A medical device for use on the human eye is described. The device is placed in an extrocular location in a patient and delivers an electrical current that stimulates the retina of patients who are blind or have vision disorders. It has at least one electrode that makes contact with the scleral surface of the eye, the electrode typically being activated by an electrical stimulator. The device produces electrical pulses which pass through the electrodes on the scleral surface of the eye, to activate the retina of the eye, which causes the patient to experience improved vision, visual sensations or the prevention of deterioration of vision. By this means, sight can be restored or improved where patients have disorders of their retina or other parts of their visual system.