My daughter says she see a back dot in front of her eye what is that?

Floater vs. macula : If the black dot moves with head movement, the dot is probably a floater. In a small child, this might be congenital. A dilated retinal exam can confirm this. If it does not move, it suggests a macular lesion in the retina. Again, the examination of the retina will determine this. Solar retinopathy, from sun-gazing, is also possible.