Canada makes it very difficult to impossible for American ophthalmologists to practice there but not vice versa. You may find it impossible to get licensed. Canada requires an additional year of ophthalmology residency (not fellowship), though there are tricky ways to meet this requirement. Canadian fees are low but they compensate by having few malpractice lawsuits and keeping out new ophthalmologists from the major cities. The existing ophthalmologists will prevent new ophthalmologists, including Americans, from operating. That sort of behavior is illegal in the US but not in Canada.
That is why the US cannot pay for office visits like in Canada. The US doesn't allow existing doctors to shut out any new doctor.
Also, the original poster's tax information is wrong. Read the news in Canada. Doctors are mad at Prime Minister Justin for raising taxes on professionals, like doctors. Also be prepared to pay $4-5/gallon of gas and $6/gallon of milk, not 2.99-3.50/gallon and $1.79-2.50/gallon like in the US.
The Royal College exams are required and are difficult but every Canadian passes, unlike in the American boards. However, Americans taking the Royal College will find it very difficult to pass because Canadians have old questions saved up (unlike Americans, who generally do not cheat and save up ABO questions). Without old Canadian questions, it is difficult to impossible to pass. This is not a secret but well known to even the Royal College.