The relation between parental smoking and hypermetropia in children

Yair Morad Yuval Cohen and Lionel Kowal Assaf Herofeh Medical Center, Zrifin, Israel Royal Victorian Eye and Ear Hospital, Melbourne, Australia

Parental smoking inhibits child myopia

 Saw et al: less myopia in children of smoking mothers (-0.28 D v -1.38 D) BJO 2004  Stone et al: If one or both parents ever smoked, their children had a lower myopia prevalence (12.4% vs. 25.4%) IOVS 2006

Can parental smoking cause hypermetropia?  Maternal smoking associated with moderate hyperopia in six year old but not in 12 year old (N=4321) Ip et al Opthalmology 2008

Aim

 To examine the relation between exposure to parental smoking and the development of hypermetropia in children

Design

 The database of a Pediatric Ophthalmology Clinic was screened.

 1207 children with CR > 0.00D

 Only one child from each family was selected

 All parents underwent a telephone interview

The questionnaire

 Father of mother smoking now? In the past?  How many packets per day?

 Did mother smoke during pregnancy?

Children of farsighted parents were not included

Results

 1007 children included in the study  Mean age: 6.2 ± 3.6y (6mo - 17y)  Mean spherical equivalent: +3.0±2.3 D (0.0 - +12.75 D)

 Mothers  11% smoking today  6.6% smoked in the past  Fathers  21% smoking today  11% smoked in the past

Maternal smoking and child’s refraction

P=0.014

P=0.1

Maternal smoking during pregnancy 3 2 1 0 6 5 4 P<0.0001

Non (n=817) 0.2 (n=51) 0.5 (n=50) 0.75 (n=29)

Maternal smoking during pregnancy (PPD)

1 (n=27)

Parental smoking – not significant

Risk to develop esotropia

Mother: non-smoking 70/817 = 8.5% Age: 6.9 ± 3.39

Refraction : +5.2 Mother: smoking 17/122 =14% Age: 8.6

± 3.18

Refraction: +5.4

RR=1.63

Pilot study in Melbourne

 N = 142 participants  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

Results

 Significant association between smoking mother and child hypermetropia (Odd ratio 19.75, CI 95% 1.65-236.51, p 0.02)  Smoking mother increases the odds of moderate to severe hyperopia (>+3 D) by nearly 20 folds

Other studies

 Stone et al IOVS 2006  N=323  If one or both parents ever smoked, their children had more hyperopic mean refractions (1.83 0.24 vs.0.96 0.27 diopters;

P 0.02)

 El-Shazaly et al Ophthalmic & Physiological Optics 2012  N=300  Passive smoking exposure might be associated with hypermetropia

Smoking increases the risk for esotropia

 Tasmania, Australia (n=346)  Pediatric eye disease and Baltimore pediatric eye disease studies (n= 9970)  National Institute of Neurological Disorders and Stroke, Bethesda, Md (n= 39,227)

Possible biochemical mechanism for smoking –refraction interaction  Nicotine stimulate dopamine release

Retinal dopamine Eye growth

 Nicotinic antagonists injected to old chicks  inhibition of ocular growth  hyperopic shifting of refraction Stone RA et al IOVS 2001

Conclusions

1.

Maternal smoking increase the risk of hypermetropia in children 2.

The effect of maternal smoking is dose dependent.

3.

Cigarette smoking increase the risk of esotropia in children