An eyelid position sensor system for an ophthalmic lens comprising an electronic system is described herein for adjusting an oscillator frequency on the lens. In at least one embodiment, the frequency adjustment is based on at least one signal received by the contact lens. In a further embodiment, the at least one signal includes a signal providing a plurality of transitions to compare to transitions in an oscillator output signal. In at least one embodiment, the source of the external signal is lighting. In at least one embodiment, updating the oscillator frequency between two lenses.
