surgery and the second after 23 months. The analysis tool built into the Topcon SP-3000P SM reported the ECD as 2282 cells per square millimeter after 12 months and 1800 cells per square millimeter after 23 months. However, no single cell changed position, shape, or size in the overlapping area (colorcoded stripe-wise comparator image not shown). We conclude that the ECD loss of 482 cells per square millimeter is an artifact as a result of sampling errors.Cell-by-cell comparisons may help in tackling the problem of insufficient sampling sizes when assessing endothelial stability. Our novel method uses all morphological information from the SM images rather than limiting analysis to the cell dotting, as is the case in ECD counting. We therefore suggest comparison of subsequent SM images cell by cell in clinical trials instead of focusing on ECD alone. For this reason, we have developed an image registration program for SM images (manuscript in preparation). FIGURE 2. Superimposition (average) of 2 SM images after homologous limbokeratoplasty. The first image was recorded 12 months and the second one 23 months after surgery.