There are a few different types of questions you should know. For my interview, some of the questions that I can remember were what the differences are between opticians, optometrists, and ophthalmologists, the difference between clinicians and technicians, what kind of things were going on in my home province at the time as well as issues about the profession in general. Make sure you're aware of the state of your profession in your province - i.e. if you're in BC, make sure you've read up on refracting by opticians, etc. Be prepared to answer questions like ?why optometry, and not __ (insert other healthcare profession here)?. I think that should about cover it.