Ex.: I cannot describe perfectly because I saw it out of the corner of my eye. [Não posso descrever perfeitamente porque o vi de rabo de olho]
O Cambridge Dictionary of American Idioms mostra também outra forma equivalente: “from the corner of your eye also out the corner of your eye
not seen completely, only briefly noticed. Ex.: From the corner of his eye he thought he saw a large dog, but it was actually a coyote.”