Comparison of Imaging Properties of Bangerter Foils and Myopia Control Spectacle Lens

To evaluate whether Bangerter foils (BFs) could serve as a low-cost myopia control intervention, we measured and compared the imaging properties of fifteen BFs from two manufacturers, four myopia control spectacles, and a single-vision lens. Image quality metrics related to light-signaling theories of myopia onset and progression were evaluated in three tests: i. the assessment of the focusing properties through the maximum of the point spread function (MaxPSF), modulation transfer function (MTF), and area under the MTF (AUMTF); ii. the quantification of the scattered light (s) using the optical integration method; and iii. the calculation of the Michelson contrast (MiC) on a binary grating imaged under dark and bright illumination. BFs exhibited lower MaxPSF, AUMTF, and MTF values than the myopia control lenses. Except for one 0.6-graded BF, none of the other BFs mimicked the scattering behavior of the diffusion optics technology lenses. Moreover, BFs showed lower MiC values than with myopia control lenses under both lighting conditions. Although the BFs did not replicate the imaging properties of myopia control lenses, they still demonstrated effective contrast reduction across the lighting conditions. Whether they may help to slow myopia progression remains uncertain, perhaps even unlikely, given the fundamental imaging differences.