Purpose: Preschool myopia generally indicated a high risk of progression to high myopia. However, no previous study has reported its longitudinal evolution. This study aimed to investigate the longitudinal changes in preschool myopia and explore the associated key determinants.
Methods: Medical records of patients seeking refractions at Zhongshan Ophthalmic Center between 2009 and 2017 were retrospectively reviewed. Mean rates of change in spherical equivalent (SE) refractive errors were evaluated in patients with preschool myopia. Association between the rate of change in SE and patient characteristics at the initial visit were examined using linear mixed-effect regression models.
Results: A total of 495 cases (median initial age: 5.12 years, interquartile range [IQR], 4.12-5.76 years) were assessed with at least 2-year follow-up. The initial median SE was -3.00 D (IQR, -5.25 to -1.75 D) and the median duration of follow-up was 3.69 years (IQR, 2.89-4.99 years). On average, myopia progressed by -0.59 ± 0.47 D/year. A total of 312 (63.0%) children demonstrated myopia progression (mean rate of change in SE ≤ -0.50 D/year in either eye) and 177 (35.8%) children demonstrated refraction stability (mean rate of change < ±0.50 D/year in both eyes). Older age (β = -0.06, P = 0.003), female sex (β = -0.09, P = 0.035), and initial lower myopic SE (β = -0.07, P < 0.001) were associated with faster myopia progression.
Conclusions: Preschool myopia on average progresses, although considerable proportion of subjects demonstrates longitudinal refraction stability. The rate of myopia progression is associated with initial patient characteristics.