The refractions of children who were exposed to tobacco smoke differ from those of children who were not exposed, according to a study in Octobers Investigative Ophthalmology & Visual Science.1 Children exposed to smokingeven during pregnancytend to have less myopia and more hyperopia, according to researchers at Scheie Eye Institute in Philadelphia.

They evaluated a total of 323 patients (mean age: 8 years old). Half the participants had strabismus. All the participants parents filled out a detailed questionnaire on their smoking history and on potential risk factors for myopia. The researchers compared the results of each questionnaire to the childrens cycloplegic refractions.

Results showed that if the parents ever smoked, their children had a lower prevalence of myopia (12.4% vs. 25.4%) and more hyperopic mean refractions (1.83D +0.24D vs. 0.96D +0.27D). In addition, smoking by either parent during the pregnancy was found to have a similar effect on the childs refraction.

These links persisted even after adjusting for the childs age, parental myopia, parental education, nearwork activity, the childs body mass index and the severity of strabismus.

These findings conflict with an earlier study in Singapore conducted by some of the same investigators.2 That study found no evidence between parents smoking behavior and their childrens refractive error.2

However, the authors of the recent study conclude that nongenetic, environmental exposures may have long-term influences on refraction. Further study of the role of nicotinic acetylcholine receptors in refractive development is necessary, they say.

 

1. Stone RA, Wilson LB, Ying GS, et al. Associations between childhood refraction and parental smoking. Invest Ophthalmol Vis Sci 2006 Oct;47(10):4277-87.
2. Saw SM, Chia KS, Lindstrom JM, et al. Childhood myopia and parental smoking. Br J Ophthalmol 2004 Jul;88(7):934-7.