Repeatability and reproducibility of corneal endothelial measurements using the topcon SP-1P specular microscope

PURPOSE: To evaluate the repeatability and reproducibility of corneal endothelial parameters measured with the Topcon SP-1P specular microscope in healthy eyes, comparing single and panoramic acquisition modes. METHODS: This reproducibility study included 137 eyes from 79 healthy adults. Endothelial cell density (ECD), average cell area, coefficient of variation (CV), hexagonality, and pachymetry were measured twice by two independent examiners using both single and panoramic modes. Statistical agreement was assessed using intraclass correlation coefficients (ICC), repeatability coefficients (RC), and Bland-Altman analysis. RESULTS: Intra-observer reproducibility for ECD, average cell area, and pachymetry was excellent in both modes (ICC ≥ 0.95). However, the panoramic mode consistently showed improved precision, with higher ICCs and lower RCs for most morphometric variables. Inter-observer agreement was also excellent for ECD (ICC 0.94) and average cell area (ICC 0.95). Significant systematic differences were found between acquisition modalities; specifically, ECD was on average 7.27% lower in single mode compared to panoramic mode (p < 0.001). CONCLUSION: The Topcon SP-1P demonstrates high reproducibility for primary endothelial parameters, particularly when using the panoramic acquisition mode. Since systematic differences exist between modalities, single and panoramic measurements are not directly interchangeable, highlighting the importance of standardizing techniques for longitudinal clinical monitoring.