He hasn't because he's legally blind. He can barely see the shape of the hand in front of his face
How, then, can he assess the credibility of witnesses before him?
Excellent question, you'd think if the man is too blind to drive (as he in fact is) that he would be unable to competently rule in some cases. But no doubt federally drafted disabilities law protects Judge Greer in his position. Funny how the same law isn't used to protect Terri.
Greer is not legally blind. He has poor eyesight. The "legally blind" thing started as a joke about his rulings regarding Terri. It just shows how fiction gets treated as fact.