Not sure what kind of accident she had but if it effects her vision then I would go with L eye. Otherwise let her try both before you buy and let her decide which is comfortable.
I too suffer from this dominance problem, not only with eye but other sports and activities are also crossed. I slolum(spelling????) water sky left footed, skateboard L footed(100 years ago) lol. I can shoot a gun L or R and I have right handed bows and 1 L handed one. I shoot the most accurate right handed using a blinder over my L eye so I can keep both eyes open.
Oh yea and I use a Left handed mouse at work and at home
I say just let her be the judge:cocktail: :cocktail: