Morphometric analysis of the corneal endothelium with three different specular microscopes

The morphometry of the central corneal endothelium of 10 eyes in 10 subjects was analyzed with three different specular microscopes. Computer-assisted analysis was performed with only two microscopes (Zeiss and Keeler Konan sp 3300) because the third microscope (Topcon sp 1000) could not be adapted to our computerized system. With this Topcon microscope a grid with standard densities was used to compare the images with, in addition, we also performed manual cell counting on the same Topcon images. The coefficient of variation of the cell analysis of three different images per cornea with the four methods varied between 3.4 and 4.7 percent. One-way analysis of variance showed a significant difference between the Zeiss and the other microscopes. So only the Keeler Konan and the Topcon microscopes could be used interchangeably. The computerized image analysis permitted also an evaluation of the hexagonality. The results of polygonality were not significantly different between the Zeiss and the Keeler Konan. For clinical purposes the Topcon specular microscope is more advantageous than the other two methods, since it is the most rapid way to record and analyze specular images. But for more precise measurements an image processing system is indispensable.