Fig (1) (a, b) Occlusion test is performed with patient’s hand placed 3cm in front of the ipsilateral eye, avoiding facial or spectacle contact. (c) The Bangerter occlusion foil is a disposable self-adhesive foil, which can be cut to size to fit over a spectacle lens. 0.8 density foil shown here. (d) Bangerter occlusion foil (0.2 density) placed over right spectacle lens.