title: Optic nerve hypoplasia in children and adolescents; prevalence, ocular characteristics and behavioural problems.
abstract: OBJECTIVE
  To report prevalence, ocular characteristics and coexisting behavioural problems in children and adolescents with optic nerve hypoplasia (ONH), which is a common cause of visual impairment in children in western countries, often associated with neurological or endocrinological problems and where autism has been reported in severe cases with blindness.
  
  
  METHODS
  This is a population-based cross-sectional study of patients <20 years of age who had been diagnosed with ONH and lived in the county of Stockholm in December 2009. Ophthalmological assessments including fundus photographs with optic disc analyses were made. A questionnaire was used to screen for behaviour and development.
  
  
  RESULTS
  The prevalence of ONH in all living children <18 years of age in Stockholm was 17.3/100 000 with a prevalence of visual impairment (<0.3) of 3.9/100 000. In total, 66 patients, median age 9.3 years (0.6-19.4), 36 with bilateral and 30 with unilateral ONH, were included in the current study; 53 were re-examined clinically, group A, and 13 agreed to retrospective analyses of existing medical records, group B. Analyses of the optic discs were made in fundus photographs from 53 patients comparing a semi-automated (Retinal Size Tool) and a manual method (Zeki). There was a strong curvilinear correlation (r(S)  = -0.91 p < 0.0001 for both eyes). Behavioural problems were more common (p < 0.05) in bilateral ONH.
  
  
  CONCLUSIONS
  Optic nerve hypoplasia is a common ocular malformation with a prevalence of 17.3/100 000 children and adolescents <18 years of age in Stockholm. Unilateral ONH seems as common as bilateral.
authors.affiliation: Department of Clinical Neuroscience, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden; Department of Paediatric Ophthalmology and Strabismus, St. Erik Eye Hospital, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Kristina
authors.initials: K
authors.lastname: Teär Fahnehjelm
authors.forename: Sara
authors.initials: S
authors.lastname: Dahl
authors.forename: Lene
authors.initials: L
authors.lastname: Martin
authors.forename: Ulla
authors.initials: U
authors.lastname: Ek
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior; D002648:Child; D002652:Child Behavior; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D001523:Mental Disorders / Q000175:diagnosis / Q000453:epidemiology*; D009898:Optic Disk / Q000473:pathology; D009901:Optic Nerve Diseases / Q000151:congenital* / Q000175:diagnosis / Q000453:epidemiology; D015995:Prevalence; D012189:Retrospective Studies; D011795:Surveys and Questionnaires; D013548:Sweden / Q000453:epidemiology; D014792:Visual Acuity / Q000502:physiology; D058609:Visual Field Tests; D055815:Young Adult
keywords: behaviour; disc area; optic nerve hypoplasia; prevalence