It is estimated that some 2–6% of children in Western countries have strabismus which may lead to amblyopia and visual loss. Little is known about risk factors for strabismus but low birth weight has been an associated risk factor. A study of Danish data (Tobias Torp-Pedersen and colleagues. Int J Epidemiol 2010;39:1229–39) has shown several perinatal factors to be associated with later strabismus. …