my DS had his first eye appt at 3 years old (when my optometrist recommended first eye checkup). He looked at pictures on the wall and then into a computer machine.

The Dr was able to tell me DS' eyes are fine now but he'll need glasses in the future, probably when he is school age.

Headaches and squinting at things farther away could be signs of trouble seeing. I got glasses when I had trouble seeing the chalkboard in school.

of testing kids without the use of letters. and at my dd's ophthalmologist, they moved the pictures and told the kid to say when the two pictures met, and shit like this to determine when the vision gets blurry. it's kind of neat, actually. but you have to go to a place that specializes in kid/family eye care. i would suggest too that if the issue is cropping up now at 4, you check the eyes by an ophthalmologist, rather than an optometrist, to look for any deformities in the eye. if you have the coverage, that is.

needs to be able to tell them if it is clear of fuzzy. I think they use pictures so they don't need to be able to read.