H. Naumann

Research output: Contribution to journalArticlepeer-review


Purpose. To study the morphologic properties of divergent cut angles after nonmechanical trephination for penetrating keratoplasty in donors and recipients and to assess its implications for donor-recipient stability in an experimental porcine model. Methods. An excimer laser 193-nm corneal trephination was performed in 30 enucleated porcine eyes by using a modified 'open mask' (stainless steel sheet 10CrNi18), to obtain round donor buttons and corresponding recipient beds 7 mm in diameter at the level of Bowman's layer. An automated globe-rotation device allowed different cut angles toward the optical axis. Three cut angles were intended: 0°, 15°divergent, and 35°divergent. Quality of the cuts was assessed by means of histology and scanning electron microscopy (SEM). In a different setting, after alignment of the donor button and corresponding recipient bed in an artificial anterior chamber, intracameral pressure was increased stepwise, modifying the height of a bottle of balanced saline solution connected to the chamber. Criterion for 'instability' was the movement of the donor button in all four quadrants during observation with a surgical microscope (x12). Results. Reproducible cut angles and smooth cut surfaces of donors and recipients were confirmed by histologic and SEM evaluation. Macroscopically, a good alignment of a divergent donor button in a corresponding recipient bed was achieved. Instability of the donor buttons occurred with a water column niveau at 2 cm in the 0°cut, at 3 cm in 15°divergent cuts, and at 4.5 cm in 35°divergent cuts. Conclusion. The stability of a corneal donor button in a recipient bed seems to increase in proportion with the degree of divergence of the trephination angle. Considering the good histologic quality and macroscopic alignment obtained, divergent cut angles may allow a reduction of sutures, assuring a watertight wound closure in penetrating keratoplasty.

Original languageEnglish (US)
Pages (from-to)410-416
Number of pages7
Issue number4
StatePublished - 1998
Externally publishedYes


  • Divergent cut angle
  • Donor
  • Excimer laser
  • Morphological properties
  • Nonmechanical trephination
  • Penetrating keratoplasty
  • Recipient stability
  • Suture technique

ASJC Scopus subject areas

  • Ophthalmology


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