In a sensor system for determining the control signal supplied to the ciliary muscles of an eye for adjusting the focal length of the lens of an eye, a contact element of an electrically non-conductive material and provided with sensors is disposed on the cornea of the eye so that the sensors are arranged in contact with an annular area of the cornea next to the ciliary eye muscles so as to be able to sense the focal adjustment signals supplied to the ciliary muscles and the sensed adjustment signals are supplied to a signal processing unit which provides a control signal to a lens system with adjustable focal length for adjusting the focal length thereof depending on the focal adjustment signals of the ciliary eye muscles.
