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Enzyme-Assisted Deep Anterior Lamellar KeratoplastyA New Method of Lamellar DissectionA Wetlab-Based Pilot Study

Lange, Alex P. MD, FEBO*; Moloney, Gregory MBBS, FRANZCO*; Arino, Mayte MD*; Ng, Anthony MD; McCarthy, J. Martin MD, FRCSC*; White, Valerie A. MD, MHSc, FRCPC†,*; Holland, Simon P. MD, FRCSC*

Cornea:
doi: 10.1097/ICO.0b013e31823f8f5d
Techniques
Abstract

Purpose: To explore the safety of a new technique of lamellar dissection, using enzymatic digestion of the corneal stroma and extracellular matrix.

Methods: This was a wetlab-based pilot study of hyaluronidase and trypsin-assisted deep anterior lamellar keratoplasty (DALK) in cadaveric human corneal tissue. Enzyme-assisted DALK was performed on 17 tissues. These underwent histologic analysis using a pneumatic dissection specimen as control. Rates of perforation and Descemet membrane (DM) exposure were recorded by clinical observation and by optical coherence tomography in selected cases. Where possible, pre- and postsurgical endothelial cell counts were obtained via specular microscopy. Two tissues from the same donor were halved, with each half soaked in a different solution (Optisol, balanced salt solution, hyaluronidase, and trypsin) for 13.5 hours to observe maximal effect.

Results: Successful exposure of DM was achieved in 8 specimens. In the remaining 9, manual dissection was possible to a residual depth of 25 to 90 μm where measured with optical coherence tomography. Three tissues had perforation of DM, all via manual maneuvers. No deleterious effects on residual host tissue were observed by light microscopy with no significant rates of endothelial cell loss in 8 tissues in which a predissection cell count was obtainable. The 2 enzymes had differing effects on soaked specimens that were reflected intraoperatively.

Conclusion: Preliminary results of this ex vivo study are encouraging that enzymolysis may represent an effective innovation in DALK surgery with an acceptable safety profile. Further studies are required to refine the technique and application of the enzymes in vivo.

Author Information

*Eye Care Center, Cornea Unit, Departments of Ophthalmology

Pathology & Laboratory Medicine, University of British Columbia, Vancouver, Canada.

Reprints: Alex P. Lange, Eye Care Center Section G, Cornea Unit, Department of Ophthalmology, University of British Columbia, 2555 Willow St, Vancouver, BC V5Z 3N9, Canada (e-mail: alex@lange.ch).

The authors state that they have no conflicts of interests to disclose.

The authors state that they have no proprietary interest in the products named in this article.

A. P. Lange and G. Moloney contributed equally to this work.

Received July 18, 2011

Accepted October 14, 2011

© 2013 Lippincott Williams & Wilkins, Inc.