Dr. Armstrong earned his MD from the Warren Alpert Medical School of Brown University, where his research covered a range of topics, such as optical coherence tomography (OCT) angiography in pediatric choroidal neovascularization, OCT angiography to assess pigmented epithelial detachments, pediatric eye injuries treated in United States emergency departments, and motor vehicle crash-associated eye injuries in the United States.

While in medical school, Dr. Armstrong concurrently earned a Master of Public Health degree, with a focus on Health Care Policy and Management from the Harvard School of Public Health, where he had the opportunity to advise international non-governmental organizations and the Jordanian Government on Syrian refugee policies resulting from the Syrian civil war. His training included a leadership concentration. He has an impressive track record of involvement in health policy and public health, primarily focusing on issues affecting patients’ access to care. He has served as a fellow at the U.S. Food and Drug Administration and worked with the Massachusetts Governor’s office to secure resident access to the state’s prescription drug monitoring program.

After completing his residency at Harvard Ophthalmology, Dr. Grayson served as Chief Resident and Director of Mass. Eye and Ear's Ocular Trauma Service for AY 2019-2020. During that time, he oversaw and coordinated trauma coverage at Mass. Eye and Ear and Brigham and Women’s Hospital and served as a vital mentor, teacher, and peer resource to Harvard Ophthalmology’s 24 residents.

Within organized medicine, Dr. Armstrong has served on the executive committee of the Massachusetts Society of Eye Physicians and Surgeons, on multiple committees of the Massachusetts Medical Society, and on the Board of Directors of the American Medical Association’s Political Action Committee (AMPAC). He was recently elected to serve on the American Medical Association’s Board of Trustees for a two-year term.