This study in the February issue of Ophthalmology examines whether lower atropine concentrations are effective at preventing myopic progression in children while causing fewer side effects compared with higher concentrations. The results demonstrate that treatment with the lowest concentration given, 0.01%, resulted in fewer side effects and minimal impact on visual function while retaining comparable efficacy at controlling myopia progression compared with higher concentrations.
Subjects in this double-masked study were 400 children aged 6 to 12 with myopia of at least -2.0 D and astigmatism of -1.50 D or less. They were randomly assigned in a 2:2:1 ratio to 0.5%, 0.1% and 0.01% atropine, nightly for two years.
A previous study the authors conducted compared atropine 1% with placebo in children of the same age. After two years, atropine 1% was effective at slowing myopia progression compared with placebo but caused visual side effects resulting from cycloplegia and mydriasis.
In the current study, the authors found that after two years, differences in myopia progression (0.19 D) and axial length change (0.14 mm) between the treatment groups were small and clinically insignificant. Mean myopia progression at two years was -0.30 ± 0.60, -0.38 ± 0.60 and -0.49 ± 0.63 D in the atropine 0.5%, 0.1% and 0.01% groups, respectively (P = 0.02 between the 0.01% and 0.5% groups; P > 0.05 between other concentrations). This compared with myopia progression of -1.20 ± 0.69 D in the placebo group over two years in the authors' previous study.
The mean increase in axial length in the current study was 0.27 ± 0.25, 0.28 ± 0.28 and 0.41 ± 0.32 mm in the 0.5%, 0.1% and 0.01% groups, respectively (P < 0.01 between the 0.01% and 0.1% groups and between the 0.01% and 0.5% groups).
Atropine 0.01% had a negligible effect on accommodation and pupil size, and no effect on near visual acuity. Allergic conjunctivitis and dermatitis were the most common adverse effects, with 16 cases in the 0.1% and 0.5% atropine groups combined and no cases in the 0.01% group.
The authors say that in designing the current study, atropine 0.01% was initially assumed to have minimal effect and act as a potential control, which is why fewer subjects were allocated to this group. However, contrary to expectations, atropine 0.01% had significant clinical effects on myopia progression, accommodation and pupil size.