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;

Mean cycloplegic refractive error in emmetropic adults ¿ The Tehran Eye Study Jos J. Rozema; Rafael Iribarren; Hassan Hashemi; Mehdi Khabazkhoob; Akbar Fotouhi;

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