I got my first migraine when I was 16. Can it cause partial loss of vision?

Temporarily. Scotomata and hemianopsia are common components of migraine. Visual illusions with progressive loss of half of the visual field is a common presentation for a migraine event. This usually recovers even before the headache begins. In women on birth control there have been reports of permanent loss of visual function due to ischemia of the occipital lobe of the brain. Fortunately, this is rare.