Comparison Of Central Corneal Thickness,using Measurements Of Three Imaging Systems In Patients With Dry Eye

Objective: People with different degrees of dry eyes may have an influence on the measurement of central corneal thickness due to the unstable tear film status.Sirius anterior segment analyzer and Pentacam three-dimensional anterior segment analysis system are commonly used clinical anterior segment measuring instruments.To investigate the consistency of measuring corneal thickness with A-Scan,Pentacam,and Sirius in dry eye patients.Since the measurement of central corneal thickness uses a different working principle than Type A-Scan,the data obtained is also different.Methods: A retrospective analysis was performed on 100 patients(182 eyes)who visited the myopia treatment center at our hospital from September 2018 to September2019.According to DR-1(Kowa,Nagoya,Japan)dry eye tester,patients were divided into Grade 2/+2(moderate)and Grade 3/+3(severe)dry eye group in the two groups,respectively.A-Scan,Pentacam,and Sirius was then used to measure their corneal thickness of the thinnest point,and then compared using paired sample t-test,Pearson correlation analysis and Bland-Altman method were used to assess the consistency of these devices.Currently,to the best of my knowledge,a comparative analysis of CCT measurements in dry eye patients has not been done before.Results: SPSS24.0 software(SPSS Inc.,Chicago,IL)and Medcalc 11.4.2.0 software(Medcalc software bvba)were used for statistical analysis of the data.(P<0.05)was considered statistically significant.The kolmogorov-smirnov test was used to check that the distribution of the dataset conforms to a normal distribution.The mean values of central corneal thickness measured by Pentacam,Sirius and A-Scan were 548.57±22.46μm,541.70±23.50 μm and 535.85±23.33 μm respectively.There was no statistically significant difference in the measurement results of the three devices(P < 0.05),and there was a high correlation between the all devices.Bland-Altman analysis showed that Sirius,Pentacam and A-Scan had good consistency.In the mild dry eye group,the 95%consistency was reported between Sirius and Pentacam ranged from-7.65 to-5.29μm,the 95% consistency between Pentacam and A-Scan was found 12.01 to14.37μm,and the 95% consistency between Sirius and A-Scan was 5.63 to 7.80μm.In the severe dryeye group,the 95% consistency between Sirius and Pentacam ranged from-9.36 to-6.05 μm,the 95% consistency between Pentacam and A-Scan was 10.12～13.29 μm,and the 95% consistency between Sirius and a-super was 2.30～5.69 μm.There was no statistically significant difference in the measurement results of each instrument in the three groups(P > 0.05).Conclusion: In the assessment of dry eyes corneas,the Sirius measured CCT values closer to A-Scan ultrasound pachymetry and with less variability compared with Pentacam.The(interobserver)reproducibility with the Sirius was highest of all modalities.The measurements of the three instruments had significant linear correlations with one another,and all methods had highly satisfactory measurement repeatability.