An Unexpected Association between Childhood Hyperopia and Parental Smoking

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

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 Mar;42(3):557-65 – 1-week old chicks, injected with nicotinic antagonists – Chlorisondamine & mecamylamine – Inhibition of ocular growth and shifting refraction toward hyperopia

Background

•

Childhood myopia and parental smoking

.

Saw SM, Chia KS, Lindstrom JM, Tan DT, Stone RA Br J Ophthalmol. 2004 Jul;88(7):934-7. – N=1334, 8-11 yo school children –

Maternal smoking is suggestive of being associated with hyperopic refraction in children (p=0.03; but only 1.7% of mother smoked)

– Paternal smoking is not associated with refractive error or axial length

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 Oct;47(10):4277-87. – N=323 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 (1.83

±0.24 vs 0.96±0.27 diopters; P =0.02)

– Smoking by either parent during the mother’s pregnancy had a similar effect

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 Apr;115(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 (p=0.055) • Not significant when controlled for ethnicity – Moderate hyperopia is significantly associated with amblyopia, strabismus, poor stereoacuity and abnormal convergence

The Pilot Study

• 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 parent[s] • Information regarding parental smoking status, gestational smoking status, parental refractive error and ethnicity were collected

Associations between Childhood Refraction and Parental Smoking

Patient’s cycloplegic refraction: Right Eye: _______________________ Left Eye: ___________________________

QUESTION 1.

Parents’ race (please tick): Father: Caucasian______Asian: ______ Mother: Caucasian: ______ Asian: ______ Other (please write): _____________ Other (please write): ______________

QUESTION 2.

Are either of the patient’s parents long or short-sighted (tick which)? Father: hyperopic _____ Mother: hyperopic _____ myopic _______ unknown: _____ myopic _______ unknown: _____

QUESTION 3.

Do either of the patient’s parents smoke? Father: yes / no / former smoker Mother: yes / no / former smoker

If both parents answered no to question 3, the questionnaire is now complete

.

QUESTION 4.

If yes, how long have you smoked for? Father 1: _______ years Mother: _______ years

QUESTION 5.

Did you smoke during the patient’s gestation? Father: yes / no

QUESTION 6.

If you have since quit, at what age was the patient when you stopped? Father: ________ years Mother: yes / no Mother: _________ years

Results

• N = 142 participants – Mild hyperopia (+0.25 - +1.75) = 59 – Moderate hyperopia (+2.00 - +5.75) = 59 – Severe hyperopia (>+6.00) = 15 – Myopia = 8 • Mean age = 5.29, SD = 2.99, Range 0-12yo • 52% female • 21% mother smoke; 16% smoked during pregnancy • 26% father smoke; 32% smoked during pregnancy • 32% have either parent smoking now • 38% have parent smoking during pregnancy

Parental Smoking Father Smoking Father ExSmoking

Mother Smoking

Mother ExSmoking Gestational Smoking Father Smoking Mother Smoking Refraction Father hyperopia Father myopia Mother hyperopia

Mother myopia

0.11 0.94 0.59 2.09

0.32

Odds Ratio 0.25 1.77 2.44

19.75

3.90 2.02 0.42 Adjusted for age & ethnicity

Results

95% CI 0.03-1.99 0.15-20.50 0.43-13.95

1.65-236.51

0.66-23.08 0.11-36.15 0.02-8.96 0.01-0.18 0.22-3.96 0.21-1.68 0.56-7.79

0.13-0.80

0.07 0.93 0.32 0.27

0.02

Significance 0.19 0.65 0.32

0.02

0.13 0.63 0.58

Discussion • Gestational smoking is NOT associated with hyperopia • Having a mother who is smoking now increases the odds of moderate to severe hyperopia (>+3 DS) by nearly

20 folds

• Mother with myopia is protective of a child having > moderate hyperopia

Discussion

• This is a biased population and a small sample • Larger study will be 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 ( [email protected]

) or Elaine Wong ( [email protected]

)