June 2013
Volume 54, Issue 15
Free
ARVO Annual Meeting Abstract  |   June 2013
Effect of Specular Focal Distance on Endothelial Cell Counting Accuracy
Author Affiliations & Notes
  • Jackie Hai
    HAI Laboratories, Inc., Lexington, MA
  • Vivian Xue
    HAI Laboratories, Inc., Lexington, MA
  • Footnotes
    Commercial Relationships Jackie Hai, HAI Laboratories, Inc. (E); Vivian Xue, HAI Laboratories, Inc. (E)
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2013, Vol.54, 559. doi:https://doi.org/
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      Jackie Hai, Vivian Xue; Effect of Specular Focal Distance on Endothelial Cell Counting Accuracy. Invest. Ophthalmol. Vis. Sci. 2013;54(15):559. doi: https://doi.org/.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract
 
Purpose
 

To quantify the relationship between specular focal distance and image distortion, in order to determine a predictive model of cell counting error based on amount of deviance from true endothelial cell shape and size.

 
Methods
 

High resolution specular image of a standard calibration lens was captured in focus to establish baseline pachymetry of 0μm. Subsequent images captured 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm and 100μm from the baseline were analyzed for changes in area caused by optical distortion. Analysis was carried out in a single-blind trial with 10 sample counts performed for each specular image to determine mean areas.

 
Results
 

Given a true area of 10,000μm2 for the baseline distance of 0μm, a negative correlation was found to exist between focal distance (F) and mean area (A). For F=30μm, A=9666μm2; F=40μm, A=9444μm2; F=50μm, A=9180μm2; F=60μm, A=9055μm2; F=70μm, A=8869μm2; F=80μm, A=8767μm2; F=90μm, A=8694μm2; F=100μm, A=8467μm2. Using simple linear regression, the cell density error (E) can be extrapolated based on deviance from true area. For F=10μm, E=1.26%; F=20μm, E=2.90%; F=30μm, E=4.58%; F=40μm, E=6.53%; F=50μm, E=8.12%; F=60μm, E=9.99%; F=70μm, E=11.92%; F=80μm, E=13.91%; F=90μm, E=15.98%; F=100μm, E=18.13%.

 
Conclusions
 

Cell counting error can be considered negligible at 0-29μm, non-negligible at 30-59μm and problematic at 60-100μm of focal deviance.

 
 
Specular images of donor cornea captured 100 micrometers out of focus, 60 micrometers out of focus, 30 micrometers out of focus, and 0 micrometers out of focus (i.e. completely in focus).
 
Specular images of donor cornea captured 100 micrometers out of focus, 60 micrometers out of focus, 30 micrometers out of focus, and 0 micrometers out of focus (i.e. completely in focus).
 
 
Table: Projected cell density counting error based on deviance from true focus and true area.
 
Table: Projected cell density counting error based on deviance from true focus and true area.
 
Keywords: 481 cornea: endothelium • 550 imaging/image analysis: clinical • 549 image processing  
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