Temporary loss of vision

What causes temporary loss of vision? my episodes last a few seconds and last one was 12 seconds. i have been to optimologist ans neurogolist and they both found nothing and mri was clear.Do you have any suggestions?

[Sandra M Brown, MD]

Well, ideally we would have a lot more information about your vision loss spells.  But with two normal examinations, the most likely causes are 1) postural hypotension, where your blood pressure drops when you go from sitting to standing and temporarily your occipital cortex is deprived of blood and stops processing vision signals, or 2) migraine, which can cause vision loss without headache, although not usually for just a few seconds.  If this can happen without a posture change, and if you have other sensations such as dizziness, weakness or disorientation during these brief spells, then possibly there is some interruption of the blood flow to the entire back of the brain.  This would need to be assessed with an MRA or a CT angiogram.

[domo1996]

i have been reading up on postural hypotension and they say it happens after exercising then standing still and standing up from sitting. most of mine have been after exercising/tumbling at cheer practice. The neurologist has me on Keppra because he thinks it might be seizures. I still have episodes just not as frequent. What do you think?