I have forehead dents, due to a horizontal bony deficiency and fat grafting done for scarring. I want to get filler to fill in these dents, but now I'm hearing from expert filler injectors that they would never fill the forehead (especially the location of my dents) because of risks of blindness. Does the utilization of ultrasound combined with an experienced plastic surgeon/injector eliminate this risk? Can filler migrate in the months/years after, causing blindness later?