Prenatal and childhood exposure to smoking and retinal nerve fibre layer thickness: A meta‐analysis of three independent birth cohorts

PURPOSE: To examine retinal nerve fibre layer (RNFL) characteristics in relation to prenatal and postnatal smoking exposure in three independent birth cohorts: two Danish and one Australian cohort. METHODS: A combined meta-analysis of peripapillary retinal nerve fibre thickness in the Copenhagen Prospective Studies on Asthma in Childhood 2000 cohort (COPSAC2000), the Copenhagen Child Cohort 2000 (CCC2000), and Generation 2 of the Raine Study, utilizing optical coherence tomography. RESULTS: Compared with participants not exposed to smoking (COPSAC2000 = 209, CCC2000 = 1008, Raine Study Gen2 = 991), 35 COPSAC2000 participants exposed to smoking throughout pregnancy had the most prominent deficits in peripapillary RNFL thickness in the inferior (-10.4% (-16.7; -4.2%), p = 0.001) and nasal (-10.0% (-18.3; -1.7%), p = 0.02) sectors, while 221 CCC2000 participants exposed to smoking had the most prominent deficit in the inferonasal sector (-8.4% (-11.3; -5.4%), p < 0.001), and 112 Raine Study Gen2 participants exposed to smoking (more than 10 cigarettes per day) had the most prominent deficit in the inferonasal sector (-8.9% (-13.0; -4.8%), p < 0.001). In a combined meta-analysis of the three cohorts, deficits in both the global and sectoral (superior, nasal, inferior and temporal) RNFL were observed from exposure to prenatal smoking. CONCLUSIONS: Prenatal smoking was associated with deficits in the peripapillary RNFL both globally and sectorally in combined meta-analyses of the three cohorts, which suggest an overall adverse effect of early life smoking exposure on later RNFL status.