Detecting refractive parameters, such as AL and CR, quickly and accurately in children with ametropia is critical. This pilot study is the first to assess the accuracy of Myopia Master in evaluating axial length, keratometry, and refractive measurement in children.
In this study, the AL measured with Myopia Master showed a significant correlation and near-perfect consistency with the other two instruments. Previously, IOLMaster 500 was considered the standard method for AL measurements, adopting the principle of partial coherence interferometry (PCI), with its high precision due to ultrasonic biometric measurement.6, 7 An infrared light with a wavelength of 760 µm is the light source to measure the optical path length from the anterior surface of the cornea to the retinal pigment epithelium and obtain the AL readings.8, 9 Based on the principle of swept-source optical coherence tomography (SS-OCT), IOLMaster 700 uses a laser with a wavelength and bandwidth of 1050 nm and 20 nm, respectively, to scan the optical cross-section images at different depths, visualizing the longitudinal sections of the eye structures.10 Therefore, a higher acquisition rate and a reduced risk of inaccurate measurement due to incorrect fixation can be obtained with this method by imaging the fovea of the macula.10, 11 PCI is also used in Myopia Master with an 880 nm wavelength. The high consistency between IOLMaster 700 and IOLMaster 500 has been confirmed by previous studies.12, 13 The mean differences between the AL measured with the three systems were minimal, with no significant difference or clinical significance, and the corresponding deviation of diopter could be ignored.13 Therefore, the Myopia Master can accurately measure the AL in ametropic children.
The CR measured with Myopia Master also showed a significant correlation and near-perfect consistency with the other two instruments. The CR results obtained with Myopia Master showed no statistically significant or clinical difference from the other two instruments. IOLMaster 700 measures the CR in 18 points in three hexagons (1.5 mm, 2.4 mm, and 3.2 mm) from the center.14 The mire ring is used in ARK-1 to measure the CR, calculating the mean-weighted power of points on the eight rings 3 mm from the center.15 Previous studies have proven that the CR readings using IOLMaster 700 could be used as standard data and regarded as a control, as in the current study.16 The difference between the Myopia Master and the other two devices could be partially explained by the large fluctuation of the K value measured with PCI. Shammas and Chan evaluated the keratometry measured with a PCI device in 121 eyes and reported a 95% LoA range between − 0.55 and + 0.52 D, suggesting that the precision needs to be improved in particularly steep corneas.6 According to these research findings, we suppose that the Myopia Master could accurately measure the CR in most typical conditions. However, in special cases, such as eyes with steep corneas, adjustments could be needed for CR evaluations.
There was a significant difference in SE measurements between Myopia Master and ARK-1 or manifest refraction; significant differences were also noticed in cylinder measurements (Myopia Master vs. manifest refraction and ARK-1 vs. manifest refraction). No statistically significant differences were found in the spherical and SE measurements between ARK-1 and manifest refraction. The results of our study are consistent with previous findings.4 As the consistency between Myopia Master and manifest refraction is adequate, monitoring parameters with Myopia Master could help acquire more accurate results in clinical practice. Thus, the correlation and consistency between the three systems showed they can be interchangeable, and the SE measured with the Myopia Master is also feasible for clinical application.
There were some limitations in the present study. First, the sample size was relatively small; further studies using larger databases are warranted to provide more information and detailed results at different ages. Second, the selected population was children with ametropia, and adults were not included for comparative analysis. The consistency between the conventional measurements and Myopia Master in adults needs to be verified.
In conclusion, Myopia Master, as an integrated three-in-one system for AL, CR and SE measurement, can provide multiple biometrical parameters in a single assessment with high efficiency and accuracy.