Agreement between two non-contact specular microscopes: Topcon SP2000P versus Rhine-Tec

Endothelial cell density (ECD) assessment with the noncontact Topcon SP2000P specular microscope is known to be reliable when the automated mode is followed by manual corrections (touched-up mode). We compared its agreement with Rhine-Tec, a new noncontact specular microscope, in 270 eyes of 160 patients, by comparing the ECD measured in the automated and touched-up modes with that of Topcon touched-up. Good agreement existed between either touched-up modes with a mean difference of only 2 cells/mm2 95% CI (−27; 23) whereas agreement with the Rhine-Tec automated mode was poor with an overestimation by a mean of 226 cells/mm2 95% CI (172; 281). Background The Topcon SP2000P non-contact specular microscope (Topcon, Tokyo, Japan) is widely used to measure corneal endothelial cell density (ECD). It uses a cell contour recognition algorithm based on contrast differences, and ECD derived from an automated delineation of cell boundaries with manual correction of inaccurately drawn cells (“touched-up” mode) has been validated.1,2 A new commercially available non-contact specular microscope Rhine-Tec (Rhine-Tec, Krefeld, Germany) determines ECD by a cell-centre method ...