title: Myopia and myopic progression among schoolchildren: a three-year follow-up study.
abstract: OBJECTIVE
  To discuss the factors that might explain the rate of myopic progression and the degree of myopia after a 3-year follow-up among schoolchildren with myopia.
  
  
  METHODS
  Myopic progression among 238 schoolchildren was followed up in a randomized clinical trial of myopia treatment. The associations between the explanatory factors and myopic progression and the final value of the spherical equivalent after the follow-up were studied by analysis of variance and regression analysis.
  
  
  RESULTS
  Myopia progressed faster among girls than boys. According to the regression models for the boys, 25% of the variation of myopic progression and 57% of the final spherical equivalent could be explained by initial spherical equivalent, age at receiving first spectacles, time spent on sports and outdoor activities, and on reading and close work. Among the girls, 30% of myopic progression could be explained by age at receiving first spectacles, time spent on reading and close work, and reading distance. Similarly, 49% of the final spherical equivalent could be explained by age at receiving first spectacles, initial spherical equivalent, time spent on reading and close work, and reading distance. The rest of the variations could not be explained by the variables measured in this study.
  
  
  CONCLUSIONS
  The factors with the most significant relationships to myopic progression were sex, age of onset, and degree of myopia at the beginning of the follow-up. Myopic progression and final myopia were related to time spent on reading and close work and to reading distance but not, however, to accommodation stimulus.
authors.affiliation: Department of Ophthalmology, Central Hospital of Central Finland, Jyväskylä.
authors.forename: O
authors.initials: O
authors.lastname: Pärssinen
authors.forename: A L
authors.initials: AL
authors.lastname: Lyyra
mesh_terms: D000065:Accommodation, Ocular; D000367:Age Factors; D002648:Child; D003290:Convergence, Ocular; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008019:Life Style; D008137:Longitudinal Studies; D008297:Male; D009216:Myopia / Q000503:physiopathology* / Q000628:therapy; D011932:Reading; D012044:Regression Analysis; D012737:Sex Factors