Abstract
Purpose: :
Accurate reproducible measurement of central corneal thickness is essential in refractive surgery and advanced glaucoma diagnostics. The methods should provide significant and valid results. Four technics were reviewed: contact ultrasound pachymetry as usual standard pachymetry and new non contact pachymetry technics as Anterior Segment Module (ASM) of Spectralis-OCT (Heidelberg Engineering), SL-OCT (Heidelberg Engineering) and Pentacam (Oculus Inc., Wetzlar, Germany).
Methods: :
Measurements of corneal thickness of 71 patients (46 women, 25 men) were taken at two following days by four different methods, each day three times consecutively. The reproducibility was evaluated by the calculation of the intraclass correlation coefficient (ICC) and by the Bland-Altman-Plots.
Results: :
Intrasession repeatability of measurements was ICC 0.991 at the first and 0.990 at the second day for SL-OCT, ICC 0.993 at the first and 0.995 at the second day for ASM of Spectralis-OCT. For Pentacam and ultrasound pachymetry means were calculated by themselves. Between 2 following days of measurement intersession repeatability was 0.950 (P=0.001) for SL-OCT; 0.927 (P=0.001) for ASM of Spectralis-OCT, 0.931 (P=0.001) for Pentacam and 0.958 (P= 0.001) for ultrasound pachymetry.
Conclusions: :
Pentacam, SL-OCT, and ASM of Spectralis-OCT provide non-touch technology without the need for local anesthesia and limit the risk of infection or artifacts. All show good significant reproducible results. Datas of the new technic of ASM of Spectralis-OCT by Heidelberg Engineering have to be evaluated manually but provide nevertheless reproducible datas.
Keywords: anterior segment • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • refractive surgery: corneal topography