title: Effect of undercorrection on myopia progression in 12-year-old children.
abstract: BACKGROUND
  To prospectively observe the effects of undercorrection of myopia on myopia progression and axial elongation in a population of 12-year-old Chinese children.
  
  
  METHODS
  A total of 2,267 children in the Anyang Childhood Eye Study were examined at baseline, and 1,769 were followed for 1 year. Ocular examinations included cycloplegic autorefraction, axial length, visual acuity, vertometry, and accommodative lag. Questionnaires were completed by children and parents. Undercorrection of myopia was determined at baseline if presenting visual acuity could be improved by at least 2 lines with subjective refraction.
  
  
  RESULTS
  Of 253 myopic children with spectacles and available information, 120 (47.4 %) were undercorrected (-4.63D  to -0.50D) and 133 (52.6 %) were fully corrected. In a multivariate model adjusting for age, gender, number of myopic parents, time spent on near work and outdoor activities per day, usage and time for wearing spectacles per day, children with undercorrection had significantly more baseline myopia (P < 0.01) and longer axial length (P = 0.03) than children with full correction. However, there were no significant differences in myopia progression (P = 0.46) and axial elongation (P = 0.96) at 1 year between the two groups of children. The regression analysis showed that myopia progression significantly decreased with increasing amount of undercorrection (r (2) = 0.02, P = 0.02) in all children. Accommodative lag significantly decreased with increasing amounts of undercorrection (P < 0.01).
  
  
  CONCLUSIONS
  Based on this 1-year study in Chinese children, undercorrection or full correction of myopia by wearing spectacles did not show any differences in myopia progression or axial elongation.
authors.affiliation: Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Sciences Key Laboratory, Beijing, 100730, China.
authors.forename: Si Yuan
authors.initials: SY
authors.lastname: Li
authors.forename: Shi-Ming
authors.initials: SM
authors.lastname: Li
authors.forename: Yue Hua
authors.initials: YH
authors.lastname: Zhou
authors.forename: Luo Ru
authors.initials: LR
authors.lastname: Liu
authors.forename: He
authors.initials: H
authors.lastname: Li
authors.forename: Meng Tian
authors.initials: MT
authors.lastname: Kang
authors.forename: Si Yan
authors.initials: SY
authors.lastname: Zhan
authors.forename: Ningli
authors.initials: N
authors.lastname: Wang
authors.forename: Michel
authors.initials: M
authors.lastname: Millodot
mesh_terms: D000065:Accommodation, Ocular / Q000502:physiology; D044466:Asian People; D058452:Axial Length, Eye / Q000473:pathology; D002648:Child; D002681:China / Q000453:epidemiology; D018450:Disease Progression; D005139:Eyeglasses; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009216:Myopia / Q000175:diagnosis* / Q000208:ethnology / Q000628:therapy*; D011446:Prospective Studies; D011795:Surveys and Questionnaires; D014792:Visual Acuity / Q000502:physiology