Morphometric analysis of the corneal endothelium with three different specular microscopes

Abstract

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.

Coupling of HRT II and AS-OCT to evaluate corneal endothelial cell loss and in vivo visualization of the Ahmed glaucoma valve implant

“…Moreover, when comparing studies that performed ECD measurement with specular microscopy between them, significantly different ECD values may occur. [30][31][32] However, we report and compare our results with other studies using specular microscopy in terms of percentage change, measured in each case with the same method, and therefore allowing for valid comparisons.…”

Validity of Endothelial Cell Analysis Methods and Recommendations for Calibration in Topcon SP-2000P Specular Microscopy

“…Most other studies on endothelial assessment methods report a slight systematic difference in ECD when compared with either manual counts or other analysis methods. [1][2][3][12][13][14] In conclusion, when comparing corrected IMAGEnet ECDs to the manual ECDs or ECDs obtained with other assessment methods, a correction factor has to be taken into account. However, the corrected IMAGEnet ECD has a high validity when very accurate ECD measurements are needed, eg, as in follow-up studies.…”

Further analysis of assessments of the coefficient of variation of corneal endothelial cell areas from specular microscopic images

“…Such an assessment can be made by comparing the image to a set of reference grids or by actually counting the number of cells included within a specified region of interest (ROI), that is, a manual count of endothelial cell density. With the introduction of newer instruments over the past decade or so, there have been numerous comparisons made to determine the accuracy and/or reliability (repeatability) of various image analysis software systems that could replace a manual counting of the endothelial cells to provide an estimates of the ECD for a patient at a particular assessment 4–30 . Overall, most systems seem to provide reasonable estimates of ECD both when inter‐instrument and/or inter‐operator differences are taken into account.…”

“…There have been many assessments of the reliability of endothelial cell analysis systems to provide estimates of the endothelial cell density (ECD) 4–30 . While some of these reports provide data on the reliability of COV assessments, 11–14,16–18,23,25,26,29,30 these are reported in rather different ways such that comparisons are very difficult.…”