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K Negahban, J Ruberti, G Qiu, H Gong; Regional Variation Of Corneal Endothelial Cell Density, Implications For Sampling In Eye Bank Eyes . Invest. Ophthalmol. Vis. Sci. 2002;43(13):3175.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Corneal endothelial cells play a critical role in maintenance of corneal transparency after transplantation. Typically, surgeons require a minimum endothelial cell density (ECD) of 2000 cells/mm2. The sample size of central endothelial cells counted to determine (ECD) is typically 30, 50 or 100. This study seeks to determine if this sample size (30 to 100 cells) is adequate to compensate for regional differences of corneal endothelial cell population. Methods: Human eye bank eyes were used. The corneal endothelial cell images were photographed using a specular microscope (HAI system). Sample sizes of 30, 50 and 100 cells were counted in three regions (center, left and right) of the central corneas. Counts of 200 cells were also taken in two different areas of the central corneal image. Statistical analyses were conducted to determine how sample size affected the variance about the mean. For each eye, the average cell density and standard deviations for each sampling size were determined. A paired Student's t-test was used to determine whether or not the standard deviations were significant for each sampling method. Results: Regional variation of corneal endothelial cell density was found to affect the smaller size sample counts significantly. Average standard deviation (ASD) of the 200 cell sample was ± 28.8; ASD of the 100 cell sample was ± 70.8; ASD of the 50 cell samples was ± 241.3; ASD of the 30 cells was ± 272.6. No significant statistical difference was found between 30 and 50 cell counts (p≷0.05). Significant statistical difference was found between 50 and 100 cell counts (p<0.05). No significant statistical difference was found between 100 and 200 cell counts (p≷0.05). Conclusion: Our data suggest that there is significant regional variation of corneal endothelial cell density even within the central cornea, and this variation is capable of significantly affecting the accuracy of 30 and 50 cell sampling techniques. A sample size of 100 cells is statistically superior to 50 and 30 cells, and sampling 200 cells is not statistically better than sampling 100 cells. We recommend using at least a 100 cell sample to determine ECD in eye bank corneas that are candidates for transplantation.
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