AIM: To compare the difference, correlation and consistency of the new anterior segment coherence tomography CASIA2 and PentacamHR in measuring apex corneal thickness, thinnest corneal thickness, corneal thinnest point position and anterior chamber depth.

METHODS: A prospective study. A total of 40 myopic patients(80 eyes)who received refractive surgery were enrolled from the March 2021 to April 2021 in Hefei Aier Eye Hospital. CASIA2 and PentacamHR were used respectively to measure apex corneal thickness, thinnest corneal thickness, position of thinnest corneal point and depth of anterior chamber. The paired t-test was used to compare the differences of the parameters. Pearson correlation coefficient and Bland-Altman 95% consistency limit method were used to measure the correlation and consistency of the two instruments.

RESULTS: The corneal apex thickness and the thinnest corneal thickness measured by CASIA2 were smaller than those measured by PentacamHR(all P<0.001), but the consistency limit was narrow(-26.6-11.6, -29.53-13.51μm). There was no significant difference between the results of anterior chamber depth measured by CASIA2 and PentacamHR(t=1.634,P=0.106). The results of the position distribution of the thinnest point measured by the two instruments showed good consistency(right eye:Z=0.000, P>0.999; left eye:Z=0.149,P=0.882), and there was no significant difference in the X-axis displacement and Y-axis displacement of the thinnest point, and the distance between the thinnest point and the corneal apex(P>0.05).

CONCLUSION:The apex corneal thickness, the thinnest corneal thickness, the position of the thinnest corneal point and the anterior chamber depth measured by the CASIA2 and PentacamHR are in good consistency. However, in clinical work, the slight differences between the parameters of the two instruments should be taken into consideration, and it is not recommended to replace them directly.Moreover, the extremely high scanning speed of CASIA2 makes it more advantageous than PentacamHR in clinical application.