Dr. Tennant graduated from high school at age 16 by finishing his junior and senior years simultaneously in 1957. He finished college (except for three hours credit) in 2 1/2 years at Texas Tech University. He was awarded the Phi Kappa Phi and Pre-med of the Year Award.

He attended the University of Houston School of Optometry and was accepted into the University of Texas Southwestern Medical School in 1960 at age 19. He graduated in the top ten of his class in 1964 with an MD degree. Dr. Tennant interned at Methodist Hospital of Dallas and then completed a residency in ophthalmology at Parkland Hospital in Dallas and Harvard/Mass Eye and Ear in Boston. He is also a fellow of the American Society of Ophthalmic Plastic and Reconstructive Surgery and the American Academy of Ophthalmology. Dr. Tennant was director of the Ophthalmic Plastic Surgery Clinic at Parkland Hospital/Southwestern Medical School and founded the Dallas Eye Institute.

He holds patents on surgical instruments, intraocular lenses and other devices and has written books on cataract surgery, life-style management, and Integrative Medicine. With the assistance of his anesthesiologist, Monte Hellman, MD and his internist, Javier Ramirez, MD, Dr. Tennant developed and refined the techniques to allow eye surgery to be safely performed in an outpatient setting instead of a hospital.

Along with Drs. David McIntyre and Douglas Williamson, Dr. Tennant founded the Outpatient Ophthalmic Surgery Society and taught surgeons around the world to do outpatient eye surgery and was instrumental in getting Congress to pay for outpatient surgery, saving Medicare millions of dollars every year. He was chairman of the ad hoc committee that wrote the rules that govern outpatient surgicenters in Texas. Dr. Tennant is one of the few surgeons to be awarded the Corboy Award for Contributions to Ophthalmology and the Recognition Award from the American Academy of Ophthalmology. Dr. Tennant was one of the first surgeons in the U.S. to place intraocular lenses in eyes after cataract surgery, eliminating the need for thick, incapacitating glasses after cataract surgery. He redesigned the European lenses to eliminate defects and was awarded patents for his designs.

Dr. Tennant is an International Diplomat of the Sovereign Medical Order of the Knight's Hospitaller. This is a sovereign ecclesiastical and medical nation dedicated to the availability of natural medicine for the poor. It is recognized by the United Nations.

He has also has been awarded the degree of Doctor of Natural Medicine by the World Organization of Natural Medical Practitioners.

Pope Benedict XVI has awarded Dr. Tennant the Order of St. Sylvester Pope and Martyr. It is intended to award Roman Catholic laymen who are actively involved in the life of the church, particularly as it is exemplified in the exercise of their professional duties and mastership of the different arts. It is also conferred on non-Catholics, but more rarely than the Order of St. Gregory. Dr. Tennant, a non-Catholic, was honored for his contributions to medicine.

Dr. Tennant is licensed by the Arizona Board of Homeopathic and Integrated Medicine Examiners MD(H).  Texas does not have such a board.