Repetitibility evaluation of a New Optical Biometer for Myopia Control in medical students

Purpose : Myopia has become a public health problem; estimates have reported that by 2050 almost half of the world's population will have myopia and about 10% will have high myopia. Visual work and usage of electronic devices have been described among the etiological factors of myopia. Medical students are a population well-known for intense visual work in the form of learning and are considered a risk group. Recently, some devices have been developed for monitoring myopia and its response to treatment, which has been validated mainly in the pediatric population since it is the most important target population. Our objective was to evaluate the repeatability of an equipment aimed at monitoring myopia

Methods : This is a prospective, cross-sectional, observational repetitibility study. Ocular biometry was performed on 50 studied eyes of 50 medicine students. Students who used contact lenses, with any previous surgery or corneal disease were excluded. Refractive error was measured with an auto kerato-refractometer (KR-8900, Topcon, Corp) on three occasions, considering the average of them for the results. For the biometric evaluation, five set of measurements were taken with the Myah equipment (Topcon, Corp.) by the same experienced examiner. Before each measurement, the subjects were asked to sit back, the device was realigned, and they were instructed to blink completely. Flattest meridian (Kf) and the steepest meridian (Ks), and axial length (AL) were recorded. Repeatability was evaluated using the coefficient of variation (CV), the within subject standard deviation (Sw), and the intraclass correlation coefficient (ICC).

Results : Thirty-eight women and twelve men were studied with a mean age of 21.64 ±0.18 years (range 19 to 26 years), the average spherical equivalent was – 1.29 ± 0.23 D, 60% had a spherical equivalent ≤ −0.5 D. The median AL measurement with its interquartile range (IQR) in the 5 measurements was: 23.87 IQR 1.42mm, 23.85 IQR 1.40mm, 23.88 IQR 1.37 mm, 23.88 IQR 1.41 and 23.89 IQR 1.38. The ICC for AL with a two-factor mixed model for absolute agreement was 0.999, 0.995 for Kf, and 0.993 for Ks. The Sw was 0.03, 0.09, and 0.13; the CV was 0.000, 0.001, and 0.002 for AL, Kf, and Ks, respectively.

Conclusions : The Myah device provides consistent measurements of corneal radius and AL in a group of medical students, validating their usefulness in clinical practice