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Joao Godinho, F�bio Ursulino Reis Carvalho, Ricardo Holzchuh, Fernando Cesar Abib, Richard Y Hida; Specular microscope using automatic counting can generate unacceptable Sample error in normal corneas. Invest. Ophthalmol. Vis. Sci. 2018;59(9):2911.
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© ARVO (1962-2015); The Authors (2016-present)
The specular microscope (SM) has a computer program that defines the borders of endothelial cells (EC) and automatically calculates the studied area. Since this analysis is performed automatically, it may contain interpretation errors generated by its technology’s imperfections or flaw. The purpose of this study is to analyze the sample error and estimate the discarded cell area in automatic mode of sequential procedures in normal corneas.
Forty patients of general outpatient clinic in Santa Casa de São Paulo, chosen randomly were included in this study. Three consecutive examinations (Groups 1, 2, and 3, respectively) were performed by a single examiner in which the patient was requested to stand up and sit down again immediately between procedures. One best image was chosen from all 16 images obtained from each SM (CEM-530 Non-Contact SM- NIDEK®, Gamagori, Japan). The following endothelial data was generated automatically by the SM: counted cells (CC), endothelial cell density (ECD), average cell area (AVG), coefficient of variation (CV), and hexagonality percentage (HEX). Sample error was calculated using reliability index program (Cells Analyzer® software, Technical, Brazil USA Pattent). For this study, data was considered as “ACCEPTABLE” if SE < 0.05 in all 3 sequential exams. Data was considered as “CONFLICTING” if SE ≥ 0.05 in at least one exam. Data was considered as “UNACCEPTABLE” if SE ≥ 0.05 in all sequential exams. Only left eyes were considered in this study. To estimate the discarded cell area calculated by the SM, we divided the non-evaluated area of the image (image size µm2 - [CC x AVG]µm2) by AVG.
75% of the left eyes analyzed were considered as “ACCEPTABLE”; 17.5% as “CONFLICTING”; and 7.5% as “UNACCEPTABLE” (Figure 1). Discarded cell area calculated by the SM software ranges from 28% to 81% and average 71,737 ± 11,591 µm2 that represent an average of 202.82 ± 43.16 endothelial cells per image (Figure 2).
Even in normal eyes, the non-contact SM can only generate “ACCEPTABLE” sample error in only 75% of the cases. A great variation of discarded cell area might indicate that technology must improve to benefit from more precise calculation using these discarded cells.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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