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Comparative Study
. 2017 Apr;36(4):419-424.
doi: 10.1097/ICO.0000000000001148.

Precision of Epithelial Defect Measurements

Purak C Parikh  1 , Nita G Valikodath, Christopher B Estopinal, Roni M Shtein, Alan Sugar, Leslie M Niziol, Maria A Woodward
Affiliations
Comparative Study

Precision of Epithelial Defect Measurements

Purak C Parikh et al. Cornea. 2017 Apr.

Abstract

Purpose: To ensure optimal care of patients, cornea specialists measure corneal features, including epithelial defects (ED), with slit-lamp calipers. However, caliper measurements are subject to interphysician variability. We examined the extent of variability in ED measurements between cornea specialists and discuss the potential clinical impact.

Methods: A total of 48 variably sized EDs were created in pig eyes. Three cornea specialists measured the maximum vertical and horizontal ED lengths to the nearest 10th of a millimeter using slit-lamp microscopy. An absolute difference in ED measurement between cornea specialists of 0.5 mm was chosen to be the a priori threshold for clinical significance and was evaluated by the Wilcoxon signed-rank test. Interrater reliability was assessed by intraclass correlation coefficients.

Results: The average absolute difference in the vertical ED length between pairs of examiners ranged from 0.54 to 0.63 mm, and that of the horizontal ED length ranged from 0.44 to 0.46 mm. These differences in ED measurement were not significantly different from 0.5 mm (all P > 0.06). However, pairs of examiners differed in vertical ED length measurements by >0.5 mm in 44% to 52% of EDs and by >1.0 mm in 13% to 17% of EDs. Pairs of examiners differed in horizontal ED length measurements by >0.5 mm in 31% to 40% of EDs and by >1.0 mm in 10% to 15% of EDs. The intraclass correlation coefficient was 0.85 (95% confidence interval, 0.77-0.91) for vertical and 0.84 (95% confidence interval, 0.74-0.90) for horizontal ED measurements.

Conclusions: Cornea specialists showed good reliability in the measured EDs; however, depending on the threshold for clinical significance, a nontrivial percentage of cases have high interexaminer clinical variability.

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Conflict of interest statement

Conflicts of Interest: All other authors have no significant conflicts of interest or sources of funding to report.

Figures

Figure 1
Figure 1
Comparison of ED measurement between examiners. A strong, positive linear trend was observed for all pairs of examiners with respect to abrasion measurement.
Figure 2
Figure 2
Measurement differences between examiners displayed as proportions grouped by the absolute difference between ED measurements. 2A displays the vertical length measurements and 2B displays the horizontal length measurements.
See this image and copyright information in PMC

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