Many of us have had visual disturbances, double vision, occular (also called atypical) migraines and other visual phenomena, both before and after surgery. You want to rule out eye disease or damage, and strokes. After that, it just falls into the murky occular migraine category. It's not impossible that you have a separate and important issue, but the general experience here is that it comes and goes, but doesn't seem to amount to anything but a bother in the end.
Please go to an ophthalmologist first. The cardiologist will either send you there or to a neurologist. However, it will likely be a neurologist, as he won't know any ophthalmologists. They travel in different circles.
I am not looking to knock neurologists, but if you read their tortured literature about occular migraines, migraines in general, and related symptoms on the web, you will likely come to the conclusion (as I did) that they are still in the dark ages as far as causation and prevention of that particular problem. They are in chaotic disagreement with each other about the entire subject. The web is chock-full of migraine theories, discussions, and arguments, and easily supports that viewpoint.
If you go to the ophthalmologist first, s/he can rule out mircovascular blockages in your eyes, eye damage or disease, and other pressing physical optical possibilities which a neurologist is not equipped to do.
If you then wish to continue to a neurologist, you will at least know the eyes themselves are functional.
Best wishes,