When you say "Ocular Migraines" do you mean you experience something like zig-zaggy, flashing patterns in your vision that last some 10 to 30 minutes or more?

If so, I get those too. They suck.

Here's a few things I've learned that are triggers for me:

Too much coffee. I can't drink more than one cup in the morning. If I do, I increase the odds of getting one a lot.

Waiting too long to eat. If I get too hungry it will trigger one.

Stress. This is always a trigger.

Constipation. This too is a sure trigger.

Dehydration. While this may not be a trigger by itself, I've noticed it as a consistent enough factor to include it.

Too many hours staring at a computer monitor. This too is always a trigger, although, it may not occur until the day after I've done that.

A bright glare flashing into my eyes, like a flash of the sun off a windshield of a car will set one off, but only if I can point back to one of the above triggers.

Any combo of the above greatly increases the odds I'll get one. If I'm stressed, constipated or hungry, drink two cups of coffee in the morning, and don't take my vitamins, then sit down and stare at a computer monitor, I will most certainly get one.

As for prevention, aside from avoiding the above, I've found that taking two packets of "Emergen-C" vitamins every morning after I have my coffee, and before I eat anything, does more to help prevent them than anything else I've done. It instantly takes the "Edge" off the caffeine buzz and I can feel them working before I even finish drinking them. I mix both packets with just a couple ounces of water, stir until it quits fizzing, and drink it slowly, letting the vitamins absorb into my system while still in my mouth and on my tongue.

While this may not help you, I've also found that taking a small bit of codeine will dramatically reduce both the severity and duration of an event, but only if I take it as soon as I feel one coming on. For me, I know I'm getting one if I get a blurry spot, or tiny "Spark", in my vision. When I do take codeine, I take a small bit of a pill (1/4 or less) and let it dissolve on my tongue.

Codeine also helps a lot with the crappy feeling I get sometimes after I have an event, but does little to cut one short if taken when one is going on full blown.

I hope some of this will help you. I imagine that triggers and preventative measures and treatments may differ with individuals. It took me years to realize the few I mention that affect me.