Comparison of Corneal Thickness Measurements with the Orbscan and Ultrasonic Pachymetry

ABSTRACT

To verify the accuracy and reproducibility of corneal thickness measurements obtained with Orbscan (Orbtek, Inc., Salt Lake City, USA), the measurements were compared with those taken with an ultrasound pachymeter (Omega Compuscan, Storz). Central corneal thickness was measured by each method in 100 eyes of 50healthy subjects. The averages by the two methods were compared. One examiner took the measurements twice by each method in 20 eyes of 10 subjects, and intraexaminer reproducibility was evaluated. Two examiners measured the thickness in 20 eyes of 10 subjects and interexaminer reproducibility was assessed. The average corneal thickness was 550.27+/-3.56 micrometer in the Orbscan measurements and 526.62+/-3.70 micrometer in the ultrasound pachymetry There was a statistically significant difference between the two methods. Significant difference was noticed but this showed a constant corresponding correlation with the Orbscan showing a 4.4%lower average. The intraexaminer and interexaminer reproducibility showed high reliability(Guttman split-half point<0.99). The Orbscan pachymetry is a highly reliable method and may be widely used in clinical practice.