Do specular images of endothelial cell density post DMEK preparation tell you anything new?

Abstract

Purpose : To compare a single eye bank’s measurement of endothelial cell density (ECD) of Descemet Membrane Endothelial Keratoplasty (DMEK) grafts before and after preparation using two separate counting methods.

Methods : A series of sixty donor tissues were prepared for DMEK surgery. Two to four specular microscoic images of the central endothelium were taken both before and after preparation and ECDs evaluated for a total of 345 unique images. An eye bank technician analyzed each image using a center dot (CD) method and then averaged those values. Images were then masked and provided to the Cornea Image Analysis Reading Center (CIARC) for independent analysis by certified readers using the HAI variable frame (VF) method and a dual grading and adjudication process.

Results : Average ECD was 2678 ± 259 cells/mm² before preparation when measured by CD method. Final ECD was 2599 ± 280 cells/mm² measured by the VF method (p<0.001, n=176). After preparation the ECD was 2719 ± 265 cells/mm² using the CD method and 2615 ± 344 cells/mm² using the VF method (p<0.001, n=169). The difference in ECD before and after DMEK preparation was not found to be statistically significant when evaluated using the CD method (p=0.19). The difference before and after DMEK preparation also was not found to be statistically significant when evaluated using the VF method (p=0.64). After DMEK preparation 80% (48/60) of post-preparation ECD values fell within a range of ± 300 cells/mm² using the CD method and 82%(49/60) fell within this range using the VF method.

Conclusions : Our results show consistent measures of ECD before and after DMEK preparation. We did not find a statistically significant difference between ECD values before and after DMEK preparation when comparing within each method (CD or the VF method). While we did find statistically significant differences when evaluating endothelial images between methods we feel they are not clinically significant. Most eye banks when releasing donor tissue for keratoplasty do not rely on a single image and cell count, but an average of several images and ECDs to account for natural variation in ECD along Descemet membrane. In this study, post-prep image quality was diminished after DMEK preparation compared to the pre-preparation images and may have contributed to the non-significant ECD increase. More accurate results may be observed in future studies with improved image quality.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.