AIM: To compare CASIA SS-1000 and Sirius OCT sweep anterior segment analyzer instrument for measuring normal corneal vertex thickness(CCT)and the thinnest corneal thickness(TCT)results the difference, correlation and consistency, and provide a theoretical basis for clinical application.

METHODS: This was a prospective study. A total of 34 normal subjects were collected. The subjects were measured by the same skilled operator. The SS-1000 OCT was first used, and then the corneal thickness was measured repeatedly by Sirius anterior segment analyzer. Paired t test and Bland-Altman were used to evaluate the consistency of corneal apex and corneal thinnest point between SS-1000 OCT and Sirius anterior segment analyzer.

RESULTS: The mean corneal apex measured by SS-1000 OCT and Sirius corneal topography were 517.62±25.29μm and 518.47±27.23μm CCT, respectively. The thinnest points of SS-1000 OCT and Sirius anterior segment analyzer CCT were 513.53±25.06μm and 515.32±26.69μm, respectively. Paired t test showed that the difference on corneal thickness of vertex was not statistically significant(P>0.05), but the thinnest corneal thickness was statistically significant(P<0.05). Pearson analysis of the two devices, the correlation is 0.969, 0.965. The results of 95% consistency limiting analysis on the corneal vertex thickness by Bland-Altman was(-14.22μm, 12.52μm), that of the thinnest corneal thickness was(-15.61μm, 12.03μm), 4%(3/68)was out of the 95% consistency limiting, but the thinnest corneal thickness was of a little larger differences.

CONCLUSION: SS-1000 OCT measurement of CCT and Sirius anterior segment analyzer is highly consistent, in clinical work can be considered alternative, but the thinnest point of the cornea can not be replaced each other.