Abstract
PURPOSE: To investigate and compare seasonal variations in axial length (AL) in myopic children with defocus incorporated multiple segments (DIMS) spectacle lenses combined with 0.01% atropine (DIMSA) and orthokeratology (OK) lenses. METHODS: The present retrospective study involved 428 subjects, mean age 9.70 ± 1.94 years, categorized into two groups: DIMSA (203 cases), and OK lenses (225 cases). Data were classified as "summer" or "winter" based on the midpoint of the 6 months between visits. Initial clinical visit (baseline) and one-year follow-up data were collected, and only data from the right eye was retrieved for analysis. Axial elongation over time and between groups was analyzed. RESULTS: The mean change in AL at 1 year was 0.18 ± 0.19 mm in the DIMSA group and 0.19 ± 0.15 mm in the OK group, with no significance between the two groups (p>0.05). In both groups, the change of AL in winter was significantly higher than that in summer (P<0.01). A similar seasonal pattern was found among children 7-8 years of age in the DIMSA group and 7-12 years of age in the OK group, as well as for those with an initial AL < 26 mm. CONCLUSION: DIMSA and OK lenses show similar reductions in myopia progression at different times of the year. Axial elongation decreased in summer, and this phenomenon disappears with increasing age and AL.