Commentaire sur Le Deutéronome 34:7

לא כהתה עינו HIS EYE WAS NOT DIM — even after he had died (Sifrei Devarim 357:34).

בן מאה ועשרים שנה במותו. he was 120 years old at his death. This means that at the precise moment his soul left him Moses had completed 120 years. Another nuance the Torah may have in mind by writing the word "at his death" is that seeing the Torah reported only afterwards that neither Moses' eyesight nor his vigor had diminished that this statement was true up until the moment Moses died.

לא כהתה עינו, “his eyesight had not become weaker.” This is actually a reference to the rays of light which the skin of Moses’ forehead emitted, a gift which he had brought with him from Mount Sinai (Exodus 34,29). The word עין here does not mean “eye,” but means the same as in the description of the properties of the manna which the Torah described as “like the sparkling, i.e. עין of ‘bedolach’” in apperance (a gemstone called “crystal” by Rashi in Numbers 11,7). Another instance where the word עין does not mean “eye,” though it appears so at first glance, is found in Ezekiel 1,22 כעין הקרח הנורא. It can hardly mean “as the terrible eye of the ice,” but must mean: “as the sparkle of the awesome ice.”