[Repeatability of the new anterior segment optical coherence tomographic device and its consistency with the...

Objective: To investigate the repeatability and consistency of corneal biological parameters measured by the new anterior segment optical coherence tomographic device (Dream-OCT) and the Scheimpflug imaging device (Pentacam). Methods: This was a cross-sectional study. Clinical data of myopic patients (right eyes) who underwent corneal refractive surgery at the Eye Hospital of Tianjin Medical University from July to September 2024 were collected using the consecutive enrollment method, including corneal biological parameters measured continuously three times by Dream-OCT and Pentacam. The central corneal thickness (CCT), horizontal corneal diameter (WTW), steep keratometry (Ks), flat keratometry (Kf), and mean keratometry (Km) of the anterior corneal surface, posterior corneal surface, and total cornea were recorded, as well as the astigmatism degree, astigmatism axis of the anterior corneal surface, posterior corneal surface, and total cornea, and the astigmatism degree component J₀ at the 0° or 90° axis and the astigmatism degree component J₄₅ at the 45° or 135° axis. The intraclass correlation coefficient (ICC), paired t test, or Wilcoxon test, and Bland-Altman analysis were used to assess the repeatability, difference, and agreement of the data obtained by the two devices. Results: A total of 100 patients with myopia (100 right eyes) were enrolled, including 50 males and 50 females, with an average age of (23.35±3.82) years. The ICC of various corneal biological parameters measured by Pentacam and Dream-OCT were ≥0.830 and ≥0.840, respectively, with the ICC values of Dream-OCT being slightly higher than those of Pentacam. The CCT measured by Dream-OCT [(537.76±25.89) μm] was lower than that measured by Pentacam [(550.05±25.26) μm], while the WTW [(11.78±0.39) mm], Ks [(43.97±1.31), (-6.48±0.21), (43.64±1.37) D], Kf [(42.63±1.10), (-6.08±0.20), (42.39±1.22) D], and Km [(43.27±1.23), (-6.29±0.20), (43.00±1.24) D] of the anterior corneal surface, posterior corneal surface, and total cornea measured by Dream-OCT were all higher than the corresponding values measured by Pentacam, with statistically significant differences (all P<0.05). There were no statistically significant differences in the other corneal biological parameters between the two instruments (all P>0.05). The 95% limits of agreement between the two instruments were wide for CCT (-3.514 to 28.094 μm), anterior corneal astigmatism axis (-29.504° to 33.123°), posterior corneal astigmatism axis (-10.370° to 11.650°), total corneal astigmatism axis (-29.926° to 34.169°), total corneal Ks (-1.770 to 0.439 D), Kf (-1.535 to 0.297 D), Km (-1.479 to 0.303 D), and astigmatism power (-0.917 to 1.063 D). In contrast, the 95% limits of agreement were narrow for WTW and Ks, Kf, Km, and astigmatism power of the anterior and posterior corneal surfaces. Conclusions: Both Dream-OCT and Pentacam demonstrated good repeatability in measuring corneal biometric parameters. The two instruments showed excellent consistency in measuring WTW, as well as the refractive power and astigmatic power of the anterior and posterior corneal surfaces, and thus can be used interchangeably in clinical practice. However, their agreement was poor for measurements of CCT, astigmatism axis, total corneal refractive power, and astigmatic power, suggesting that the two devices are not interchangeable for these parameters.