|Title||Comparison of Central Corneal Thickness Measurements With Low-Coherence Interferometry and Ultrasound Pachymetry among Normal individuals|
|Author, Co-Author||Shadi Akbarian, Shahin Yazdani, Azadeh Doozande, Mahtab Haghighat, Mohammad Pakravan, Mehdi Yaseri|
Great Hall Foyer
|Abstract|| Purpose: To evaluate central corneal thickness using low coherence interferometry compared with ultrasound technique and the repeatability of values for both devices.
Methods: In this cross-sectional study, 131 eyes from normal subjects underwent low coherence interferometry (LenStar 900, Haag-Streit, Koeniz, Switzerland) and ultrasonic pachymetry (UP-1000, Nidek Technologies, Gamagori, Japan) to determine central corneal thickness (CCT). Paired t-test was used to evaluate the differences between the two sets. To show the agreement between the two devices, Intra Cluster Correlation (ICC) and 95% limit of agreement (LoA) were applied. Bland-Altman scatter plot was used to demonstrate this agreement as well. To evaluate the reliability of each device, the values were examined for three times for a control group and another Intra Cluster Correlation and Cronbach's Alpha were used. To correct the Lenstar values based on Ultrasound, we used linear regression model.
Results: Mean CCT values were 538 ± 34 and 530 ± 34 with ultrasonic and lenstar devices, respectively. It was also 537 ± 31 when the corrected lenstar values were repeatedly evaluated for the control group. Regression analysis showed a high correlation between values obtained by both devices (0.918, pż0.001). ICC and Cronbach's Alpha depicted a higher repeatability for lenstar than ultrasonic pachymetry (0.993, 0.998). We reached a formula for corrected lenstar value as “Corrected Lenstar = 0.9 * Lenstar + 54”.
Conclusions: CCT value measured by low-coherence interferometry is not statistically of high correlation and agreement with ultrasonic CCT- and could not replace the gold-standard technique, but it showed that low-coherence interferometry is reliable enough for obtaining CCT. The obtained formula is suggested for calibration purposes of Lestar© compared with UP technique.
|Affiliation of Co-Authors||Shahid Beheshti University of Medical Sciences, Shahid Beheshti University of Medical Sciences, Shahid Beheshti University of Medical Sciences, Shahid Beheshti University of Medical Sciences, Shahid Beheshti University of Medical Sciences|