He specializes in medical retina, emerging treatments for macular degeneration and diabetic eye disease. He pioneered steroids for diabetic retinopathy and conducted the first trial of intravitreal injections for any eye disease. He has also developed internet-based software to track outcomes of treatment of macular disease, the Fight Retinal Blindness! Project, which currently has hundreds of active contributors in ANZ, Europe and Asia. His lab studies outer retinal metabolism and Muller cell biology with a major interest in the pathogenesis of MacTel type 2. Professor Mark Gillies was the first Australian ophthalmologist to be awarded a PhD, which he received for his work on diabetic retinopathy at the Walter and Eliza Hall Institute. He has appeared on numerous occasions in national media (Evening News of all major networks, ABC radio as local expert, see also attached copy of article in The Australian) to lobby for Government support for Photodynamic Therapy around 2000-1 (granted 2002), public education on diabetic retinopathy and macular degeneration.