Abstract:   Objective To compare the difference, correlation and agreement of anterior chamber biological parameters measured by Scheimpflug tomography Pentacam AXL and swept-source anterior segment optical coherence tomography CASIA 2 in myopic eyes. Design Diagnostic technique evaluation. Participants 50 myopic patients (50 eyes) of Beijing Tongren Hospital from December 2021 to December 2022, with an average age of (29.62±6.79) years. The data of the right eye was included for analysis. Method Pentacam AXL and CASIA 2 were used to measure anterior chamber depth (ACD), including ACD (Epi), which means the distance from the corneal epithelium to the anterior surface of the lens, and ACD (Endo), which means the distance from the corneal endothelium to the anterior surface of the lens, anterior chamber volume (ACV) and anterior chamber angle (ACA). Paired t-test, Pearson correlation analysis and Bland-Altman analysis were used to evaluate the differences, correlation and agreement between the two measurements. Main Outcome Measures The value of ACD (Epi), ACD (Endo), ACV, ACA, 95% limits of agreement (LoA) and the probability of points inside the boundary line of 95%LoA in Bland-Altman analysis. Results ACD (Epi), ACD (Endo), ACV and ACA measured by Pentacam AXL were (3.60±0.22)mm, (3.09±0.22)mm, (175.48±23.53)mm3 and (40.27±5.30)°, respectively. ACD (Epi), ACD (Endo), ACV and ACA measured by CASIA 2 were (3.66±0.21)mm, (3.15±0.21)mm, (175.97±21.58)mm3 and(47.04±8.66)°, respectively. Compared with the values in Pentacam AXL, the ACD (Epi), ACD (Endo) and ACA were larger in CASIA 2 with significant differences (t=8.04, 7.67, 5.25, all P<0.001). There was no significant difference in ACV (t=0.53, P=0.60). The correlation of ACD (Epi) (r=0.969, P<0.001), ACD (Endo) (r=0.964, P<0.001) and ACV (r=0.961, P<0.001) were significant. There was no significant correlation of ACA (r=0.216, P=0.132) between Pentacam AXL and CASIA 2. The Bland Atman analysis showed that the 95% LoA of ACD (Epi), ACD (Endo), ACV and ACA were (-0.04~0.17)mm, (-0.05~0.18)mm, (-12.49~13.47)mm3 and(-11.11~24.65)°. The probability of points inside the boundary line of 95% LoA were 48 (96%), 48 (96%), 50 (100%) and 45 (90%). Conclusion Pentacam AXL and CASIA 2 had slight difference as well as good correlation and agreement in the measurement of ACD, which can be clinically interchangeable. There was no significant difference as well as good correlation and agreement in ACV, which can be clinically interchangeable. Since there was significant difference, no significant correlation and poor agreement between Pentacam AXL and CASIA 2 in ACA measurement, they were not clinically interchangeable. (Ophthalmol CHN, 2024, 33: 441-445)

Key words:  anterior chamber depth, anterior chamber volume, anterior chamber angle, myopia