I don't know if there is any link, but I would guess that it is just co-incidence - does either parent (sorry don't know if you are mum or dad) wear glasses and/ or have astigmatism - astigmatism is very common - and I think that there is a genetic link as well. Most people with bad eyesight will have astigmatism to some degree.
Is there any particular reason that you want to know, presumably she needed the medication anyway, were you made aware of any possible side affects at the time, or do you think that the benefit of the absence of seizures out weighed the risk of having to wear glasses?
I think that the attitudes to glasses have changed a lot throughout the years and kids at school are much more accepting - In fact it is quite cool now according to my son. girls especially are keen to get some designer frames.
The frames they do now for kids are great and are mostly free - we go to optical express and my son has had some lovely designerglasses (he has "head" ones with the thick side frames at the moment) all free expect for an optional 12 pound for a scratch coating.
I wouldn't have thought that you should feel angry or guilty is the drugs did affect her eyes as she obviously needed them at the time.
Hope all goes well.