Or HaChaim on Genesis 35:28/אור החיים על בראשית ל״ה:כ״ח

1 ויהיו ימי יצחק מאת שנה ושמונים שנה, Isaac lived to be one hundred and eighty years old. The reason that the Torah does not add אשר חי, "which he lived," as it did when reporting Abraham's death or Jacob's death or even Joseph's death, may have been that from the day of his birth until the time he was bound on the altar no wife had been assigned to Isaac; our sages in Kohelet Rabbah section 9 state that anyone who lives without a wife is not really considered as "living." On the other hand, our sages also say that as a result of the עקדה Isaac began to lose his eyesight (Bereshit Rabbah 65,10). A person who is deprived of his eyesight cannot be described as truly "alive."

2Alternatively: since he did not bring חיים with him on his way to the עקדה, the Torah did not see fit to mention the word חיים in his connection.