Unseeing means looking without taking anything in. Unseeing eyes, stare unseeing, an unseeing gaze.
It is literary and describes shock, grief or deep distraction rather than blindness — the eyes are open and working and nothing is registering. It nearly always attaches to eyes or to a stare, and almost never to anything else.
1adjectiveunseeingLooking without taking anything in.
“She stared out of the window with unseeing eyes, lost in her grief.”
unseeing is a manner.
From un- + seeing.
Etymology from Wiktionary, CC BY-SA