Abstract
Purpose :
The 3-year Low-Concentration Atropine for Myopia Progression (LAMP) Study has greatly enhanced knowledge of the use of low-concentration atropine for myopia control. Because the year 1 control group in the LAMP Study was switched to treatment in years 2 and 3, long-term efficacy could not be directly calculated.
Methods :
Our recent meta-analysis of over 80 studies of axial elongation among untreated myopic children concludes that it slows by an average of 15.0% per year (95% CI of 11.4% to 18.4%). We used this 15% slowing per year to predict axial elongation in years 2 and 3 and the 3-year cumulative absolute reduction in axial elongation for each concentration of atropine. The 3-year slowing of myopia progression was also calculated by applying a ratio of progression to elongation derived from the untreated participants in years 1 and 3.
Results :
The 93 children initially assigned to placebo elongated by 0.41 mm in year 1. Applying 15% slowing per year predicts elongation of 0.35 and 0.30 mm in years 2 and 3, respectively, projecting a cumulative untreated 3-year axial elongation of 1.05 mm (Figure 1). The mean axial elongation among the 127 children completing the year-3 washout was also 0.30 mm. The axial elongation for children treated throughout the 3-year study with 0.05%, 0.025%, and 0.01% atropine was 0.50, 0.74 and 0.89 mm, respectively (Figure 1). Thus, the corresponding 3-year cumulative absolute reduction in axial elongation is 0.55, 0.31, and 0.16 mm. The 93 untreated children in year 1 progressed by –0.81 D and elongated by 0.41 mm—a ratio of –1.98 D/mm. Additionally, the 127 untreated children in year 3 progressed by –0.61 D and elongated by 0.30 mm—a ratio of –1.99 D/mm. Applying either of these ratios to the 3-year untreated axial elongation of 1.05 mm gives a 3-year progression of –2.09 D. Comparing this with the mean progression among those treated continuously for 3 years, yields projected 3-year slowing of progression of 1.36, 0.78, and 0.49 D for 0.05%, 0.025%, and 0.01% atropine, respectively.
Conclusions :
Applying a 15% annual slowing of axial elongation from a comprehensive meta-analysis allows prediction of the 3-year efficacy of low-concentration atropine in the LAMP Study.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.