As already mentioned you will find nothing in the regs (CAR 424) about keratoconus. That's in part because in Canada, Aviation Medical Examiners do not have the authority to grant medical certificates. The most they can do is to extend the validity period of an existing one. This is very different than in the US where an AME can issue you a medical certificate on the spot.
So in Canada, the AME simply examines you against the standard in 424, which requires normal vision with no diseases or other abnormalities. The AME then prepares a report and sends it in to Transport Canada Civil Aviation Medicine (CAM) for evaluation by Transport Canada's medical staff. This process usually takes several weeks.
Any abnormality, including keratoconus, will then be considered by CAM doctors on a case-by-case basis. They'll want to see a lot of evidence / documentation that your condition is stable and without other complications before issuing you a medical certificate.