Comparison of Anterior Segment Biometric Parameters Measured by Pentacam and Sirius in Healthy Myopic Eyes

To compare the correlation and agreement between measurements of anterior segment biometric parameters obtained with Pentacam and Sirius in healthy myopic eyes.

A total of 679 patients with myopia aged 17-49 years (mean ± SD, 23.37 ± 5.93 years) were enrolled, including 431 males (63.5%) and 248 females (36.5%). The spherical equivalent (SE) of the right eye ranged from -0.63 D to -14.75 D (mean ± SD, -4.44 ± 1.84 D). Central corneal thickness (CCT), anterior chamber depth (ACD), flat keratometry (Kf), steep keratometry (Ks), and corneal astigmatism (AST) were measured with each device. Paired t-tests or Wilcoxon signed-rank tests, correlation analysis, intraclass correlation coefficient (ICC) analysis, and Bland-Altman analysis were used to assess correlation and agreement between the two systems.

CCT did not differ significantly between the two devices (p > 0.05), whereas ACD, Kf, Ks, and AST differed significantly (all p < 0.05). Pentacam yielded lower ACD, Kf, and AST values but a higher Ks value than Sirius. All parameters were significantly and positively correlated (r = 0.929-0.984, all p < 0.001). All ICC values exceeded 0.92 (lower limits of the 95% CIs >0.91, all p < 0.001), indicating excellent agreement. Bland-Altman plots showed that the differences in all parameters clustered closely around zero, with narrow 95% limits of agreement.

Pentacam and Sirius measurements showed high correlation and good agreement and can provide complementary clinical references. However, systematic biases were observed in the absolute ACD, Kf, Ks, and AST values obtained with the two devices. Device-specific reference ranges are therefore advisable.