Secondhand smoke exposure may increase risk of early-onset myopia: Study

A new study published in the recent issue of BMC Ophthalmology journal showed that exposure to secondhand smoke (SHS) was linked to an increased risk of early-onset myopia.

In the past few years, myopia has become more common, and by 2050, it is predicted that 49.8% of people worldwide will have the disease. Along with myopia's rising incidence, younger people's early beginning of myopia also raises questions about their increased risk of acquiring extreme myopia.

Children who are exposed to SHS are more likely to develop meningitis, asthma, wheezing, respiratory tract infections, and sudden infant death syndrome. Although prior research has shown links between SHS exposure and myopia, the findings are still debatable. Therefore, Yuchang Lu and  team undertook this study to look at how secondhand smoke exposure affects the prevalence and risk of myopia in Chinese children who are not myopic.

This retrospective cohort included 232 kids between the ages of 5 and 10 in all, 128 of whom had been exposed to SHS and 104 of whom had not. Measurements were made of baseline parameters, including gender, age, weight, axial length (AL), average corneal K-reading (Ave-K), intraocular pressure (IOP), spherical equivalent refraction (SER), pupil diameter (PD), and subfoveal choroidal thickness (SFCT). The focus of follow-up evaluations at 3-, 6-, 9-, and 12-month visits was on SER and AL changes.

Parental and behavioral characteristics, such as parental myopia status, parental education level, and the amount of time spent outside and working close to the source each day, were gathered from medical records using questionnaires. To determine the variables that significantly affect axial elongation during a one-year period, linear regression was used.

This study found that, at −0.64 ± 0.41 D/year, the SHS group's mean spherical refraction myopic shift was substantially higher than the control group's (-0.47 ± 0.52 D/year). Axial elongation was substantially higher in the SHS group than in the control group.

The 12-month axial elongation was significantly predicted by SHS exposure, baseline SER, and parental myopia, according to multivariate linear regression analysis. Overall, children who are not myopic and are exposed to SHS are more likely to acquire early-onset myopia, which suggests that the public should pay more attention to the problem of SHS.

Reference:

Lu, Y., Li, X., Deng, Y., Wang, K., Li, Y., & Zhao, M. (2025). Secondhand smoke (SHS) exposure is associated with an increased risk of developing myopia among nonmyopic children in China. BMC Ophthalmology, 25(1). https://doi.org/10.1186/s12886-025-03890-7