The percentage of induced magnification was +3%, +1.5%, 0%, −1.5%, and −3%. To check the accuracy of the trial lens magnifiers, we measured all the parameters that determine the shape factor and the power factor of an ophthalmic lens. We verified, by means of a very good approximation, that the size lenses were correctly manufactured, that is, the power factor was zero, independent of the distant vertex, and the shape factor was equal to the magnification of the lens. These lenses were inserted in front of the right eye in the most external groove of the trial frame and were applied in random order. Thus, the subject could not see which lens had been used. To avoid vertical maladjustments (deviation) of the two semicircles, it is important that the trial frame be adjusted correctly and that the subject remain directly in front of the test when the measurements of aniseikonia are taken through the simulation lenses.