Purpose: The aim of this study was to compare 4 noncontact specular microscopes for the assessment of the corneal endothelium in a heterogeneous sample of eyes.
Methods: This prospective study included 22 healthy eyes, 16 eyes with cornea guttata and 31 eyes that had undergone penetrating keratoplasty or Descemet stripping automated endothelial keratoplasty. Corneal endothelial cell parameters of all eyes were assessed with the CellChek XL (Konan Medical, Hyogo, Japan), Perseus (Bon Optic, Lübeck, Germany), EM-3000 (Tomey, Nagoya, Japan), and CEM-530 (Nidek Co, Ltd, Gamagori, Japan) in a randomized order. Bland-Altman plots of interdevice agreement were produced. The time taken for data entry, scanning, and automated image analysis was recorded, and instrument repeatability was analyzed.
Results: The mean age was 61 ± 19 years (range, 24-88). The measurement success rate was 100% in healthy corneas, ranged between 64.5% and 93.5% in eyes with corneal grafts, and between 0% and 18.8% in eyes with cornea guttata. Comparative analysis of endothelial cell parameters revealed significant differences in endothelial cell density readings in the total study population and in subgroups (P < 0.01).
Conclusions: The CEM-530 and Perseus were extremely fast, showed highly repeatable measurements, and are recommendable for screening purposes. The CellChek XL device was slower, but extensive postprocessing options and an exportable database make this instrument suitable for compromised corneas and for research purposes. The EM-3000 device ranged between the fast devices and the CellChek XL and comes with reliable automated cell-counting software. However, careful interpretation of results from automated image analysis software is mandatory.