Abstract
Purpose: :
To use meta-analysis to synthesize and compare treatment effects of various myopia intervention methods in children, including bifocal/progressive additional lens (PAL), pharmaceutical agents, regular single vision contact lens, corneal reshaping contact lens (CRCL) and new lens designs.
Methods: :
A thorough literature search for myopia intervention studies in children aged 6-16 yrs was conducted in PubMed, Scopus, VisionCite, and the Cochrane Library. 15 randomized myopia intervention trials with study durations of 10 mos-3 yrs and 3 2-yr CRCL studies with historical controls were included. The main outcome was myopia progression over the entire study period except for CRCL/RGP/soft contact lenses where the change in axial length was used. The overall treatment effect by intervention method was computed by averaging treatment effects of individual studies weighted by sample size and variability of the estimation. The treatment effect is given with its 95% confidence interval. The heterogeneity of progression rate with SVL, a commonly used control, across studies was tested using the Q-statistic.
Results: :
Pharmaceutical agents (atropine/pirenzepine n=4) had an overall myopia progression reduction of 0.42D (0.36, 0.49). For bifocal/PAL/multifocal (n=6), the reduction was 0.28D (0.20, 0.35). No treatment effect was found in soft/RGP contact lens (n=3), 0.04mm (-0.01, 0.10). Axial elongation (n=3) with CRCL was slower by 0.25mm (0.18, 0.32) than its control. 2 trials with new lens designs (dual focus soft contact lens and lenses to reduce peripheral hyperopia) had a reduction of 0.15D (0.08, 0.22). At 1-year, the treatment size trend by intervention method agreed with those with longer follow-ups. The progression rate for SVL ranged from 0.37D/yr to 0.93D/yr across studies, a significant variation (Q-test, p<0.001).
Conclusions: :
Most myopia intervention methods produced small to moderate treatment effects, with the largest effect found with atropine. The CRCL showed promising results but a randomized trial is needed. The big variation of progression rate in the controls of different trials implies that how to select controls may affect the size or even the direction of the treatment effect. Therefore, rigorous randomized clinical trials with a moderate period of follow-up are needed to confirm the efficacy of any new intervention methods.
Keywords: myopia • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials • clinical (human) or epidemiologic studies: biostatistics/epidemiology methodology