Differential Effects on Ocular Biometrics by 0.05%, 0.025%, and 0.01% Atropine

Purpose

To evaluate changes in ocular biometrics in groups receiving 0.05%, 0.025%, and 0.01% atropine compared with placebo over 1 year based on the Low-Concentration Atropine for Myopia Progression (LAMP) study.

Design

Double-blinded, randomized, placebo-controlled trial.

Participants

Three hundred eighty-three children aged 4 to 12 years who were assigned randomly to receive 0.05%, 0.025%, 0.01% atropine, or placebo once daily in both eyes and completed the first year of the LAMP study.

Methods

Cycloplegic spherical equivalent (SE), axial length (AL), corneal curvature (K), and anterior chamber depth (ACD) were measured by IOLMaster. Corneal astigmatism and lens power were calculated. The ocular biometric parameter changes were compared among groups. Contributions to SE progression from ocular parameters were determined and compared among groups.

Main Outcome Measures

Changes in ocular biometrics and their associations with the changes in SE.

Results

Over 1 year, changes in AL were 0.20 ± 0.25 mm, 0.29 ± 0.20 mm, 0.36 ± 0.29 mm, and 0.41 ± 0.22 mm in the 0.05% atropine, 0.025% atropine, 0.01% atropine, and placebo groups, respectively (P < 0.001), with a concentration-dependent response. Corneal power remained stable, and its changes were similar across all atropine concentrations: –0.02 ± 0.14 diopter (D), –0.01 ± 0.14 D, –0.01 ± 0.12 D, and 0.01 ± 0.14 D in the 0.05% atropine, 0.025% atropine, 0.01% atropine, and placebo groups, respectively (P = 0.10). Lens power decreased over time in each concentration, but its changes also were similar across all concentrations: –0.31 ± 0.43 D, –0.38 ± 0.47 D, –0.40 ± 0.43 D, and –0.41 ± 0.43 D in the 0.05% atropine, 0.025% atropine, 0.01% atropine, and placebo groups, respectively (P = 0.24). Changes in ACD remained similar across all concentrations (P = 0.41). The contributions to SE progression from the ocular biometric changes after adjusting for age and gender in each concentration were similar across all groups (P > 0.05).

Conclusions

Low-concentrations of atropine (0.05%, 0.025%, and 0.01%) have no clinical effect on corneal or lens power. Antimyopic effects of low-concentration atropine act mainly on reducing AL elongation, and therefore could reduce the risk of subsequent myopia complications.