title: A nationwide Danish study of 1027 cases of congenital/infantile cataracts: etiological and clinical classifications.
abstract: OBJECTIVE
  To study the distribution of congenital/infantile cataract in the entire population of Denmark according to etiological and clinical classifications.
  
  
  METHODS
  Population-based cohort study with retrospective chart review.
  
  
  METHODS
  All children (0 to 17 years old) who were born between 1959 and 2001 and registered with congenital/infantile cataract in Denmark during the period 1977 to 2001. Cases were ascertained from the mandatory Danish National Register of Patients, and all medical records were reviewed.
  
  
  METHODS
  Etiological and clinical classifications of the cataract cases were based on information from the medical records.
  
  
  METHODS
  Classification of congenital/infantile cataract according to presumed etiology; gender; clinical appearance, including laterality and morphology; and the time trends according to etiology and laterality.
  
  
  RESULTS
  A total of 1027 children with congenital/infantile cataract, 529 boys and 498 girls, were included, of whom 64% were bilateral. Males predominated with bilateral cataract, whereas females predominated with unilateral cases. Isolated cataract was the most frequent clinical presentation (71% of all cases), followed by an even proportion of cataract associated with additional ocular dysmorphology and cataract associated with systemic anomalies. Almost two thirds of all cases had an unknown etiology (idiopathic). Idiopathic cases showed a higher proportion of unilateral cataract and of additional ocular dysmorphology compared with cases of known etiology. The etiology was unknown in 87% of unilateral cases and in 50% of bilateral cases. The distribution by presumed etiology was stable during the study period, except for cataract caused by maternal infections, which decreased mainly due to the elimination of congenital rubella.
  
  
  CONCLUSIONS
  With the exception of the decline of congenital rubella, the proportion of congenital/infantile cataract cases of unknown, genetic, and infectious origins has been stable since the late 1970s. The causes of 87% of unilateral cataracts and 50% of bilateral congenital/infantile cataracts remain unknown, making the prevention of the disease a continuing challenge.
authors.affiliation: Department of Epidemiology Research, Danish Epidemiology Science Centre, Statens Serum Institut, Copenhagen, Denmark. bgd@ssi.dk
authors.forename: Birgitte
authors.initials: B
authors.lastname: Haargaard
authors.forename: Jan
authors.initials: J
authors.lastname: Wohlfahrt
authors.forename: Hans C
authors.initials: HC
authors.lastname: Fledelius
authors.forename: Thomas
authors.initials: T
authors.lastname: Rosenberg
authors.forename: Mads
authors.initials: M
authors.lastname: Melbye
mesh_terms: D000293:Adolescent; D002386:Cataract / Q000145:classification / Q000151:congenital* / Q000453:epidemiology* / Q000209:etiology; D002648:Child; D002675:Child, Preschool; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D012042:Registries; D012189:Retrospective Studies; D012307:Risk Factors