An electro-active phoropter and a method of using the electro-active phoropter to measure a patient's vision prescription is disclosed. The electro-active phoropter includes a series of individually addressable electro-active lenses. The lenses have either a positive or negative optical power when an electrical potential is applied across the lens and a neutral optical power when no electrical potential is applied across the lens. Each lens provides an optical power that is part of a net optical power of the series of lenses when a patient views through the phoropter. The optical power of the phoropter can be incrementally adjusted by changing the distribution of the electrical potential across the different lenses of the series to provide increasing or decreasing optical power until a patient achieves a desired level of clarity and a vision prescription has been determined.