Dr Turnbull is employed as both a research fellow and lecturer in the School of Optometry and Vision Science. He graduated from the University of Auckland with a Bachelor of Optometry (Hons), then worked in private practice in Christchurch, before returning to undertake a PhD with Dr John Phillips investigating emmetropisation in squid. After completing his PhD, he worked as a contact lens specialist in the University Eye Clinic, before starting a Postdoctoral Fellowship under Professor Steven Dakin and Dr Phillips. He teaches and examines both undergraduate and postgraduate optometry students. His current research investigates utilising technology, including virtual reality, infrared eye-tracking, arterial spin labelling magnetic resonance imaging (ASL-MRI), and multifocal electroretinograms (mf-ERG) to create fast and objective measures of visual function and ocular response for conditions such as myopia, diabetic retinopathy, and age-related macular degeneration.