empty eyes; thousand-yard stare; blank gaze
Describes a lifeless, expressionless look, as if the person has lost all emotion or energy. Often used for someone who is exhausted, depressed, or emotionally drained.
After the long meeting, he had the eyes of a dead fish.
彼女の死んだ魚の目を見て、何かあったのかと心配になった。
Seeing her blank, lifeless eyes, I worried that something had happened.
Literally 'eyes of a dead fish'. The expression is a straightforward metaphor comparing a person's lifeless gaze to the dull, unseeing eyes of a dead fish.