argus-eyed, hawk-eyed, keen-sighted, lynx-eyed, quick-sighted, sharp-eyed, sharp-sighted (adj)

having very keen vision

"quick-sighted as a cat"

argus-eyed, open-eyed, vigilant, wakeful (adj)

carefully observant or attentive; on the lookout for possible danger

"a policy of open-eyed awareness"; "the vigilant eye of the town watch"; "there was a watchful dignity in the room"; "a watchful parent with a toddler in tow"

argus-eyed (Adjective)

Ever vigilant.