Exploring endothelial cell loss caused by orientation stamps on pre-loaded Descemet membrane endothelial keratoplasty (DMEK) grafts

Abstract

Purpose : To quantify endothelial cell loss (ECL) caused by orientation stamps on pre-stripped and pre-loaded DMEK grafts, and to examine a method for reducing ECL by using a smaller stamp.

Methods : Ten pre-stripped and ten pre-loaded DMEK grafts were prepared with S-stamps. Five additional pre-loaded DMEK grafts were prepared with both a S-stamp and a smaller F-stamp in different paracentral areas of the graft. All DMEK grafts were stored in viewing chambers filled with 20 mL of Optisol-GS for three days at 4°C. ECL was quantified using Calcein-AM staining and FIJI Weka Segmentation. ECL of the entire DMEK grafts and ECL in the 2 mm circular areas surrounding the orientation stamps were quantified and compared.

Results : S-stamps on pre-stripped DMEK grafts contributed an average ECL of 1.1±0.5% (range: 0.6-2.2%) towards total graft damage. In contrast, S-stamps on pre-loaded DMEK grafts contributed approximately twice the amount of cell loss compared to pre-stripped grafts (average: 2.0±0.7%, range: 1.3-3.1%, P=0.004). Overall ECL for pre-stripped grafts (average: 7.1±3.3%, range: 3.3-13.7%) and pre-loaded grafts (average: 11.3±4.2, range: 6.9-19.4%) were similar to previous reports. In the five additional grafts marked with both a S-stamp and a smaller F-stamp, the S-stamp caused an average ECL of 2.1±0.7% (1.4-3.2%) while the smaller F-stamp caused an average ECL of 1.1±0.2% (range: 0.9-1.3%, P=0.015).

Conclusions : While orientation stamps can aide in assessing proper graft placement, these stamps cause localized areas of endothelial cell loss in DMEK grafts. Loss of endothelial cells associated with graft stamping was greater in pre-loaded tissue than in pre-stripped tissue, and was less with a smaller F-stamp as compared to a larger S-stamp. Using a smaller stamp could aide in minimizing endothelial cell loss of pre-loaded DMEK grafts.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

 

Top: Corneoscleral cap with S and F stamps on DMEK graft. Middle: Photographs of stamped graft areas stained with Calcein-AM. Bottom: FIJI Weka segmentation of stamped graft areas for visualization and analysis of endothelial cell loss.