Corneal biometry changes with 0.01% atropine for myopia control: a randomised controlled trial and case of incidental keratoconus

Abstract Changes in corneal curvature have been reported with low-concentration atropine eyedrops for myopia treatment and have been suggested to play a role in the refractive changes observed during atropine therapy. A case of keratoconus was identified from the Western Australia atropine for the treatment of myopia (WA-ATOM) cohort. We tested the null hypothesis that 0.01% atropine eyedrops produce no change in corneal parameters or ectasia risk compared to placebo. Children with progressive myopia (6–16 years; n = 153) were randomly assigned to receive 0.01% atropine eyedrops or a placebo (2:1 ratio) for 2 years, followed by a 1-year washout. Scheimpflug imaging was performed at baseline, 24-months, and 36-months. Changes in corneal parameters were compared between the treatment and placebo groups using linear mixed models. One child allocated to the treatment group developed keratoconus during the treatment phase. At 24 and 36 months, the atropine group had significantly lower BAD-D values compared to placebo, with reductions of − 0.075 (95% CI − 0.126 to − 0.023, p = 0.027) and − 0.115 (95% CI − 0.168 to − 0.063, p = 0.005) from baseline, respectively ( p = 0.029 and 0.005). At 36 months, a significant steepening of K max of + 0.301D (95% CI 0.214 to 0.389, p = 0.039) was observed in the atropine group. All other corneal parameters and cylindrical power remained similar between the groups. The case of incidental keratoconus in the treatment group (1 out of 153 children) is compatible with population prevalence rates. No signal suggesting a treatment-related increase in corneal ectatic changes was identified within the limitations of this cohort, and these findings provide reassurance from a safety perspective, but clinicians should be aware of the rare possibility of keratoconus and refer patients with suspicious corneal findings.