yeah, i think they can. i'm not a vet or anything so i really don't know. but google that and see what comes up. i think they can come on suddenly. i think for now just make sure he's eating and all. with stuff like that, they don't actually die of the eye problem, they die of the side effects, like not being albe to catch food so they starve. so i don't really think theres' any rush. good luck!