Dr. Greenberg currently serves as Chairman of the Board of Second Sight Medical Products. He is a Founder of the company and served as President, CEO and Director from 1998 until August 2015. From 1991 to 1997, Dr. Greenberg conducted pre-clinical and clinical trials demonstrating the feasibility of retinal electrical stimulation to elicit visual perceptions. From 1997 to 1998, he served as a Medical Officer and lead reviewer at the Office of Device Evaluation at the U.S. Food and Drug Administration in the Neurological Devices Division. In 1998, he received his medical and doctorate degrees from The Johns Hopkins School of Medicine.