Comparison of corneal thickness and corneal aspherieity measured by Oculyzer and Sirius

Objective To study the difference of corneal thickness measured by Oculyzer,Sirius and A mode ultrasound,and to compare the difference of Q-values of the anterior corneal surface measured by Oculyzer and Sirius.Methods Central corneal thickness(CCT) in 50 eyes of 25 myopia patients were measured by Oculyzer,Sirius and A mode ultrasound before refractive surgery,respectively.The difference of CCT was compared,and the correlation and concordance of three measurements were analyzed.Thinnest Corneal Thickness(TCT) and Q-values in 50 eyes were measured by Oculyzer and Sirius.The difference of TCT and Q-values were compared,and the correlation and concordance of two measurements were analyzed.Results The mean CCT measured by Oculyzer,Sirius and A mode ultrasound were(546.70 ± 31.94)μm,(535.96 ± 31.96)μm,(541.00 ± 32.60)μm,respectively.The CCT measured by Oculyzer was obvious higher than A mode ultrasound,the CCT measured by Sirius was obvious lower than that was measured by A mode ultrasound,there were statistical differences(both P0.05).There was a significant correlation in CCT measured by three measurements(P0.05),the Bland-Altman Plots displayed relatively good agreement limits of agreement between the three instruments.The mean TCT measured by Oculyzer and Sirius were(543.96 ± 31.73)μm and(533.00 ± 32.19)μm.The TCT measured by Oculyzer was obvious higher than Sirius,there were statistical differences(P 0 05).There was a significant correlation in TCT measured by two measurements(P 0.05),the Bland-Altman Plots displayed relatively good agreement limits of agreement between the two instruments.The mean Q-value measured by Oculyzer and Sirius were-0.1912±0.1134 and-0.1202±0.1083.The Q-value measured by Oculyzer was obvious prolateness than Sirius,there were statistical differences(P0.05).There was no significant correlation in Q-value measured by the two measurements(P0.05),but the Bland-Altman Plots displayed relatively good agreement limits of agreement between the two instruments.Conclusion Oculyzer and Sirius have good agreement with the gold standard A-mode ultrasound,the CCT and TCT measured by Oculyzer was thicker than that was measured by Sirius,bud the two instruments revealed a high correlation and good consistence;the anterior corneal surface was more prolateness measured by Oculyzer than Sirius,The CCT,TCT and Q-value measured by two measurements have certain correlation,but also have the difference,these instruments should not be used interchangeably for CCT and TCT measurement in clinic.