| Objective:To analyze the difference and consistency between corneal surface curvature and corneal astigmatism in normal subjects by Cassini and Pentacam.Methods:A case-control study was conducted.Select 29 normal subjects（58 eyes）,of whom 13 were male and 16 female,aged 22 to 35 years of age.The anterior and posterior surface curvatures,astigmatism and their axial positions were measured by Cassini and Pentacam,and the related parameters were statistically analyzed.Results:The K1,K2,J0,J45 of anterior corneal surface obtained by Cassini were（42.7571±1.7692）D,（43.7138±1.9454）D,（0.3294±0.3996）,（-0.6197±0.1979）,respectively.The K1,K2,J0,J45 of anterior corneal surface obtained by Pentacam were（42.7431+1.6911）D,（43.7172+1.8246）D,（0.4302+0.3182）,（-0.6040+0.1945）,respectively.The results of paired t-test were 0.452,-0.086,-3.431,-0.647,respectively.There were no significant differences among the results of the two instruments in the measurement of anterior corneal surface of K1,K2,J0 and J45（P>0.05）.Bland-Altman plot showed that the results of the two instruments were in good consistency of the anterior corneal surface.The K1,K2,J0,J45 of posterior corneal surface obtained by Cassini were（-5.8802±0.3368）D,（-6.2064±0.3523）D,（-0.1189±0.1056）,（-0.0007±0.9112）,respectively.The K1,K2,J0,J45 of posterior corneal surface obtained by Pentacam were（-6.1664±0.2678）D,（-6.5190±0.3225）D,（-0.1611±0.1078）,（-0.0058±0.0485）,respectively.The results of paired t-test were 8.688,8.848,2.837,2.537,respectively.There were significant differences among the results of the two instruments in the measurement of posterior corneal surface of K1,K2,J0 and J45（P<0.05）.Bland-Altman plot showed that the results of the two instruments were not in good consistency of the posterior corneal surface.Conclusion:The curvature and astigmatism of anterior corneal surface can be replaced by each other,but the parameters of posterior corneal surface are different,and they can not be replaced by each other. |
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