Apparently, a blind kohen can't serve in the Mikdash:
The Sages taught in a baraita: When it is stated that a blind man [iver] is disqualified from performing the Temple service (see Leviticus 21:18), this applies whether he is blind in both of his eyes or blind in one of his eyes. With regard to a priest who cannot see due to pale spots on the eye or due to tears streaming from the eye that are constant, from where is it derived that he is disqualified? The same verse states: “A blind man [ish iver].” The superfluous word “ish” serves to include these conditions as well.
Eli was said to have had failing sight and eventually blindness in his final days:
"One day, Eli was asleep in his usual place; his eyes had begun to fail and he could barely see." (Shmuel 1:3:2)
"Now Eli was ninety-eight years old; his eyes were fixed in a blind stare." (Shmuel 1:4:15)
Is there any source that states that he stopped being acting Kohen Gadol at some point due to his blindness, or was he acting-Kohen Gadol1 until his death?
1 As opposed to kohanim who were considered inactive KGs, such as what Rabbi Meir says in Yoma 12b, or ex-KGs according to Rabbi Yossi; kohanim that served even for a short time as KG, perhaps because the official KG had some kind of temporary blemish that disqualified him until it healed or rectified.