Abstract
Abstract: :
Purpose: The ConfoScan 3 confocal microscope records clear images of the corneal endothelium. Can this instrument be used interchangeably with specular microscopes to assess morphology of the endothelium? In this study we compared morphologic variables of corneal endothelial cells from images recorded by the ConfoScan 3 confocal microscope and a noncontact specular microscope. Methods:Endothelium from 50 normal corneas of 25 subjects were recorded by using a ConfoScan 3 confocal microscope (Nidek Technologies, Inc., Greensboro, NC) and a Konan Noncon Robo noncontact specular microscope (Konan Medical, Inc., Hyogo, Japan). Distances were calibrated from images of a standard scale. Endothelial cell density (ECD), coefficient of variation of cell area (CV), and percentage of hexagonal cells (HEX) were determined in images from both instruments by using the HAI CAS System Corners Method (HAI Labs, Inc., Lexington, MA). Images from the ConfoScan 3 were also assessed by using the automated endothelial analysis software provided by the manufacturer, with and without manual correction. Differences between methods were examined by using repeated measures analysis of variance and the Student–Newman–Keuls procedure. Results:The ECD was 2634 ± 186 cells/mm2 (mean ± SD), 2660 ± 173 cells/mm2, and 2713 ± 229 cells/mm2 by the Robo and ConfoScan 3 Corners methods, and manually–corrected ConfoScan 3 software respectively. Differences between the Robo and corrected Confoscan 3 were significant (p=0.001); other differences were not significant. The CV and HEX were not significantly different between these three methods; CV was 28.0 ± 4.9%, 29.0 ± 4.5%, and 29.4 ± 4.5% respectively (p>0.05), and HEX was 61.5 ± 8.5%, 59.7 ± 9.2%, and 59.2 ± 8.0% respectively (p>0.05). The uncorrected analysis program provided with the ConfoScan 3 indicated a higher ECD (2737 ± 285 cells/mm3), than the Robo and ConfoScan 3 Corners methods did (p=0.001), and higher CV (37.6 ± 7.5 %) and lower HEX (52.3 ± 8.9 %) than all other methods (p<0.001). Conclusions:In normal corneas, endothelial images from the ConfoScan 3 confocal microscope can be used interchangeably with the Konan Noncon Robo noncontact specular microscope when the Corners method is used to assess the morphology of the corneal endothelium. The automated assessment program supplied with the ConfoScan 3 must be manually corrected, and when corrected, overestimates ECD by about 3% compared to the Robo Corners method.
Keywords: cornea: clinical science • cornea: endothelium • imaging/image analysis: clinical