An intra-body communication system for monitoring physiological changes in a patient is provided. The system can include a first device implanted into a patient's body； a second device spaced apart from the first device； and a receiver for detecting and/or decoding the signals to monitor physiological changes in the patient. The first device and second device are capable of engaging in a two-way communication through transmission of one or more signals through at least a portion of the patient's body between the first device and the second device. In one embodiment, the signal may be an optical signal.
