The Short-term Effect of Atropine 0.1% on the Axial Length and Choroid of Children Treated for Myopia Progression Prevention, Measured by Optical Coherence Tomography Angiography.

Purpose: To investigate the short-term effect of atropine to better understand its mechanism of action in myopia prevention. The current study investigates whether atropine's effect on the axial length arises from an increase in choroidal thickness using swept-source optical coherence tomography angiography (OCTA).

Methods: Twenty-five myopic children (25 eyes) (9 boys and 16 girls; mean age: 11.8 years, range: 7 to 15 years) were enrolled following documented myopia progression and axial length increase in the preceding 6 months. Using swept-source OCTA, choroidal thickness and choroidal stromal volume (CSV) were measured at baseline and after 1 month of daily atropine 0.1% use. Axial length measurements were taken on the same days.

Results: Following 1 month of daily atropine 0.1% instillation, choroidal thickness increased from 284.24 ± 65.05 to 308.04 ± 70.65 µm (Δ 22.41 ± 4.20 µm, P < .01), CSV increased from 11.88 ± 5.20 to 12.96 ± 5.86 mm³ (Δ 1.08 ± 1.02 mm³, P < .01), and axial length decreased from 25.37 ± 1.21 to 25.33 ± 1.21 mm (Δ 0.044 ± 0.016 mm, P < .05). The CSV and choroidal thickness increase show a negative correlation with the axial length decrease of -0.462 and -0.374, respectively, demonstrating a weak to moderate correlation.

Conclusions: One month of daily atropine 0.1% eye drop administration results in an acute decrease in axial length concurrent with an increase in choroidal thickness and CSV. A direct cause-and-effect relationship between these two parameters is plausible. [J Pediatr Ophthalmol Strabismus. 20XX;X(X):XXXXXX.].