title: Biometric changes in the eyes of Norwegian university students--a three-year longitudinal study.
abstract: OBJECTIVE
  The aim of this study was to investigate the changes in biometric measurements and corresponding refractive errors during a three-year period among university students exposed to high educational demands.
  
  
  METHODS
  A three-year longitudinal cohort study was performed among 149 Norwegian engineering students (79 females and 70 males, mean age 20.6+/-1.2 years) measuring their refraction and ocular dimensions at the beginning and at the end of the period. The examinations included refraction, keratometry, and A-scan ultrasonographic measurements of the ocular components, all made in cycloplegia.
  
  
  RESULTS
  After three years the mean refractive change was -0.52+/-0.45 D (p<0.05), which was accompanied by a change in lens thickness of 0.07+/-0.10 mm (p<0.05), and a vitreous chamber elongation of 0.27+/-0.30 mm (p<0.05). The results refer to the right eye. Stratification of the sample based on their initial refraction (myopes, emmetropes, and hyperopes) showed refractive change towards myopia for all subgroups as well as a significant increase in lens thickness and vitreous chamber depth. No significant three-year change in anterior chamber depth or corneal curvature was found in any of the groups. For all groups, vitreous chamber elongation gave a notable dioptric change in myopic direction.
  
  
  CONCLUSIONS
  A shift in refraction towards myopia after puberty is accompanied by vitreous chamber elongation which can explain the dioptric change in myopic direction.
authors.affiliation: Department of Ophthalmology, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim. bkinge@online.no
authors.forename: B
authors.initials: B
authors.lastname: Kinge
authors.forename: A
authors.initials: A
authors.lastname: Midelfart
authors.forename: G
authors.initials: G
authors.lastname: Jacobsen
authors.forename: J
authors.initials: J
authors.lastname: Rystad
mesh_terms: D000328:Adult; D000375:Aging / Q000473:pathology; D000869:Anterior Eye Segment / Q000000981:diagnostic imaging / Q000473:pathology; D001699:Biometry / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007908:Lens, Crystalline / Q000000981:diagnostic imaging / Q000473:pathology*; D008297:Male; D009216:Myopia / Q000175:diagnosis* / Q000209:etiology; D009664:Norway; D012029:Refraction, Ocular; D012189:Retrospective Studies; D013334:Students; D011795:Surveys and Questionnaires; D014463:Ultrasonography; D014495:Universities; D014822:Vitreous Body / Q000000981:diagnostic imaging / Q000473:pathology*