“And it was when Yitzchak grew old, his eyes dimmed and he could not see” (Bereishis 27). This teaches that anger causes loss of sight. Before this verse it says, “And they (the wives of Esav) were a source of bitterness for Yitzchak and Rivkah,” and after that it says, “Yitzchak grew old.” (Midrash Aggadah, parashas Toldos; Midrash Lekach Tov) Anger ruins the power of sight, as it says, “And my eye was smitten from rage” (Iyov 17). The verse also says (Tehillim 6), “My eye has been clouded from anger.” (Sefer Hamiddos)
