Comparison of Nidek Automated, Automated Adjusted, and Manual Center Methods of Corneal Endothelial Cell Analysis

Abstract

Purpose: : To compare corneal endothelial cell image analysis using the Konan KSS-300 center method and the Nidek automated endothelial analysis system with and without manual correction.

Methods: : Twenty five randomly selected images of good to excellent quality of the central corneal endothelium were obtained from a sample of images by confocal microscopy performed with a Nidek Confoscan 4 (40x objective) collected as part of a study of the corneal effects of dosing taprenepag isopropyl (PF-04217329) qAM for 14 days. The study included 32 patients (24 non-Japanese and 8 Japanese) with a prior history of glaucoma or ocular hypertension, normal slit lamp exam, and no history of ocular trauma, intraocular surgery or intraocular inflammation. Images were captured at baseline, days 7 and 13 on treatment, and day 35. Identical images were analyzed using the Konan KSS-300 center method and the Nidek automated endothelial analysis system provided by the manufacturer (Nidek Technologies, Inc., Greensboro, NC) with (Nidek automated-adjusted) and without manual correction (Nidek automated). All three methods of image analysis were used to determine endothelial cell density (ECD) as well as coefficient of variation (CV) and % of hexagonal cells (%HEX) and were statistically evaluated for differences by the Student’s paired t-tests.

Results: : The mean ECD (± SD) determined using the Nidek automated (2468 ± 384 cells/mm²) image analysis software was higher but not statistically significant when compared to the ECD determined with the Konan KSS- 300 center method (2355 ± 552 cells/mm²). The Nidek automated-adjusted (2346 ± 561 cells/mm²) was equivalent to the KSS-300 center method. The mean CV was significantly higher for Nidek automated analysis method (p= 0.001) while the %HEX was significantly lower (p= 0.01) when compared to the Konan method. The Nidek automated-adjusted CV (p= 0.27) and %HEX (p= 0.64) was equivalent to the KSS-300 center method.

Conclusions: : The Nidek automated endothelial image analysis software with and without manual editing (automated-adjusted) produces results comparable to the manual Konan KSS-300 center method for determination of ECD but requires manual adjustment for other morphometric parameters.

Keywords: cornea: endothelium • imaging/image analysis: clinical