A system for determining a prescription for an eye of a person, the system being configured to communicate with a mobile device including at least one first light source adapted to illuminate the eye with first light having a first optical wavelength, at least one second light source adapted to illuminate the eye with second light having a second optical wavelength different from the first wavelength, and a processor that measures the photorefraction of the eye at the first wavelength based on at least one picture of the eye recorded when illuminating the eye with first light, measures the photorefraction of the eye at the second wavelength based on at least one picture of the eye recorded when illuminating the eye with second light, determines the prescription for the eye based on the measured photorefraction at the first wavelength and the measured photorefraction at the second wavelength.