This thread is about a year old but I figured I would drop in my own 2 cents. I've had CH since puberty. Occular migraines started when I was around 30 or so. As others have described I have angular prismatic pulsing blind spots that I can see with my eyes closed. These seem to be a problem with my vision (brain) rather than the eyes themselves. I have these rarely when in a cluster cycle but I'll usually experience a few leading up to a cycle. I just now had my first occular issue in over a year (which prompted me to check the forum here and made it a pain to register as I couldn't see half my screen). This means I'm probably set for another cluster cycle this spring. I'll start another thread on that to track this cycle.
If it is any use to the OP, these seem to be harmless but I agree they are definitely scary. I've had to pull over when driving and wait them out because I couldn't see the road. Fortunately they tend to not last more than 20 minutes and spread slowly. Today's aura started in the lower left side of my vision and spread to take out most of the left side which then faded to just corners of my vision. 25 minutes and it is almost completely gone. When I'm in a full-blown CH cycle these often include the nausea and the restlessness I get from the headaches but today there was no pain or nausea. Lucky me... I only went legally blind for a half hour. As for causes or triggers I've noticed changes to my sleep patterns and stress seem to bring these on but the primary thing I notice is I get them at work when I've been staring at my monitor too hard for too long. I suspect I'm breathing too shallowly or even unconsciously holding my breath so there could be an oxygen connection. If I ever learn more I'll be sure to share it here.