Dr. O'Hea is a specialized breast surgeon who comes to Stony Brook from Memorial Sloan-Kettering Cancer Center in New York, where during 1995–96 he held the prestigious position of "special fellow" on the breast service there. He joined the board of Carol M. Baldwin Breast Cancer Research Fund in 1997.

Dr. O'Hea's special interests include skin-sparing mastectomy, lymphedema prevention, and sentinel node biopsy in patients with breast cancer.

Dr. O'Hea received his MD from Georgetown University School of Medicine in 1986, with Alpha Omega Alpha honors. He then received his training in general surgery at St. Vincent 's Hospital and Medical Center of New York, graduating from the residency program there in 1991.

Subsequently, Dr. O'Hea served as a general surgeon in the US Army for four years, in order to fulfill an obligation incurred by an Army scholarship for medical school. During this period of service he organized a multidisciplinary breast clinic at the DeWitt Army Community Hospital in Virginia.