Adam Clarke on Genesis 27:1

Isaac was old - It is conjectured, on good grounds, that Isaac was now about one hundred and seventeen years of age, and Jacob about fifty-seven; though the commonly received opinion makes Isaac one hundred and thirty-seven, and Jacob seventy-seven; but see note on Gen 31:55, etc.

And his eyes were dim - This was probably the effect of that affliction, of what kind we know not, under which Isaac now labored; and from which, as well as from the affliction, he probably recovered, as it is certain he lived forty if not forty-three years after this time, for he lived till the return of Jacob from Padan-aram; Gen 35:27-29.