Four methods of measuring human corneal endothelial cells from specular photomicrographs.

We measured central corneal endothelial cell density and area from contact specular photomicrographs of ten normal and ten abnormal corneas, comparing the precision, cost, and speed of four methods: a rectangle, planimeter, digitizer, and cell sizer. The rectangle, planimeter, and digitizer gave results that differed less than 10% from each other; therefore, the three methods can be used interchangeably for clinical purposes. There are statistically significant differences among the three techniques that may be important in basic research. The cell sizer gave a rapid, less precise estimate of mean cell area and cell density. The planimeter and digitizer measured individual endothelial cell size, and the latter entered data directly into a computer that printed both a copy of the endothelial mosaic and a histogram of cell size frequency, and computed cell density and mean cell area. We make the following recommendations: Count cells in a rectangle used for routine clinical measurement. use a cell sizer for rough estimation, as in an eyebank setting. Use a computerized digitizer to study individual endothelial cell size.