In his travels to places of war, disaster, poverty and human struggle, Mathias has photographed several conflicts and their effects on the civilian population, producing a body of emotionally moving documentary work that captures key moments and turning points in history. His works have been featured in The Washington Post, The Guardian, The Australian, and other newspapers worldwide, as well as non-government organization magazines such as Oxfam USA, Oxfam Australia, Care International and Australian Volunteers International, amongst others. Mathias has lectured on the subject of photography at Temasek Polytechnic from 2008 to 2010, and has taught workshops in Australia, Singapore, Indonesia, Philippines and Malaysia. His photographs have been exhibited in Australia and Singapore, and are held in the permanent collection of the State Library of Australia and the National Library of Australia.