Prenatal and childhood exposure to smoking and retinal nerve fibre layer thickness: A meta-analysis of three independent birth cohorts.
Linna Zhu, Inger Christine Munch, Samantha Sze-Yee Lee et al.
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In 30 seconds
This meta-analysis combined optical coherence tomography data from three independent Danish and Australian birth cohorts to assess retinal nerve fibre layer (RNFL) thickness in relation to prenatal and childhood smoking exposure. Prenatal smoking was associated with thinner peripapillary RNFL globally and across superior, nasal, inferior and temporal sectors. The largest reported cohort-specific deficits included inferior RNFL thickness of -10.4% (-16.7; -4.2%), p = 0.001, among participants exposed throughout pregnancy in COPSAC2000. The findings suggest an association between early-life smoking exposure and later RNFL status, but do not establish causation.
Key findings
- In COPSAC2000, exposure throughout pregnancy was associated with inferior RNFL thickness of -10.4% (-16.7; -4.2%), p = 0.001.
- In CCC2000, prenatal smoking was associated with an inferonasal RNFL deficit of -8.4% (-11.3; -5.4%), p < 0.001.
- In Raine Study Gen2, exposure to more than 10 cigarettes per day was associated with an inferonasal deficit of -8.9% (-13.0; -4.8%), p < 0.001.
- Combined analyses found global and sectoral RNFL deficits associated with prenatal smoking.
Why it matters
The findings link prenatal smoking exposure with measurable differences in retinal structure later in life across three birth cohorts. RNFL thickness may therefore be relevant when studying potential ocular correlates of early-life exposures. The results reinforce the importance of considering prenatal exposure history in research on later retinal status, while the observational associations do not show that smoking caused the differences.
What to keep in mind
The evidence is based on cohort data and therefore cannot establish that smoking caused the RNFL differences.