Greetings.
I am a PADI divemaster and believe that although you "may" wear contact lenses underwater, such is not at all adviceable. It is true that you may see with contacts, however, as with any Open Water Courses, you will be required to clear your mask underwater. The possibility of loosing your lenses remains very high.
Prescription / Degree enabled lenses (for masks) are available and cost aprox $100-200 for a set.
Hopes the above helps