Second-hand smoke exposure increases risk of myopia among young children: JAMA

A paper published in the Journal of American Medical Association suggests that exposure to second-hand smoke (SHS) is associated with increased axial length, myopic refraction, increased likelihood of developing moderate and severe myopia.

Second-hand smoke can put your eye health at risk. However, its association with myopia is unknown. Therefore, Youjuan Zhang and his team conducted this study to investigate the association between her SHS exposure and myopia in children.

Cross-sectional data from the population-based Hong Kong Children's Eye Survey were used. Data were collected from 5 March 2015 to 12 September 2021 at the Center for Ophthalmology, The Chinese University of Hong Kong. Participants also included children aged 6 to 8 years. Exposure to secondhand smoke was assessed using a validated questionnaire. All participants underwent extensive ophthalmologic and physical examinations.

A generalized estimation formula was established to investigate the relationship between SHS exposure and spherical equivalent and axial length. Logistic regression model for myopia rate. Linear regression model for the onset of myopia.

The main results of this study are:

1. A total of 12,630 children were included in the analysis. Of the participants, 4,092 (32.4%) were exposed to her SHS.

2. Considering age, sex, parental myopia, BMI, time close to work, time outdoors, and family income, SHS exposure was associated with greater myopic refraction and longer axial length. .

3. Children exposed to SHS were at increased risk of developing moderate and severe myopia. The associations between SHS exposure and spherical equivalence and axial length were stronger in younger children.

4. 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 age at which children were exposed to SHS.

5. Exposure to SHS was associated with an earlier mean age (SD) at myopia onset.

6. Each increment of 10 lines per day in SHS exposure not only increased the myopic refraction and increased axial length, increasing the likelihood of developing moderate and severe myopia, but also increased myopia.

6. It was also associated with early onset.

In summary, the higher the SHS exposure and the younger the child, the more advanced the onset and progression of myopia associated with SHS exposure. For children's eye care, it is important to eliminate exposure to SHS, especially in homes with small children.

Reference:

Zhang, Y., Zhang, X. J., Yuan, N., Zhang, Y., Wang, Y. M., Tang, F., Ng, M. P., Wong, I. C. K., Ip, P., Kam, K. W., Young, A. L., Chen, L. J., Tham, C. C., Pang, C. P., & Yam, J. C. (2023). Analysis of Secondhand Smoke Exposure and Myopia Among Children Aged 6 to 8 Years in Hong Kong. In JAMA Network Open (Vol. 6, Issue 5, p. e2313006). American Medical Association (AMA). https://doi.org/10.1001/jamanetworkopen.2023.13006