What twin studies have taught us about myopia

Myopia has become epidemic, particularly in East Asia, and is a major cause of visual impairment worldwide. Twin studies are an important resource to investigate the genetics and the gene-environment interaction in myopia. This article aims to provide an overview of major findings regarding myopia from different types of twin studies, from the heritability of myopia-related traits to novel findings of genome-wide association studies. In the postgenomic era, twin studies will continue to serve as a unique method in the investigation of gene-environment interaction.