Abstract
Purpose :
Myopia progression is typically measured through change in spherical equivalent (SER) and axial length, but SER progression is driven by underlying changes in one or more of the eye's biometric components. We investigated 2-year change in the contribution of axial length (AXL), corneal power (CP) and internal dioptric power (IDP) (lens power and anterior chamber depth) to SER using the refractive mechanism map.
Methods :
The Myopia Outcome Study of Atropine in Children (MOSAIC) is a double-blind, randomized placebo-controlled trial of 0.01% atropine eye drops in myopic Irish participants aged 6-16 years. SER was measured by autorefraction (WAM-5500, Grand Seiko, Japan) 30 minutes after instillation of 1% cyclopentolate. AXL and corneal radius were measured with Aladdin biometer (Topcon, Japan). Contributions of AXL, CP and IDP to SER were calculated using age and sex matched emmetropic eye data and change in each of these components assessed at the 12-, 18- and 24-month visits using linear mixed models with random intercept terms for eye, a visit-treatment interaction term and adjustment for the outcome's baseline value.
Results :
138 (81.4%) and 68 (81.9%) subjects assigned to the atropine 0.01% and placebo groups, completed the 24-month visit. There were no significant differences in age, sex, SER, and AXL, CP and IDP contributions to SER at baseline (all p>0.05). At 24 months, AXL contribution to SER was more negative in both groups but notably less myopic in the atropine 0.01% group (mean change = -0.45D, 95% confidence interval [CI]: -0.53, -0.37), compared to the placebo group (-0.60D, 95% CI: -0.74, -0.53; p=0.007). There was a slight positive change in CP contribution to SER (atropine 0.01% mean change = 0.05D, 95% CI: 0.03, 0.07; placebo mean change = 0.04D, 95% CI: 0.01, 0.07) and a slight negative change in IDP contribution to SER (atropine 0.01% mean change = -0.08D, 95% CI: -0.12, -0.04; placebo mean change = -0.02D, 95% CI: -0.08, 0.03), but changes were not significantly different between treatment groups (p=0.63 and p=0.07 respectively).
Conclusions :
Treatment with atropine 0.01% eye drops reduced AXL contribution to SER by about 0.15D relative to the placebo group and did not significantly impact CP and IDP contributions to SER. This indicates 0.01% atropine affects myopic progression primarily by altering axial length growth.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.