The application relates to an adjustable spectral transmittance eyewear. Embodiments of the present invention relate to the eyewear having an electrically switchable spectral transmittance lens(es). The eyewear includes a lens driver that controls the variable spectral transmittance lens(es). The lens driver is functional to alter a duration of a spectral transmittance state based on a desired frequency and/or duty cycle of the spectral transmittance state. A user may provide an input indicating the desired level of difficulty provided by the eyewear, wherein the input may indicate that the frequency, the duty cycle, or a combination of the two should be changed. As a result of changing a perceived level of difficulty presented by the eyewear, a wearer of the eyewear may train his or her visual abilities to provide a competitive advantage.