Nine RCTs (1,464 children) were included in the review. Study quality was considered generally high; Jadad scores ranged from 3 to 5 out of 5. All studies reported appropriate methods of randomisation; most used allocation concealment and blinding. Only four trials used an intention-to-treat method of analysis, but follow-up and compliance rates were generally high. Follow-up ranged from six to 36 months (mean 20.1 months).
Compared to single vision lenses, multifocal lenses had a positive effect on refraction levels which was statistically significant (WMD 0.25D, 95% CI 0.13 to 0.38; nine trials). There was evidence of heterogeneity (Ι²=66%).
A statistically significant reduction in axial length was observed, favouring multifocal lenses (WMD -0.12mm, 95% CI -0.18 to -0.05; six trials). Evidence of heterogeneity was found (Ι²=65%).
Subgroup analyses showed that the positive effect of multifocal lenses on refraction was statistically significant in Asian children (six trials, p<0.00001) but not in Caucasian children (three trials). There was a significant reduction in refraction for children with low (under -3.0D) myopia (p=0.0007) and moderate (over -3.0D) myopia (p<0.00001), but those with moderate myopia had greater benefits. Results remained statistically significant at up to 24 months, but not beyond 30 months.