I am Dutch myself, and I don't see a single problem with this sentence. It can be used to refer to glasses (seeing as the Dutch for glasses is 'bril' and also singular (the plural is brillen)), but also to someone's eye. For instance if a little kid asks someone whilst pointing to a lady's eye: "Mama, waar is dat voor?" (=Mommy, what is that used for?), the mother could respond with: "Ze ziet ermee"
Thanks for your info, however can I ask about the sentence you made in your reply - "waar is dat voor?"; shouldn't is mean "where is that for?" or waar can both indicate locations as well as functions?
I am learning things from both the quiz and the comments and it is proved to work quite well for me. I will sincerely appreciate if you could kindly answer this question