Prevalence of refractive error within a Portuguese sample of optometric records Vera Lúcia Alves Carneiro; José Manuel González-Méijome;

Prevalence of refractive errors among school students in Iraq ¿ A systematic review and meta-analysis Hassan A. Aljaberi; I.R. Ali; Zaydoon Tariq M. Noori;

Prevalence of astigmatism among 99,515 children in different areas of Xi'an City, China Ye Zhang; Xiaokang He; Wei Dong; Zihao Wang; Chengfei Liu; Yanying Li; Zhaojiang Du;