A Comparison of Three Methods for Trephining Donor Corneal Buttons: Endothelial Cell Loss and Microscopic Ultrastructural Evaluation

Abstract

Purpose: To evaluate the ultrastructure of the cut edge and associated endothelial cell loss following donor cornea trephination with a standard punch, vacuum punch, and vacuum trephine and artificial anterior chamber system.

Materials and Methods: This laboratory investigation compared trephinations (8.0 mm) performed on human corneas using either a standard posterior punch (n = 12), vacuum posterior punch (n = 12), or vacuum trephine and artificial anterior chamber system (n = 12). Specular microscopy was performed before and after trephination to determine central endothelial cell density. Light and scanning electron microscopy were performed to evaluate the structure of the trephined edge. Endothelial cell-free distances from the trephinated edges were measured on light microscopy sections.

Results: Central endothelial cell loss (cells/mm²) after trephination was –14.0 ± 49.9 (SD) for the standard posterior punch, –85.6 ± 87.0 for the vacuum posterior punch, –116.0 ± 223.1 for the vacuum trephine and artificial anterior chamber system. Endothelial cell-free distances from the trephined margin were 63 ± 22 μm, 85 ± 13 μm, and 123 ± 48 μm for the three respective methods. The edges of grafts cut with anterior trephination were inward sloping from the epithelial to endothelial surfaces, while both posterior punches created outward sloping edges. Increased fibrillar disruption at edges was seen following anterior trephination.

Conclusion: Different trephination methods produce distinct cut morphologies with the anterior trephination approach, resulting in more irregular margins. The anterior approach was associated with increased variability and greater endothelial cell loss than the studied posterior approaches. The use of corneal scissors may contribute to the morphologic features of the corneal button seen following anterior trephination.

KEYWORDS::

• Cornea
• Endothelial loss
• Penetrating keratoplasty
• Transplant
• Trephination

ACKNOWLEDGMENTS

The authors thank Nick Mamalis, M.D., Marshall W. McEntire, B.S., and Utah Lions Eye Bank for assistance with specimen handling and analysis. This work was supported in part by a grant from Research to Prevent Blindness (RPB, Inc., New York, NY) and an unrestricted educational grant from Allergan Inc. (Irvine, CA). Trephines were donated by Katena Products Inc., Denville, NJ.

Declaration of interest: The authors have no financial or proprietary interest in any material or method mentioned in the manuscript. This project was supported in part by an unrestricted educational grant from Allegran Inc., Irvine, CA., to the Department of Opthalmology and Visual Sciences at the University of Utah, John A. Moran Eye Center, Salt Lake City, UT. The authors report no conflict of interest. The authors alone are responsible for the content and writing of the paper.