Complex sentence: Upon completion, he was Assistant Professor of Ophthalmology at Johns Hopkins University from 1964-1966 and Associate Professor of Ophthalmology and Biophysics from 1966-1971.
Split into simpler sentences: Upon completion, he was Assistant Professor of Ophthalmology at Johns Hopkins University from 1964-1966. Also while at Johns Hopkins Dr. Dowling was Associate Professor of Ophthalmology and Biophysics from 1966-1971.