Secondhand Smoke Exposure Linked To Increased Risk Of Myopia In Children

New research has revealed a significant association between exposure to secondhand smoke and the development of myopia in children. The study published in JAMA Network Open conducted in Hong Kong by researchers from the Chinese University of Hong Kong, indicates that children exposed to secondhand smoke are more likely to develop moderate and high myopia, experience greater myopic refraction, and have longer axial length.

The cross-sectional analysis conducted by Zhang Y and team included participants aged 6 to 8 years from the Hong Kong Children Eye Study. The study found that children exposed to secondhand smoke exhibited an onset of myopia approximately two months earlier than children without exposure. The association between secondhand smoke exposure and myopia development was particularly pronounced in those with higher exposure levels and among younger children.

Participants underwent comprehensive ophthalmic and physical examinations, and validated questionnaires were used to evaluate secondhand smoke exposure. The study categorised children as either non-exposed or exposed based on the smoking behaviour of their family members. Ocular parameters such as spherical equivalent and axial length were assessed in relation to secondhand smoke exposure.

● After adjusting for various factors, including age, sex, parental myopia, body mass index (BMI), near-work time, outdoor time, and family income, the analysis revealed several significant associations.

● Children exposed to secondhand smoke exhibited greater myopic refraction and longer axial length.

● They were 1.30 and 2.64 times more likely to develop moderate and high myopia, respectively, compared to the non-exposure group.

● The findings contribute to our understanding of the genetic and environmental factors involved in myopia development, highlighting nicotine exposure as a potential risk factor.

● With up to 40% of children worldwide exposed to secondhand smoke, this research emphasizes the importance of investigating the impact of secondhand smoke on eye health.

The study identified significant interactions between age and secondhand smoke exposure. The association of secondhand smoke exposure with myopia severity and axial length was found to be more pronounced in younger children. Each additional year of exposure to secondhand smoke was associated with decreased spherical equivalence and increased axial length.

The study emphasizes the importance of considering secondhand smoke exposure as a potential risk factor for myopia in children. Healthcare providers should be aware of the association and discuss the potential risks with parents and caregivers. The findings also highlight the need for public health interventions to reduce secondhand smoke exposure in children.

The study acknowledges some limitations, including the reliance on current smoking quantity rather than long-term exposure duration. Nevertheless, the results support the hypothesis that greater exposure to secondhand smoke is associated with increased myopic refraction and axial length.

This study provides compelling evidence linking secondhand smoke exposure to an increased risk of myopia development in children. The findings underscore the importance of creating smoke-free environments and raising awareness about the potential ocular health risks associated with secondhand smoke exposure. By understanding and addressing these risk factors, healthcare professionals can contribute to the early detection and prevention of myopia in children.

Reference:

Zhang Y, Zhang XJ, Yuan N, et al. Analysis of Secondhand Smoke Exposure and Myopia Among Children Aged 6 to 8 Years in Hong Kong. JAMA Netw Open. 2023;6(5):e2313006. doi:10.1001/jamanetworkopen.2023.13006