A Nomogram for Producing Consistently Thin Posterior Lamellar Microkeratome Cuts for DSAEK

Authors

Luke Lennox, MD, James Reidy, MD

Keywords

Endothelium, Cornea; Eye Banks; Keratoplasty, Lamellar; Nomogram

Abstract

Title: A nomogram for producing consistently thin posterior lamellar microkeratome cuts for DSAEK.

Objectives: Recent literature has shown that a post-cut thickness of <132um produces better visual results after DSAEK. Our goal is to determine what variables influence post-cut thickness and to subsequently improve the settings and nomogram used.

Method: 717 donor corneas were prepared between 2010 and 2012. Controlled variables included: precut corneal thickness, microkeratome head size (250, 300, or 350um), IOP during cut (90mmHg), presence or absence of epithelium, and speed of the cut (3-6 sec). Starting in Jan 2014, average cut duration was increased to 20-30 seconds and post-cut thickness was determined.

Results: The median post-cut thickness of the posterior lamellar cornea using the original nomogram was 139um: 60% measured between 100-150um and 95% measured between 100-175um. Upon adjusting the nomogram and increasing cut duration, median post-cut thickness for 91 cuts was 117um: 84% measured between 100-150um and 98% measured between 100-175um.

Conclusion: With much slower cut speeds and a minor change in the nomogram, we reduced our overall median post-cut thickness by 15.8%. In doing so, 73% of our PostCTs were <132um. This is in stark contrast to the 35% achieved previously. We hope that this change will help other eye banks, as it is a simple, cost-free modification that has improved our results.

References