title: The prevalence of amblyopia in Germany: data from the prospective, population-based Gutenberg Health Study.
abstract: BACKGROUND
  Amblyopia is due to insufficient development of the visual system in early childhood and is a major source of lifelong impairment of visual acuity. Too little is known about the prevalence of amblyopia in Germany and the frequency of its various causes.
  
  
  METHODS
  The Gutenberg Health Study of the University of Mainz Faculty of Medicine is an ongoing population-based, prospective, monocentric cohort study with 15 010 participants aged 35 to 74. All participants are examined for the presence of ocular, cardiovascular, neoplastic, metabolic, immunologic, and mental diseases. 3227 participants aged 35 to 44 underwent ophthalmological examination from 2007 to 2012. Amblyopia was defined as impaired visual acuity in the absence of any organic pathology capable of explaining the condition, and in the presence of a known risk factor for amblyopia.
  
  
  RESULTS
  Amblyopia, when defined as a visual acuity less than or equal to 0.63, was present in 182 participants (5.6%, 95% confidence interval [CI] 4.9-6.5%), 120 of whom had a visual acuity less than or equal to 0.5 (3.7%, 95% CI 3.3-5.2%). A narrower definition of amblyopia requiring, in addition, an interocular difference in acuity of at least two lines yielded slightly lower prevalence figures: 5.0% (95% CI 4.2-5.8%) and 3.7% (95% CI 3.1-4.4%), respectively. The causes of amblyopia (visual acuity ≤ 0.63) were anisometropia (different refractive strengths of the two eyes) in 49% of participants, strabismus (a squint) in 23%, both of these factors in 17%, and visual deprivation in 2%. 3 patients (2%) had relative amblyopia due to a traumatic cataract sustained in early childhood. 7% of the participants with amblyopia had binocular amblyopia.
  
  
  CONCLUSIONS
  This study yielded a prevalence figure of 5.6% for amblyopia in Germany-a higher figure than in other, comparable population-based studies, which have generally yielded figures of ca. 3% for visual acuity ≤ 0.63. The distribution of the causes of amblyopia is similar across studies.
authors.affiliation: Department of Ophthalmology at the University Medical Center of the Johannes Gutenberg University Mainz, Institute of Medical Biostatistics, Epidemiology and Informatics (IMBEI) at the University Medical Center of the Johannes Gutenberg University Mainz, Department of Germany Preventive Cardiology and Preventive Medicine, Center for Thrombosis and Hemostasis, German Center for Cardiovascular Disease (DZHK) at the University Medical Center of the Johannes Gutenberg University Mainz.
authors.forename: Heike M
authors.initials: HM
authors.lastname: Elflein
authors.forename: Susanne
authors.initials: S
authors.lastname: Fresenius
authors.forename: Julia
authors.initials: J
authors.lastname: Lamparter
authors.forename: Susanne
authors.initials: S
authors.lastname: Pitz
authors.forename: Norbert
authors.initials: N
authors.lastname: Pfeiffer
authors.forename: Harald
authors.initials: H
authors.lastname: Binder
authors.forename: Philipp
authors.initials: P
authors.lastname: Wild
authors.forename: Alireza
authors.initials: A
authors.lastname: Mirshahi
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000550:Amblyopia / Q000175:diagnosis* / Q000453:epidemiology*; D015984:Causality; D015897:Comorbidity; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D017678:Sex Distribution; D014792:Visual Acuity