Analysis of Changes in Refraction and Biometry of Atropine- and Placebo-Treated Eyes

To analyze changes in refraction and associated biometric changes in atropine- and placebo-treated eyes in the Atropine for Treatment of Myopia study (ATOM1).

A total of 400 myopic children, aged 6 to 12 years, were assigned randomly to receive 1% atropine or a placebo agent in one eye daily for 2 years, after which drops were stopped and children monitored for another year. Cycloplegic autorefraction, A-scan biometry, and automated keratometry were performed at the initial visit, 2 weeks (baseline), and at 4, 8, 12, 16, 20, 24, 30, and 36 months.

A total of 313 children (78.3%) completed the study. In placebo-treated eyes, there was myopic progression of -1.55 diopters (D), between baseline and 36 months, associated with reductions in corneal curvature (K; -0.13 D) and anterior chamber depth (ACD; -0.17 mm) and increases in lens thickness (LT; 0.05 mm), vitreous chamber depth (VCD; 0.65 mm), and axial length (AL; 0.53 mm). Multivariate analysis of change in spherical equivalent demonstrated that the hyperopic shift (0.20 D) noted in atropine-treated eyes between baseline and 4 months, and the myopic rebound (-0.74 D) noted between 24 to 30 months when atropine was stopped, were associated with a reduction and increase in VCD and AL, respectively, after adjusting for age and sex. Changes in K, ACD, and LT were less relevant. Between 4 and 24 months, atropine-treated eyes demonstrated gradual myopic progression (-0.40 D), accompanied by reduction in K (-0.06 D) and ACD (-0.07 mm) and increase in VCD (0.13 mm) and AL (0.06 mm).

Atropine appeared to slow myopia progression mainly by reducing or slowing the growth in VCD, and thereby AL. (ClinicalTrials.gov number, NCT00371124.)