title: Refractive errors.
abstract: BACKGROUND
  All over the world, refractive errors are among the most frequently occuring treatable distur - bances of visual function. Ametropias have a prevalence of nearly 70% among adults in Germany and are thus of great epidemiologic and socio-economic relevance.
  
  
  METHODS
  In the light of their own clinical experience, the authors review pertinent articles retrieved by a selective literature search employing the terms "ametropia, "anisometropia," "refraction," "visual acuity," and epidemiology."
  
  
  RESULTS
  In 2011, only 31% of persons over age 16 in Germany did not use any kind of visual aid; 63.4% wore eyeglasses and 5.3% wore contact lenses. Refractive errors were the most common reason for consulting an ophthalmologist, accounting for 21.1% of all outpatient visits. A pinhole aperture (stenopeic slit) is a suitable instrument for the basic diagnostic evaluation of impaired visual function due to optical factors. Spherical refractive errors (myopia and hyperopia), cylindrical refractive errors (astigmatism), unequal refractive errors in the two eyes (anisometropia), and the typical optical disturbance of old age (presbyopia) cause specific functional limitations and can be detected by a physician who does not need to be an ophthalmologist.
  
  
  CONCLUSIONS
  Simple functional tests can be used in everyday clinical practice to determine quickly, easily, and safely whether the patient is suffering from a benign and easily correctable type of visual impairment, or whether there are other, more serious underlying causes.
authors.affiliation: Aalen University of Applied Sciences, Competence Center Vision Research, Study Program Ophthalmic Optics; Department of Ophthalmology, T¨bingen University Hospital, T¨bingen.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Schiefer
authors.forename: Christina
authors.initials: C
authors.lastname: Kraus
authors.forename: Peter
authors.initials: P
authors.lastname: Baumbach
authors.forename: Judith
authors.initials: J
authors.lastname: Ungewiß
authors.forename: Ralf
authors.initials: R
authors.lastname: Michels
mesh_terms: D001251:Astigmatism; D005139:Eyeglasses; D005858:Germany; D006801:Humans; D015995:Prevalence; D012030:Refractive Errors; D014792:Visual Acuity