Snails have eyes on the tips of their tentacles. In the case of the Pulmonates [lung breathers] who have two pairs of tentacles, the eyes sit at the tip of the top pair. Snails have very poor vision. Even though they have a lens on their eye, they have no muscles to focus the images.
Snails do not have colour vision, so their vision is in black and white, as well as being fuzzy. While their actual eyes might not be especially useful for seeing with, snails actually have light sense cells covering their entire bodies.