Factors Related to Axial Length Elongation in Myopic Children Who Received 0.05% Atropine Treatment

Purpose: To evaluate the longitudinal changes of axial length (AL) and factors associated with AL growth in myopic children receiving 0.05% atropine. Methods: This single-center retrospective study included children aged 4-13 years with myopia of at least -0.5 diopters (D) treated with 0.05% atropine eye drops from November 2016 to May 2021. Predictive factors for AL change were evaluated using linear mixed models. Results: Among 109 patients (218 eyes), 58 (53.2%) were male and the mean age at treatment was 8.5 +/- 2.0 years. At baseline measurement, the mean spherical equivalent was -4.05 +/- 2.34 diopters (D), and AL was 25.00 +/- 0.97 mm. The mean follow-up duration was 25.4 (12-58) months, and the mean AL elongation was 0.23 +/- 0.17 mm/year during the follow-up periods. AL shortening of >= 0.05 mm at subsequent visit occurred in 18 patients (26 eyes). The mean AL change in the group without initial AL shortening was statistically larger than that in the group with initial AL shortening (0.26 +/- 0.16 mm/year vs. 0.02 +/- 0.17 mm/year, P < 0.001). In linear mixed model, the age at atropine treatment and initial AL shortening were significantly associated with respect to AL growth (beta coefficient: -0.032 and -0.122, respectively, P < 0.001 for both). Conclusions: Our study found that older age and initial AL shortening are predictors of favorable response after 0.05% atropine treatment. Children with AL shortening at initial subsequent visit may be associated with good long-term response, and younger children may require higher concentration of atropine for optimal response.