WordNet sense 1 (exhibiting childlike simplicity and credulity):

childlike, simple, wide-eyed, dewy-eyed

WordNet sense 2 (marked by or showing unaffected simplicity and lack of guile or worldly experience):

naif, naive

WordNet sense 3 (having large round wide-open eyes):

saucer-eyed

WordNet sense 4 (having an eye or eyes or eyelike feature especially as specified; often used in combination):

eyed