Subfoveal choroidal thickening (SFChT) can serve as a biomarker for assessing long-term outcomes of atropine treatment for myopia in pediatric patients, according to research published in American Journal of Ophthalmology.
Researchers evaluated 314 pediatric patients who completed second-year follow-up visits in the Low-Concentration Atropine for Myopia Progression (LAMP) study (clinicaltrials.gov identifier: NCT02130167). They assigned patients to 1of 4 groups and administered various concentrations of atropine. Group 1 received 0.05% (n=81), group 2 received 0.025% (n=80), group 3 received 0.01% (n=86), and a “switch-over” group received 0.05% atropine (n=69). Previously, this “switch-over” group had served as a control group, but researchers chose to administer treatment for ethical considerations.
SFChT significantly increased in individuals in the 0.025% and 0.05% atropine groups after the first year, and in the “switch-over” group during the second year. The 0.05% (P <.001) and 0.025% atropine groups (P =.001) experienced a significant increase in SFChT at 4 months before stabilizing. Researchers note the changes were concentration-dependent (β=0.89, P <.001).
SFChT changes, atropine concentration, and age were linked with spherical equivalent (SE) progression and axial length (AL) elongation over the course of the 2 year study.
Investigators found that choroidal thickening mediated 15.5% of the effect (P =.01) on SE progression from 0.05% atropine, and 12.4% of the effect (P =.04) on SE progression from 0.025% atropine compared with a reference group of 0.01% atropine.
“Notably, the factor most strongly associated with treatment efficacy was concentration level (β=0.601), followed by age (β=0.153) and then choroidal thickening effect (β=0.074),” according to the researchers. “Consistent with our previous reports, atropine treatment efficacy is concentration-dependent — the higher the concentration, the greater the response. It is also age-dependent — the younger the patient’s age, the lower the response. Young children therefore require a higher concentration of atropine for better treatment responses.”
Limitations of the study included switching the placebo group to 0.05% atropine treatment during the second year, possible interobserver variations in choroidal imaging measurements, and the possibly confounding effect of muscarinic antagonists on choroidal thickness.
Yam JC, Jiang Y, Lee J, et al. The association of choroidal thickening by atropine with treatment effects for myopia: two-year clinical trial of the LAMP study. Am J Ophthalmol. Published online December 20, 2021. doi:10.1016/j.ajo.2021.12.014