I’m very similar in that I get ocular migraines sometimes after more intense workouts/rides. It’s not just cycling but hard runs can trigger them as well. Only seem exercise related.
As others have said it does seem related to hydration/fuelling as I would notice them more if I’d had a boozy weekend and trained in a Monday or if I had not eaten/drank enough before or particularly after the ride i.e waited an hour for a main meal rather than having something straight after.
I think they have reduced somewhat since really focussing on the possible cause but still get them every now and again. Usually a couple of Aspirin as soon as I feel the symptoms and some carby/sugary food really reduces how bad they are and doesn’t stop me training the day after one which they used too.