A method includes: sensing light information reflecting from an eye of a driver of a vehicle using an optical sensor mounted in the vehicle; measuring, by a control unit equipped in the vehicle, a plurality of eye parameters based on the sensed light information; calculating, by the control unit, an endangerment score indicating a driving state of the driver according to the plurality of eye parameters; determining, by the control unit, whether the calculated endangerment score exceeds an endangerment threshold; and executing, by the control unit, a corrective action in response to determining that the calculated endangerment score exceeds the endangerment threshold.