The epidemiology of refraction

Summary Both, ophthalmologist and vision researcher are aware that refractive errors are a major risk factor for the development of ocular diseases and therefore, their epidemiology is not only of interest for academia. The refractive state of an eye is determined by the distance between the position of the focal plane and the photoreceptor plane, when accommodation is relaxed. When focal plane and photoreceptor plane coincide, the refractive state is zero, a condition called emmetropia. If refractive errors develop, typical visual functions such as visual acuity or contrast sensitivity are affected, which results in blurry distance vision in the case of myopia. As myopia has become a major concern worldwide due to its increasing prevalence especially in Asian countries and with its known major implications on ocular health that also considerably affect the economy, epidemiological studies are especially focused on the elongation of the eye. This talk will summarize epidemiological findings regarding the development of all the ocular components that influence the refractive state (cornea, crystalline lens, axial length) and geographic (environmental) influences.