Secondhand smoke bad for eye health in children

Children exposed to secondhand smoke (SHS) appear to have a thinner peripapillary retinal nerve fibre layer (p-RNFL), which in turn contributes to an increased risk of irreversible visual impairment in the future, a study has found.

The study used data from the from the population-based Hong Kong Children Eye Study and included 3,103 school children aged 6–8 years. All children underwent comprehensive ophthalmic examinations, with p-RNFL thickness assessed using spectral domain optical coherence tomography.

In total, 1,097 children (35.4 percent) had exposure to SHS. Compared with nonexposed children, those with SHS exposure had similar age (p=0.83), gender (p=0.17), birth weight (p=0.23), body mass index (p=0.44), axial length (p=0.34), but had lower family income (p<0.001) and lower parental education level (p<0.001).

SHS exposure was associated with a decrease of 4.4 μm in p-RNFL thickness (p<0.001). Other factors associated with a thinner p-RNFL were a higher number of smokers in the family (p<0.001) and greater quantity of SHS (p<0.001).

Being the only part of central nervous system (CNS) that can be directly visualized, RNFL is a putative biomarker of axonal damage. The findings suggest that toxicity from SHS can adversely affect CNS development.

More studies are warranted to establish whether the p-RNFL thinning will slow down, stop, or even be reversed after SHS exposure is halted.