title: Is there a link between passive smoke exposure and early-onset myopia in preschool Asian children?
abstract: To investigate the association of passive tobacco smoke exposure with early-onset myopia among three-year-old children in Singapore.
  
  
  
  Pregnant mothers who attended their first trimester clinic at two major maternity units were recruited into the GUSTO birth cohort. The current analysis comprised 572 three-year-old children, who underwent cycloplegic autorefraction and axial length (AL) measurements. Myopia was defined as spherical equivalent (SE) of ≤-0.50 dioptres (D). Either parent completed questionnaires describing their child's exposure to passive smoke at six months, one and two years of age.
  
  
  
  There were 197 children (36.2%) who were exposed to passive smoke from birth to before six months. Compared to non-exposed children, children exposed to any passive smoke from birth to before six months experienced greater myopia prevalence (adjusted OR = 2.79; 95% CI: 1.24-6.29; p = 0.01). The odds of myopia in a child was greater if a smoker smokes at home, in the family car, or in the presence of the child (adjusted OR = 3.95; 95% CI: 1.41-11.09; p < 0.01) compared to non-exposed child. In contrast to myopia, childhood exposure to passive smoke did not systematically shift mean values for SE or AL.
  
  
  
  In this prospective birth cohort study, we found that childhood exposure to passive smoke from birth to before six months slightly increased the risk of early-onset myopia. This may indicate a delayed response to passive smoke exposure before six months and the development of myopia at three years of age. Our study is limited by the small number of myopic children at this young age. Thus, larger prospective studies using more objective cotinine level measures are required to fully establish and understand the influence of tobacco smoke on refractive development in older children.
authors.affiliation: Saw Swee Hock School of Public Health, National University of Singapore, Singapore, Singapore.
authors.forename: Sharon Yu Lin
authors.initials: SY
authors.lastname: Chua
authors.affiliation: Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore.|DUKE-NUS Graduate Medical School, School of Public Health, Singapore, Singapore.
authors.forename: Mohammad Kamran
authors.initials: MK
authors.lastname: Ikram
authors.affiliation: Saw Swee Hock School of Public Health, National University of Singapore, Singapore, Singapore.
authors.forename: Chuen Seng
authors.initials: CS
authors.lastname: Tan
authors.affiliation: University of Pennsylvania School of Medicine, Philadelphia, USA.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Stone
authors.affiliation: Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore and National Health System, Singapore, Singapore.
authors.forename: Shirong
authors.initials: S
authors.lastname: Cai
authors.affiliation: Singapore Institute for Clinical Sciences, Agency for Science and Technology (A'STAR), Singapore, Singapore.|Liggins Institute, University of Auckland, Auckland, New Zealand.
authors.forename: Peter D
authors.initials: PD
authors.lastname: Gluckman
authors.affiliation: Department of Obstetrics & Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore and National Health System, Singapore, Singapore.|Singapore Institute for Clinical Sciences, Agency for Science and Technology (A'STAR), Singapore, Singapore.
authors.forename: Seng Chong
authors.initials: SC
authors.lastname: Yap
authors.affiliation: Department of Paediatric Endocrinology, KK Women's and Children's Hospital, Singapore, Singapore.
authors.forename: Fabian
authors.initials: F
authors.lastname: Yap
authors.affiliation: Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore.|DUKE-NUS Graduate Medical School, School of Public Health, Singapore, Singapore.|Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
authors.forename: Tien-Yin
authors.initials: TY
authors.lastname: Wong
authors.affiliation: Department of Ophthalmology, National University Hospital, Singapore, Singapore.
authors.forename: Cheryl S
authors.initials: CS
authors.lastname: Ngo
authors.affiliation: Saw Swee Hock School of Public Health, National University of Singapore, Singapore, Singapore.|Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore.|DUKE-NUS Graduate Medical School, School of Public Health, Singapore, Singapore.
authors.forename: Seang-Mei
authors.initials: SM
authors.lastname: Saw
mesh_terms: D017668:Age of Onset; D002675:Child, Preschool; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009216:Myopia / Q000453:epidemiology* / Q000209:etiology; D015995:Prevalence; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology*; D018570:Risk Assessment; D012307:Risk Factors; D012846:Singapore / Q000453:epidemiology; D011795:Surveys and Questionnaires; D013997:Time Factors; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
chemical_list: D014028:Tobacco Smoke Pollution
keywords: axial length; myopia; passive smoke; spherical equivalent; young children