Ah. With my daughter it's a slight squint that she should grow out of. Apparently when the eye is turned at a certain angle towards the nose, the optic nerve head is more likely to be caught by the flash and it just so happens that my child's eye naturally turns that way as a matter of course, so from certain angles it shows up white.
I wish I could be like you and not worry about things like this lol. I guess I am a bit of a pessimist ... still, nothing like being terrified your baby has cancer for four weeks to bring about a change in attitude. The outcome could have been awful and I am so grateful it wasn't!