Dr. Dahl is currently Assistant Professor of Ophthalmology at the NY College of Medicine and is director of ophthalmology residency training at the Mid Hudson Family Practice Institute. He has been practicing ophthalmology and ophthalmic surgery for more than 30 years. Dr. Dahl has been teaching ophthalmology to primary-care physicians, internists, pediatricians and emergency-room physicians for more than 20 years. He frequently lectures to medical personnel on computer applications. He was a research associate at Guys' Hospital, London, and was founder and director of the Ophthalmic Ultrasound Laboratory at Harvard Medical School. He has been involved in research involving diabetes mellitus and glaucoma. He is a fellow of the American Academy of Ophthalmology and a fellow of the American College of Surgeons.
He has participated in third-world volunteer missions to third-world nations. He is a GLG scholar and has been listed among America's Top Ophthalmologists by Consumers' Research Council for the last five years. He is an editor of eMedicine.com, chief editor of Consumer Health Online, and the author of scientific articles and book chapters. He is licensed to practice medicine in New York state and Colorado.