Dr. Keenan earned his medical degree from the Georgetown University School of Medicine in 1983 after earning a B.S. in Biology from Villanova University. Upon completion of his internship at the Wilmington Medical Center in Delaware, he served in the United States Navy Medical Corps/United States Marine Corps for three years, followed by practicing as a member of Emergency Medical Associates at Taylor Hospital/Crozer-Chester Medical Center for two years.
Dr. Keenan subsequently completed his ophthalmology residency at The New York Hospital/Cornell Medical Center and a fellowship in corneal/external disease with University Ophthalmic Consultants of Washington in Washington, D.C.
Dr. Keenan is a Diplomate of the American Board of Ophthalmology.