In Rashi on Bereishit 28:13, there is an explanation as to why the text speaks of "the God of Isaac" even though Isaac is still alive. {text and translation from Chabad] }
ואלהי יצחק: אף על פי שלא מצינו במקרא שייחד הקב"ה שמו על הצדיקים בחייהם לכתוב אלהי פלוני, משום שנאמר (איוב טו טו) הן בקדושיו לא יאמין, כאן ייחד שמו על יצחק לפי שכהו עיניו וכלוא היה בבית, והרי הוא כמת, ויצר הרע פסק ממנו:
and the God of Isaac: Although we do not find in Scripture that the Holy One, blessed be He, associates His name with that of the righteous during their lifetimes by writing “the God of so-and-so,” for it is said (Job 15:15):“Lo! He does not believe in His holy ones,” [i.e., God does not consider even His holy ones as righteous until after their deaths, when they are no longer subject to the evil inclination,] nevertheless, here He associated His name with Isaac because his eyes had become dim, and he was confined in the house, and he was like a dead person, the evil inclination having ceased from him (Tanchuma Toledoth 7).
This seems to explain that being blind and housebound either causes the evil inclination to be removed, or that those 2 qualities, along with the removal of the evil inclination creates a status of "like a dead person."
Is there any halachic implication to that? Would someone visiting Isaac be tamei met? Would someone today who is blind and housebound (especially a tzaddik) be considered "dead" for any practical purposes?