to open the eyes (or ears): to bring the faculty of perception into action, whether by waking, granting sight, or turning one's gaze toward someone
This verb names one specific act: the opening of eyes. In nearly every verse it is eyes that are opened, and just once it is the ears (Isaiah 42:20). That narrow focus sets it apart from the ordinary verb for opening, פָּתַח, which opens doors, gates, mouths, wombs, and hands. When the text wants to speak of the organs of perception coming into use, it reaches for this word.
From that literal act the word moves naturally into the realm of perception. When God "opens" someone's eyes, the person suddenly sees what was there all along: the well that saves Hagar and her son, the fiery horses ringed around Elisha, or, in Eden, a painful new awareness of self. The eyes were never physically shut; what changes is that the person now perceives.
Two uses stand on their own. The prophets promise that God will open the eyes of the blind, a signature act of his saving work. And a recurring image speaks of God's own eyes being open toward people, a plea (or a warning) that he is watching, attentive to human need and to human wrongdoing alike.