Comparison of the Measurement of Corneal Endothelial Cell Density (ECD) by Two Different Non-Contact Specular Microscopes

Abstract

Purpose:: The purpose of the study was to evaluate differences between endothelial cell counts by means of the semi-automatic SP-2000P Specular Microscope (SM) (Topcon/Japan) and the novel video-based Sea Eagle System (SES) (Rhine-Tec/Germany). Determination of endothelial cell density is crucial for diagnosis in corneal disorders, especially before and after corneal surgery (e.g. keratoplasty).

Methods:: Measurements were performed on 100 corneas of 50 patients with corneal diseases. An image was acquired with both devices and the number of cells was subsequently calculated. The SM performs a semi-automatic cell count measurement, whereas the SES cell detection runs automatically. Measurement data was compared and statistically evaluated.

Results:: Mean age of patients was 59.8 years (SD 11.2). Mean cell count for the right eyes was 2192.9 cells/mm² (SD 576.5) for SM and 2163.3 cells/mm² (SD 534.0) for SES respectively. Left eyes` cell count was 2340.6 cells/mm² (SD 519.6) for SM and 2316.6 cells/mm² (SD 474.5) for SES respectively. No statistically significant difference was found between both devices (p=0.32 and p=0.3). Pearson's correlation coefficient was 0.843 for the right eyes and 0.901 for the left eyes, respectively.

Conclusions:: Both specular microscopic devices for endothelial cell count are comparable for clinical use in terms of precision. However, with the SES direct on-screen comparison with previous measurements is possible and therefore more applicable for routine follow-up.

Keywords: cornea: endothelium • imaging/image analysis: clinical • microscopy: light/fluorescence/immunohistochemistry