Usage patterns
目つきが〈形容詞〉to have a ~ look in one's eyes
He has a sharp look in his eyes.
〈形容詞〉目つきで〈人〉を見るto look at someone with a ~ expression in one's eyes
She looked at me with a scary look in her eyes.
目つきが変わるfor the look in one's eyes to change
The look in his eyes changed when he heard the story.