Purpose: The methods for specular microscopy evaluation across eye banks differ, which may result in variability in endothelial cell density (ECD) values that influence the surgeon's decision about donor tissue. A comparison of instruments and analysis methods is conducted in this study.
Methods: Specular images were captured from 97 donor corneas using both HAI and Konan specular microscopes. A single best quality image of each cornea from each instrument was graded using the respective inherent software and analysis method (HAI: variable frame method; Konan: center method). All raw specular images were standardized for dimensions and regraded in the CellChek system in a blinded fashion. The grading variances and paired t test were performed between instruments in both inherent and standardized analyses. Correlation and Bland-Altman analyses between instruments were also performed.
Results: Using the software inherent within HAI and Konan, the mean ECD readings for the 97 corneas were 2764 ± 583 and 2605 ± 517 cell/mm (P = 0.045), respectively, with a variance of 8.05% (range 0.26%-27.2%). HAI resulted in a higher ECD value in 79 corneas (81.4%). In CellChek software analysis, the mean ECD readings did not differ (2609 ± 514 and 2496 ± 507 cells/mm, respectively, P = 0.127), with a variance of 5.6% (range 0.24%-19.8%).
Conclusions: There is a slight statistically significant mean difference between the ECD values obtained from the 2 specular microscopes, which is negated by standardization to a single analysis method. Eye banks and surgeons should use caution in making decisions based only on very small differences in ECD between otherwise equivalent corneal donor tissues.