title: Baseline characteristics of nearwork-induced transient myopia.
abstract: OBJECTIVE
  The purpose of the present study was to describe the baseline refractive and nearwork-induced transient myopia (NITM) characteristics of the Beijing Myopia Progression Study, a 3-year cohort study, that has three overall specific aims: to investigate the natural history of NITM in schoolchildren living in the inner city of Beijing aged between 7 and 17 years; to investigate the possible relation between NITM and permanent myopia; and to determine the possible associations with NITM (eg, parental history).
  
  
  METHODS
  Three hundred eighty-six students (187 males and 199 females) were enrolled. The mean ages were 8.4 ± 1.1 years and 14.2 ± 1.6 years for the primary school and secondary school students, respectively. Baseline refractive aspects were determined clinically. Initial NITM and its decay were assessed objectively immediately after binocularly viewing and performing a sustained near task (5 minutes; 5 diopters [D]), incorporating a cognitive demand with full distance refractive correction in place.
  
  
  RESULTS
  Initial NITM (mean ± SD) / decay time (median, first quartile, and third quartile) was 0.18 ± 0.16 D / 50 (20, 90) seconds, 0.09 ± 0.13 D / 30 (10, 40) seconds, and 0.10 ± 0.19 D / 20 (10, 40) seconds among the myopic, emmetropic, and hyperopic students, respectively, for the combined school levels. Initial NITM and decay time were significantly larger/longer in the myopic versus the other two refractive groups.
  
  
  CONCLUSIONS
  The present findings demonstrate that in a large sample of school-aged children with myopia, the initial NITM magnitude was significantly larger and the decay duration was significantly longer than that observed in age-matched children with either emmetropia or hyperopia. Follow-up for the next 3 years will provide insight into the possible role of NITM in the development of permanent myopia.
authors.affiliation: Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Lin
authors.forename: Balamurali
authors.initials: B
authors.lastname: Vasudevan
authors.forename: Yuan Bo
authors.initials: YB
authors.lastname: Liang
authors.forename: Yi Cao
authors.initials: YC
authors.lastname: Zhang
authors.forename: Li Ya
authors.initials: LY
authors.lastname: Qiao
authors.forename: Shi Song
authors.initials: SS
authors.lastname: Rong
authors.forename: Si Zhen
authors.initials: SZ
authors.lastname: Li
authors.forename: Ning Li
authors.initials: NL
authors.lastname: Wang
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Ciuffreda
mesh_terms: D000065:Accommodation, Ocular; D000293:Adolescent; D002648:Child; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009216:Myopia / Q000175:diagnosis / Q000503:physiopathology*; D012029:Refraction, Ocular