An Unexpected Association between Childhood Hyperopia and Parental Smoking

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An Unexpected Association between Childhood
Hyperopia and Parental Smoking

• Dr Elaine YH Wong
• Ms Leanne Finch
• Dr Christine Chen
• Dr Lionel Kowal

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Background

• Effects of nicotinic antagonists on ocular growth
  and experimental myopia
• Stone RA, Sugimoto R, Gill AS, Liu J, Capehart C,
  Lindstrom JM
• Invest Ophthalmol Vis Sci. 2001 Mar42(3)557-65
• 1-week old chicks, injected with nicotinic
  antagonists Chlorisondamine mecamylamine
• Inhibition of ocular growth and shift of
  refraction towards hyperopia

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Background

• Childhood myopia and parental smoking.
• Saw SM, Chia KS, Lindstrom JM, Tan DT, Stone RA
• Br J Ophthalmol. 2004 Jul88(7)934-7.
• N1334, 8-11 yo school children
• Maternal smoking ? associated with hyperopic
  refraction in children (p0.03 but only 1.7 of
  mothers smoked)
• Paternal smoking is not associated with
  refractive error or axial length

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Background

• Associations between childhood refraction and
  parental smoking.
• Stone RA, Wilson LB, Ying GS, Liu C, Criss JS,
  Orlow J, Lindstrom JM, Quinn GE
• Invest Ophthalmol Vis Sci. 2006
  Oct47(10)4277-87.
• N323 from tertiary paediatric clinic
• If one or both parents ever smoked, their
  children had a lower myopia prevalence (12.4 vs.
  25.4 P 0.004) and more hyperopic mean
  refractions (1.830.24 vs 0.960.27 diopters P
  0.02)
• Smoking by either parent during the mothers
  pregnancy had a similar effect

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Background

• Prevalence of hyperopia and associations with eye
  findings in 6- and 12-year-olds.
• Ip JM, Robaei D, Kifley A, Wang JJ, Rose KA,
  Mitchell P
• Ophthalmology. 2008 Apr115(4)678-685.
• N 1765 (6 yo) N 2353 (12yo)
• Maternal smoking associated with moderate
  hyperopia in 6 yo but not 12 yo
• Smoking during pregnancy borderline significant
  with moderate hyperopia (p0.055)
• Not significant when controlled for ethnicity
• Moderate hyperopia is significantly associated
  with amblyopia, strabismus, poor stereoacuity and
  abnormal convergence

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The Pilot S tudy

• Aim
• To explore the relationship between hyperopia and
  parental smoking in a population who present to a
  subspecialty strabismus practice
• Methods
• Patients between the age of 0 -12 undergoing a
  cycloplegic retinoscopy were recruited
• A short questionnaire was administered to the
  accompanying parents
• Information regarding parental smoking status,
  gestational smoking status, parental refractive
  error and ethnicity were collected

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Results

• N 142 participants
• Mild hyperopia (0.25 - 1.75) 59
• Moderate hyperopia (2.00 - 5.75) 59
• Severe hyperopia (gt6.00) 15
• Myopia 8
• Mean age 5.29, SD 2.99, range 0-12y
• 52 female
• 21 of mothers smoke 16 smoked during pregnancy
• 26 of fathers smoke 32 smoked during pregnancy
• 32 have either parent smoking now
• 38 have a parent smoking during pregnancy

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Results
Adjusted for age ethnicity
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Discussion In this cohort

• Gestational smoking is NOT associated with
  hyperopia
• Having a mother who is smoking now increases the
  odds of moderate to severe hyperopia (gt3 DS) by
  nearly 20 fold
• Mother with myopia is protective of a child
  having gt moderate hyperopia

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Discussion

• This is a biased population and a small sample
• A larger study is required, hopefully from
  sources other than a private strabismus practice
• Relationship of smoking, hyperopia and strabismus
  will need to be explored
• If anyone like to contribute patients, please
  contact
• Lionel Kowal (strabism_at_netspace.net.au) or
• Elaine Wong (e.wong_at_unimelb.edu.au)