I'd get a second opinion from another ophthalmologist and get the neurologist involved, too.
I am a retired ophthalmologist. I agree that you should get a second opinion. However, your daughter may have experienced the temporary (20 minutes or so) of an ophthalmic migraine. The experience is called a scintillating actions. It may and often does occur without the headache. Migraine headaches usually occur insensitivity to light (photophobia.) They frequently run in family's and can occur early in life. If you do some research and discuss it with your doctor it may help. An ophthalmic migraine has very diagnostic characteristics. Good luck.
Sorry. This system corrected my spelling incorrectly.
Temporary blindness of an ophthalmic migraine
Scintillating scotoma
Those are key to your research. Give us follow-up.