The prevalence of myopia is high and increasing: it is now around 25% in USA and Europe, but up to 70% in parts of Asia. Myopia poses significant socioeconomic problems. In addition to the cost of spectacles or contact lenses it increases the risk of glaucoma and cataract. High myopia also increases the risk of retinal detachment, retinal degeneration and visual impairment, and imposes an increasing burden on our health system. Myopia is characterized by blurry distance vision; it results from abnormal enlargement of the eye. The causes are poorly understood, but they include genetic and environmental factors.