It sounds to me like Ocular Migraine. I've suffered from it for years. I never, ever get headaches but the zig zag lines, which can rotate around your vision, sometimes blocking up to 90% of my vision can last up to one hour. They can be very frightening because from the time it starts, which is sometimes as a little bright dot, it can spread across your field of vision within seconds, in colors of red, black, white, yellow and lavender. Everything looks the same whether your eyes are opened or closed, just consumed with these flashing lights. In my case, afterwords Im disorientated and slow to focus or think, but do have her see an ophthalmologist (who specializes in diseases of the eyes) not an optometrist (who only does glasses). The chances are if she sees her doctor he'll refer her to a neurologist who'll send her for a cat scan or MRI, its pretty much standard procedure with her symptoms. Tell her not to worry, as my eye doctor says, relax....and watch the pretty colors!!!! Wish it was that easy!