Comparison of Central Corneal Thickness Measurements With Low-Coherence Interferometry and Ultrasound Pachymetry among Normal individuals

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
Topic
Year
2015
Day
Thursday
Program Number
155077
Room
Great Hall Foyer
Affiliation
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
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