JAMA Ophthalmology, December 2019
Yuan et al. assessed the relationship between choroidal thickness and secondhand smoke exposure in children between the ages of 6 and 8. They found that secondhand smoke correlates with choroidal thinning in an exposure-dependent manner.
For this study, the researchers included 1,400 patients recruited from the population-based Hong Kong Children Eye Study. All participants underwent detailed ophthalmic investigations, including measurement of choroidal thickness via swept-source optical coherence tomography. History of secondhand cigarette smoke was obtained from a questionnaire completed by parents or guardians. The correlation between choroidal thickness and exposure to secondhand smoke was assessed with multiple linear regression analyses, controlling for confounding factors.
Of the 1,400 participating children, 459 (32.8%) had been exposed to secondhand cigarette smoke. After adjustment for age, sex, body mass index, axial length, and birth weight, secondhand smoke was found to correlate with thinner choroidal parameters. When choroidal measurements were compared, those of smoke-exposed children were 8.3 μm thinner in the central subfield, 7.2 μm narrower in the inner inferior, 6.4 μm narrower in the outer inferior, 6.4 μm thinner in the inner temporal, and 7.3 μm thinner in the outer temporal.
Choroidal thinning was more common in families with multiple smokers and in homes with larger amounts of secondhand smoke. For each additional smoker, choroidal thinning increased by 7.86 μm in the central subfield, 4.51 μm in the outer superior, 6.23 μm in the inner inferior, 5.59 μm in the outer inferior, 6.06 μm in the inner nasal region, and 6.55 μm in the outer nasal region. Increasing exposure to secondhand smoke by one cigarette per day was linked to further choroidal thinning of 0.54 μm in the central subfield, 0.42 μm in the inner temporal sector, and 0.47 μm in the outer temporal sector.
Although these findings suggest that secondhand smoke is linked to choroidal thinning in children, the authors cautioned that the association does not necessarily indicate a causal effect. (Also see related commentary by Cécile Delacourt, PhD, in the same issue.)
The original article can be found here.