Abstract
Purpose :
To classify myopia using the refractive mechanism map (RMM) model and determine the relationship between baseline myopia classification and 24-month change in spherical equivalent refraction (SER) and axial length, as well as atropine 0.01% treatment efficacy.
Methods :
The RMM calculates the contributions of each of the axial length, corneal power, and internal refractive power (predominantly lens) components to the measured refractive error. Myopia was classified by determining the dominant myopic component. A total of 250 European myopic children aged 6–16 years participated in The Myopia Outcome Study of Atropine in Children (MOSAIC) clinical trial between March 2019 and September 2023. Participants were randomly assigned 2:1 to use atropine 0.01% or placebo eye drops nightly for the first 2 years. Axial length and corneal curvature were measured with a biometer (Aladdin, Topcon, Japan) and refractive error using cycloplegic autorefraction. Statistical analysis was conducted using linear mixed models, including a 3-way interaction between visit, treatment, and dominant myopia component, adjusting for age and sex, and including random intercept terms to account for within-subject correlation.
Results :
At baseline, treatment groups were well balanced, and the mean (SD) age of participants was 11.8 (2.4) years, and 62% were female. Using the RMM, 213 (85.2%) participants were classified as axial myopes, 33 (13.2%) were corneal myopes, 3 (1.2%) had myopia from IRP, and 1 (0.4%) had missing data. At 24-months, 204 (82%) attended the visit (175 axial myopes, 28 corneal myopes, and 1 myopia from IRP). Compared to the axial myopia group, over 2 years, the corneal myopia group had 0.15D less myopia progression (p=0.06) and 0.08mm less axial elongation (p=0.01), after adjusting for age and sex. In the axial group, atropine significantly slowed axial length elongation (mean effect=-0.08mm, p=0.001) and SER progression (mean effect=+0.12D, p=0.01), but had no significant effect in the cornea group (axial length: mean effect=-0.03mm, p=0.51; SER: mean effect=-0.15D, p=0.18).
Conclusions :
Approximately 15% of participants enrolled in the MOSAIC clinical were not axial myopes. Axial myopes showed higher myopia progression on average, compared to corneal myopes, and had a stronger treatment response to atropine 0.01% eye drops.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.