Abstract
Purpose :
To compare myopia progression and axial elongation in children wearing +2.50 D add multifocal vs. single vision (SV) contact lenses to evaluate whether the treatment effect of optical myopia control is better for fast progressors or uniform across the range of myopia progression or axial elongation.
Methods :
The Bifocal Lenses In Nearsighted Kids (BLINK) Study randomized 294 children 7-11 years old to wear Biofinity soft contact lenses for three years in either a D-design with a +2.50 D add, +1.50 D add (not analyzed here), or SV. Cycloplegic refractive error, measured with the Grand Seiko WAM-5500, was between -0.75 D to -5.00 D (sphere, inclusive) at baseline with less than 1.00 D of astigmatism. Axial length was measured with the Haag-Streit Lenstar. Three-year myopia progression and axial elongation for SV (n=96) and +2.50 D add (n=95) groups were plotted against their cumulative frequency Z-scores with slopes estimated by linear regression (Brennan et al., 2021). The skew and kurtosis for three-year change were compared using p-values estimated by bootstrapping.
Results :
The slopes of the best fit lines in the Z-score plot for refractive error were statistically significantly different with an estimated 0.11 D less progression with +2.50 D add compared to SV contact lenses for every standard deviation increase in myopia progression (p=0.0003). There was no statistically significant difference in the slopes for axial elongation between +2.50 D add and SV contact lenses (p=0.10). The two treatment group distributions for either myopia progression or axial elongation were symmetric with similar standard deviations and no statistical evidence of differences in skew or kurtosis (p-values between 0.25 and 0.39).
Conclusions :
The myopia control benefit from wearing +2.50 D add contact lenses was generally uniform across the range of myopia progression and axial elongation. Differences between treated and control groups only varied by ±0.11 D across two standard deviations of myopia progression with no significant variation across the range of axial elongation. These variations were not large enough to create meaningful differences between treated and control group distributions of the three-year change. A uniform treatment benefit suggests that all children should be considered candidates for optical myopia control rather than prioritizing those at risk for fast progression.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.