Bangerter Foil BarPortions of Bangerter Foils are enclosed within an acrylic bar. The Bangerter Foil Bar is used to determine when the preference switches from dominant eye to the less dominant eye. Makes it easy to determine the appropriate foil for use in treating amblyopia and diplopia. All available Bangerter Occlusion Foils are within the bar Acuity levels range from 1. 0 to 0. 0 ( 20 20 to Total Occlusion).