To the Editor We thank Bountziouka et al1 for their cohort study investigating the trends in childhood visual function and its association with early-life social position in the United Kingdom. The authors reported an association between higher social position at birth and in childhood with reduced risk of visual impairment.
However, we must express concern that the selection of maternal education and paternal occupation as markers of prenatal and childhood social position, respectively, are crude and incomplete. It is commendable that both maternal and paternal factors were considered, but social position is a complex, multifactorial entity. For this reason, selection of these 2 factors alone might simply be misleading and inaccurate.2 We recommend including more direct measures, such as the form of schooling that the child received (state, grammar, or public). Alternatively, we recommend using indices for social position derived from multiple key measures (including parental employment, education, income, and/or geographical location of home accommodations), such as the Hollingshead Index.3 Either approach would more accurately encapture childhood social status.