Comparison of biometric and topographic measurements in patients with low and moderate myopia with respect to common parameters: a cross-sectional study

Aims: To compare biometric and topographic measurements obtained with the Aladdin optical biometer and the Pentacam Scheimpflug imaging system in eyes with low and moderate myopia, and to assess agreement between the two devices. Methods: This retrospective study included the right eyes of 58 patients with low or moderate myopia. Myopia was classified according to spherical equivalent. White-to-white corneal diameter (WTW), flat keratometry (K1), steep keratometry (K2), mean keratometry, corneal astigmatism, and anterior chamber depth (ACD) were compared between the devices. Correlations were assessed using Pearson correlation analysis, while agreement was evaluated using the intraclass correlation coefficient and Bland-Altman analysis. Results: The mean age of the patients was 29.62±9.22 years, and the mean spherical equivalent was -2.55±1.35 D. Thirty-four eyes were classified as low myopia and 24 as moderate myopia. Aladdin produced lower WTW, K1, K2, and mean keratometry values than Pentacam, whereas ACD values were higher with Aladdin (p<0.001 for all). Corneal astigmatism measurements did not differ significantly between the devices (p=0.582). Strong correlations were found for all shared parameters, with Pearson correlation coefficients ranging from 0.932 to 0.987. Agreement was high for WTW, keratometry, and corneal astigmatism, but lower for ACD. Bland-Altman analysis showed that the largest systematic difference occurred in ACD. The anterior chamber angle was significantly wider in the moderate myopia group, while the remaining parameters were similar between the myopia groups. Conclusion: Measurements obtained with Aladdin and Pentacam were strongly correlated in eyes with low and moderate myopia, but clinically relevant systematic differences were present, particularly for ACD. During preoperative assessment and follow-up, WTW, keratometry, and ACD should preferably be measured with the same device rather than used interchangeably.