I can't speak to this as I have never taken the Canadian boards but speaking to some classmates who did and did NOT pass, they said that essentially prescribing philosophy was different in Canada than in the USA. They claimed that they did not pass the case analysis section because for every patient who had some sort of binocular problem, they answered that the best treatment was vision therapy. The answer that was looked for was prism. ON the national board exam in the USA, the correct answer WOULD have been VT. When they retook the test and answered "prism" to every binocular vision question, they passed with flying colors.
It seems like the passing results of the Canadian optometry exam is probably not the best tool to use when judging the education of the various American optometry schools.