Dr. Brenton is a native of Mason City and received his medical degree from the University of Iowa with a degree in ophthalmology. He did a transitional internship at Gundersen Clinic in LaCrosse, Wisconsin. Dr Brenton completed a 6 month research fellowship, at the University of Iowa, in glaucoma with visual field research. While at Iowa, he developed flicker fusion as an office testing of optic nerve function. He returned to Mason City in 1988 to join the North Iowa Eye Clinic. He is certified in LASIK and Phototherapeutic Keratotomy (PTK).

Dr. Brenton's wife, Cheryl, is also from Mason City, and they were married in 1980. They have three children, Claire, Janet, and Eric. His hobbies include wildlife art, fishing, and canoeing.