everythingisinorder

I'm a <teenage> female diagnosed with asthma and a seizure disorder NOS (complex partial seizures, no grand mal experiences). I've also always had fluctuating blood pressure, varying between fairly low and just about average.

Lately during exercise, I've had some interesting (and slightly disconcerting) experiences. In a karate class, while doing some aerobic exercise, I've been experiencing short bursts of bizarre vision changes. At first, I noticed myself slowing down a bit. I wasn't reacting as fast as I should to commands and my kicks lacked. Then, my vision would suddenly burst into an ultra-vivid array of pixel-like tiny squares. Kind of like looking at a sharp TV, just extremely close up. Certain colours jumped out at me, and I recall remarking in my head how many shades of blue and yellow I noticed. My head also buzzed a bit, and all sounds were thunderous but in a way didn't quite register in my head.

This occurred 4 times within an hour. After the first occurrence (about 20 minutes in to the class), it recurred about every 10 minutes.

The reason I don't post this in a subforum about asthma or epilepsy is because a) I had no breathing trouble, but I took my inhaler regardless after the first and second attacks, and it made no difference, and b) I am on anti-epileptic medication, but what auras I do recall were not like this.
In addition, the buzzing in my head was very similar to when I have bouts of extreme lightheadedness and uncontrollable laughter, both associated with my low blood pressure.

(It wasn't dehydration, either. My neurologist warns that I may dehydrate very quickly while on the medication, so I drink water every 10-15 minutes during exercise. I checked my lip at the time of the incident(s) for signs of dehydration, and found none. I drank some water regardless, and there was no effect; the other 3 episodes soon followed.)

So, my question for all: Would this type of vision change and such be associated with hypotension or hypertension? Some other kind of circulation issue? Or is there some direct link I am missing with one of my pre-diagnosed conditions to this experience?

Thank you kindly. :]

- Allison