Secondhand smoke increased the risk of myopia in childrenPassive smoking increased the likelihood of myopia in children. At younger ages, high myopia was also more likely to occur.
Researchers from the Chinese University of Hong Kong evaluated the effect of secondhand smoke on the development of myopia in children. The results of the study are published in JAMA NetworkOpen.
Secondhand smoke was associated with a 0.09 D decrease in spherical equivalent and a 0.05 mm increase in axial eye length. Smoking ten cigarettes per day reduced the spherical equivalent by 0.07 D and increased the axial length of the eye by 0.04 mm. The effects of secondhand smoke were more pronounced in younger children.
In addition, secondhand smoke exposure led to the onset of myopia at younger ages. Children exposed to secondhand smoke were 30% more likely to have moderate myopia and 2.64 times more likely to have high myopia. Increasing exposure to secondhand smoke by ten cigarettes per day increased the likelihood of moderate myopia by 23% and severe myopia by 75%.
The study included 12630 children, with an average age of 7.37 years. Exposure to secondhand smoke was 4,092. The analysis took into account gender, age, presence of myopia in parents, body mass index, amount of time spent outdoors, and family income. On average, people who lived with the participants smoked 10.5 cigarettes a day.
Myopia was considered mild if the spherical equivalent was -3.00 to -0.50 D, moderate if the spherical equivalent was -6.00 to -3.00 D, and severe if the spherical equivalent was below -6.00 D.