Secondhand smoke exposure linked to myopia in children

Secondhand smoke (SHS) exposure is associated with greater myopic refraction, longer axial length, and increased odds of developing moderate and high myopia, according to a study published online May 11 in JAMA Network Open.

Youjuan Zhang, Ph.D., from The Chinese University of Hong Kong, and colleagues examined the association between SHS exposure and childhood myopia using cross-sectional data from a population-based study involving 12,630 children aged 6 to 8 years.

The researchers found that 32.4 percent of the children had SHS exposure. SHS exposure was associated with greater myopic refraction and longer axial length (β = −0.09 and 0.05) after adjustment for age, sex, parental myopia, body mass index, near-work time, outdoor time, and family income. The likelihood of developing moderate and high myopia was increased for children with SHS exposure (odds ratios, 1.30 and 2.64, respectively).

In younger children, the association of SHS exposure with spherical equivalence and axial length was magnified; SHS exposure was associated with a 0.07-D decrease in spherical equivalence and a 0.05-mm increase in axial length for each younger year of a child's exposure to SHS. SHS exposure was associated with an earlier mean age at myopia onset (72.8 versus 74.6 months). Every 10-cigarette-per-day increase in SHS exposure was associated with greater myopic refraction (β = −0.07), axial length (β = 0.04), and odds of developing moderate and high myopia (odds ratios, 1.23 and 1.75, respectively), as well as earlier myopia onset (β = −1.30).

"Eliminating SHS exposure for eye care among children is important, particularly in families with young children," the authors write.

One author disclosed financial ties to the pharmaceutical industry.

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