VISION PROBLEMS

I have a vision problem that shows up every so often, last time was 6 months ago and only lasts about five minutes, with no pain realated. I find that while reading a news paper or watcing TV, I will lose one or 2 letters in the beginning of a word or half a face.I tried closing each eye lid and still have the problem. Which leads me to believe it is in the brain.
I went for a eye examine a few months back and was told it was probaly a silent migraine.
I also supper from HFS ( hemo facial spasms) for about ten years, but have got that uder control for the last  two years.
My question:
is this a sign that I might be a canidate for a stroke down the line. I have no high blood pressure or hyp tension.
Thank you for your time and interest.
Jack H