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A. R. Schaefer, F. C. Abib, Tâ. T. M. Schaefer, R. Holzchuh, R. Godois; Corneal Endothelial Cell Sample Size of Specular Microscopy With Three Different Statistical Power - A Critical Study. Invest. Ophthalmol. Vis. Sci. 2007;48(13):2705.
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© ARVO (1962-2015); The Authors (2016-present)
To know the corneal endothelial specular microscopy sample size with three different statistical power.
Retrospective study performed with right eye of 103 contact lens users who had undergone corneal specular microscopy in 12 consecutive months. The Bio-Optics specular microscopy was used with Bambi 2000 Plus software. The sample size was computed with CELLS ANALYZER - Corneal Endothelial Statistical LabPat Rec with patient age, endothelial density, endothelial cell area, variation coefficient and hexagonal cell percentual. The choose statistical powers were confidence reliability (CR) of 90% and relative error (RE) of 0.1 for triage finality, CR of 95% and RE 0.05 for endothelial diagnosis and follow-up and CR 99% and RE 0.01 for endothelial diagnosis, follow-up and research finalities.
The sex distribution was 72 (69.24%) of the eyes of female patients and 32 (30.76%) of male patients. Minimum age was 13 years, maximum 76 years and the average 34±11.5 years. Minimum counted cells was 116 cells, maximum 715 cells and the average 330±119 cells. Computed sample size with CELLS ANALYZER - Corneal Endothelial Statistical Lab - CR of 90% and RE of 0.1: Minimum sample size was 12 cells, maximum 71 cells and the average 27±11 cells. The minimum endothelial sample error was 2.1%, maximum was 4.9% and average 3.38±0.58, all exams had planned relative error (0.1 or 10%) largest than calculated what determine statically correct sample size for all exams. CR of 95% and RE 0.05: Minimum sample size was 65 cells, maximum 389 cells and the average 148±60 cells. The minimum endothelial sample error was 1.79%, maximum was 4.18% and average 2.18±0.48, all exams had planned relative error (0.05 or 5%) largest than calculated what determine statically correct sample size for all exams. CR 99% and RE 0.01: Minimum sample size was 2775 cells, maximum 15897 cells and the average 6240±2427 cells. The minimum endothelial sample error was 2.77%, maximum was 6.46% and average 4.43±0.77, all exams had planned relative error (0.01 or 1%) shortest than calculated what determine statically incorrect sample size for all exams.
All sample size was correct with 90% CR and 0.1 RE with small sample size only for triage finality, all sample size was correct with 95% CR and 0.05 RE with possible sample size with some different endothelial images and with 99% CR and 0.01 RE all exams counted small number of the cells for the actual corneal specular microscopy technology.
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