Comparison of corneal endothelial cell images from a noncontact specular microscope and a scanning confocal microscope.
OBJECTIVE
We compared endothelial cell density (ECD) from images recorded by the ConfoScan 3 confocal microscope and a noncontact specular microscope.


METHODS
Endothelial micrographs of 50 normal corneas of 25 subjects were acquired by a Konan Noncon Robo noncontact specular microscope (Konan Medical, Inc., Hyogo, Japan) and a ConfoScan 3 confocal microscope (Nidek Technologies, Inc, Greensboro, NC). ECD was determined in images from both instruments by using the HAI CAS System Corners Method (HAI Labs, Inc., Lexington, MA). Distances in the images from both machines were calibrated from images of an external scale. Images from the ConfoScan 3 were also assessed using the automated endothelial analysis software provided by the manufacturer, with and without manual correction.


RESULTS
The ECD was 2634 +/- 186 cells/mm(2) (mean +/- SD) and 2664 +/- 173 cells/mm(2) by the Robo and ConfoScan 3 Corners methods, respectively. Differences between these 2 methods were not significant. When the automated analysis software was used, however, significant differences were found (P = 0.001). The uncorrected analysis program provided with the ConfoScan 3 indicated a higher ECD (2742 +/- 284 cells/mm(3)) than the Corners method did with images from the Robo and ConfoScan 3. The ECD from the manually corrected ConfoScan 3 method was 2716 +/- 229 cells/mm(3), not significantly different from the ConfoScan 3 Corners method but significantly different from the Robo Corners method.


CONCLUSIONS
The ConfoScan 3 can be used interchangeably with the Robo when the Corners method is used to assess ECD and the magnification of both microscopes is calibrated with an external scale. If the proprietary software provided with the ConfoScan 3 is used, it should be manually corrected.
Kitzmann
Anna S
AS
Department of Ophthalmology, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
Winter
Eric J
EJ
Nau
Cherie B
CB
McLaren
Jay W
JW
Hodge
David O
DO
Bourne
William M
WM
D000328:Adult; D002452:Cell Count; D004728:Endothelium, Corneal / Q000648:ultrastructure*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D012016:Reference Values