ועיני לאה רכות אמוראי דר' יוחנן תרגם קודמוי ועיני לאה הוו רכיכין א"ל עינוהי דאימך הוו רכיכין ומהו רכות רכות מבכיה
"And Leah's eyes were 'rakot'" - one of R' Yochanan's interpreters translated this [to Aramaic] before him as "And Leah's eyes were [naturally] weak".
He [R' Yochanan] said to him: "Your mother's eyes were naturally weak. And what does 'rakot' mean? They were weak from crying [out of unhappiness that she was expected to marry Esav]."
(From Breishit Rabbah)