A corneal hydration sensing system includes an illumination system configured to provide an illumination beam of terahertz radiation, an optical system arranged in an optical path of the illumination system to relay and direct at least a portion of the illumination beam of terahertz radiation onto a cornea of a subject and to receive at least a portion of terahertz radiation reflected from the cornea to provide a return beam of terahertz radiation, and a detection system arranged in an optical path of the return beam of terahertz radiation. The detection system is configured to provide a detection signal from detecting at least a portion of the return beam of terahertz radiation. The corneal hydration sensing system also includes a signal processing system configured to communicate with the detection system to receive the detection signal. The signal processing system processes the detection signal to provide a measure of an amount of hydration sensed in the cornea of the subject.