title: Relationship between habitual refractive errors and headache complaints in schoolchildren.
abstract: OBJECTIVE
  Refractive error (RE) is considered to be a possible cause for headaches. We aimed to gain insight into the relation between habitual RE (sphere and astigmatism) and headache complaints.
  
  
  METHODS
  In a cross-sectional study the habitual refractive state of 487 children, aged between 11 and 13 years, was measured using an autorefractometer (Topcon, RM-8000B). Headache complaints were measured using a questionnaire. Data were analyzed using Pearson correlation coefficients, bivariate analysis, and multiple logistic regression analysis.
  
  
  RESULTS
  For right eyes we found 15% habitual myopia < -0.50 D and 12% habitual hyperopia > +0.50 D; habitual astigmatism > 0.25 D was found in 33% of children. Pearson R between right and left eyes was 0.76 for the spherical component and 0.42 for the cylindrical. In the total group of children 70% reported the occurrence of headache in the last year. These headaches were reported as "often or frequent" by 37% of children, "severe" by 15%, "with long duration" by 45%, and "with severe burden" by 27%. In the total sample we found various associations between gender, sphere/cylinder components of habitual RE, and headache complaints. Headache was reported more in girls than in boys. Of the total variance of headache complaints in girls, the sphere component of habitual RE explained 4% of frequency, 6% of intensity, 2% of duration, and 2% of amount of burden. Of the total variance of headache complaints in boys the cylinder component of habitual RE explained 3% of frequency, and 4% in amount of burden.
  
  
  CONCLUSIONS
  Habitual RE and headache complaints are relatively common conditions in schoolchildren aged between 11 and 13 years. Headache complaints showed a small but statistically significant association with the sphere component of habitual RE in girls and the cylinder component of habitual RE in boys. The associations found between habitual RE and headache complaints indicate that habitual RE might be a risk factor for headache in children.
authors.affiliation: Department of General Practice, University of Maastricht, The Netherlands. theo.hendricks@hag.unimaas.nl
authors.forename: Theo J W
authors.initials: TJ
authors.lastname: Hendricks
authors.forename: John
authors.initials: J
authors.lastname: DE Brabander
authors.forename: Frans G
authors.initials: FG
authors.lastname: van Der Horst
authors.forename: Fred
authors.initials: F
authors.lastname: Hendrikse
authors.forename: J André
authors.initials: JA
authors.lastname: Knottnerus
mesh_terms: D000293:Adolescent; D002648:Child; D003430:Cross-Sectional Studies; D005139:Eyeglasses; D005260:Female; D006184:Habits; D006261:Headache / Q000453:epidemiology / Q000209:etiology*; D006801:Humans; D008297:Male; D009426:Netherlands / Q000453:epidemiology; D015995:Prevalence; D011379:Prognosis; D012029:Refraction, Ocular / Q000502:physiology; D012030:Refractive Errors / Q000150:complications* / Q000453:epidemiology / Q000628:therapy; D011795:Surveys and Questionnaires