<P> Global refractive errors have been estimated to affect 800 million to 2.3 billion . The incidence of myopia within sampled population often varies with age, country, sex, race, ethnicity, occupation, environment, and other factors . Variability in testing and data collection methods makes comparisons of prevalence and progression difficult . </P> <P> The prevalence of myopia has been reported as high as 70--90% in some Asian countries, 30--40% in Europe and the United States, and 10--20% in Africa . Myopia is about twice as common in Jews than in people of non-Jewish ethnicity . Myopia is less common in African people and associated diaspora . In Americans between the ages of 12 and 54, myopia has been found to affect African Americans less than Caucasians . </P> <P> In some parts of Asia, myopia is very common . </P> <Ul> <Li> Singapore is believed to have the highest prevalence of myopia in the world; up to 80% of people there have myopia, but the accurate figure is unknown . </Li> <Li> China's myopia rate is 31%: 400 million of its 1.3 billion people are myopic . The prevalence of myopia in high school in China is 77%, and in college is more than 80% . </Li> <Li> In some areas, such as China and Malaysia, up to 41% of the adult population is myopic to 1.00 dpt, and up to 80% to 0.5 dpt . </Li> <Li> A study of Jordanian adults aged 17 to 40 found over half (54%) were myopic . </Li> <Li> Some research suggests the prevalence of myopia in India in the general population is only 7% . </Li> </Ul>

Myopia is a condition of the eye where the crystalline lens focuses